318 lines
9.7 KiB
Python
318 lines
9.7 KiB
Python
"""
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This module provides :class:`GitIgnoreBasicPattern` which implements Git's
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`gitignore`_ patterns as documented. This differs from how Git actually behaves
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when including files in excluded directories.
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.. _`gitignore`: https://git-scm.com/docs/gitignore
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"""
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from typing import (
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Optional) # Replaced by `X | None` in 3.10.
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from pathspec import util
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from pathspec._typing import (
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AnyStr, # Removed in 3.18.
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assert_unreachable,
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override) # Added in 3.12.
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from .base import (
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GitIgnorePatternError,
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_BYTES_ENCODING,
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_GitIgnoreBasePattern)
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class GitIgnoreBasicPattern(_GitIgnoreBasePattern):
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"""
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The :class:`GitIgnoreBasicPattern` class represents a compiled gitignore
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pattern as documented. This is registered as "gitignore".
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"""
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# Keep the dict-less class hierarchy.
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__slots__ = ()
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@staticmethod
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def __normalize_segments(
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is_dir_pattern: bool,
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pattern_segs: list[str],
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) -> tuple[Optional[list[str]], Optional[str]]:
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"""
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Normalize the pattern segments to make processing easier.
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*is_dir_pattern* (:class:`bool`) is whether the pattern is a directory
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pattern (i.e., ends with a slash '/').
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*pattern_segs* (:class:`list` of :class:`str`) contains the pattern
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segments. This may be modified in place.
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Returns a :class:`tuple` containing either:
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- The normalized segments (:class:`list` of :class:`str`; or :data:`None`).
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- The regular expression override (:class:`str` or :data:`None`).
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"""
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if not pattern_segs[0]:
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# A pattern beginning with a slash ('/') should match relative to the root
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# directory. Remove the empty first segment to make the pattern relative
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# to root.
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del pattern_segs[0]
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elif len(pattern_segs) == 1 or (len(pattern_segs) == 2 and not pattern_segs[1]):
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# A single segment pattern with or without a trailing slash ('/') will
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# match any descendant path. This is equivalent to "**/{pattern}". Prepend
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# double-asterisk segment to make pattern relative to root.
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if pattern_segs[0] != '**':
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pattern_segs.insert(0, '**')
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else:
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# A pattern without a beginning slash ('/') but contains at least one
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# prepended directory (e.g., "dir/{pattern}") should match relative to the
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# root directory. No segment modification is needed.
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pass
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if not pattern_segs:
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# After normalization, we end up with no pattern at all. This must be
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# because the pattern is invalid.
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raise ValueError("Pattern normalized to nothing.")
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if not pattern_segs[-1]:
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# A pattern ending with a slash ('/') will match all descendant paths if
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# it is a directory but not if it is a regular file. This is equivalent to
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# "{pattern}/**". Set empty last segment to a double-asterisk to include
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# all descendants.
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pattern_segs[-1] = '**'
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# EDGE CASE: Collapse duplicate double-asterisk sequences (i.e., '**/**').
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# Iterate over the segments in reverse order and remove the duplicate double
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# asterisks as we go.
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for i in range(len(pattern_segs) - 1, 0, -1):
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prev = pattern_segs[i-1]
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seg = pattern_segs[i]
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if prev == '**' and seg == '**':
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del pattern_segs[i]
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seg_count = len(pattern_segs)
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if seg_count == 1 and pattern_segs[0] == '**':
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if is_dir_pattern:
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# The pattern "**/" will be normalized to "**", but it should match
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# everything except for files in the root. Special case this pattern.
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return (None, '/')
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else:
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# The pattern "**" will match every path. Special case this pattern.
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return (None, '.')
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elif (
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seg_count == 2
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and pattern_segs[0] == '**'
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and pattern_segs[1] == '*'
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):
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# The pattern "*" will be normalized to "**/*" and will match every
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# path. Special case this pattern for efficiency.
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return (None, '.')
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elif (
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seg_count == 3
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and pattern_segs[0] == '**'
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and pattern_segs[1] == '*'
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and pattern_segs[2] == '**'
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):
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# The pattern "*/" will be normalized to "**/*/**" which will match every
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# file not in the root directory. Special case this pattern for
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# efficiency.
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return (None, '/')
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# No regular expression override, return modified pattern segments.
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return (pattern_segs, None)
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@override
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@classmethod
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def pattern_to_regex(
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cls,
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pattern: AnyStr,
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) -> tuple[Optional[AnyStr], Optional[bool]]:
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"""
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Convert the pattern into a regular expression.
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*pattern* (:class:`str` or :class:`bytes`) is the pattern to convert into a
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regular expression.
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Returns a :class:`tuple` containing:
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- *pattern* (:class:`str`, :class:`bytes` or :data:`None`) is the
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uncompiled regular expression.
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- *include* (:class:`bool` or :data:`None`) is whether matched files
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should be included (:data:`True`), excluded (:data:`False`), or is a
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null-operation (:data:`None`).
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"""
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if isinstance(pattern, str):
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pattern_str = pattern
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return_type = str
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elif isinstance(pattern, bytes):
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pattern_str = pattern.decode(_BYTES_ENCODING)
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return_type = bytes
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else:
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raise TypeError(f"{pattern=!r} is not a unicode or byte string.")
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original_pattern = pattern_str
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del pattern
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if pattern_str.endswith('\\ '):
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# EDGE CASE: Spaces can be escaped with backslash. If a pattern that ends
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# with a backslash is followed by a space, do not strip from the left.
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pass
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else:
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# EDGE CASE: Leading spaces should be kept (only trailing spaces should be
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# removed).
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pattern_str = pattern_str.rstrip()
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regex: Optional[str]
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include: Optional[bool]
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if not pattern_str:
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# A blank pattern is a null-operation (neither includes nor excludes
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# files).
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return (None, None)
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elif pattern_str.startswith('#'):
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# A pattern starting with a hash ('#') serves as a comment (neither
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# includes nor excludes files). Escape the hash with a backslash to match
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# a literal hash (i.e., '\#').
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return (None, None)
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if pattern_str.startswith('!'):
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# A pattern starting with an exclamation mark ('!') negates the pattern
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# (exclude instead of include). Escape the exclamation mark with a back
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# slash to match a literal exclamation mark (i.e., '\!').
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include = False
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# Remove leading exclamation mark.
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pattern_str = pattern_str[1:]
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else:
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include = True
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# Split pattern into segments.
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pattern_segs = pattern_str.split('/')
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# Check whether the pattern is specifically a directory pattern before
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# normalization.
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is_dir_pattern = not pattern_segs[-1]
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if pattern_str == '/':
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# EDGE CASE: A single slash ('/') is not addressed by the gitignore
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# documentation. Git treats it as a no-op (does not match any files). The
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# straight forward interpretation is to treat it as a directory and match
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# every descendant path (equivalent to '**'). Remove the directory pattern
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# flag so that it is treated as '**' instead of '**/'.
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is_dir_pattern = False
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# Normalize pattern to make processing easier.
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try:
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pattern_segs, override_regex = cls.__normalize_segments(
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is_dir_pattern, pattern_segs,
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)
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except ValueError as e:
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raise GitIgnorePatternError((
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f"Invalid git pattern: {original_pattern!r}"
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)) from e # GitIgnorePatternError
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if override_regex is not None:
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# Use regex override.
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regex = override_regex
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elif pattern_segs is not None:
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# Build regular expression from pattern.
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try:
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regex_parts = cls.__translate_segments(pattern_segs)
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except ValueError as e:
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raise GitIgnorePatternError((
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f"Invalid git pattern: {original_pattern!r}"
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)) from e # GitIgnorePatternError
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regex = ''.join(regex_parts)
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else:
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assert_unreachable((
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f"{override_regex=} and {pattern_segs=} cannot both be null."
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)) # assert_unreachable
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# Encode regex if needed.
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out_regex: AnyStr
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if regex is not None and return_type is bytes:
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out_regex = regex.encode(_BYTES_ENCODING)
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else:
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out_regex = regex
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return (out_regex, include)
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@classmethod
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def __translate_segments(cls, pattern_segs: list[str]) -> list[str]:
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"""
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Translate the pattern segments to regular expressions.
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*pattern_segs* (:class:`list` of :class:`str`) contains the pattern
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segments.
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Returns the regular expression parts (:class:`list` of :class:`str`).
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"""
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# Build regular expression from pattern.
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out_parts = []
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need_slash = False
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end = len(pattern_segs) - 1
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for i, seg in enumerate(pattern_segs):
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if seg == '**':
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if i == 0:
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# A normalized pattern beginning with double-asterisks ('**') will
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# match any leading path segments.
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# - NOTICE: '(?:^|/)' benchmarks slower using p15 (sm=0.9382,
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# hs=0.9966, re2=0.9337).
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out_parts.append('^(?:.+/)?')
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elif i < end:
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# A pattern with inner double-asterisks ('**') will match multiple (or
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# zero) inner path segments.
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out_parts.append('(?:/.+)?')
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need_slash = True
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else:
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assert i == end, (i, end)
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# A normalized pattern ending with double-asterisks ('**') will match
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# any trailing path segments.
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out_parts.append('/')
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else:
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# Match path segment.
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if i == 0:
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# Anchor to root directory.
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out_parts.append('^')
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if need_slash:
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out_parts.append('/')
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if seg == '*':
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# Match whole path segment.
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out_parts.append('[^/]+')
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else:
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# Match segment glob pattern.
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out_parts.append(cls._translate_segment_glob(seg))
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if i == end:
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if seg == '*':
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# A pattern ending with an asterisk ('*') will match a file or
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# directory (without matching descendant paths). E.g., "foo/*"
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# matches "foo/test.json", "foo/bar/", but not "foo/bar/hello.c".
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out_parts.append('/?$')
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else:
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# A pattern ending without a slash ('/') will match a file or a
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# directory (with paths underneath it). E.g., "foo" matches "foo",
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# "foo/bar", "foo/bar/baz", etc.
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out_parts.append('(?:/|$)')
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need_slash = True
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return out_parts
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# Register GitIgnoreBasicPattern as "gitignore".
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util.register_pattern('gitignore', GitIgnoreBasicPattern)
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