Issue 620412: Max recursion limit with "*?" pattern (original) (raw)

Issue620412

Created on 2002-10-08 19:40 by thorstein, last changed 2022-04-10 16:05 by admin. This issue is now closed.

Messages (3)
msg12660 - (view)	Author: Thorstein Thorsteinsson (thorstein)	Date: 2002-10-08 19:40
I ran into the following problem trying to parse an ms outlook mail box. Cut down to its bare essentials: > cat tst.py import re mstr = (11000*' ') + 'A' pattern = re.compile('.*?A') pattern.search(mstr) > python tst.py Traceback (most recent call last): File "tst.py", line 5, in ? pattern.search(mstr) RuntimeError: maximum recursion limit exceeded > python Python 2.2.1c1 (#6, Jul 20 2002, 09:40:07) [GCC 2.96 20000731 (Mandrake Linux 8.1 2.96-0.62mdk)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> The combination of a longish string with ".*?" gives the error. Using ".*" is ok. Could "non-greedy" matching be implemented non-recursively? If I understand correctly, the limit exceeded is USE_RECURSION_LIMIT in Modules/_sre.c. It is slightly confusing because we also have the Python recursion limit (my first reaction was to bump it up with sys.setrecursionlimit(), but that of course didn't help).
msg12661 - (view)	Author: Gustavo Niemeyer (niemeyer) *	Date: 2003-05-24 16:49
Logged In: YES user_id=7887 As Gary Herron correctly pointed me out, this was fixed in 2.3 with the introduction of a new opcode to handle single character non-greedy matching. This won't be fixed in 2.2.3, but hopefully will be backported to 2.2.4 together with other regular expression fixes.
msg12662 - (view)	Author: Thorstein Thorsteinsson (thorstein)	Date: 2003-05-27 14:45
Logged In: YES user_id=587322 I've tried my example with Python 2.3, and the error has disappeared. So as far as I'm concerned, this bug reported can be deleted. Thanks. Thorstein