Bugs item #1721518, was opened at 2007-05-18 20:12 Message generated for change (Comment added) made by goatchurch You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1721518&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Regular Expressions Group: Python 2.4 Status: Open Resolution: None Priority: 4 Private: No Submitted By: Julian Todd (goatchurch) Assigned to: Gustavo Niemeyer (niemeyer) Summary: Small case which hangs Initial Comment: import re s = "Add.1, 2020 and Add.1, 2021-2023, 2025, 2028 and 2029 and Add.1) R" r = "(?:\s|,|and|Add\S*?|Parts?|\([^\)]*\)|[IV\-\d]+)*$" print "It's going to crash" print re.search(r, s) print "It hasn't crashed" ---------------------------------------------------------------------- >Comment By: Julian Todd (goatchurch) Date: 2007-05-18 22:37 Message: Logged In: YES user_id=301384 Originator: YES I can shorten it further to: s = "Add.1, 2020 Add.1, 20212023, 2025, 2028 and 2029 Add.1) R" r = "(?:\s|,|and|Add\S*?|[\d]+)*$" Sometimes it finishes after a long time when you shorten the s-string from the front. If you take the "R" from the end it goes through straight away. It's even very slow with match. ---------------------------------------------------------------------- Comment By: Georg Brandl (gbrandl) Date: 2007-05-18 20:55 Message: Logged In: YES user_id=849994 Originator: NO I assume this is one of the pathological cases where the RE algorithm backtracks "to death". That's not really a bug, but a limitation. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1721518&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
