fname stringlengths 63 176 | rel_fname stringclasses 706
values | line int64 -1 4.5k | name stringlengths 1 81 | kind stringclasses 2
values | category stringclasses 2
values | info stringlengths 0 77.9k ⌀ |
|---|---|---|---|---|---|---|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 329 | visit_const | def | function | def visit_const(self, node: nodes.Const) -> None:
if self._py36_plus:
# f-strings require Python 3.6
if node.pytype() == "builtins.str" and not isinstance(
node.parent, nodes.JoinedStr
):
self._detect_replacable_format_call(node)
def _detect_replacable_format_call(self, node: nodes.Const) -> None:
"""Check whether a string is used in a call to format() or '%' and whether it
can be replaced by an f-string
"""
if (
isinstance(node.parent, nodes.Attribute)
and node.parent.attrname == "format"
):
# Don't warn on referencing / assigning .format without calling it
if not isinstance(node.parent.parent, nodes.Call):
return
if node.parent.parent.args:
for arg in node.parent.parent.args:
# If star expressions with more than 1 element are being used
if isinstance(arg, nodes.Starred):
inferred = utils.safe_infer(arg.value)
if (
isinstance(inferred, astroid.List)
and len(inferred.elts) > 1
):
return
# Backslashes can't be in f-string expressions
if "\\" in arg.as_string():
return
elif node.parent.parent.keywords:
keyword_args = [
i[0] for i in utils.parse_format_method_string(node.value)[0]
]
for keyword in node.parent.parent.keywords:
# If keyword is used multiple times
if keyword_args.count(keyword.arg) > 1:
return
keyword = utils.safe_infer(keyword.value)
# If lists of more than one element are being unpacked
if isinstance(keyword, nodes.Dict):
if len(keyword.items) > 1 and len(keyword_args) > 1:
return
# If all tests pass, then raise message
self.add_message(
"consider-using-f-string",
node=node,
line=node.lineno,
col_offset=node.col_offset,
)
elif isinstance(node.parent, nodes.BinOp) and node.parent.op == "%":
# Backslashes can't be in f-string expressions
if "\\" in node.parent.right.as_string():
return
inferred_right = utils.safe_infer(node.parent.right)
# If dicts or lists of length > 1 are used
if isinstance(inferred_right, nodes.Dict):
if len(inferred_right.items) > 1:
return
elif isinstance(inferred_right, nodes.List):
if len(inferred_right.elts) > 1:
return
# If all tests pass, then raise message
self.add_message(
"consider-using-f-string",
node=node,
line=node.lineno,
col_offset=node.col_offset,
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 332 | pytype | ref | function | if node.pytype() == "builtins.str" and not isinstance(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 335 | _detect_replacable_format_call | ref | function | self._detect_replacable_format_call(node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 337 | _detect_replacable_format_call | def | function | def _detect_replacable_format_call(self, node: nodes.Const) -> None:
"""Check whether a string is used in a call to format() or '%' and whether it
can be replaced by an f-string
"""
if (
isinstance(node.parent, nodes.Attribute)
and node.parent.attrname == "format"
):
# Don't warn on referencing / assigning .format without calling it
if not isinstance(node.parent.parent, nodes.Call):
return
if node.parent.parent.args:
for arg in node.parent.parent.args:
# If star expressions with more than 1 element are being used
if isinstance(arg, nodes.Starred):
inferred = utils.safe_infer(arg.value)
if (
isinstance(inferred, astroid.List)
and len(inferred.elts) > 1
):
return
# Backslashes can't be in f-string expressions
if "\\" in arg.as_string():
return
elif node.parent.parent.keywords:
keyword_args = [
i[0] for i in utils.parse_format_method_string(node.value)[0]
]
for keyword in node.parent.parent.keywords:
# If keyword is used multiple times
if keyword_args.count(keyword.arg) > 1:
return
keyword = utils.safe_infer(keyword.value)
# If lists of more than one element are being unpacked
if isinstance(keyword, nodes.Dict):
if len(keyword.items) > 1 and len(keyword_args) > 1:
return
# If all tests pass, then raise message
self.add_message(
"consider-using-f-string",
node=node,
line=node.lineno,
col_offset=node.col_offset,
)
elif isinstance(node.parent, nodes.BinOp) and node.parent.op == "%":
# Backslashes can't be in f-string expressions
if "\\" in node.parent.right.as_string():
return
inferred_right = utils.safe_infer(node.parent.right)
# If dicts or lists of length > 1 are used
if isinstance(inferred_right, nodes.Dict):
if len(inferred_right.items) > 1:
return
elif isinstance(inferred_right, nodes.List):
if len(inferred_right.elts) > 1:
return
# If all tests pass, then raise message
self.add_message(
"consider-using-f-string",
node=node,
line=node.lineno,
col_offset=node.col_offset,
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 353 | safe_infer | ref | function | inferred = utils.safe_infer(arg.value)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 360 | as_string | ref | function | if "\\" in arg.as_string():
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 365 | parse_format_method_string | ref | function | i[0] for i in utils.parse_format_method_string(node.value)[0]
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 372 | safe_infer | ref | function | keyword = utils.safe_infer(keyword.value)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 380 | add_message | ref | function | self.add_message(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 389 | as_string | ref | function | if "\\" in node.parent.right.as_string():
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 392 | safe_infer | ref | function | inferred_right = utils.safe_infer(node.parent.right)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/recommendation_checker.py | pylint/checkers/refactoring/recommendation_checker.py | 403 | add_message | ref | function | self.add_message(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 51 | _if_statement_is_always_returning | def | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 55 | _is_trailing_comma | def | function | def _is_trailing_comma(tokens: List[tokenize.TokenInfo], index: int) -> bool:
"""Check if the given token is a trailing comma.
:param tokens: Sequence of modules tokens
:type tokens: list[tokenize.TokenInfo]
:param int index: Index of token under check in tokens
:returns: _True if the token is a comma which trails an expression
:rtype: bool
"""
token = tokens[index]
if token.exact_type != tokenize.COMMA:
return _False
# Must have remaining tokens on the same line such as NEWLINE
left_tokens = list(itertools.islice(tokens, index + 1, None))
more_tokens_on_line = _False
for remaining_token in left_tokens:
if remaining_token.start[0] == token.start[0]:
more_tokens_on_line = _True
# If one of the remaining same line tokens is not NEWLINE or COMMENT
# the comma is not trailing.
if remaining_token.type not in (tokenize.NEWLINE, tokenize.COMMENT):
return _False
if not more_tokens_on_line:
return _False
def get_curline_index_start():
"""Get the index denoting the start of the current line."""
for subindex, token in enumerate(reversed(tokens[:index])):
# See Lib/tokenize.py and Lib/token.py in cpython for more info
if token.type == tokenize.NEWLINE:
return index - subindex
return 0
curline_start = get_curline_index_start()
expected_tokens = {"return", "yield"}
return any(
"=" in prevtoken.string or prevtoken.string in expected_tokens
for prevtoken in tokens[curline_start:index]
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 82 | get_curline_index_start | def | function | def get_curline_index_start():
"""Get the index denoting the start of the current line."""
for subindex, token in enumerate(reversed(tokens[:index])):
# See Lib/tokenize.py and Lib/token.py in cpython for more info
if token.type == tokenize.NEWLINE:
return index - subindex
return 0
curline_start = get_curline_index_start()
expected_tokens = {"return", "yield"}
return any(
"=" in prevtoken.string or prevtoken.string in expected_tokens
for prevtoken in tokens[curline_start:index]
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 90 | get_curline_index_start | ref | function | curline_start = get_curline_index_start()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 98 | _is_inside_context_manager | def | function | def _is_inside_context_manager(node: nodes.Call) -> bool:
frame = node.frame(future=_True)
if not isinstance(
frame, (nodes.FunctionDef, astroid.BoundMethod, astroid.UnboundMethod)
):
return _False
return frame.name == "__enter__" or utils.decorated_with(
frame, "contextlib.contextmanager"
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 99 | frame | ref | function | frame = node.frame(future=True)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 104 | decorated_with | ref | function | return frame.name == "__enter__" or utils.decorated_with(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 109 | _is_a_return_statement | def | function | def _is_a_return_statement(node: nodes.Call) -> bool:
frame = node.frame(future=_True)
for parent in node.node_ancestors():
if parent is frame:
break
if isinstance(parent, nodes.Return):
return _True
return _False
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 110 | frame | ref | function | frame = node.frame(future=True)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 111 | node_ancestors | ref | function | for parent in node.node_ancestors():
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 119 | _is_part_of_with_items | def | function | def _is_part_of_with_items(node: nodes.Call) -> bool:
"""Checks if one of the node's parents is a ``nodes.With`` node and that the node itself is located
somewhere under its ``items``.
"""
frame = node.frame(future=_True)
current = node
while current != frame:
if isinstance(current, nodes.With):
items_start = current.items[0][0].lineno
items_end = current.items[-1][0].tolineno
return items_start <= node.lineno <= items_end
current = current.parent
return _False
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 123 | frame | ref | function | frame = node.frame(future=True)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 134 | _will_be_released_automatically | def | function | def _will_be_released_automatically(node: nodes.Call) -> bool:
"""Checks if a call that could be used in a ``with`` statement is used in an alternative
construct which would ensure that its __exit__ method is called.
"""
callables_taking_care_of_exit = frozenset(
(
"contextlib._BaseExitStack.enter_context",
"contextlib.ExitStack.enter_context", # necessary for Python 3.6 compatibility
)
)
if not isinstance(node.parent, nodes.Call):
return _False
func = utils.safe_infer(node.parent.func)
if not func:
return _False
return func.qname() in callables_taking_care_of_exit
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 146 | safe_infer | ref | function | func = utils.safe_infer(node.parent.func)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 149 | qname | ref | function | return func.qname() in callables_taking_care_of_exit
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 152 | ConsiderUsingWithStack | def | class | __iter__ get_stack_for_frame clear_all |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 164 | get_stack_for_frame | def | function | def get_stack_for_frame(
self, frame: Union[nodes.FunctionDef, nodes.ClassDef, nodes.Module]
):
"""Get the stack corresponding to the scope of the given frame."""
if isinstance(frame, nodes.FunctionDef):
return self.function_scope
if isinstance(frame, nodes.ClassDef):
return self.class_scope
return self.module_scope
def clear_all(self) -> None:
"""Convenience method to clear all stacks."""
for stack in self:
stack.clear()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 174 | clear_all | def | function | def clear_all(self) -> None:
"""Convenience method to clear all stacks."""
for stack in self:
stack.clear()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 180 | RefactoringChecker | def | class | __init__ _init open _dummy_rgx _is_bool_const _is_actual_elif _check_simplifiable_if process_tokens leave_module visit_tryexcept _check_redefined_argument_from_local visit_for visit_excepthandler visit_with _check_superfluous_else _check_superfluous_else_return _check_superfluous_else_raise _check_superfluous_else_break _check_superfluous_else_continue _type_and_name_are_equal _is_dict_get_block _check_consider_get visit_if _check_consider_using_min_max_builtin visit_ifexp _check_simplifiable_ifexp leave_functiondef leave_classdef visit_raise _check_stop_iteration_inside_generator _check_exception_inherit_from_stopiteration _check_consider_using_comprehension_constructor _check_consider_using_generator visit_call _has_exit_in_scope _check_quit_exit_call _check_super_with_arguments _check_raising_stopiteration_in_generator_next_call _check_nested_blocks _emit_nested_blocks_message_if_needed _emit_consider_using_with_if_needed _duplicated_isinstance_types _check_consider_merging_isinstance _check_consider_using_in _check_chained_comparison _apply_boolean_simplification_rules _simplify_boolean_operation _check_simplifiable_condition visit_boolop _is_simple_assignment _check_swap_variables visit_assign visit_return _append_context_managers_to_stack _check_consider_using_with _check_use_list_or_dict_literal _check_consider_using_join visit_augassign visit_comprehension _check_unnecessary_comprehension _is_and_or_ternary _and_or_ternary_arguments visit_functiondef _check_consistent_returns _is_if_node_return_ended _is_raise_node_return_ended _is_node_return_ended _has_return_in_siblings _is_function_def_never_returning _check_return_at_the_end _check_unnecessary_dict_index_lookup |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 461 | ConsiderUsingWithStack | ref | function | self._consider_using_with_stack = ConsiderUsingWithStack()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 462 | _init | ref | function | self._init()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 465 | _init | def | function | def _init(self):
self._nested_blocks = []
self._elifs = []
self._nested_blocks_msg = None
self._reported_swap_nodes = set()
self._can_simplify_bool_op = _False
self._consider_using_with_stack.clear_all()
def open(self):
# do this in open since config not fully initialized in __init__
self._never_returning_functions = set(self.config.never_returning_functions)
@astroid.decorators.cachedproperty
def _dummy_rgx(self):
return lint_utils.get_global_option(self, "dummy-variables-rgx", default=None)
@staticmethod
def _is_bool_const(node):
return isinstance(node.value, nodes.Const) and isinstance(
node.value.value, bool
)
def _is_actual_elif(self, node):
"""Check if the given node is an actual elif.
This is a problem we're having with the builtin ast module,
which splits `elif` branches into a separate if statement.
Unfortunately we need to know the exact type in certain
cases.
"""
if isinstance(node.parent, nodes.If):
orelse = node.parent.orelse
# current if node must directly follow an "else"
if orelse and orelse == [node]:
if (node.lineno, node.col_offset) in self._elifs:
return _True
return _False
def _check_simplifiable_if(self, node):
"""Check if the given if node can be simplified.
The if statement can be reduced to a boolean expression
in some cases. For instance, if there are two branches
and both of them return a boolean value that depends on
the result of the statement's test, then this can be reduced
to `bool(test)` without losing any functionality.
"""
if self._is_actual_elif(node):
# Not interested in if statements with multiple branches.
return
if len(node.orelse) != 1 or len(node.body) != 1:
return
# Check if both branches can be reduced.
first_branch = node.body[0]
else_branch = node.orelse[0]
if isinstance(first_branch, nodes.Return):
if not isinstance(else_branch, nodes.Return):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'return bool(test)'"
elif isinstance(first_branch, nodes.Assign):
if not isinstance(else_branch, nodes.Assign):
return
# Check if we assign to the same value
first_branch_targets = [
target.name
for target in first_branch.targets
if isinstance(target, nodes.AssignName)
]
else_branch_targets = [
target.name
for target in else_branch.targets
if isinstance(target, nodes.AssignName)
]
if not first_branch_targets or not else_branch_targets:
return
if sorted(first_branch_targets) != sorted(else_branch_targets):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'var = bool(test)'"
else:
return
if not first_branch_is_bool or not else_branch_is_bool:
return
if not first_branch.value.value:
# This is a case that can't be easily simplified and
# if it can be simplified, it will usually result in a
# code that's harder to understand and comprehend.
# Let's take for instance `arg and arg <= 3`. This could theoretically be
# reduced to `not arg or arg > 3`, but the net result is that now the
# condition is harder to understand, because it requires understanding of
# an extra clause:
# * first, there is the negation of truthness with `not arg`
# * the second clause is `arg > 3`, which occurs when arg has a
# a truth value, but it implies that `arg > 3` is equivalent
# with `arg and arg > 3`, which means that the user must
# think about this assumption when evaluating `arg > 3`.
# The original form is easier to grasp.
return
self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 471 | clear_all | ref | function | self._consider_using_with_stack.clear_all()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 478 | _dummy_rgx | def | function | def _dummy_rgx(self):
return lint_utils.get_global_option(self, "dummy-variables-rgx", default=None)
@staticmethod
def _is_bool_const(node):
return isinstance(node.value, nodes.Const) and isinstance(
node.value.value, bool
)
def _is_actual_elif(self, node):
"""Check if the given node is an actual elif.
This is a problem we're having with the builtin ast module,
which splits `elif` branches into a separate if statement.
Unfortunately we need to know the exact type in certain
cases.
"""
if isinstance(node.parent, nodes.If):
orelse = node.parent.orelse
# current if node must directly follow an "else"
if orelse and orelse == [node]:
if (node.lineno, node.col_offset) in self._elifs:
return _True
return _False
def _check_simplifiable_if(self, node):
"""Check if the given if node can be simplified.
The if statement can be reduced to a boolean expression
in some cases. For instance, if there are two branches
and both of them return a boolean value that depends on
the result of the statement's test, then this can be reduced
to `bool(test)` without losing any functionality.
"""
if self._is_actual_elif(node):
# Not interested in if statements with multiple branches.
return
if len(node.orelse) != 1 or len(node.body) != 1:
return
# Check if both branches can be reduced.
first_branch = node.body[0]
else_branch = node.orelse[0]
if isinstance(first_branch, nodes.Return):
if not isinstance(else_branch, nodes.Return):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'return bool(test)'"
elif isinstance(first_branch, nodes.Assign):
if not isinstance(else_branch, nodes.Assign):
return
# Check if we assign to the same value
first_branch_targets = [
target.name
for target in first_branch.targets
if isinstance(target, nodes.AssignName)
]
else_branch_targets = [
target.name
for target in else_branch.targets
if isinstance(target, nodes.AssignName)
]
if not first_branch_targets or not else_branch_targets:
return
if sorted(first_branch_targets) != sorted(else_branch_targets):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'var = bool(test)'"
else:
return
if not first_branch_is_bool or not else_branch_is_bool:
return
if not first_branch.value.value:
# This is a case that can't be easily simplified and
# if it can be simplified, it will usually result in a
# code that's harder to understand and comprehend.
# Let's take for instance `arg and arg <= 3`. This could theoretically be
# reduced to `not arg or arg > 3`, but the net result is that now the
# condition is harder to understand, because it requires understanding of
# an extra clause:
# * first, there is the negation of truthness with `not arg`
# * the second clause is `arg > 3`, which occurs when arg has a
# a truth value, but it implies that `arg > 3` is equivalent
# with `arg and arg > 3`, which means that the user must
# think about this assumption when evaluating `arg > 3`.
# The original form is easier to grasp.
return
self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 479 | get_global_option | ref | function | return lint_utils.get_global_option(self, "dummy-variables-rgx", default=None)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 482 | _is_bool_const | def | function | def _is_bool_const(node):
return isinstance(node.value, nodes.Const) and isinstance(
node.value.value, bool
)
def _is_actual_elif(self, node):
"""Check if the given node is an actual elif.
This is a problem we're having with the builtin ast module,
which splits `elif` branches into a separate if statement.
Unfortunately we need to know the exact type in certain
cases.
"""
if isinstance(node.parent, nodes.If):
orelse = node.parent.orelse
# current if node must directly follow an "else"
if orelse and orelse == [node]:
if (node.lineno, node.col_offset) in self._elifs:
return _True
return _False
def _check_simplifiable_if(self, node):
"""Check if the given if node can be simplified.
The if statement can be reduced to a boolean expression
in some cases. For instance, if there are two branches
and both of them return a boolean value that depends on
the result of the statement's test, then this can be reduced
to `bool(test)` without losing any functionality.
"""
if self._is_actual_elif(node):
# Not interested in if statements with multiple branches.
return
if len(node.orelse) != 1 or len(node.body) != 1:
return
# Check if both branches can be reduced.
first_branch = node.body[0]
else_branch = node.orelse[0]
if isinstance(first_branch, nodes.Return):
if not isinstance(else_branch, nodes.Return):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'return bool(test)'"
elif isinstance(first_branch, nodes.Assign):
if not isinstance(else_branch, nodes.Assign):
return
# Check if we assign to the same value
first_branch_targets = [
target.name
for target in first_branch.targets
if isinstance(target, nodes.AssignName)
]
else_branch_targets = [
target.name
for target in else_branch.targets
if isinstance(target, nodes.AssignName)
]
if not first_branch_targets or not else_branch_targets:
return
if sorted(first_branch_targets) != sorted(else_branch_targets):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'var = bool(test)'"
else:
return
if not first_branch_is_bool or not else_branch_is_bool:
return
if not first_branch.value.value:
# This is a case that can't be easily simplified and
# if it can be simplified, it will usually result in a
# code that's harder to understand and comprehend.
# Let's take for instance `arg and arg <= 3`. This could theoretically be
# reduced to `not arg or arg > 3`, but the net result is that now the
# condition is harder to understand, because it requires understanding of
# an extra clause:
# * first, there is the negation of truthness with `not arg`
# * the second clause is `arg > 3`, which occurs when arg has a
# a truth value, but it implies that `arg > 3` is equivalent
# with `arg and arg > 3`, which means that the user must
# think about this assumption when evaluating `arg > 3`.
# The original form is easier to grasp.
return
self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 487 | _is_actual_elif | def | function | def _is_actual_elif(self, node):
"""Check if the given node is an actual elif.
This is a problem we're having with the builtin ast module,
which splits `elif` branches into a separate if statement.
Unfortunately we need to know the exact type in certain
cases.
"""
if isinstance(node.parent, nodes.If):
orelse = node.parent.orelse
# current if node must directly follow an "else"
if orelse and orelse == [node]:
if (node.lineno, node.col_offset) in self._elifs:
return _True
return _False
def _check_simplifiable_if(self, node):
"""Check if the given if node can be simplified.
The if statement can be reduced to a boolean expression
in some cases. For instance, if there are two branches
and both of them return a boolean value that depends on
the result of the statement's test, then this can be reduced
to `bool(test)` without losing any functionality.
"""
if self._is_actual_elif(node):
# Not interested in if statements with multiple branches.
return
if len(node.orelse) != 1 or len(node.body) != 1:
return
# Check if both branches can be reduced.
first_branch = node.body[0]
else_branch = node.orelse[0]
if isinstance(first_branch, nodes.Return):
if not isinstance(else_branch, nodes.Return):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'return bool(test)'"
elif isinstance(first_branch, nodes.Assign):
if not isinstance(else_branch, nodes.Assign):
return
# Check if we assign to the same value
first_branch_targets = [
target.name
for target in first_branch.targets
if isinstance(target, nodes.AssignName)
]
else_branch_targets = [
target.name
for target in else_branch.targets
if isinstance(target, nodes.AssignName)
]
if not first_branch_targets or not else_branch_targets:
return
if sorted(first_branch_targets) != sorted(else_branch_targets):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'var = bool(test)'"
else:
return
if not first_branch_is_bool or not else_branch_is_bool:
return
if not first_branch.value.value:
# This is a case that can't be easily simplified and
# if it can be simplified, it will usually result in a
# code that's harder to understand and comprehend.
# Let's take for instance `arg and arg <= 3`. This could theoretically be
# reduced to `not arg or arg > 3`, but the net result is that now the
# condition is harder to understand, because it requires understanding of
# an extra clause:
# * first, there is the negation of truthness with `not arg`
# * the second clause is `arg > 3`, which occurs when arg has a
# a truth value, but it implies that `arg > 3` is equivalent
# with `arg and arg > 3`, which means that the user must
# think about this assumption when evaluating `arg > 3`.
# The original form is easier to grasp.
return
self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 503 | _check_simplifiable_if | def | function | def _check_simplifiable_if(self, node):
"""Check if the given if node can be simplified.
The if statement can be reduced to a boolean expression
in some cases. For instance, if there are two branches
and both of them return a boolean value that depends on
the result of the statement's test, then this can be reduced
to `bool(test)` without losing any functionality.
"""
if self._is_actual_elif(node):
# Not interested in if statements with multiple branches.
return
if len(node.orelse) != 1 or len(node.body) != 1:
return
# Check if both branches can be reduced.
first_branch = node.body[0]
else_branch = node.orelse[0]
if isinstance(first_branch, nodes.Return):
if not isinstance(else_branch, nodes.Return):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'return bool(test)'"
elif isinstance(first_branch, nodes.Assign):
if not isinstance(else_branch, nodes.Assign):
return
# Check if we assign to the same value
first_branch_targets = [
target.name
for target in first_branch.targets
if isinstance(target, nodes.AssignName)
]
else_branch_targets = [
target.name
for target in else_branch.targets
if isinstance(target, nodes.AssignName)
]
if not first_branch_targets or not else_branch_targets:
return
if sorted(first_branch_targets) != sorted(else_branch_targets):
return
first_branch_is_bool = self._is_bool_const(first_branch)
else_branch_is_bool = self._is_bool_const(else_branch)
reduced_to = "'var = bool(test)'"
else:
return
if not first_branch_is_bool or not else_branch_is_bool:
return
if not first_branch.value.value:
# This is a case that can't be easily simplified and
# if it can be simplified, it will usually result in a
# code that's harder to understand and comprehend.
# Let's take for instance `arg and arg <= 3`. This could theoretically be
# reduced to `not arg or arg > 3`, but the net result is that now the
# condition is harder to understand, because it requires understanding of
# an extra clause:
# * first, there is the negation of truthness with `not arg`
# * the second clause is `arg > 3`, which occurs when arg has a
# a truth value, but it implies that `arg > 3` is equivalent
# with `arg and arg > 3`, which means that the user must
# think about this assumption when evaluating `arg > 3`.
# The original form is easier to grasp.
return
self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 513 | _is_actual_elif | ref | function | if self._is_actual_elif(node):
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 525 | _is_bool_const | ref | function | first_branch_is_bool = self._is_bool_const(first_branch)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 526 | _is_bool_const | ref | function | else_branch_is_bool = self._is_bool_const(else_branch)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 548 | _is_bool_const | ref | function | first_branch_is_bool = self._is_bool_const(first_branch)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 549 | _is_bool_const | ref | function | else_branch_is_bool = self._is_bool_const(else_branch)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 572 | add_message | ref | function | self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 574 | process_tokens | def | function | def process_tokens(self, tokens):
# Process tokens and look for 'if' or 'elif'
for index, token in enumerate(tokens):
token_string = token[1]
if token_string == "elif":
# AST exists by the time process_tokens is called, so
# it's safe to assume tokens[index+1] exists.
# tokens[index+1][2] is the elif's position as
# reported by CPython and PyPy,
# token[2] is the actual position and also is
# reported by IronPython.
self._elifs.extend([token[2], tokens[index + 1][2]])
elif _is_trailing_comma(tokens, index):
if self.linter.is_message_enabled("trailing-comma-tuple"):
self.add_message("trailing-comma-tuple", line=token.start[0])
@utils.check_messages("consider-using-with")
def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 586 | _is_trailing_comma | ref | function | elif _is_trailing_comma(tokens, index):
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 587 | is_message_enabled | ref | function | if self.linter.is_message_enabled("trailing-comma-tuple"):
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 588 | add_message | ref | function | self.add_message("trailing-comma-tuple", line=token.start[0])
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 590 | check_messages | ref | function | @utils.check_messages("consider-using-with")
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 591 | leave_module | def | function | def leave_module(self, _: nodes.Module) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.module_scope
)
self._init()
@utils.check_messages("too-many-nested-blocks")
def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 593 | _emit_consider_using_with_if_needed | ref | function | self._emit_consider_using_with_if_needed(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 596 | _init | ref | function | self._init()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 598 | check_messages | ref | function | @utils.check_messages("too-many-nested-blocks")
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 599 | visit_tryexcept | def | function | def visit_tryexcept(self, node: nodes.TryExcept) -> None:
self._check_nested_blocks(node)
visit_tryfinally = visit_tryexcept
visit_while = visit_tryexcept
def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 600 | _check_nested_blocks | ref | function | self._check_nested_blocks(node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 605 | _check_redefined_argument_from_local | def | function | def _check_redefined_argument_from_local(self, name_node):
if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
return
if not name_node.lineno:
# Unknown position, maybe it is a manually built AST?
return
scope = name_node.scope()
if not isinstance(scope, nodes.FunctionDef):
return
for defined_argument in scope.args.nodes_of_class(
nodes.AssignName, skip_klass=(nodes.Lambda,)
):
if defined_argument.name == name_node.name:
self.add_message(
"redefined-argument-from-local",
node=name_node,
args=(name_node.name,),
)
@utils.check_messages(
"redefined-argument-from-local",
"too-many-nested-blocks",
"unnecessary-dict-index-lookup",
)
def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 606 | match | ref | function | if self._dummy_rgx and self._dummy_rgx.match(name_node.name):
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 612 | scope | ref | function | scope = name_node.scope()
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 616 | nodes_of_class | ref | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 620 | add_message | ref | function | self.add_message(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 626 | check_messages | ref | function | @utils.check_messages(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 631 | visit_for | def | function | def visit_for(self, node: nodes.For) -> None:
self._check_nested_blocks(node)
self._check_unnecessary_dict_index_lookup(node)
for name in node.target.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
@utils.check_messages("redefined-argument-from-local")
def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 632 | _check_nested_blocks | ref | function | self._check_nested_blocks(node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 633 | _check_unnecessary_dict_index_lookup | ref | function | self._check_unnecessary_dict_index_lookup(node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 635 | nodes_of_class | ref | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 636 | _check_redefined_argument_from_local | ref | function | self._check_redefined_argument_from_local(name)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 638 | check_messages | ref | function | @utils.check_messages("redefined-argument-from-local")
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 639 | visit_excepthandler | def | function | def visit_excepthandler(self, node: nodes.ExceptHandler) -> None:
if node.name and isinstance(node.name, nodes.AssignName):
self._check_redefined_argument_from_local(node.name)
@utils.check_messages("redefined-argument-from-local")
def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 641 | _check_redefined_argument_from_local | ref | function | self._check_redefined_argument_from_local(node.name)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 643 | check_messages | ref | function | @utils.check_messages("redefined-argument-from-local")
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 644 | visit_with | def | function | def visit_with(self, node: nodes.With) -> None:
for var, names in node.items:
if isinstance(var, nodes.Name):
for stack in self._consider_using_with_stack:
# We don't need to restrict the stacks we search to the current scope and outer scopes,
# as e.g. the function_scope stack will be empty when we check a ``with`` on the class level.
if var.name in stack:
del stack[var.name]
break
if not names:
continue
for name in names.nodes_of_class(nodes.AssignName):
self._check_redefined_argument_from_local(name)
def _check_superfluous_else(self, node, msg_id, returning_node_class):
if not node.orelse:
# Not interested in if statements without else.
return
if self._is_actual_elif(node):
# Not interested in elif nodes; only if
return
if _if_statement_is_always_returning(node, returning_node_class):
orelse = node.orelse[0]
if (orelse.lineno, orelse.col_offset) in self._elifs:
args = ("elif", 'remove the leading "el" from "elif"')
else:
args = ("else", 'remove the "else" and de-indent the code inside it')
self.add_message(msg_id, node=node, args=args)
def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 655 | nodes_of_class | ref | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 656 | _check_redefined_argument_from_local | ref | function | self._check_redefined_argument_from_local(name)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 658 | _check_superfluous_else | def | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 663 | _is_actual_elif | ref | function | if self._is_actual_elif(node):
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 667 | _if_statement_is_always_returning | ref | class | |
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 673 | add_message | ref | function | self.add_message(msg_id, node=node, args=args)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 675 | _check_superfluous_else_return | def | function | def _check_superfluous_else_return(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-return", returning_node_class=nodes.Return
)
def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 676 | _check_superfluous_else | ref | function | return self._check_superfluous_else(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 680 | _check_superfluous_else_raise | def | function | def _check_superfluous_else_raise(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-raise", returning_node_class=nodes.Raise
)
def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 681 | _check_superfluous_else | ref | function | return self._check_superfluous_else(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 685 | _check_superfluous_else_break | def | function | def _check_superfluous_else_break(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-break", returning_node_class=nodes.Break
)
def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 686 | _check_superfluous_else | ref | function | return self._check_superfluous_else(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 690 | _check_superfluous_else_continue | def | function | def _check_superfluous_else_continue(self, node):
return self._check_superfluous_else(
node, msg_id="no-else-continue", returning_node_class=nodes.Continue
)
@staticmethod
def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 691 | _check_superfluous_else | ref | function | return self._check_superfluous_else(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 696 | _type_and_name_are_equal | def | function | def _type_and_name_are_equal(node_a, node_b):
for _type in (nodes.Name, nodes.AssignName):
if all(isinstance(_node, _type) for _node in (node_a, node_b)):
return node_a.name == node_b.name
if all(isinstance(_node, nodes.Const) for _node in (node_a, node_b)):
return node_a.value == node_b.value
return _False
def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 704 | _is_dict_get_block | def | function | def _is_dict_get_block(self, node):
# "if <compare node>"
if not isinstance(node.test, nodes.Compare):
return _False
# Does not have a single statement in the guard's body
if len(node.body) != 1:
return _False
# Look for a single variable assignment on the LHS and a subscript on RHS
stmt = node.body[0]
if not (
isinstance(stmt, nodes.Assign)
and len(node.body[0].targets) == 1
and isinstance(node.body[0].targets[0], nodes.AssignName)
and isinstance(stmt.value, nodes.Subscript)
):
return _False
# The subscript's slice needs to be the same as the test variable.
slice_value = stmt.value.slice
if not (
self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
and self._type_and_name_are_equal(slice_value, node.test.left)
):
return _False
# The object needs to be a dictionary instance
return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 727 | _type_and_name_are_equal | ref | function | self._type_and_name_are_equal(stmt.value.value, node.test.ops[0][1])
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 728 | _type_and_name_are_equal | ref | function | and self._type_and_name_are_equal(slice_value, node.test.left)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 733 | safe_infer | ref | function | return isinstance(utils.safe_infer(node.test.ops[0][1]), nodes.Dict)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 735 | _check_consider_get | def | function | def _check_consider_get(self, node):
if_block_ok = self._is_dict_get_block(node)
if if_block_ok and not node.orelse:
self.add_message("consider-using-get", node=node)
elif (
if_block_ok
and len(node.orelse) == 1
and isinstance(node.orelse[0], nodes.Assign)
and self._type_and_name_are_equal(
node.orelse[0].targets[0], node.body[0].targets[0]
)
and len(node.orelse[0].targets) == 1
):
self.add_message("consider-using-get", node=node)
@utils.check_messages(
"too-many-nested-blocks",
"simplifiable-if-statement",
"no-else-return",
"no-else-raise",
"no-else-break",
"no-else-continue",
"consider-using-get",
)
def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 736 | _is_dict_get_block | ref | function | if_block_ok = self._is_dict_get_block(node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 738 | add_message | ref | function | self.add_message("consider-using-get", node=node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 743 | _type_and_name_are_equal | ref | function | and self._type_and_name_are_equal(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 748 | add_message | ref | function | self.add_message("consider-using-get", node=node)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 750 | check_messages | ref | function | @utils.check_messages(
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 759 | visit_if | def | function | def visit_if(self, node: nodes.If) -> None:
self._check_simplifiable_if(node)
self._check_nested_blocks(node)
self._check_superfluous_else_return(node)
self._check_superfluous_else_raise(node)
self._check_superfluous_else_break(node)
self._check_superfluous_else_continue(node)
self._check_consider_get(node)
self._check_consider_using_min_max_builtin(node)
def _check_consider_using_min_max_builtin(self, node: nodes.If):
"""Check if the given if node can be refactored as a min/max python builtin."""
if self._is_actual_elif(node) or node.orelse:
# Not interested in if statements with multiple branches.
return
if len(node.body) != 1:
return
body = node.body[0]
# Check if condition can be reduced.
if not hasattr(body, "targets") or len(body.targets) != 1:
return
target = body.targets[0]
if not (
isinstance(node.test, nodes.Compare)
and not isinstance(target, nodes.Subscript)
and not isinstance(node.test.left, nodes.Subscript)
and isinstance(body, nodes.Assign)
):
return
# Check that the assignation is on the same variable.
if hasattr(node.test.left, "name"):
left_operand = node.test.left.name
elif hasattr(node.test.left, "attrname"):
left_operand = node.test.left.attrname
else:
return
if hasattr(target, "name"):
target_assignation = target.name
elif hasattr(target, "attrname"):
target_assignation = target.attrname
else:
return
if not (left_operand == target_assignation):
return
if len(node.test.ops) > 1:
return
if not isinstance(body.value, (nodes.Name, nodes.Const)):
return
operator, right_statement = node.test.ops[0]
if isinstance(body.value, nodes.Name):
body_value = body.value.name
else:
body_value = body.value.value
if isinstance(right_statement, nodes.Name):
right_statement_value = right_statement.name
elif isinstance(right_statement, nodes.Const):
right_statement_value = right_statement.value
else:
return
# Verify the right part of the statement is the same.
if right_statement_value != body_value:
return
if operator in {"<", "<="}:
reduced_to = "{target} = max({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-max-builtin", node=node, args=(reduced_to,)
)
elif operator in {">", ">="}:
reduced_to = "{target} = min({target}, {item})".format(
target=target_assignation, item=body_value
)
self.add_message(
"consider-using-min-builtin", node=node, args=(reduced_to,)
)
@utils.check_messages("simplifiable-if-expression")
def visit_ifexp(self, node: nodes.IfExp) -> None:
self._check_simplifiable_ifexp(node)
def _check_simplifiable_ifexp(self, node):
if not isinstance(node.body, nodes.Const) or not isinstance(
node.orelse, nodes.Const
):
return
if not isinstance(node.body.value, bool) or not isinstance(
node.orelse.value, bool
):
return
if isinstance(node.test, nodes.Compare):
test_reduced_to = "test"
else:
test_reduced_to = "bool(test)"
if (node.body.value, node.orelse.value) == (_True, _False):
reduced_to = f"'{test_reduced_to}'"
elif (node.body.value, node.orelse.value) == (_False, _True):
reduced_to = "'not test'"
else:
return
self.add_message("simplifiable-if-expression", node=node, args=(reduced_to,))
@utils.check_messages(
"too-many-nested-blocks",
"inconsistent-return-statements",
"useless-return",
"consider-using-with",
)
def leave_functiondef(self, node: nodes.FunctionDef) -> None:
# check left-over nested blocks stack
self._emit_nested_blocks_message_if_needed(self._nested_blocks)
# new scope = reinitialize the stack of nested blocks
self._nested_blocks = []
# check consistent return statements
self._check_consistent_returns(node)
# check for single return or return None at the end
self._check_return_at_the_end(node)
self._return_nodes[node.name] = []
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.function_scope
)
self._consider_using_with_stack.function_scope.clear()
@utils.check_messages("consider-using-with")
def leave_classdef(self, _: nodes.ClassDef) -> None:
# check for context managers that have been created but not used
self._emit_consider_using_with_if_needed(
self._consider_using_with_stack.class_scope
)
self._consider_using_with_stack.class_scope.clear()
@utils.check_messages("stop-iteration-return")
def visit_raise(self, node: nodes.Raise) -> None:
self._check_stop_iteration_inside_generator(node)
def _check_stop_iteration_inside_generator(self, node):
"""Check if an exception of type StopIteration is raised inside a generator."""
frame = node.frame(future=_True)
if not isinstance(frame, nodes.FunctionDef) or not frame.is_generator():
return
if utils.node_ignores_exception(node, StopIteration):
return
if not node.exc:
return
exc = utils.safe_infer(node.exc)
if not exc or not isinstance(exc, (astroid.Instance, nodes.ClassDef)):
return
if self._check_exception_inherit_from_stopiteration(exc):
self.add_message("stop-iteration-return", node=node)
@staticmethod
def _check_exception_inherit_from_stopiteration(exc):
"""Return _True if the exception node in argument inherit from StopIteration."""
stopiteration_qname = f"{utils.EXCEPTIONS_MODULE}.StopIteration"
return any(_class.qname() == stopiteration_qname for _class in exc.mro())
def _check_consider_using_comprehension_constructor(self, node):
if (
isinstance(node.func, nodes.Name)
and node.args
and isinstance(node.args[0], nodes.ListComp)
):
if node.func.name == "dict":
element = node.args[0].elt
if isinstance(element, nodes.Call):
return
# If we have an `IfExp` here where both the key AND value
# are different, then don't raise the issue. See #5588
if (
isinstance(element, nodes.IfExp)
and isinstance(element.body, (nodes.Tuple, nodes.List))
and len(element.body.elts) == 2
and isinstance(element.orelse, (nodes.Tuple, nodes.List))
and len(element.orelse.elts) == 2
):
key1, value1 = element.body.elts
key2, value2 = element.orelse.elts
if (
key1.as_string() != key2.as_string()
and value1.as_string() != value2.as_string()
):
return
message_name = "consider-using-dict-comprehension"
self.add_message(message_name, node=node)
elif node.func.name == "set":
message_name = "consider-using-set-comprehension"
self.add_message(message_name, node=node)
def _check_consider_using_generator(self, node):
# 'any' and 'all' definitely should use generator, while 'list' and 'tuple' need to be considered first
# See https://github.com/PyCQA/pylint/pull/3309#discussion_r576683109
checked_call = ["any", "all", "list", "tuple"]
if (
isinstance(node, nodes.Call)
and node.func
and isinstance(node.func, nodes.Name)
and node.func.name in checked_call
):
# functions in checked_calls take exactly one argument
# check whether the argument is list comprehension
if len(node.args) == 1 and isinstance(node.args[0], nodes.ListComp):
# remove square brackets '[]'
inside_comp = node.args[0].as_string()[1:-1]
call_name = node.func.name
if call_name in {"any", "all"}:
self.add_message(
"use-a-generator",
node=node,
args=(call_name, inside_comp),
)
else:
self.add_message(
"consider-using-generator",
node=node,
args=(call_name, inside_comp),
)
@utils.check_messages(
"stop-iteration-return",
"consider-using-dict-comprehension",
"consider-using-set-comprehension",
"consider-using-sys-exit",
"super-with-arguments",
"consider-using-generator",
"consider-using-with",
"use-list-literal",
"use-dict-literal",
)
def visit_call(self, node: nodes.Call) -> None:
self._check_raising_stopiteration_in_generator_next_call(node)
self._check_consider_using_comprehension_constructor(node)
self._check_quit_exit_call(node)
self._check_super_with_arguments(node)
self._check_consider_using_generator(node)
self._check_consider_using_with(node)
self._check_use_list_or_dict_literal(node)
@staticmethod
def _has_exit_in_scope(scope):
exit_func = scope.locals.get("exit")
return bool(
exit_func and isinstance(exit_func[0], (nodes.ImportFrom, nodes.Import))
)
def _check_quit_exit_call(self, node):
if isinstance(node.func, nodes.Name) and node.func.name in BUILTIN_EXIT_FUNCS:
# If we have `exit` imported from `sys` in the current or global scope, exempt this instance.
local_scope = node.scope()
if self._has_exit_in_scope(local_scope) or self._has_exit_in_scope(
node.root()
):
return
self.add_message("consider-using-sys-exit", node=node)
def _check_super_with_arguments(self, node):
if not isinstance(node.func, nodes.Name) or node.func.name != "super":
return
# pylint: disable=too-many-boolean-expressions
if (
len(node.args) != 2
or not isinstance(node.args[1], nodes.Name)
or node.args[1].name != "self"
or not isinstance(node.args[0], nodes.Name)
or not isinstance(node.args[1], nodes.Name)
or node_frame_class(node) is None
or node.args[0].name != node_frame_class(node).name
):
return
self.add_message("super-with-arguments", node=node)
def _check_raising_stopiteration_in_generator_next_call(self, node):
"""Check if a StopIteration exception is raised by the call to next function.
If the next value has a default value, then do not add message.
:param node: Check to see if this Call node is a next function
:type node: :class:`nodes.Call`
"""
def _looks_like_infinite_iterator(param):
inferred = utils.safe_infer(param)
if inferred:
return inferred.qname() in KNOWN_INFINITE_ITERATORS
return _False
if isinstance(node.func, nodes.Attribute):
# A next() method, which is now what we want.
return
inferred = utils.safe_infer(node.func)
if getattr(inferred, "name", "") == "next":
frame = node.frame(future=_True)
# The next builtin can only have up to two
# positional arguments and no keyword arguments
has_sentinel_value = len(node.args) > 1
if (
isinstance(frame, nodes.FunctionDef)
and frame.is_generator()
and not has_sentinel_value
and not utils.node_ignores_exception(node, StopIteration)
and not _looks_like_infinite_iterator(node.args[0])
):
self.add_message("stop-iteration-return", node=node)
def _check_nested_blocks(self, node):
"""Update and check the number of nested blocks."""
# only check block levels inside functions or methods
if not isinstance(node.scope(), nodes.FunctionDef):
return
# messages are triggered on leaving the nested block. Here we save the
# stack in case the current node isn't nested in the previous one
nested_blocks = self._nested_blocks[:]
if node.parent == node.scope():
self._nested_blocks = [node]
else:
# go through ancestors from the most nested to the less
for ancestor_node in reversed(self._nested_blocks):
if ancestor_node == node.parent:
break
self._nested_blocks.pop()
# if the node is an elif, this should not be another nesting level
if isinstance(node, nodes.If) and self._is_actual_elif(node):
if self._nested_blocks:
self._nested_blocks.pop()
self._nested_blocks.append(node)
# send message only once per group of nested blocks
if len(nested_blocks) > len(self._nested_blocks):
self._emit_nested_blocks_message_if_needed(nested_blocks)
def _emit_nested_blocks_message_if_needed(self, nested_blocks):
if len(nested_blocks) > self.config.max_nested_blocks:
self.add_message(
"too-many-nested-blocks",
node=nested_blocks[0],
args=(len(nested_blocks), self.config.max_nested_blocks),
)
def _emit_consider_using_with_if_needed(self, stack: Dict[str, nodes.NodeNG]):
for node in stack.values():
self.add_message("consider-using-with", node=node)
@staticmethod
def _duplicated_isinstance_types(node):
"""Get the duplicated types from the underlying isinstance calls.
:param nodes.BoolOp node: Node which should contain a bunch of isinstance calls.
:returns: Dictionary of the comparison objects from the isinstance calls,
to duplicate values from consecutive calls.
:rtype: dict
"""
duplicated_objects = set()
all_types = collections.defaultdict(set)
for call in node.values:
if not isinstance(call, nodes.Call) or len(call.args) != 2:
continue
inferred = utils.safe_infer(call.func)
if not inferred or not utils.is_builtin_object(inferred):
continue
if inferred.name != "isinstance":
continue
isinstance_object = call.args[0].as_string()
isinstance_types = call.args[1]
if isinstance_object in all_types:
duplicated_objects.add(isinstance_object)
if isinstance(isinstance_types, nodes.Tuple):
elems = [
class_type.as_string() for class_type in isinstance_types.itered()
]
else:
elems = [isinstance_types.as_string()]
all_types[isinstance_object].update(elems)
# Remove all keys which not duplicated
return {
key: value for key, value in all_types.items() if key in duplicated_objects
}
def _check_consider_merging_isinstance(self, node):
"""Check isinstance calls which can be merged together."""
if node.op != "or":
return
first_args = self._duplicated_isinstance_types(node)
for duplicated_name, class_names in first_args.items():
names = sorted(name for name in class_names)
self.add_message(
"consider-merging-isinstance",
node=node,
args=(duplicated_name, ", ".join(names)),
)
def _check_consider_using_in(self, node):
allowed_ops = {"or": "==", "and": "!="}
if node.op not in allowed_ops or len(node.values) < 2:
return
for value in node.values:
if (
not isinstance(value, nodes.Compare)
or len(value.ops) != 1
or value.ops[0][0] not in allowed_ops[node.op]
):
return
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, nodes.Call):
return
# Gather variables and values from comparisons
variables, values = [], []
for value in node.values:
variable_set = set()
for comparable in value.left, value.ops[0][1]:
if isinstance(comparable, (nodes.Name, nodes.Attribute)):
variable_set.add(comparable.as_string())
values.append(comparable.as_string())
variables.append(variable_set)
# Look for (common-)variables that occur in all comparisons
common_variables = reduce(lambda a, b: a.intersection(b), variables)
if not common_variables:
return
# Gather information for the suggestion
common_variable = sorted(list(common_variables))[0]
comprehension = "in" if node.op == "or" else "not in"
values = list(collections.OrderedDict.fromkeys(values))
values.remove(common_variable)
values_string = ", ".join(values) if len(values) != 1 else values[0] + ","
suggestion = f"{common_variable} {comprehension} ({values_string})"
self.add_message("consider-using-in", node=node, args=(suggestion,))
def _check_chained_comparison(self, node):
"""Check if there is any chained comparison in the expression.
Add a refactoring message if a boolOp contains comparison like a < b and b < c,
which can be chained as a < b < c.
Care is taken to avoid simplifying a < b < c and b < d.
"""
if node.op != "and" or len(node.values) < 2:
return
def _find_lower_upper_bounds(comparison_node, uses):
left_operand = comparison_node.left
for operator, right_operand in comparison_node.ops:
for operand in (left_operand, right_operand):
value = None
if isinstance(operand, nodes.Name):
value = operand.name
elif isinstance(operand, nodes.Const):
value = operand.value
if value is None:
continue
if operator in {"<", "<="}:
if operand is left_operand:
uses[value]["lower_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operator in {">", ">="}:
if operand is left_operand:
uses[value]["upper_bound"].add(comparison_node)
elif operand is right_operand:
uses[value]["lower_bound"].add(comparison_node)
left_operand = right_operand
uses = collections.defaultdict(
lambda: {"lower_bound": set(), "upper_bound": set()}
)
for comparison_node in node.values:
if isinstance(comparison_node, nodes.Compare):
_find_lower_upper_bounds(comparison_node, uses)
for _, bounds in uses.items():
num_shared = len(bounds["lower_bound"].intersection(bounds["upper_bound"]))
num_lower_bounds = len(bounds["lower_bound"])
num_upper_bounds = len(bounds["upper_bound"])
if num_shared < num_lower_bounds and num_shared < num_upper_bounds:
self.add_message("chained-comparison", node=node)
break
@staticmethod
def _apply_boolean_simplification_rules(operator, values):
"""Removes irrelevant values or returns shortcircuiting values.
This function applies the following two rules:
1) an OR expression with _True in it will always be true, and the
reverse for AND
2) _False values in OR expressions are only relevant if all values are
false, and the reverse for AND
"""
simplified_values = []
for subnode in values:
inferred_bool = None
if not next(subnode.nodes_of_class(nodes.Name), _False):
inferred = utils.safe_infer(subnode)
if inferred:
inferred_bool = inferred.bool_value()
if not isinstance(inferred_bool, bool):
simplified_values.append(subnode)
elif (operator == "or") == inferred_bool:
return [subnode]
return simplified_values or [nodes.Const(operator == "and")]
def _simplify_boolean_operation(self, bool_op):
"""Attempts to simplify a boolean operation.
Recursively applies simplification on the operator terms,
and keeps track of whether reductions have been made.
"""
children = list(bool_op.get_children())
intermediate = [
self._simplify_boolean_operation(child)
if isinstance(child, nodes.BoolOp)
else child
for child in children
]
result = self._apply_boolean_simplification_rules(bool_op.op, intermediate)
if len(result) < len(children):
self._can_simplify_bool_op = _True
if len(result) == 1:
return result[0]
simplified_bool_op = copy.copy(bool_op)
simplified_bool_op.postinit(result)
return simplified_bool_op
def _check_simplifiable_condition(self, node):
"""Check if a boolean condition can be simplified.
Variables will not be simplified, even in the value can be inferred,
and expressions like '3 + 4' will remain expanded.
"""
if not utils.is_test_condition(node):
return
self._can_simplify_bool_op = _False
simplified_expr = self._simplify_boolean_operation(node)
if not self._can_simplify_bool_op:
return
if not next(simplified_expr.nodes_of_class(nodes.Name), _False):
self.add_message(
"condition-evals-to-constant",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
else:
self.add_message(
"simplifiable-condition",
node=node,
args=(node.as_string(), simplified_expr.as_string()),
)
@utils.check_messages(
"consider-merging-isinstance",
"consider-using-in",
"chained-comparison",
"simplifiable-condition",
"condition-evals-to-constant",
)
def visit_boolop(self, node: nodes.BoolOp) -> None:
self._check_consider_merging_isinstance(node)
self._check_consider_using_in(node)
self._check_chained_comparison(node)
self._check_simplifiable_condition(node)
@staticmethod
def _is_simple_assignment(node):
return (
isinstance(node, nodes.Assign)
and len(node.targets) == 1
and isinstance(node.targets[0], nodes.AssignName)
and isinstance(node.value, nodes.Name)
)
def _check_swap_variables(self, node):
if not node.next_sibling() or not node.next_sibling().next_sibling():
return
assignments = [node, node.next_sibling(), node.next_sibling().next_sibling()]
if not all(self._is_simple_assignment(node) for node in assignments):
return
if any(node in self._reported_swap_nodes for node in assignments):
return
left = [node.targets[0].name for node in assignments]
right = [node.value.name for node in assignments]
if left[0] == right[-1] and left[1:] == right[:-1]:
self._reported_swap_nodes.update(assignments)
message = "consider-swap-variables"
self.add_message(message, node=node)
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
"consider-using-with",
)
def visit_assign(self, node: nodes.Assign) -> None:
self._append_context_managers_to_stack(node)
self.visit_return(node) # remaining checks are identical as for return nodes
@utils.check_messages(
"simplify-boolean-expression",
"consider-using-ternary",
"consider-swap-variables",
)
def visit_return(self, node: nodes.Return) -> None:
self._check_swap_variables(node)
if self._is_and_or_ternary(node.value):
cond, truth_value, false_value = self._and_or_ternary_arguments(node.value)
else:
return
if all(
isinstance(value, nodes.Compare) for value in (truth_value, false_value)
):
return
inferred_truth_value = utils.safe_infer(truth_value)
if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
truth_boolean_value = _True
else:
truth_boolean_value = inferred_truth_value.bool_value()
if truth_boolean_value is _False:
message = "simplify-boolean-expression"
suggestion = false_value.as_string()
else:
message = "consider-using-ternary"
suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
self.add_message(message, node=node, args=(suggestion,))
def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
if _is_inside_context_manager(node):
# if we are inside a context manager itself, we assume that it will handle the resource management itself.
return
if isinstance(node.targets[0], (nodes.Tuple, nodes.List, nodes.Set)):
assignees = node.targets[0].elts
value = utils.safe_infer(node.value)
if value is None or not hasattr(value, "elts"):
# We cannot deduce what values are assigned, so we have to skip this
return
values = value.elts
else:
assignees = [node.targets[0]]
values = [node.value]
if Uninferable in (assignees, values):
return
for assignee, value in zip(assignees, values):
if not isinstance(value, nodes.Call):
continue
inferred = utils.safe_infer(value.func)
if (
not inferred
or inferred.qname() not in CALLS_RETURNING_CONTEXT_MANAGERS
or not isinstance(assignee, (nodes.AssignName, nodes.AssignAttr))
):
continue
stack = self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
)
varname = (
assignee.name
if isinstance(assignee, nodes.AssignName)
else assignee.attrname
)
if varname in stack:
existing_node = stack[varname]
if astroid.are_exclusive(node, existing_node):
# only one of the two assignments can be executed at runtime, thus it is fine
stack[varname] = value
continue
# variable was redefined before it was used in a ``with`` block
self.add_message(
"consider-using-with",
node=existing_node,
)
stack[varname] = value
def _check_consider_using_with(self, node: nodes.Call):
if _is_inside_context_manager(node) or _is_a_return_statement(node):
# If we are inside a context manager itself, we assume that it will handle the resource management itself.
# If the node is a child of a return, we assume that the caller knows he is getting a context manager
# he should use properly (i.e. in a ``with``).
return
if (
node
in self._consider_using_with_stack.get_stack_for_frame(
node.frame(future=_True)
).values()
):
# the result of this call was already assigned to a variable and will be checked when leaving the scope.
return
inferred = utils.safe_infer(node.func)
if not inferred:
return
could_be_used_in_with = (
# things like ``lock.acquire()``
inferred.qname() in CALLS_THAT_COULD_BE_REPLACED_BY_WITH
or (
# things like ``open("foo")`` which are not already inside a ``with`` statement
inferred.qname() in CALLS_RETURNING_CONTEXT_MANAGERS
and not _is_part_of_with_items(node)
)
)
if could_be_used_in_with and not _will_be_released_automatically(node):
self.add_message("consider-using-with", node=node)
def _check_use_list_or_dict_literal(self, node: nodes.Call) -> None:
"""Check if empty list or dict is created by using the literal [] or {}."""
if node.as_string() in {"list()", "dict()"}:
inferred = utils.safe_infer(node.func)
if isinstance(inferred, nodes.ClassDef) and not node.args:
if inferred.qname() == "builtins.list":
self.add_message("use-list-literal", node=node)
elif inferred.qname() == "builtins.dict" and not node.keywords:
self.add_message("use-dict-literal", node=node)
def _check_consider_using_join(self, aug_assign):
"""We start with the augmented assignment and work our way upwards.
Names of variables for nodes if match successful:
result = '' # assign
for number in ['1', '2', '3'] # for_loop
result += number # aug_assign
"""
for_loop = aug_assign.parent
if not isinstance(for_loop, nodes.For) or len(for_loop.body) > 1:
return
assign = for_loop.previous_sibling()
if not isinstance(assign, nodes.Assign):
return
result_assign_names = {
target.name
for target in assign.targets
if isinstance(target, nodes.AssignName)
}
is_concat_loop = (
aug_assign.op == "+="
and isinstance(aug_assign.target, nodes.AssignName)
and len(for_loop.body) == 1
and aug_assign.target.name in result_assign_names
and isinstance(assign.value, nodes.Const)
and isinstance(assign.value.value, str)
and isinstance(aug_assign.value, nodes.Name)
and aug_assign.value.name == for_loop.target.name
)
if is_concat_loop:
self.add_message("consider-using-join", node=aug_assign)
@utils.check_messages("consider-using-join")
def visit_augassign(self, node: nodes.AugAssign) -> None:
self._check_consider_using_join(node)
@utils.check_messages("unnecessary-comprehension", "unnecessary-dict-index-lookup")
def visit_comprehension(self, node: nodes.Comprehension) -> None:
self._check_unnecessary_comprehension(node)
self._check_unnecessary_dict_index_lookup(node)
def _check_unnecessary_comprehension(self, node: nodes.Comprehension) -> None:
if (
isinstance(node.parent, nodes.GeneratorExp)
or len(node.ifs) != 0
or len(node.parent.generators) != 1
or node.is_async
):
return
if (
isinstance(node.parent, nodes.DictComp)
and isinstance(node.parent.key, nodes.Name)
and isinstance(node.parent.value, nodes.Name)
and isinstance(node.target, nodes.Tuple)
and all(isinstance(elt, nodes.AssignName) for elt in node.target.elts)
):
expr_list = [node.parent.key.name, node.parent.value.name]
target_list = [elt.name for elt in node.target.elts]
elif isinstance(node.parent, (nodes.ListComp, nodes.SetComp)):
expr = node.parent.elt
if isinstance(expr, nodes.Name):
expr_list = expr.name
elif isinstance(expr, nodes.Tuple):
if any(not isinstance(elt, nodes.Name) for elt in expr.elts):
return
expr_list = [elt.name for elt in expr.elts]
else:
expr_list = []
target = node.parent.generators[0].target
target_list = (
target.name
if isinstance(target, nodes.AssignName)
else (
[
elt.name
for elt in target.elts
if isinstance(elt, nodes.AssignName)
]
if isinstance(target, nodes.Tuple)
else []
)
)
else:
return
if expr_list == target_list and expr_list:
args: Optional[Tuple[str]] = None
inferred = utils.safe_infer(node.iter)
if isinstance(node.parent, nodes.DictComp) and isinstance(
inferred, astroid.objects.DictItems
):
args = (f"{node.iter.func.expr.as_string()}",)
elif (
isinstance(node.parent, nodes.ListComp)
and isinstance(inferred, nodes.List)
) or (
isinstance(node.parent, nodes.SetComp)
and isinstance(inferred, nodes.Set)
):
args = (f"{node.iter.as_string()}",)
if args:
self.add_message(
"unnecessary-comprehension", node=node.parent, args=args
)
return
if isinstance(node.parent, nodes.DictComp):
func = "dict"
elif isinstance(node.parent, nodes.ListComp):
func = "list"
elif isinstance(node.parent, nodes.SetComp):
func = "set"
else:
return
self.add_message(
"unnecessary-comprehension",
node=node.parent,
args=(f"{func}({node.iter.as_string()})",),
)
@staticmethod
def _is_and_or_ternary(node):
"""Returns true if node is 'condition and true_value or false_value' form.
All of: condition, true_value and false_value should not be a complex boolean expression
"""
return (
isinstance(node, nodes.BoolOp)
and node.op == "or"
and len(node.values) == 2
and isinstance(node.values[0], nodes.BoolOp)
and not isinstance(node.values[1], nodes.BoolOp)
and node.values[0].op == "and"
and not isinstance(node.values[0].values[1], nodes.BoolOp)
and len(node.values[0].values) == 2
)
@staticmethod
def _and_or_ternary_arguments(node):
false_value = node.values[1]
condition, true_value = node.values[0].values
return condition, true_value, false_value
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
self._return_nodes[node.name] = list(
node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef)
)
def _check_consistent_returns(self, node: nodes.FunctionDef) -> None:
"""Check that all return statements inside a function are consistent.
Return statements are consistent if:
- all returns are explicit and if there is no implicit return;
- all returns are empty and if there is, possibly, an implicit return.
Args:
node (nodes.FunctionDef): the function holding the return statements.
"""
# explicit return statements are those with a not None value
explicit_returns = [
_node for _node in self._return_nodes[node.name] if _node.value is not None
]
if not explicit_returns:
return
if len(explicit_returns) == len(
self._return_nodes[node.name]
) and self._is_node_return_ended(node):
return
self.add_message("inconsistent-return-statements", node=node)
def _is_if_node_return_ended(self, node: nodes.If) -> bool:
"""Check if the If node ends with an explicit return statement.
Args:
node (nodes.If): If node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Do not check if inner function definition are return ended.
is_if_returning = any(
self._is_node_return_ended(_ifn)
for _ifn in node.body
if not isinstance(_ifn, nodes.FunctionDef)
)
if not node.orelse:
# If there is not orelse part then the if statement is returning if :
# - there is at least one return statement in its siblings;
# - the if body is itself returning.
if not self._has_return_in_siblings(node):
return _False
return is_if_returning
# If there is an orelse part then both if body and orelse part should return.
is_orelse_returning = any(
self._is_node_return_ended(_ore)
for _ore in node.orelse
if not isinstance(_ore, nodes.FunctionDef)
)
return is_if_returning and is_orelse_returning
def _is_raise_node_return_ended(self, node: nodes.Raise) -> bool:
"""Check if the Raise node ends with an explicit return statement.
Args:
node (nodes.Raise): Raise node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# a Raise statement doesn't need to end with a return statement
# but if the exception raised is handled, then the handler has to
# ends with a return statement
if not node.exc:
# Ignore bare raises
return _True
if not utils.is_node_inside_try_except(node):
# If the raise statement is not inside a try/except statement
# then the exception is raised and cannot be caught. No need
# to infer it.
return _True
exc = utils.safe_infer(node.exc)
if exc is None or exc is astroid.Uninferable or not hasattr(exc, "pytype"):
return _False
exc_name = exc.pytype().split(".")[-1]
handlers = utils.get_exception_handlers(node, exc_name)
handlers = list(handlers) if handlers is not None else []
if handlers:
# among all the handlers handling the exception at least one
# must end with a return statement
return any(self._is_node_return_ended(_handler) for _handler in handlers)
# if no handlers handle the exception then it's ok
return _True
def _is_node_return_ended(self, node: nodes.NodeNG) -> bool:
"""Check if the node ends with an explicit return statement.
Args:
node (nodes.NodeNG): node to be checked.
Returns:
bool: _True if the node ends with an explicit statement, _False otherwise.
"""
# Recursion base case
if isinstance(node, nodes.Return):
return _True
if isinstance(node, nodes.Call):
try:
funcdef_node = node.func.inferred()[0]
if self._is_function_def_never_returning(funcdef_node):
return _True
except astroid.InferenceError:
pass
# Avoid the check inside while loop as we don't know
# if they will be completed
if isinstance(node, nodes.While):
return _True
if isinstance(node, nodes.Raise):
return self._is_raise_node_return_ended(node)
if isinstance(node, nodes.If):
return self._is_if_node_return_ended(node)
if isinstance(node, nodes.TryExcept):
handlers = {
_child
for _child in node.get_children()
if isinstance(_child, nodes.ExceptHandler)
}
all_but_handler = set(node.get_children()) - handlers
return any(
self._is_node_return_ended(_child) for _child in all_but_handler
) and all(self._is_node_return_ended(_child) for _child in handlers)
if (
isinstance(node, nodes.Assert)
and isinstance(node.test, nodes.Const)
and not node.test.value
):
# consider assert _False as a return node
return _True
# recurses on the children of the node
return any(self._is_node_return_ended(_child) for _child in node.get_children())
@staticmethod
def _has_return_in_siblings(node: nodes.NodeNG) -> bool:
"""Returns _True if there is at least one return in the node's siblings."""
next_sibling = node.next_sibling()
while next_sibling:
if isinstance(next_sibling, nodes.Return):
return _True
next_sibling = next_sibling.next_sibling()
return _False
def _is_function_def_never_returning(self, node: nodes.FunctionDef) -> bool:
"""Return _True if the function never returns. _False otherwise.
Args:
node (nodes.FunctionDef): function definition node to be analyzed.
Returns:
bool: _True if the function never returns, _False otherwise.
"""
if isinstance(node, nodes.FunctionDef) and node.returns:
return (
isinstance(node.returns, nodes.Attribute)
and node.returns.attrname == "NoReturn"
or isinstance(node.returns, nodes.Name)
and node.returns.name == "NoReturn"
)
try:
return node.qname() in self._never_returning_functions
except TypeError:
return _False
def _check_return_at_the_end(self, node):
"""Check for presence of a *single* return statement at the end of a
function. "return" or "return None" are useless because None is the
default return type if they are missing.
NOTE: produces a message only if there is a single return statement
in the function body. Otherwise _check_consistent_returns() is called!
Per its implementation and PEP8 we can have a "return None" at the end
of the function body if there are other return statements before that!
"""
if len(self._return_nodes[node.name]) > 1:
return
if len(node.body) <= 1:
return
last = node.body[-1]
if isinstance(last, nodes.Return):
# e.g. "return"
if last.value is None:
self.add_message("useless-return", node=node)
# return None"
elif isinstance(last.value, nodes.Const) and (last.value.value is None):
self.add_message("useless-return", node=node)
def _check_unnecessary_dict_index_lookup(
self, node: Union[nodes.For, nodes.Comprehension]
) -> None:
"""Add message when accessing dict values by index lookup."""
# Verify that we have an .items() call and
# that the object which is iterated is used as a subscript in the
# body of the for.
# Is it a proper items call?
if (
isinstance(node.iter, nodes.Call)
and isinstance(node.iter.func, nodes.Attribute)
and node.iter.func.attrname == "items"
):
inferred = utils.safe_infer(node.iter.func)
if not isinstance(inferred, astroid.BoundMethod):
return
iterating_object_name = node.iter.func.expr.as_string()
# Verify that the body of the for loop uses a subscript
# with the object that was iterated. This uses some heuristics
# in order to make sure that the same object is used in the
# for body.
children = (
node.body if isinstance(node, nodes.For) else node.parent.get_children()
)
for child in children:
for subscript in child.nodes_of_class(nodes.Subscript):
if not isinstance(subscript.value, (nodes.Name, nodes.Attribute)):
continue
value = subscript.slice
if isinstance(node, nodes.For) and (
isinstance(subscript.parent, nodes.Assign)
and subscript in subscript.parent.targets
or isinstance(subscript.parent, nodes.AugAssign)
and subscript == subscript.parent.target
):
# Ignore this subscript if it is the target of an assignment
# Early termination; after reassignment dict index lookup will be necessary
return
if isinstance(subscript.parent, nodes.Delete):
# Ignore this subscript if it's used with the delete keyword
return
# Case where .items is assigned to k,v (i.e., for k, v in d.items())
if isinstance(value, nodes.Name):
if (
not isinstance(node.target, nodes.Tuple)
# Ignore 1-tuples: for k, in d.items()
or len(node.target.elts) < 2
or value.name != node.target.elts[0].name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.lookup(value.name)[1][-1].lineno > node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=(node.target.elts[1].as_string()),
)
# Case where .items is assigned to single var (i.e., for item in d.items())
elif isinstance(value, nodes.Subscript):
if (
not isinstance(node.target, nodes.AssignName)
or node.target.name != value.value.name
or iterating_object_name != subscript.value.as_string()
):
continue
if (
isinstance(node, nodes.For)
and value.value.lookup(value.value.name)[1][-1].lineno
> node.lineno
):
# Ignore this subscript if it has been redefined after
# the for loop. This checks for the line number using .lookup()
# to get the line number where the iterating object was last
# defined and compare that to the for loop's line number
continue
# check if subscripted by 0 (key)
inferred = utils.safe_infer(value.slice)
if not isinstance(inferred, nodes.Const) or inferred.value != 0:
continue
self.add_message(
"unnecessary-dict-index-lookup",
node=subscript,
args=("1".join(value.as_string().rsplit("0", maxsplit=1)),),
)
|
playground/e9b22a58-260b-483f-88d7-7a5fe9f8b1d4/pylint/pylint/checkers/refactoring/refactoring_checker.py | pylint/checkers/refactoring/refactoring_checker.py | 760 | _check_simplifiable_if | ref | function | self._check_simplifiable_if(node)
|
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