200 lines
6.6 KiB
Python
200 lines
6.6 KiB
Python
"""Filename matching with shell patterns.
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fnmatch(FILENAME, PATTERN) matches according to the local convention.
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fnmatchcase(FILENAME, PATTERN) always takes case in account.
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The functions operate by translating the pattern into a regular
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expression. They cache the compiled regular expressions for speed.
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The function translate(PATTERN) returns a regular expression
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corresponding to PATTERN. (It does not compile it.)
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"""
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import os
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import posixpath
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import re
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import functools
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__all__ = ["filter", "fnmatch", "fnmatchcase", "translate"]
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# Build a thread-safe incrementing counter to help create unique regexp group
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# names across calls.
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from itertools import count
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_nextgroupnum = count().__next__
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del count
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def fnmatch(name, pat):
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"""Test whether FILENAME matches PATTERN.
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Patterns are Unix shell style:
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* matches everything
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? matches any single character
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[seq] matches any character in seq
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[!seq] matches any char not in seq
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An initial period in FILENAME is not special.
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Both FILENAME and PATTERN are first case-normalized
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if the operating system requires it.
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If you don't want this, use fnmatchcase(FILENAME, PATTERN).
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"""
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name = os.path.normcase(name)
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pat = os.path.normcase(pat)
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return fnmatchcase(name, pat)
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@functools.lru_cache(maxsize=256, typed=True)
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def _compile_pattern(pat):
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if isinstance(pat, bytes):
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pat_str = str(pat, 'ISO-8859-1')
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res_str = translate(pat_str)
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res = bytes(res_str, 'ISO-8859-1')
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else:
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res = translate(pat)
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return re.compile(res).match
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def filter(names, pat):
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"""Construct a list from those elements of the iterable NAMES that match PAT."""
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result = []
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pat = os.path.normcase(pat)
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match = _compile_pattern(pat)
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if os.path is posixpath:
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# normcase on posix is NOP. Optimize it away from the loop.
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for name in names:
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if match(name):
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result.append(name)
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else:
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for name in names:
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if match(os.path.normcase(name)):
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result.append(name)
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return result
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def fnmatchcase(name, pat):
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"""Test whether FILENAME matches PATTERN, including case.
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This is a version of fnmatch() which doesn't case-normalize
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its arguments.
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"""
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match = _compile_pattern(pat)
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return match(name) is not None
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def translate(pat):
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"""Translate a shell PATTERN to a regular expression.
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There is no way to quote meta-characters.
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"""
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STAR = object()
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res = []
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add = res.append
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i, n = 0, len(pat)
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while i < n:
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c = pat[i]
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i = i+1
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if c == '*':
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# compress consecutive `*` into one
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if (not res) or res[-1] is not STAR:
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add(STAR)
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elif c == '?':
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add('.')
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elif c == '[':
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j = i
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if j < n and pat[j] == '!':
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j = j+1
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if j < n and pat[j] == ']':
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j = j+1
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while j < n and pat[j] != ']':
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j = j+1
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if j >= n:
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add('\\[')
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else:
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stuff = pat[i:j]
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if '-' not in stuff:
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stuff = stuff.replace('\\', r'\\')
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else:
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chunks = []
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k = i+2 if pat[i] == '!' else i+1
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while True:
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k = pat.find('-', k, j)
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if k < 0:
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break
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chunks.append(pat[i:k])
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i = k+1
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k = k+3
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chunk = pat[i:j]
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if chunk:
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chunks.append(chunk)
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else:
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chunks[-1] += '-'
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# Remove empty ranges -- invalid in RE.
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for k in range(len(chunks)-1, 0, -1):
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if chunks[k-1][-1] > chunks[k][0]:
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chunks[k-1] = chunks[k-1][:-1] + chunks[k][1:]
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del chunks[k]
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# Escape backslashes and hyphens for set difference (--).
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# Hyphens that create ranges shouldn't be escaped.
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stuff = '-'.join(s.replace('\\', r'\\').replace('-', r'\-')
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for s in chunks)
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# Escape set operations (&&, ~~ and ||).
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stuff = re.sub(r'([&~|])', r'\\\1', stuff)
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i = j+1
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if not stuff:
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# Empty range: never match.
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add('(?!)')
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elif stuff == '!':
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# Negated empty range: match any character.
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add('.')
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else:
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if stuff[0] == '!':
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stuff = '^' + stuff[1:]
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elif stuff[0] in ('^', '['):
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stuff = '\\' + stuff
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add(f'[{stuff}]')
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else:
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add(re.escape(c))
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assert i == n
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# Deal with STARs.
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inp = res
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res = []
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add = res.append
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i, n = 0, len(inp)
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# Fixed pieces at the start?
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while i < n and inp[i] is not STAR:
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add(inp[i])
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i += 1
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# Now deal with STAR fixed STAR fixed ...
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# For an interior `STAR fixed` pairing, we want to do a minimal
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# .*? match followed by `fixed`, with no possibility of backtracking.
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# We can't spell that directly, but can trick it into working by matching
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# .*?fixed
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# in a lookahead assertion, save the matched part in a group, then
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# consume that group via a backreference. If the overall match fails,
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# the lookahead assertion won't try alternatives. So the translation is:
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# (?=(?P<name>.*?fixed))(?P=name)
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# Group names are created as needed: g0, g1, g2, ...
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# The numbers are obtained from _nextgroupnum() to ensure they're unique
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# across calls and across threads. This is because people rely on the
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# undocumented ability to join multiple translate() results together via
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# "|" to build large regexps matching "one of many" shell patterns.
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while i < n:
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assert inp[i] is STAR
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i += 1
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if i == n:
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add(".*")
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break
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assert inp[i] is not STAR
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fixed = []
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while i < n and inp[i] is not STAR:
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fixed.append(inp[i])
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i += 1
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fixed = "".join(fixed)
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if i == n:
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add(".*")
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add(fixed)
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else:
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groupnum = _nextgroupnum()
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add(f"(?=(?P<g{groupnum}>.*?{fixed}))(?P=g{groupnum})")
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assert i == n
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res = "".join(res)
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return fr'(?s:{res})\Z'
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