Python中fnmatch模块的使用详情-创新互联

fnamtch就是filenamematch, 在python中利用符合linuxshell风格的匹配模块来进行文件名的匹配筛选工作。

fnmatch()函数匹配能力介于简单的字符串方法和强大的正则表达式之间，如果在数据处理操作中只需要简单的通配符就能完成的时候，这通常是一个比较合理的方案。此模块的主要作用是文件名称的匹配，并且匹配的模式使用的Unix shell风格。源码很简单：

"""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"]

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

def filter(names, pat):
  """Return the subset of the list 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

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


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].replace('\\','\\\\')
        i = j+1
        if stuff[0] == '!':
          stuff = '^' + stuff[1:]
        elif stuff[0] == '^':
          stuff = '\\' + stuff
        res = '%s[%s]' % (res, stuff)
    else:
      res = res + re.escape(c)
  return r'(?s:%s)\Z' % res

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