thanks to vye16 ❤

fb5159d over 2 years ago

46.7 kB

	import io
	import json
	import platform
	import re
	import sys
	import tokenize
	import traceback
	from contextlib import contextmanager
	from dataclasses import replace
	from datetime import datetime
	from enum import Enum
	from json.decoder import JSONDecodeError
	from pathlib import Path
	from typing import (
	Any,
	Dict,
	Generator,
	Iterator,
	List,
	MutableMapping,
	Optional,
	Pattern,
	Sequence,
	Set,
	Sized,
	Tuple,
	Union,
	)

	import click
	from click.core import ParameterSource
	from mypy_extensions import mypyc_attr
	from pathspec import PathSpec
	from pathspec.patterns.gitwildmatch import GitWildMatchPatternError

	from _black_version import version as __version__
	from black.cache import Cache, get_cache_info, read_cache, write_cache
	from black.comments import normalize_fmt_off
	from black.const import (
	DEFAULT_EXCLUDES,
	DEFAULT_INCLUDES,
	DEFAULT_LINE_LENGTH,
	STDIN_PLACEHOLDER,
	)
	from black.files import (
	find_project_root,
	find_pyproject_toml,
	find_user_pyproject_toml,
	gen_python_files,
	get_gitignore,
	normalize_path_maybe_ignore,
	parse_pyproject_toml,
	wrap_stream_for_windows,
	)
	from black.handle_ipynb_magics import (
	PYTHON_CELL_MAGICS,
	TRANSFORMED_MAGICS,
	jupyter_dependencies_are_installed,
	mask_cell,
	put_trailing_semicolon_back,
	remove_trailing_semicolon,
	unmask_cell,
	)
	from black.linegen import LN, LineGenerator, transform_line
	from black.lines import EmptyLineTracker, LinesBlock
	from black.mode import (
	FUTURE_FLAG_TO_FEATURE,
	VERSION_TO_FEATURES,
	Feature,
	Mode,
	TargetVersion,
	supports_feature,
	)
	from black.nodes import (
	STARS,
	is_number_token,
	is_simple_decorator_expression,
	is_string_token,
	syms,
	)
	from black.output import color_diff, diff, dump_to_file, err, ipynb_diff, out
	from black.parsing import InvalidInput # noqa F401
	from black.parsing import lib2to3_parse, parse_ast, stringify_ast
	from black.report import Changed, NothingChanged, Report
	from black.trans import iter_fexpr_spans
	from blib2to3.pgen2 import token
	from blib2to3.pytree import Leaf, Node

	COMPILED = Path(__file__).suffix in (".pyd", ".so")

	# types
	FileContent = str
	Encoding = str
	NewLine = str


	class WriteBack(Enum):
	NO = 0
	YES = 1
	DIFF = 2
	CHECK = 3
	COLOR_DIFF = 4

	@classmethod
	def from_configuration(
	cls, *, check: bool, diff: bool, color: bool = False
	) -> "WriteBack":
	if check and not diff:
	return cls.CHECK

	if diff and color:
	return cls.COLOR_DIFF

	return cls.DIFF if diff else cls.YES


	# Legacy name, left for integrations.
	FileMode = Mode


	def read_pyproject_toml(
	ctx: click.Context, param: click.Parameter, value: Optional[str]
	) -> Optional[str]:
	"""Inject Black configuration from "pyproject.toml" into defaults in `ctx`.

	Returns the path to a successfully found and read configuration file, None
	otherwise.
	"""
	if not value:
	value = find_pyproject_toml(ctx.params.get("src", ()))
	if value is None:
	return None

	try:
	config = parse_pyproject_toml(value)
	except (OSError, ValueError) as e:
	raise click.FileError(
	filename=value, hint=f"Error reading configuration file: {e}"
	) from None

	if not config:
	return None
	else:
	# Sanitize the values to be Click friendly. For more information please see:
	# https://github.com/psf/black/issues/1458
	# https://github.com/pallets/click/issues/1567
	config = {
	k: str(v) if not isinstance(v, (list, dict)) else v
	for k, v in config.items()
	}

	target_version = config.get("target_version")
	if target_version is not None and not isinstance(target_version, list):
	raise click.BadOptionUsage(
	"target-version", "Config key target-version must be a list"
	)

	default_map: Dict[str, Any] = {}
	if ctx.default_map:
	default_map.update(ctx.default_map)
	default_map.update(config)

	ctx.default_map = default_map
	return value


	def target_version_option_callback(
	c: click.Context, p: Union[click.Option, click.Parameter], v: Tuple[str, ...]
	) -> List[TargetVersion]:
	"""Compute the target versions from a --target-version flag.

	This is its own function because mypy couldn't infer the type correctly
	when it was a lambda, causing mypyc trouble.
	"""
	return [TargetVersion[val.upper()] for val in v]


	def re_compile_maybe_verbose(regex: str) -> Pattern[str]:
	"""Compile a regular expression string in `regex`.

	If it contains newlines, use verbose mode.
	"""
	if "\n" in regex:
	regex = "(?x)" + regex
	compiled: Pattern[str] = re.compile(regex)
	return compiled


	def validate_regex(
	ctx: click.Context,
	param: click.Parameter,
	value: Optional[str],
	) -> Optional[Pattern[str]]:
	try:
	return re_compile_maybe_verbose(value) if value is not None else None
	except re.error as e:
	raise click.BadParameter(f"Not a valid regular expression: {e}") from None


	@click.command(
	context_settings={"help_option_names": ["-h", "--help"]},
	# While Click does set this field automatically using the docstring, mypyc
	# (annoyingly) strips 'em so we need to set it here too.
	help="The uncompromising code formatter.",
	)
	@click.option("-c", "--code", type=str, help="Format the code passed in as a string.")
	@click.option(
	"-l",
	"--line-length",
	type=int,
	default=DEFAULT_LINE_LENGTH,
	help="How many characters per line to allow.",
	show_default=True,
	)
	@click.option(
	"-t",
	"--target-version",
	type=click.Choice([v.name.lower() for v in TargetVersion]),
	callback=target_version_option_callback,
	multiple=True,
	help=(
	"Python versions that should be supported by Black's output. By default, Black"
	" will try to infer this from the project metadata in pyproject.toml. If this"
	" does not yield conclusive results, Black will use per-file auto-detection."
	),
	)
	@click.option(
	"--pyi",
	is_flag=True,
	help=(
	"Format all input files like typing stubs regardless of file extension (useful"
	" when piping source on standard input)."
	),
	)
	@click.option(
	"--ipynb",
	is_flag=True,
	help=(
	"Format all input files like Jupyter Notebooks regardless of file extension "
	"(useful when piping source on standard input)."
	),
	)
	@click.option(
	"--python-cell-magics",
	multiple=True,
	help=(
	"When processing Jupyter Notebooks, add the given magic to the list"
	f" of known python-magics ({', '.join(sorted(PYTHON_CELL_MAGICS))})."
	" Useful for formatting cells with custom python magics."
	),
	default=[],
	)
	@click.option(
	"-x",
	"--skip-source-first-line",
	is_flag=True,
	help="Skip the first line of the source code.",
	)
	@click.option(
	"-S",
	"--skip-string-normalization",
	is_flag=True,
	help="Don't normalize string quotes or prefixes.",
	)
	@click.option(
	"-C",
	"--skip-magic-trailing-comma",
	is_flag=True,
	help="Don't use trailing commas as a reason to split lines.",
	)
	@click.option(
	"--experimental-string-processing",
	is_flag=True,
	hidden=True,
	help="(DEPRECATED and now included in --preview) Normalize string literals.",
	)
	@click.option(
	"--preview",
	is_flag=True,
	help=(
	"Enable potentially disruptive style changes that may be added to Black's main"
	" functionality in the next major release."
	),
	)
	@click.option(
	"--check",
	is_flag=True,
	help=(
	"Don't write the files back, just return the status. Return code 0 means"
	" nothing would change. Return code 1 means some files would be reformatted."
	" Return code 123 means there was an internal error."
	),
	)
	@click.option(
	"--diff",
	is_flag=True,
	help="Don't write the files back, just output a diff for each file on stdout.",
	)
	@click.option(
	"--color/--no-color",
	is_flag=True,
	help="Show colored diff. Only applies when `--diff` is given.",
	)
	@click.option(
	"--fast/--safe",
	is_flag=True,
	help="If --fast given, skip temporary sanity checks. [default: --safe]",
	)
	@click.option(
	"--required-version",
	type=str,
	help=(
	"Require a specific version of Black to be running (useful for unifying results"
	" across many environments e.g. with a pyproject.toml file). It can be"
	" either a major version number or an exact version."
	),
	)
	@click.option(
	"--include",
	type=str,
	default=DEFAULT_INCLUDES,
	callback=validate_regex,
	help=(
	"A regular expression that matches files and directories that should be"
	" included on recursive searches. An empty value means all files are included"
	" regardless of the name. Use forward slashes for directories on all platforms"
	" (Windows, too). Exclusions are calculated first, inclusions later."
	),
	show_default=True,
	)
	@click.option(
	"--exclude",
	type=str,
	callback=validate_regex,
	help=(
	"A regular expression that matches files and directories that should be"
	" excluded on recursive searches. An empty value means no paths are excluded."
	" Use forward slashes for directories on all platforms (Windows, too)."
	" Exclusions are calculated first, inclusions later. [default:"
	f" {DEFAULT_EXCLUDES}]"
	),
	show_default=False,
	)
	@click.option(
	"--extend-exclude",
	type=str,
	callback=validate_regex,
	help=(
	"Like --exclude, but adds additional files and directories on top of the"
	" excluded ones. (Useful if you simply want to add to the default)"
	),
	)
	@click.option(
	"--force-exclude",
	type=str,
	callback=validate_regex,
	help=(
	"Like --exclude, but files and directories matching this regex will be "
	"excluded even when they are passed explicitly as arguments."
	),
	)
	@click.option(
	"--stdin-filename",
	type=str,
	help=(
	"The name of the file when passing it through stdin. Useful to make "
	"sure Black will respect --force-exclude option on some "
	"editors that rely on using stdin."
	),
	)
	@click.option(
	"-W",
	"--workers",
	type=click.IntRange(min=1),
	default=None,
	help="Number of parallel workers [default: number of CPUs in the system]",
	)
	@click.option(
	"-q",
	"--quiet",
	is_flag=True,
	help=(
	"Don't emit non-error messages to stderr. Errors are still emitted; silence"
	" those with 2>/dev/null."
	),
	)
	@click.option(
	"-v",
	"--verbose",
	is_flag=True,
	help=(
	"Also emit messages to stderr about files that were not changed or were ignored"
	" due to exclusion patterns."
	),
	)
	@click.version_option(
	version=__version__,
	message=(
	f"%(prog)s, %(version)s (compiled: {'yes' if COMPILED else 'no'})\n"
	f"Python ({platform.python_implementation()}) {platform.python_version()}"
	),
	)
	@click.argument(
	"src",
	nargs=-1,
	type=click.Path(
	exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True
	),
	is_eager=True,
	metavar="SRC ...",
	)
	@click.option(
	"--config",
	type=click.Path(
	exists=True,
	file_okay=True,
	dir_okay=False,
	readable=True,
	allow_dash=False,
	path_type=str,
	),
	is_eager=True,
	callback=read_pyproject_toml,
	help="Read configuration from FILE path.",
	)
	@click.pass_context
	def main( # noqa: C901
	ctx: click.Context,
	code: Optional[str],
	line_length: int,
	target_version: List[TargetVersion],
	check: bool,
	diff: bool,
	color: bool,
	fast: bool,
	pyi: bool,
	ipynb: bool,
	python_cell_magics: Sequence[str],
	skip_source_first_line: bool,
	skip_string_normalization: bool,
	skip_magic_trailing_comma: bool,
	experimental_string_processing: bool,
	preview: bool,
	quiet: bool,
	verbose: bool,
	required_version: Optional[str],
	include: Pattern[str],
	exclude: Optional[Pattern[str]],
	extend_exclude: Optional[Pattern[str]],
	force_exclude: Optional[Pattern[str]],
	stdin_filename: Optional[str],
	workers: Optional[int],
	src: Tuple[str, ...],
	config: Optional[str],
	) -> None:
	"""The uncompromising code formatter."""
	ctx.ensure_object(dict)

	if src and code is not None:
	out(
	main.get_usage(ctx)
	+ "\n\n'SRC' and 'code' cannot be passed simultaneously."
	)
	ctx.exit(1)
	if not src and code is None:
	out(main.get_usage(ctx) + "\n\nOne of 'SRC' or 'code' is required.")
	ctx.exit(1)

	root, method = (
	find_project_root(src, stdin_filename) if code is None else (None, None)
	)
	ctx.obj["root"] = root

	if verbose:
	if root:
	out(
	f"Identified `{root}` as project root containing a {method}.",
	fg="blue",
	)

	normalized = [
	(
	(source, source)
	if source == "-"
	else (normalize_path_maybe_ignore(Path(source), root), source)
	)
	for source in src
	]
	srcs_string = ", ".join(
	[
	(
	f'"{_norm}"'
	if _norm
	else f'\033[31m"{source} (skipping - invalid)"\033[34m'
	)
	for _norm, source in normalized
	]
	)
	out(f"Sources to be formatted: {srcs_string}", fg="blue")

	if config:
	config_source = ctx.get_parameter_source("config")
	user_level_config = str(find_user_pyproject_toml())
	if config == user_level_config:
	out(
	(
	"Using configuration from user-level config at "
	f"'{user_level_config}'."
	),
	fg="blue",
	)
	elif config_source in (
	ParameterSource.DEFAULT,
	ParameterSource.DEFAULT_MAP,
	):
	out("Using configuration from project root.", fg="blue")
	else:
	out(f"Using configuration in '{config}'.", fg="blue")
	if ctx.default_map:
	for param, value in ctx.default_map.items():
	out(f"{param}: {value}")

	error_msg = "Oh no! 💥 💔 💥"
	if (
	required_version
	and required_version != __version__
	and required_version != __version__.split(".")[0]
	):
	err(
	f"{error_msg} The required version `{required_version}` does not match"
	f" the running version `{__version__}`!"
	)
	ctx.exit(1)
	if ipynb and pyi:
	err("Cannot pass both `pyi` and `ipynb` flags!")
	ctx.exit(1)

	write_back = WriteBack.from_configuration(check=check, diff=diff, color=color)
	if target_version:
	versions = set(target_version)
	else:
	# We'll autodetect later.
	versions = set()
	mode = Mode(
	target_versions=versions,
	line_length=line_length,
	is_pyi=pyi,
	is_ipynb=ipynb,
	skip_source_first_line=skip_source_first_line,
	string_normalization=not skip_string_normalization,
	magic_trailing_comma=not skip_magic_trailing_comma,
	experimental_string_processing=experimental_string_processing,
	preview=preview,
	python_cell_magics=set(python_cell_magics),
	)

	if code is not None:
	# Run in quiet mode by default with -c; the extra output isn't useful.
	# You can still pass -v to get verbose output.
	quiet = True

	report = Report(check=check, diff=diff, quiet=quiet, verbose=verbose)

	if code is not None:
	reformat_code(
	content=code, fast=fast, write_back=write_back, mode=mode, report=report
	)
	else:
	try:
	sources = get_sources(
	ctx=ctx,
	src=src,
	quiet=quiet,
	verbose=verbose,
	include=include,
	exclude=exclude,
	extend_exclude=extend_exclude,
	force_exclude=force_exclude,
	report=report,
	stdin_filename=stdin_filename,
	)
	except GitWildMatchPatternError:
	ctx.exit(1)

	path_empty(
	sources,
	"No Python files are present to be formatted. Nothing to do 😴",
	quiet,
	verbose,
	ctx,
	)

	if len(sources) == 1:
	reformat_one(
	src=sources.pop(),
	fast=fast,
	write_back=write_back,
	mode=mode,
	report=report,
	)
	else:
	from black.concurrency import reformat_many

	reformat_many(
	sources=sources,
	fast=fast,
	write_back=write_back,
	mode=mode,
	report=report,
	workers=workers,
	)

	if verbose or not quiet:
	if code is None and (verbose or report.change_count or report.failure_count):
	out()
	out(error_msg if report.return_code else "All done! ✨ 🍰 ✨")
	if code is None:
	click.echo(str(report), err=True)
	ctx.exit(report.return_code)


	def get_sources(
	*,
	ctx: click.Context,
	src: Tuple[str, ...],
	quiet: bool,
	verbose: bool,
	include: Pattern[str],
	exclude: Optional[Pattern[str]],
	extend_exclude: Optional[Pattern[str]],
	force_exclude: Optional[Pattern[str]],
	report: "Report",
	stdin_filename: Optional[str],
	) -> Set[Path]:
	"""Compute the set of files to be formatted."""
	sources: Set[Path] = set()
	root = ctx.obj["root"]

	using_default_exclude = exclude is None
	exclude = re_compile_maybe_verbose(DEFAULT_EXCLUDES) if exclude is None else exclude
	gitignore: Optional[Dict[Path, PathSpec]] = None
	root_gitignore = get_gitignore(root)

	for s in src:
	if s == "-" and stdin_filename:
	p = Path(stdin_filename)
	is_stdin = True
	else:
	p = Path(s)
	is_stdin = False

	if is_stdin or p.is_file():
	normalized_path = normalize_path_maybe_ignore(p, ctx.obj["root"], report)
	if normalized_path is None:
	continue

	normalized_path = "/" + normalized_path
	# Hard-exclude any files that matches the `--force-exclude` regex.
	if force_exclude:
	force_exclude_match = force_exclude.search(normalized_path)
	else:
	force_exclude_match = None
	if force_exclude_match and force_exclude_match.group(0):
	report.path_ignored(p, "matches the --force-exclude regular expression")
	continue

	if is_stdin:
	p = Path(f"{STDIN_PLACEHOLDER}{str(p)}")

	if p.suffix == ".ipynb" and not jupyter_dependencies_are_installed(
	verbose=verbose, quiet=quiet
	):
	continue

	sources.add(p)
	elif p.is_dir():
	p = root / normalize_path_maybe_ignore(p, ctx.obj["root"], report)
	if using_default_exclude:
	gitignore = {
	root: root_gitignore,
	p: get_gitignore(p),
	}
	sources.update(
	gen_python_files(
	p.iterdir(),
	ctx.obj["root"],
	include,
	exclude,
	extend_exclude,
	force_exclude,
	report,
	gitignore,
	verbose=verbose,
	quiet=quiet,
	)
	)
	elif s == "-":
	sources.add(p)
	else:
	err(f"invalid path: {s}")
	return sources


	def path_empty(
	src: Sized, msg: str, quiet: bool, verbose: bool, ctx: click.Context
	) -> None:
	"""
	Exit if there is no `src` provided for formatting
	"""
	if not src:
	if verbose or not quiet:
	out(msg)
	ctx.exit(0)


	def reformat_code(
	content: str, fast: bool, write_back: WriteBack, mode: Mode, report: Report
	) -> None:
	"""
	Reformat and print out `content` without spawning child processes.
	Similar to `reformat_one`, but for string content.

	`fast`, `write_back`, and `mode` options are passed to
	:func:`format_file_in_place` or :func:`format_stdin_to_stdout`.
	"""
	path = Path("<string>")
	try:
	changed = Changed.NO
	if format_stdin_to_stdout(
	content=content, fast=fast, write_back=write_back, mode=mode
	):
	changed = Changed.YES
	report.done(path, changed)
	except Exception as exc:
	if report.verbose:
	traceback.print_exc()
	report.failed(path, str(exc))


	# diff-shades depends on being to monkeypatch this function to operate. I know it's
	# not ideal, but this shouldn't cause any issues ... hopefully. ~ichard26
	@mypyc_attr(patchable=True)
	def reformat_one(
	src: Path, fast: bool, write_back: WriteBack, mode: Mode, report: "Report"
	) -> None:
	"""Reformat a single file under `src` without spawning child processes.

	`fast`, `write_back`, and `mode` options are passed to
	:func:`format_file_in_place` or :func:`format_stdin_to_stdout`.
	"""
	try:
	changed = Changed.NO

	if str(src) == "-":
	is_stdin = True
	elif str(src).startswith(STDIN_PLACEHOLDER):
	is_stdin = True
	# Use the original name again in case we want to print something
	# to the user
	src = Path(str(src)[len(STDIN_PLACEHOLDER) :])
	else:
	is_stdin = False

	if is_stdin:
	if src.suffix == ".pyi":
	mode = replace(mode, is_pyi=True)
	elif src.suffix == ".ipynb":
	mode = replace(mode, is_ipynb=True)
	if format_stdin_to_stdout(fast=fast, write_back=write_back, mode=mode):
	changed = Changed.YES
	else:
	cache: Cache = {}
	if write_back not in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
	cache = read_cache(mode)
	res_src = src.resolve()
	res_src_s = str(res_src)
	if res_src_s in cache and cache[res_src_s] == get_cache_info(res_src):
	changed = Changed.CACHED
	if changed is not Changed.CACHED and format_file_in_place(
	src, fast=fast, write_back=write_back, mode=mode
	):
	changed = Changed.YES
	if (write_back is WriteBack.YES and changed is not Changed.CACHED) or (
	write_back is WriteBack.CHECK and changed is Changed.NO
	):
	write_cache(cache, [src], mode)
	report.done(src, changed)
	except Exception as exc:
	if report.verbose:
	traceback.print_exc()
	report.failed(src, str(exc))


	def format_file_in_place(
	src: Path,
	fast: bool,
	mode: Mode,
	write_back: WriteBack = WriteBack.NO,
	lock: Any = None, # multiprocessing.Manager().Lock() is some crazy proxy
	) -> bool:
	"""Format file under `src` path. Return True if changed.

	If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted
	code to the file.
	`mode` and `fast` options are passed to :func:`format_file_contents`.
	"""
	if src.suffix == ".pyi":
	mode = replace(mode, is_pyi=True)
	elif src.suffix == ".ipynb":
	mode = replace(mode, is_ipynb=True)

	then = datetime.utcfromtimestamp(src.stat().st_mtime)
	header = b""
	with open(src, "rb") as buf:
	if mode.skip_source_first_line:
	header = buf.readline()
	src_contents, encoding, newline = decode_bytes(buf.read())
	try:
	dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)
	except NothingChanged:
	return False
	except JSONDecodeError:
	raise ValueError(
	f"File '{src}' cannot be parsed as valid Jupyter notebook."
	) from None
	src_contents = header.decode(encoding) + src_contents
	dst_contents = header.decode(encoding) + dst_contents

	if write_back == WriteBack.YES:
	with open(src, "w", encoding=encoding, newline=newline) as f:
	f.write(dst_contents)
	elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
	now = datetime.utcnow()
	src_name = f"{src}\t{then} +0000"
	dst_name = f"{src}\t{now} +0000"
	if mode.is_ipynb:
	diff_contents = ipynb_diff(src_contents, dst_contents, src_name, dst_name)
	else:
	diff_contents = diff(src_contents, dst_contents, src_name, dst_name)

	if write_back == WriteBack.COLOR_DIFF:
	diff_contents = color_diff(diff_contents)

	with lock or nullcontext():
	f = io.TextIOWrapper(
	sys.stdout.buffer,
	encoding=encoding,
	newline=newline,
	write_through=True,
	)
	f = wrap_stream_for_windows(f)
	f.write(diff_contents)
	f.detach()

	return True


	def format_stdin_to_stdout(
	fast: bool,
	*,
	content: Optional[str] = None,
	write_back: WriteBack = WriteBack.NO,
	mode: Mode,
	) -> bool:
	"""Format file on stdin. Return True if changed.

	If content is None, it's read from sys.stdin.

	If `write_back` is YES, write reformatted code back to stdout. If it is DIFF,
	write a diff to stdout. The `mode` argument is passed to
	:func:`format_file_contents`.
	"""
	then = datetime.utcnow()

	if content is None:
	src, encoding, newline = decode_bytes(sys.stdin.buffer.read())
	else:
	src, encoding, newline = content, "utf-8", ""

	dst = src
	try:
	dst = format_file_contents(src, fast=fast, mode=mode)
	return True

	except NothingChanged:
	return False

	finally:
	f = io.TextIOWrapper(
	sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True
	)
	if write_back == WriteBack.YES:
	# Make sure there's a newline after the content
	if dst and dst[-1] != "\n":
	dst += "\n"
	f.write(dst)
	elif write_back in (WriteBack.DIFF, WriteBack.COLOR_DIFF):
	now = datetime.utcnow()
	src_name = f"STDIN\t{then} +0000"
	dst_name = f"STDOUT\t{now} +0000"
	d = diff(src, dst, src_name, dst_name)
	if write_back == WriteBack.COLOR_DIFF:
	d = color_diff(d)
	f = wrap_stream_for_windows(f)
	f.write(d)
	f.detach()


	def check_stability_and_equivalence(
	src_contents: str, dst_contents: str, *, mode: Mode
	) -> None:
	"""Perform stability and equivalence checks.

	Raise AssertionError if source and destination contents are not
	equivalent, or if a second pass of the formatter would format the
	content differently.
	"""
	assert_equivalent(src_contents, dst_contents)
	assert_stable(src_contents, dst_contents, mode=mode)


	def format_file_contents(src_contents: str, *, fast: bool, mode: Mode) -> FileContent:
	"""Reformat contents of a file and return new contents.

	If `fast` is False, additionally confirm that the reformatted code is
	valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
	`mode` is passed to :func:`format_str`.
	"""
	if mode.is_ipynb:
	dst_contents = format_ipynb_string(src_contents, fast=fast, mode=mode)
	else:
	dst_contents = format_str(src_contents, mode=mode)
	if src_contents == dst_contents:
	raise NothingChanged

	if not fast and not mode.is_ipynb:
	# Jupyter notebooks will already have been checked above.
	check_stability_and_equivalence(src_contents, dst_contents, mode=mode)
	return dst_contents


	def validate_cell(src: str, mode: Mode) -> None:
	"""Check that cell does not already contain TransformerManager transformations,
	or non-Python cell magics, which might cause tokenizer_rt to break because of
	indentations.

	If a cell contains ``!ls``, then it'll be transformed to
	``get_ipython().system('ls')``. However, if the cell originally contained
	``get_ipython().system('ls')``, then it would get transformed in the same way:

	>>> TransformerManager().transform_cell("get_ipython().system('ls')")
	"get_ipython().system('ls')\n"
	>>> TransformerManager().transform_cell("!ls")
	"get_ipython().system('ls')\n"

	Due to the impossibility of safely roundtripping in such situations, cells
	containing transformed magics will be ignored.
	"""
	if any(transformed_magic in src for transformed_magic in TRANSFORMED_MAGICS):
	raise NothingChanged
	if (
	src[:2] == "%%"
	and src.split()[0][2:] not in PYTHON_CELL_MAGICS \| mode.python_cell_magics
	):
	raise NothingChanged


	def format_cell(src: str, *, fast: bool, mode: Mode) -> str:
	"""Format code in given cell of Jupyter notebook.

	General idea is:

	- if cell has trailing semicolon, remove it;
	- if cell has IPython magics, mask them;
	- format cell;
	- reinstate IPython magics;
	- reinstate trailing semicolon (if originally present);
	- strip trailing newlines.

	Cells with syntax errors will not be processed, as they
	could potentially be automagics or multi-line magics, which
	are currently not supported.
	"""
	validate_cell(src, mode)
	src_without_trailing_semicolon, has_trailing_semicolon = remove_trailing_semicolon(
	src
	)
	try:
	masked_src, replacements = mask_cell(src_without_trailing_semicolon)
	except SyntaxError:
	raise NothingChanged from None
	masked_dst = format_str(masked_src, mode=mode)
	if not fast:
	check_stability_and_equivalence(masked_src, masked_dst, mode=mode)
	dst_without_trailing_semicolon = unmask_cell(masked_dst, replacements)
	dst = put_trailing_semicolon_back(
	dst_without_trailing_semicolon, has_trailing_semicolon
	)
	dst = dst.rstrip("\n")
	if dst == src:
	raise NothingChanged from None
	return dst


	def validate_metadata(nb: MutableMapping[str, Any]) -> None:
	"""If notebook is marked as non-Python, don't format it.

	All notebook metadata fields are optional, see
	https://nbformat.readthedocs.io/en/latest/format_description.html. So
	if a notebook has empty metadata, we will try to parse it anyway.
	"""
	language = nb.get("metadata", {}).get("language_info", {}).get("name", None)
	if language is not None and language != "python":
	raise NothingChanged from None


	def format_ipynb_string(src_contents: str, *, fast: bool, mode: Mode) -> FileContent:
	"""Format Jupyter notebook.

	Operate cell-by-cell, only on code cells, only for Python notebooks.
	If the ``.ipynb`` originally had a trailing newline, it'll be preserved.
	"""
	if not src_contents:
	raise NothingChanged

	trailing_newline = src_contents[-1] == "\n"
	modified = False
	nb = json.loads(src_contents)
	validate_metadata(nb)
	for cell in nb["cells"]:
	if cell.get("cell_type", None) == "code":
	try:
	src = "".join(cell["source"])
	dst = format_cell(src, fast=fast, mode=mode)
	except NothingChanged:
	pass
	else:
	cell["source"] = dst.splitlines(keepends=True)
	modified = True
	if modified:
	dst_contents = json.dumps(nb, indent=1, ensure_ascii=False)
	if trailing_newline:
	dst_contents = dst_contents + "\n"
	return dst_contents
	else:
	raise NothingChanged


	def format_str(src_contents: str, *, mode: Mode) -> str:
	"""Reformat a string and return new contents.

	`mode` determines formatting options, such as how many characters per line are
	allowed. Example:

	>>> import black
	>>> print(black.format_str("def f(arg:str='')->None:...", mode=black.Mode()))
	def f(arg: str = "") -> None:
	...

	A more complex example:

	>>> print(
	... black.format_str(
	... "def f(arg:str='')->None: hey",
	... mode=black.Mode(
	... target_versions={black.TargetVersion.PY36},
	... line_length=10,
	... string_normalization=False,
	... is_pyi=False,
	... ),
	... ),
	... )
	def f(
	arg: str = '',
	) -> None:
	hey

	"""
	dst_contents = _format_str_once(src_contents, mode=mode)
	# Forced second pass to work around optional trailing commas (becoming
	# forced trailing commas on pass 2) interacting differently with optional
	# parentheses. Admittedly ugly.
	if src_contents != dst_contents:
	return _format_str_once(dst_contents, mode=mode)
	return dst_contents


	def _format_str_once(src_contents: str, *, mode: Mode) -> str:
	src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
	dst_blocks: List[LinesBlock] = []
	if mode.target_versions:
	versions = mode.target_versions
	else:
	future_imports = get_future_imports(src_node)
	versions = detect_target_versions(src_node, future_imports=future_imports)

	context_manager_features = {
	feature
	for feature in {Feature.PARENTHESIZED_CONTEXT_MANAGERS}
	if supports_feature(versions, feature)
	}
	normalize_fmt_off(src_node)
	lines = LineGenerator(mode=mode, features=context_manager_features)
	elt = EmptyLineTracker(mode=mode)
	split_line_features = {
	feature
	for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
	if supports_feature(versions, feature)
	}
	block: Optional[LinesBlock] = None
	for current_line in lines.visit(src_node):
	block = elt.maybe_empty_lines(current_line)
	dst_blocks.append(block)
	for line in transform_line(
	current_line, mode=mode, features=split_line_features
	):
	block.content_lines.append(str(line))
	if dst_blocks:
	dst_blocks[-1].after = 0
	dst_contents = []
	for block in dst_blocks:
	dst_contents.extend(block.all_lines())
	if not dst_contents:
	# Use decode_bytes to retrieve the correct source newline (CRLF or LF),
	# and check if normalized_content has more than one line
	normalized_content, _, newline = decode_bytes(src_contents.encode("utf-8"))
	if "\n" in normalized_content:
	return newline
	return ""
	return "".join(dst_contents)


	def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
	"""Return a tuple of (decoded_contents, encoding, newline).

	`newline` is either CRLF or LF but `decoded_contents` is decoded with
	universal newlines (i.e. only contains LF).
	"""
	srcbuf = io.BytesIO(src)
	encoding, lines = tokenize.detect_encoding(srcbuf.readline)
	if not lines:
	return "", encoding, "\n"

	newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
	srcbuf.seek(0)
	with io.TextIOWrapper(srcbuf, encoding) as tiow:
	return tiow.read(), encoding, newline


	def get_features_used( # noqa: C901
	node: Node, *, future_imports: Optional[Set[str]] = None
	) -> Set[Feature]:
	"""Return a set of (relatively) new Python features used in this file.

	Currently looking for:
	- f-strings;
	- self-documenting expressions in f-strings (f"{x=}");
	- underscores in numeric literals;
	- trailing commas after * or ** in function signatures and calls;
	- positional only arguments in function signatures and lambdas;
	- assignment expression;
	- relaxed decorator syntax;
	- usage of __future__ flags (annotations);
	- print / exec statements;
	- parenthesized context managers;
	- match statements;
	- except* clause;
	- variadic generics;
	"""
	features: Set[Feature] = set()
	if future_imports:
	features \|= {
	FUTURE_FLAG_TO_FEATURE[future_import]
	for future_import in future_imports
	if future_import in FUTURE_FLAG_TO_FEATURE
	}

	for n in node.pre_order():
	if is_string_token(n):
	value_head = n.value[:2]
	if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
	features.add(Feature.F_STRINGS)
	if Feature.DEBUG_F_STRINGS not in features:
	for span_beg, span_end in iter_fexpr_spans(n.value):
	if n.value[span_beg : span_end - 1].rstrip().endswith("="):
	features.add(Feature.DEBUG_F_STRINGS)
	break

	elif is_number_token(n):
	if "_" in n.value:
	features.add(Feature.NUMERIC_UNDERSCORES)

	elif n.type == token.SLASH:
	if n.parent and n.parent.type in {
	syms.typedargslist,
	syms.arglist,
	syms.varargslist,
	}:
	features.add(Feature.POS_ONLY_ARGUMENTS)

	elif n.type == token.COLONEQUAL:
	features.add(Feature.ASSIGNMENT_EXPRESSIONS)

	elif n.type == syms.decorator:
	if len(n.children) > 1 and not is_simple_decorator_expression(
	n.children[1]
	):
	features.add(Feature.RELAXED_DECORATORS)

	elif (
	n.type in {syms.typedargslist, syms.arglist}
	and n.children
	and n.children[-1].type == token.COMMA
	):
	if n.type == syms.typedargslist:
	feature = Feature.TRAILING_COMMA_IN_DEF
	else:
	feature = Feature.TRAILING_COMMA_IN_CALL

	for ch in n.children:
	if ch.type in STARS:
	features.add(feature)

	if ch.type == syms.argument:
	for argch in ch.children:
	if argch.type in STARS:
	features.add(feature)

	elif (
	n.type in {syms.return_stmt, syms.yield_expr}
	and len(n.children) >= 2
	and n.children[1].type == syms.testlist_star_expr
	and any(child.type == syms.star_expr for child in n.children[1].children)
	):
	features.add(Feature.UNPACKING_ON_FLOW)

	elif (
	n.type == syms.annassign
	and len(n.children) >= 4
	and n.children[3].type == syms.testlist_star_expr
	):
	features.add(Feature.ANN_ASSIGN_EXTENDED_RHS)

	elif (
	n.type == syms.with_stmt
	and len(n.children) > 2
	and n.children[1].type == syms.atom
	):
	atom_children = n.children[1].children
	if (
	len(atom_children) == 3
	and atom_children[0].type == token.LPAR
	and atom_children[1].type == syms.testlist_gexp
	and atom_children[2].type == token.RPAR
	):
	features.add(Feature.PARENTHESIZED_CONTEXT_MANAGERS)

	elif n.type == syms.match_stmt:
	features.add(Feature.PATTERN_MATCHING)

	elif (
	n.type == syms.except_clause
	and len(n.children) >= 2
	and n.children[1].type == token.STAR
	):
	features.add(Feature.EXCEPT_STAR)

	elif n.type in {syms.subscriptlist, syms.trailer} and any(
	child.type == syms.star_expr for child in n.children
	):
	features.add(Feature.VARIADIC_GENERICS)

	elif (
	n.type == syms.tname_star
	and len(n.children) == 3
	and n.children[2].type == syms.star_expr
	):
	features.add(Feature.VARIADIC_GENERICS)

	return features


	def detect_target_versions(
	node: Node, *, future_imports: Optional[Set[str]] = None
	) -> Set[TargetVersion]:
	"""Detect the version to target based on the nodes used."""
	features = get_features_used(node, future_imports=future_imports)
	return {
	version for version in TargetVersion if features <= VERSION_TO_FEATURES[version]
	}


	def get_future_imports(node: Node) -> Set[str]:
	"""Return a set of __future__ imports in the file."""
	imports: Set[str] = set()

	def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]:
	for child in children:
	if isinstance(child, Leaf):
	if child.type == token.NAME:
	yield child.value

	elif child.type == syms.import_as_name:
	orig_name = child.children[0]
	assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
	assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
	yield orig_name.value

	elif child.type == syms.import_as_names:
	yield from get_imports_from_children(child.children)

	else:
	raise AssertionError("Invalid syntax parsing imports")

	for child in node.children:
	if child.type != syms.simple_stmt:
	break

	first_child = child.children[0]
	if isinstance(first_child, Leaf):
	# Continue looking if we see a docstring; otherwise stop.
	if (
	len(child.children) == 2
	and first_child.type == token.STRING
	and child.children[1].type == token.NEWLINE
	):
	continue

	break

	elif first_child.type == syms.import_from:
	module_name = first_child.children[1]
	if not isinstance(module_name, Leaf) or module_name.value != "__future__":
	break

	imports \|= set(get_imports_from_children(first_child.children[3:]))
	else:
	break

	return imports


	def assert_equivalent(src: str, dst: str) -> None:
	"""Raise AssertionError if `src` and `dst` aren't equivalent."""
	try:
	src_ast = parse_ast(src)
	except Exception as exc:
	raise AssertionError(
	"cannot use --safe with this file; failed to parse source file AST: "
	f"{exc}\n"
	"This could be caused by running Black with an older Python version "
	"that does not support new syntax used in your source file."
	) from exc

	try:
	dst_ast = parse_ast(dst)
	except Exception as exc:
	log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
	raise AssertionError(
	f"INTERNAL ERROR: Black produced invalid code: {exc}. "
	"Please report a bug on https://github.com/psf/black/issues. "
	f"This invalid output might be helpful: {log}"
	) from None

	src_ast_str = "\n".join(stringify_ast(src_ast))
	dst_ast_str = "\n".join(stringify_ast(dst_ast))
	if src_ast_str != dst_ast_str:
	log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
	raise AssertionError(
	"INTERNAL ERROR: Black produced code that is not equivalent to the"
	" source. Please report a bug on "
	f"https://github.com/psf/black/issues. This diff might be helpful: {log}"
	) from None


	def assert_stable(src: str, dst: str, mode: Mode) -> None:
	"""Raise AssertionError if `dst` reformats differently the second time."""
	# We shouldn't call format_str() here, because that formats the string
	# twice and may hide a bug where we bounce back and forth between two
	# versions.
	newdst = _format_str_once(dst, mode=mode)
	if dst != newdst:
	log = dump_to_file(
	str(mode),
	diff(src, dst, "source", "first pass"),
	diff(dst, newdst, "first pass", "second pass"),
	)
	raise AssertionError(
	"INTERNAL ERROR: Black produced different code on the second pass of the"
	" formatter. Please report a bug on https://github.com/psf/black/issues."
	f" This diff might be helpful: {log}"
	) from None


	@contextmanager
	def nullcontext() -> Iterator[None]:
	"""Return an empty context manager.

	To be used like `nullcontext` in Python 3.7.
	"""
	yield


	def patch_click() -> None:
	"""Make Click not crash on Python 3.6 with LANG=C.

	On certain misconfigured environments, Python 3 selects the ASCII encoding as the
	default which restricts paths that it can access during the lifetime of the
	application. Click refuses to work in this scenario by raising a RuntimeError.

	In case of Black the likelihood that non-ASCII characters are going to be used in
	file paths is minimal since it's Python source code. Moreover, this crash was
	spurious on Python 3.7 thanks to PEP 538 and PEP 540.
	"""
	modules: List[Any] = []
	try:
	from click import core
	except ImportError:
	pass
	else:
	modules.append(core)
	try:
	# Removed in Click 8.1.0 and newer; we keep this around for users who have
	# older versions installed.
	from click import _unicodefun # type: ignore
	except ImportError:
	pass
	else:
	modules.append(_unicodefun)

	for module in modules:
	if hasattr(module, "_verify_python3_env"):
	module._verify_python3_env = lambda: None
	if hasattr(module, "_verify_python_env"):
	module._verify_python_env = lambda: None


	def patched_main() -> None:
	# PyInstaller patches multiprocessing to need freeze_support() even in non-Windows
	# environments so just assume we always need to call it if frozen.
	if getattr(sys, "frozen", False):
	from multiprocessing import freeze_support

	freeze_support()

	patch_click()
	main()


	if __name__ == "__main__":
	patched_main()