"""
This module implements Git's wildmatch pattern matching which itself is derived
from Rsync's wildmatch. Git uses wildmatch for its ".gitignore" files.
"""
import re
import warnings
from typing import (
AnyStr,
Optional, # Replaced by `X | None` in 3.10.
Tuple) # Replaced by `tuple` in 3.9.
from .. import util
from ..pattern import RegexPattern
_BYTES_ENCODING = 'latin1'
"""
The encoding to use when parsing a byte string pattern.
"""
_DIR_MARK = 'ps_d'
"""
The regex group name for the directory marker. This is only used by
:class:`GitIgnoreSpec`.
"""
class GitWildMatchPatternError(ValueError):
"""
The :class:`GitWildMatchPatternError` indicates an invalid git wild match
pattern.
"""
pass
[docs]
class GitWildMatchPattern(RegexPattern):
"""
The :class:`GitWildMatchPattern` class represents a compiled Git wildmatch
pattern.
"""
# Keep the dict-less class hierarchy.
__slots__ = ()
[docs]
@classmethod
def pattern_to_regex(
cls,
pattern: AnyStr,
) -> Tuple[Optional[AnyStr], Optional[bool]]:
"""
Convert the pattern into a regular expression.
*pattern* (:class:`str` or :class:`bytes`) is the pattern to convert into a
regular expression.
Returns the uncompiled regular expression (:class:`str`, :class:`bytes`, or
:data:`None`); and whether matched files should be included (:data:`True`),
excluded (:data:`False`), or if it is a null-operation (:data:`None`).
"""
if isinstance(pattern, str):
return_type = str
elif isinstance(pattern, bytes):
return_type = bytes
pattern = pattern.decode(_BYTES_ENCODING)
else:
raise TypeError(f"pattern:{pattern!r} is not a unicode or byte string.")
original_pattern = pattern
if pattern.endswith('\\ '):
# EDGE CASE: Spaces can be escaped with backslash. If a pattern that ends
# with backslash followed by a space, only strip from left.
pattern = pattern.lstrip()
else:
pattern = pattern.strip()
if pattern.startswith('#'):
# A pattern starting with a hash ('#') serves as a comment (neither
# includes nor excludes files). Escape the hash with a back-slash to match
# a literal hash (i.e., '\#').
regex = None
include = None
elif pattern == '/':
# EDGE CASE: According to `git check-ignore` (v2.4.1), a single '/' does
# not match any file.
regex = None
include = None
elif pattern:
if pattern.startswith('!'):
# A pattern starting with an exclamation mark ('!') negates the pattern
# (exclude instead of include). Escape the exclamation mark with a
# back-slash to match a literal exclamation mark (i.e., '\!').
include = False
# Remove leading exclamation mark.
pattern = pattern[1:]
else:
include = True
# Allow a regex override for edge cases that cannot be handled through
# normalization.
override_regex = None
# Split pattern into segments.
pattern_segs = pattern.split('/')
# Check whether the pattern is specifically a directory pattern before
# normalization.
is_dir_pattern = not pattern_segs[-1]
# Normalize pattern to make processing easier.
# EDGE CASE: Deal with duplicate double-asterisk sequences. Collapse each
# sequence down to one double-asterisk. Iterate over the segments in
# reverse and remove the duplicate double asterisks as we go.
for i in range(len(pattern_segs) - 1, 0, -1):
prev = pattern_segs[i-1]
seg = pattern_segs[i]
if prev == '**' and seg == '**':
del pattern_segs[i]
if len(pattern_segs) == 2 and pattern_segs[0] == '**' and not pattern_segs[1]:
# EDGE CASE: The '**/' pattern should match everything except individual
# files in the root directory. This case cannot be adequately handled
# through normalization. Use the override.
override_regex = f'^.+(?P<{_DIR_MARK}>/).*$'
if not pattern_segs[0]:
# A pattern beginning with a slash ('/') will only match paths directly
# on the root directory instead of any descendant paths. So, remove
# empty first segment to make pattern relative to root.
del pattern_segs[0]
elif len(pattern_segs) == 1 or (len(pattern_segs) == 2 and not pattern_segs[1]):
# A single pattern without a beginning slash ('/') will match any
# descendant path. This is equivalent to "**/{pattern}". So, prepend
# with double-asterisks to make pattern relative to root.
# - EDGE CASE: This also holds for a single pattern with a trailing
# slash (e.g. dir/).
if pattern_segs[0] != '**':
pattern_segs.insert(0, '**')
else:
# EDGE CASE: A pattern without a beginning slash ('/') but contains at
# least one prepended directory (e.g. "dir/{pattern}") should not match
# "**/dir/{pattern}", according to `git check-ignore` (v2.4.1).
pass
if not pattern_segs:
# After resolving the edge cases, we end up with no pattern at all. This
# must be because the pattern is invalid.
raise GitWildMatchPatternError(f"Invalid git pattern: {original_pattern!r}")
if not pattern_segs[-1] and len(pattern_segs) > 1:
# A pattern ending with a slash ('/') will match all descendant paths if
# it is a directory but not if it is a regular file. This is equivalent
# to "{pattern}/**". So, set last segment to a double-asterisk to
# include all descendants.
pattern_segs[-1] = '**'
if override_regex is None:
# Build regular expression from pattern.
output = ['^']
need_slash = False
end = len(pattern_segs) - 1
for i, seg in enumerate(pattern_segs):
if seg == '**':
if i == 0 and i == end:
# A pattern consisting solely of double-asterisks ('**') will
# match every path.
output.append(f'[^/]+(?:/.*)?')
elif i == 0:
# A normalized pattern beginning with double-asterisks
# ('**') will match any leading path segments.
output.append('(?:.+/)?')
need_slash = False
elif i == end:
# A normalized pattern ending with double-asterisks ('**') will
# match any trailing path segments.
if is_dir_pattern:
output.append(f'(?P<{_DIR_MARK}>/).*')
else:
output.append(f'/.*')
else:
# A pattern with inner double-asterisks ('**') will match multiple
# (or zero) inner path segments.
output.append('(?:/.+)?')
need_slash = True
elif seg == '*':
# Match single path segment.
if need_slash:
output.append('/')
output.append('[^/]+')
if i == end:
# A pattern ending without a slash ('/') will match a file or a
# directory (with paths underneath it). E.g., "foo" matches "foo",
# "foo/bar", "foo/bar/baz", etc.
output.append(f'(?:(?P<{_DIR_MARK}>/).*)?')
need_slash = True
else:
# Match segment glob pattern.
if need_slash:
output.append('/')
try:
output.append(cls._translate_segment_glob(seg))
except ValueError as e:
raise GitWildMatchPatternError(f"Invalid git pattern: {original_pattern!r}") from e
if i == end:
# A pattern ending without a slash ('/') will match a file or a
# directory (with paths underneath it). E.g., "foo" matches "foo",
# "foo/bar", "foo/bar/baz", etc.
output.append(f'(?:(?P<{_DIR_MARK}>/).*)?')
need_slash = True
output.append('$')
regex = ''.join(output)
else:
# Use regex override.
regex = override_regex
else:
# A blank pattern is a null-operation (neither includes nor excludes
# files).
regex = None
include = None
if regex is not None and return_type is bytes:
regex = regex.encode(_BYTES_ENCODING)
return regex, include
@staticmethod
def _translate_segment_glob(pattern: str) -> str:
"""
Translates the glob pattern to a regular expression. This is used in the
constructor to translate a path segment glob pattern to its corresponding
regular expression.
*pattern* (:class:`str`) is the glob pattern.
Returns the regular expression (:class:`str`).
"""
# NOTE: This is derived from `fnmatch.translate()` and is similar to the
# POSIX function `fnmatch()` with the `FNM_PATHNAME` flag set.
escape = False
regex = ''
i, end = 0, len(pattern)
while i < end:
# Get next character.
char = pattern[i]
i += 1
if escape:
# Escape the character.
escape = False
regex += re.escape(char)
elif char == '\\':
# Escape character, escape next character.
escape = True
elif char == '*':
# Multi-character wildcard. Match any string (except slashes), including
# an empty string.
regex += '[^/]*'
elif char == '?':
# Single-character wildcard. Match any single character (except a
# slash).
regex += '[^/]'
elif char == '[':
# Bracket expression wildcard. Except for the beginning exclamation
# mark, the whole bracket expression can be used directly as regex, but
# we have to find where the expression ends.
# - "[][!]" matches ']', '[' and '!'.
# - "[]-]" matches ']' and '-'.
# - "[!]a-]" matches any character except ']', 'a' and '-'.
j = i
# Pass bracket expression negation.
if j < end and (pattern[j] == '!' or pattern[j] == '^'):
j += 1
# Pass first closing bracket if it is at the beginning of the
# expression.
if j < end and pattern[j] == ']':
j += 1
# Find closing bracket. Stop once we reach the end or find it.
while j < end and pattern[j] != ']':
j += 1
if j < end:
# Found end of bracket expression. Increment j to be one past the
# closing bracket:
#
# [...]
# ^ ^
# i j
#
j += 1
expr = '['
if pattern[i] == '!':
# Bracket expression needs to be negated.
expr += '^'
i += 1
elif pattern[i] == '^':
# POSIX declares that the regex bracket expression negation "[^...]"
# is undefined in a glob pattern. Python's `fnmatch.translate()`
# escapes the caret ('^') as a literal. Git supports the using a
# caret for negation. Maintain consistency with Git because that is
# the expected behavior.
expr += '^'
i += 1
# Build regex bracket expression. Escape slashes so they are treated
# as literal slashes by regex as defined by POSIX.
expr += pattern[i:j].replace('\\', '\\\\')
# Add regex bracket expression to regex result.
regex += expr
# Set i to one past the closing bracket.
i = j
else:
# Failed to find closing bracket, treat opening bracket as a bracket
# literal instead of as an expression.
regex += '\\['
else:
# Regular character, escape it for regex.
regex += re.escape(char)
if escape:
raise ValueError(f"Escape character found with no next character to escape: {pattern!r}")
return regex
[docs]
@staticmethod
def escape(s: AnyStr) -> AnyStr:
"""
Escape special characters in the given string.
*s* (:class:`str` or :class:`bytes`) a filename or a string that you want to
escape, usually before adding it to a ".gitignore".
Returns the escaped string (:class:`str` or :class:`bytes`).
"""
if isinstance(s, str):
return_type = str
string = s
elif isinstance(s, bytes):
return_type = bytes
string = s.decode(_BYTES_ENCODING)
else:
raise TypeError(f"s:{s!r} is not a unicode or byte string.")
# Reference: https://git-scm.com/docs/gitignore#_pattern_format
meta_characters = r"[]!*#?"
out_string = "".join("\\" + x if x in meta_characters else x for x in string)
if return_type is bytes:
return out_string.encode(_BYTES_ENCODING)
else:
return out_string
util.register_pattern('gitwildmatch', GitWildMatchPattern)
class GitIgnorePattern(GitWildMatchPattern):
"""
The :class:`GitIgnorePattern` class is deprecated by :class:`GitWildMatchPattern`.
This class only exists to maintain compatibility with v0.4.
"""
def __init__(self, *args, **kw) -> None:
"""
Warn about deprecation.
"""
self._deprecated()
super(GitIgnorePattern, self).__init__(*args, **kw)
@staticmethod
def _deprecated() -> None:
"""
Warn about deprecation.
"""
warnings.warn((
"GitIgnorePattern ('gitignore') is deprecated. Use GitWildMatchPattern "
"('gitwildmatch') instead."
), DeprecationWarning, stacklevel=3)
@classmethod
def pattern_to_regex(cls, *args, **kw):
"""
Warn about deprecation.
"""
cls._deprecated()
return super(GitIgnorePattern, cls).pattern_to_regex(*args, **kw)
# Register `GitIgnorePattern` as "gitignore" for backward compatibility with
# v0.4.
util.register_pattern('gitignore', GitIgnorePattern)