cpython/Lib/fnmatch.py

"""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 re

_cache = {}

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).
    """

    import os
    name = os.path.normcase(name)
    pat = os.path.normcase(pat)
    return fnmatchcase(name, pat)

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

    This is a version of fnmatch() which doesn't case-normalize
    its arguments.
    """

    if not _cache.has_key(pat):
        res = translate(pat)
        _cache[pat] = re.compile(res)
    return _cache[pat].match(name) is not None

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

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

    i, n = 0, len(pat)
    res = ''
    while i < n:
        c = pat[i]
        i = i+1
        if c == '*':
            res = res + '.*'
        elif c == '?':
            res = res + '.'
        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:
                res = res + '\\['
            else:
                stuff = pat[i:j]
                i = j+1
                if stuff[0] == '!':
                    stuff = '[^' + stuff[1:] + ']'
                elif stuff == '^'*len(stuff):
                    stuff = '\\^'
                else:
                    while stuff[0] == '^':
                        stuff = stuff[1:] + stuff[0]
                    stuff = '[' + stuff + ']'
                res = res + stuff
        else:
            res = res + re.escape(c)
    return res + "$"