Demo/comparisons/regextest.py

#! /usr/bin/env python

# 1)  Regular Expressions Test
# 
#     Read a file of (extended per egrep) regular expressions (one per line), 
#     and apply those to all files whose names are listed on the command line.
#     Basically, an 'egrep -f' simulator.  Test it with 20 "vt100" patterns
#     against a five /etc/termcap files.  Tests using more elaborate patters
#     would also be interesting.  Your code should not break if given hundreds
#     of regular expressions or binary files to scan.  

# This implementation:
# - combines all patterns into a single one using ( ... | ... | ... )
# - reads patterns from stdin, scans files given as command line arguments
# - produces output in the format <file>:<lineno>:<line>
# - is only about 2.5 times as slow as egrep (though I couldn't run
#   Tom's test -- this system, a vanilla SGI, only has /etc/terminfo)

import string
import sys
import regex
from regex_syntax import *

regex.set_syntax(RE_SYNTAX_EGREP)

def main():
	pats = map(chomp, sys.stdin.readlines())
	bigpat = '(' + string.joinfields(pats, '|') + ')'
	prog = regex.compile(bigpat)
	
	for file in sys.argv[1:]:
		try:
			fp = open(file, 'r')
		except IOError, msg:
			print "%s: %s" % (file, msg)
			continue
		lineno = 0
		while 1:
			line = fp.readline()
			if not line:
				break
			lineno = lineno + 1
			if prog.search(line) >= 0:
				print "%s:%s:%s" % (file, lineno, line),

def chomp(s):
	if s[-1:] == '\n': return s[:-1]
	else: return s

main()