| |
| from __future__ import annotations |
|
|
| from typing import Union, Callable, Any |
|
|
| from .exceptions import ParseException |
| from .util import col, replaced_by_pep8 |
| from .results import ParseResults |
|
|
|
|
| ParseAction = Union[ |
| Callable[[], Any], |
| Callable[[ParseResults], Any], |
| Callable[[int, ParseResults], Any], |
| Callable[[str, int, ParseResults], Any], |
| ] |
|
|
|
|
| class OnlyOnce: |
| """ |
| Wrapper for parse actions, to ensure they are only called once. |
| Note: parse action signature must include all 3 arguments. |
| """ |
|
|
| def __init__(self, method_call: Callable[[str, int, ParseResults], Any]) -> None: |
| from .core import _trim_arity |
|
|
| self.callable = _trim_arity(method_call) |
| self.called = False |
|
|
| def __call__(self, s: str, l: int, t: ParseResults) -> ParseResults: |
| if not self.called: |
| results = self.callable(s, l, t) |
| self.called = True |
| return results |
| raise ParseException(s, l, "OnlyOnce obj called multiple times w/out reset") |
|
|
| def reset(self): |
| """ |
| Allow the associated parse action to be called once more. |
| """ |
|
|
| self.called = False |
|
|
|
|
| def match_only_at_col(n: int) -> ParseAction: |
| """ |
| Helper method for defining parse actions that require matching at |
| a specific column in the input text. |
| """ |
|
|
| def verify_col(strg: str, locn: int, toks: ParseResults) -> None: |
| if col(locn, strg) != n: |
| raise ParseException(strg, locn, f"matched token not at column {n}") |
|
|
| return verify_col |
|
|
|
|
| def replace_with(repl_str: Any) -> ParseAction: |
| """ |
| Helper method for common parse actions that simply return |
| a literal value. Especially useful when used with |
| :meth:`~ParserElement.transform_string`. |
| |
| Example: |
| |
| .. doctest:: |
| |
| >>> num = Word(nums).set_parse_action(lambda toks: int(toks[0])) |
| >>> na = one_of("N/A NA").set_parse_action(replace_with(math.nan)) |
| >>> term = na | num |
| |
| >>> term[1, ...].parse_string("324 234 N/A 234") |
| ParseResults([324, 234, nan, 234], {}) |
| """ |
| return lambda s, l, t: [repl_str] |
|
|
|
|
| def remove_quotes(s: str, l: int, t: ParseResults) -> Any: |
| r""" |
| Helper parse action for removing quotation marks from parsed |
| quoted strings, that use a single character for quoting. For parsing |
| strings that may have multiple characters, use the :class:`QuotedString` |
| class. |
| |
| Example: |
| |
| .. doctest:: |
| |
| >>> # by default, quotation marks are included in parsed results |
| >>> quoted_string.parse_string("'Now is the Winter of our Discontent'") |
| ParseResults(["'Now is the Winter of our Discontent'"], {}) |
| |
| >>> # use remove_quotes to strip quotation marks from parsed results |
| >>> dequoted = quoted_string().set_parse_action(remove_quotes) |
| >>> dequoted.parse_string("'Now is the Winter of our Discontent'") |
| ParseResults(['Now is the Winter of our Discontent'], {}) |
| """ |
| return t[0][1:-1] |
|
|
|
|
| def with_attribute(*args: tuple[str, str], **attr_dict) -> ParseAction: |
| """ |
| Helper to create a validating parse action to be used with start |
| tags created with :class:`make_xml_tags` or |
| :class:`make_html_tags`. Use ``with_attribute`` to qualify |
| a starting tag with a required attribute value, to avoid false |
| matches on common tags such as ``<TD>`` or ``<DIV>``. |
| |
| Call ``with_attribute`` with a series of attribute names and |
| values. Specify the list of filter attributes names and values as: |
| |
| - keyword arguments, as in ``(align="right")``, or |
| - as an explicit dict with ``**`` operator, when an attribute |
| name is also a Python reserved word, as in ``**{"class":"Customer", "align":"right"}`` |
| - a list of name-value tuples, as in ``(("ns1:class", "Customer"), ("ns2:align", "right"))`` |
| |
| For attribute names with a namespace prefix, you must use the second |
| form. Attribute names are matched insensitive to upper/lower case. |
| |
| If just testing for ``class`` (with or without a namespace), use |
| :class:`with_class`. |
| |
| To verify that the attribute exists, but without specifying a value, |
| pass ``with_attribute.ANY_VALUE`` as the value. |
| |
| The next two examples use the following input data and tag parsers: |
| |
| .. testcode:: |
| |
| html = ''' |
| <div> |
| Some text |
| <div type="grid">1 4 0 1 0</div> |
| <div type="graph">1,3 2,3 1,1</div> |
| <div>this has no type</div> |
| </div> |
| ''' |
| div,div_end = make_html_tags("div") |
| |
| Only match div tag having a type attribute with value "grid": |
| |
| .. testcode:: |
| |
| div_grid = div().set_parse_action(with_attribute(type="grid")) |
| grid_expr = div_grid + SkipTo(div | div_end)("body") |
| for grid_header in grid_expr.search_string(html): |
| print(grid_header.body) |
| |
| prints: |
| |
| .. testoutput:: |
| |
| 1 4 0 1 0 |
| |
| Construct a match with any div tag having a type attribute, |
| regardless of the value: |
| |
| .. testcode:: |
| |
| div_any_type = div().set_parse_action( |
| with_attribute(type=with_attribute.ANY_VALUE) |
| ) |
| div_expr = div_any_type + SkipTo(div | div_end)("body") |
| for div_header in div_expr.search_string(html): |
| print(div_header.body) |
| |
| prints: |
| |
| .. testoutput:: |
| |
| 1 4 0 1 0 |
| 1,3 2,3 1,1 |
| """ |
| attrs_list: list[tuple[str, str]] = [] |
| if args: |
| attrs_list.extend(args) |
| else: |
| attrs_list.extend(attr_dict.items()) |
|
|
| def pa(s: str, l: int, tokens: ParseResults) -> None: |
| for attrName, attrValue in attrs_list: |
| if attrName not in tokens: |
| raise ParseException(s, l, "no matching attribute " + attrName) |
| if attrValue != with_attribute.ANY_VALUE and tokens[attrName] != attrValue: |
| raise ParseException( |
| s, |
| l, |
| f"attribute {attrName!r} has value {tokens[attrName]!r}, must be {attrValue!r}", |
| ) |
|
|
| return pa |
|
|
|
|
| with_attribute.ANY_VALUE = object() |
| "Value to use with :class:`with_attribute` parse action, to match any value, as long as the attribute is present" |
|
|
|
|
| def with_class(classname: str, namespace: str = "") -> ParseAction: |
| """ |
| Simplified version of :meth:`with_attribute` when |
| matching on a div class - made difficult because ``class`` is |
| a reserved word in Python. |
| |
| Using similar input data to the :meth:`with_attribute` examples: |
| |
| .. testcode:: |
| |
| html = ''' |
| <div> |
| Some text |
| <div class="grid">1 4 0 1 0</div> |
| <div class="graph">1,3 2,3 1,1</div> |
| <div>this <div> has no class</div> |
| </div> |
| ''' |
| div,div_end = make_html_tags("div") |
| |
| Only match div tag having the "grid" class: |
| |
| .. testcode:: |
| |
| div_grid = div().set_parse_action(with_class("grid")) |
| grid_expr = div_grid + SkipTo(div | div_end)("body") |
| for grid_header in grid_expr.search_string(html): |
| print(grid_header.body) |
| |
| prints: |
| |
| .. testoutput:: |
| |
| 1 4 0 1 0 |
| |
| Construct a match with any div tag having a class attribute, |
| regardless of the value: |
| |
| .. testcode:: |
| |
| div_any_type = div().set_parse_action( |
| with_class(withAttribute.ANY_VALUE) |
| ) |
| div_expr = div_any_type + SkipTo(div | div_end)("body") |
| for div_header in div_expr.search_string(html): |
| print(div_header.body) |
| |
| prints: |
| |
| .. testoutput:: |
| |
| 1 4 0 1 0 |
| 1,3 2,3 1,1 |
| """ |
| classattr = f"{namespace}:class" if namespace else "class" |
| return with_attribute(**{classattr: classname}) |
|
|
|
|
| |
| |
| replaceWith = replaced_by_pep8("replaceWith", replace_with) |
| removeQuotes = replaced_by_pep8("removeQuotes", remove_quotes) |
| withAttribute = replaced_by_pep8("withAttribute", with_attribute) |
| withClass = replaced_by_pep8("withClass", with_class) |
| matchOnlyAtCol = replaced_by_pep8("matchOnlyAtCol", match_only_at_col) |
| |
|
|
