[issue15515] Regular expression match does not return

2012-07-31 Thread Tim Peters
Tim Peters added the comment: Matthew, yes, PyPy's regex module implements regular expressions of the "computer science" (as opposed to POSIX) sense. See Friedl's book for a full explanation. Short course is that regex's flavor of regexp matching is linear-time, but cannot support "advanced"

[issue15515] Regular expression match does not return

2012-07-31 Thread Matthew Barnett
Matthew Barnett added the comment: It's probably inappropriate for me to mention that the alternative 'regex' module on PyPI completes promptly, so I won't. :-) -- ___ Python tracker __

[issue15515] Regular expression match does not return

2012-07-31 Thread Serhiy Storchaka
Serhiy Storchaka added the comment: Make a distinction between a large number of infinity. You have a bad regexp, the matching time depends exponentially on the length of the string. Try with short strings. Use the regexp r"(\w:)(\\?[\w\.\-]+)((\\[\w\.\-]+)*)(\.[\w ]+): ". It's not a bug. --

[issue15515] Regular expression match does not return

2012-07-31 Thread Caleb Rouleau
Caleb Rouleau added the comment: Thanks for the help. Apologies for the poor understanding of regular expressions. Closing this issue. -- status: open -> closed ___ Python tracker _

[issue15515] Regular expression match does not return

2012-07-31 Thread Tim Peters
Tim Peters added the comment: Matthew is right: the nested quantifiers can cause this to take a very long time when the regexp doesn't match. Note that the example cannot match, because nothing in the regexp can match the space before "warning" in the example string. But the nested quantifi

[issue15515] Regular expression match does not return

2012-07-31 Thread Matthew Barnett
Matthew Barnett added the comment: That's because it uses a pathological regular expression (catastrophic backtracking). The problem lies here: (\\?[\w\.\-]+)+ -- ___ Python tracker __

[issue15515] Regular expression match does not return

2012-07-31 Thread Caleb Rouleau
New submission from Caleb Rouleau: Version info: 2.7.1 (r271:86832, Feb 7 2011, 11:33:02) [MSC v.1500 64 bit (AMD64)] The program included never prints "done" because it never returns from re.match(). -- Caleb Rouleau -- components: Regular Expressions files: RegexBug.py messages: