Demo/comparisons/regextest.py

   1 #! /usr/bin/env python
   2
   3 # 1)  Regular Expressions Test
   4 #
   5 #     Read a file of (extended per egrep) regular expressions (one per line),
   6 #     and apply those to all files whose names are listed on the command line.
   7 #     Basically, an 'egrep -f' simulator.  Test it with 20 "vt100" patterns
   8 #     against a five /etc/termcap files.  Tests using more elaborate patters
   9 #     would also be interesting.  Your code should not break if given hundreds
  10 #     of regular expressions or binary files to scan.
  11
  12 # This implementation:
  13 # - combines all patterns into a single one using ( ... | ... | ... )
  14 # - reads patterns from stdin, scans files given as command line arguments
  15 # - produces output in the format <file>:<lineno>:<line>
  16 # - is only about 2.5 times as slow as egrep (though I couldn't run
  17 #   Tom's test -- this system, a vanilla SGI, only has /etc/terminfo)
  18
  19 import string
  20 import sys
  21 import re
  22
  23 def main():
  24     pats = map(chomp, sys.stdin.readlines())
  25     bigpat = '(' + '|'.join(pats) + ')'
  26     prog = re.compile(bigpat)
  27
  28     for file in sys.argv[1:]:
  29         try:
  30             fp = open(file, 'r')
  31         except IOError, msg:
  32             print "%s: %s" % (file, msg)
  33             continue
  34         lineno = 0
  35         while 1:
  36             line = fp.readline()
  37             if not line:
  38                 break
  39             lineno = lineno + 1
  40             if prog.search(line):
  41                 print "%s:%s:%s" % (file, lineno, line),
  42
  43 def chomp(s):
  44     return s.rstrip('\n')
  45
  46 if __name__ == '__main__':
  47     main()