Source code for fnmatch


"""Filename matching with shell patterns.

fnmatch(FILENAME, PATTERN) matches according to the local convention.
fnmatchcase(FILENAME, PATTERN) always takes case in account.

The functions operate by translating the pattern into a regular
expression.  They cache the compiled regular expressions for speed.

The function translate(PATTERN) returns a regular expression
corresponding to PATTERN.  (It does not compile it.)
"""
import os
import posixpath
import re
import functools

__all__ = ["filter", "fnmatch", "fnmatchcase", "translate"]

# Build a thread-safe incrementing counter to help create unique regexp group
# names across calls.
from itertools import count
_nextgroupnum = count().__next__
del count

[docs]def fnmatch(name, pat):
    """Test whether FILENAME matches PATTERN.

    Patterns are Unix shell style:

    *       matches everything
    ?       matches any single character
    [seq]   matches any character in seq
    [!seq]  matches any char not in seq

    An initial period in FILENAME is not special.
    Both FILENAME and PATTERN are first case-normalized
    if the operating system requires it.
    If you don't want this, use fnmatchcase(FILENAME, PATTERN).
    """
    name = os.path.normcase(name)
    pat = os.path.normcase(pat)
    return fnmatchcase(name, pat)

@functools.lru_cache(maxsize=256, typed=True)
def _compile_pattern(pat):
    if isinstance(pat, bytes):
        pat_str = str(pat, 'ISO-8859-1')
        res_str = translate(pat_str)
        res = bytes(res_str, 'ISO-8859-1')
    else:
        res = translate(pat)
    return re.compile(res).match

[docs]def filter(names, pat):
    """Construct a list from those elements of the iterable NAMES that match PAT."""
    result = []
    pat = os.path.normcase(pat)
    match = _compile_pattern(pat)
    if os.path is posixpath:
        # normcase on posix is NOP. Optimize it away from the loop.
        for name in names:
            if match(name):
                result.append(name)
    else:
        for name in names:
            if match(os.path.normcase(name)):
                result.append(name)
    return result

[docs]def fnmatchcase(name, pat):
    """Test whether FILENAME matches PATTERN, including case.

    This is a version of fnmatch() which doesn't case-normalize
    its arguments.
    """
    match = _compile_pattern(pat)
    return match(name) is not None


[docs]def translate(pat):
    """Translate a shell PATTERN to a regular expression.

    There is no way to quote meta-characters.
    """

    STAR = object()
    res = []
    add = res.append
    i, n = 0, len(pat)
    while i < n:
        c = pat[i]
        i = i+1
        if c == '*':
            # compress consecutive `*` into one
            if (not res) or res[-1] is not STAR:
                add(STAR)
        elif c == '?':
            add('.')
        elif c == '[':
            j = i
            if j < n and pat[j] == '!':
                j = j+1
            if j < n and pat[j] == ']':
                j = j+1
            while j < n and pat[j] != ']':
                j = j+1
            if j >= n:
                add('\\[')
            else:
                stuff = pat[i:j]
                if '--' not in stuff:
                    stuff = stuff.replace('\\', r'\\')
                else:
                    chunks = []
                    k = i+2 if pat[i] == '!' else i+1
                    while True:
                        k = pat.find('-', k, j)
                        if k < 0:
                            break
                        chunks.append(pat[i:k])
                        i = k+1
                        k = k+3
                    chunks.append(pat[i:j])
                    # Escape backslashes and hyphens for set difference (--).
                    # Hyphens that create ranges shouldn't be escaped.
                    stuff = '-'.join(s.replace('\\', r'\\').replace('-', r'\-')
                                     for s in chunks)
                # Escape set operations (&&, ~~ and ||).
                stuff = re.sub(r'([&~|])', r'\\\1', stuff)
                i = j+1
                if stuff[0] == '!':
                    stuff = '^' + stuff[1:]
                elif stuff[0] in ('^', '['):
                    stuff = '\\' + stuff
                add(f'[{stuff}]')
        else:
            add(re.escape(c))
    assert i == n

    # Deal with STARs.
    inp = res
    res = []
    add = res.append
    i, n = 0, len(inp)
    # Fixed pieces at the start?
    while i < n and inp[i] is not STAR:
        add(inp[i])
        i += 1
    # Now deal with STAR fixed STAR fixed ...
    # For an interior `STAR fixed` pairing, we want to do a minimal
    # .*? match followed by `fixed`, with no possibility of backtracking.
    # We can't spell that directly, but can trick it into working by matching
    #    .*?fixed
    # in a lookahead assertion, save the matched part in a group, then
    # consume that group via a backreference. If the overall match fails,
    # the lookahead assertion won't try alternatives. So the translation is:
    #     (?=(?P.*?fixed))(?P=name)
    # Group names are created as needed: g0, g1, g2, ...
    # The numbers are obtained from _nextgroupnum() to ensure they're unique
    # across calls and across threads. This is because people rely on the
    # undocumented ability to join multiple translate() results together via
    # "|" to build large regexps matching "one of many" shell patterns.
    while i < n:
        assert inp[i] is STAR
        i += 1
        if i == n:
            add(".*")
            break
        assert inp[i] is not STAR
        fixed = []
        while i < n and inp[i] is not STAR:
            fixed.append(inp[i])
            i += 1
        fixed = "".join(fixed)
        if i == n:
            add(".*")
            add(fixed)
        else:
            groupnum = _nextgroupnum()
            add(f"(?=(?P{groupnum}>.*?{fixed}))(?P=g{groupnum})")
    assert i == n
    res = "".join(res)
    return fr'(?s:{res})\Z'