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  1. import re
  2.  
  3. def parse(string):
  4.     SCHEME = r"file://"                             # File prefix
  5.     PATH_PATTERN = r"(?P<path>.+?)"                  # One or more of any character
  6.     FLAGS_PATTERN = r"(?P<flags>[^:]+)"        # The letters r, w, a, b, a '+' symbol, or any digit
  7.  
  8.     # FILE_RESOURCE_PATTERN = SCHEME + PATH_PATTERN + r":" + FLAGS_PATTERN + r"$"               # This makes the first test pass, but the second one fail
  9.     FILE_RESOURCE_PATTERN = SCHEME + PATH_PATTERN + optional(r":" + FLAGS_PATTERN) + r"$"   # This makes the second test pass, but the first one fail
  10.  
  11.     tokens = re.match(FILE_RESOURCE_PATTERN, string).groupdict()
  12.  
  13.     return tokens['path'], tokens['flags']
  14.  
  15. def optional(re):
  16.     '''Encloses the given regular expression in a group which matches 0 or 1 repetitions.'''
  17.     return '({})?'.format(re)
  18.  
  19. print(parse("file://foo:bar.txt:r+")) # == ("foo:bar.txt", "r+")
  20. print(parse("file://foobar.txt")) #== ("foobar.txt", None)
  21.  
Success #stdin #stdout 0.01s 23352KB
comments (?)
stdin 
Standard input is empty
stdout 
('foo:bar.txt', 'r+')
('foobar.txt', None)
https://ideone.com/aIYI6B
language:
Python (cpython 2.7.16)
created:
7 years ago
visibility:
public

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