afl-material: progs/catastrophic3.py@331b2c9e525f (annotated)

49 d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	1	#!/usr/bin/env python
d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	2	import re
d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	3	import sys
d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	4
420 25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	5	# case of catastrophic backtracking in Python
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	6	#
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	7	# regex: (a?){n} a{n}
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	8	# strings: aa...
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	9	#
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	10	# call with timing as:
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	11	#
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	12	# > time ./catastrophic.py 20
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	13
25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	14	# counter n given on the command line
49 d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	15	cn = sys.argv[1]
d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	16
420 25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	17	# constructing the regex
474 331b2c9e525f updated Christian Urban <urbanc@in.tum.de> parents: 420 diff changeset	18	r = '(.*)a(.{%s})bc' % cn
49 d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	19
420 25bc57b32efa updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 411 diff changeset	20	# calling the matching function
474 331b2c9e525f updated Christian Urban <urbanc@in.tum.de> parents: 420 diff changeset	21	#m = re.match(r, "axaybzbc")
331b2c9e525f updated Christian Urban <urbanc@in.tum.de> parents: 420 diff changeset	22	m = re.match(r, "a" * 100 + "a" * int(cn) + "bc")
49 d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	23
d2c6852ca8da added programs and slides Christian Urban <urbanc@in.tum.de> parents: diff changeset	24	print m.group(0)

author	Christian Urban <urbanc@in.tum.de>
	Wed, 08 Feb 2017 11:01:50 +0000
changeset 474	331b2c9e525f
parent 420	progs/catastrophic.py@25bc57b32efa
permissions	-rwxr-xr-x