Re: Inexplicably slow regex

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Re^2: Inexplicably slow regex by hgolden (Pilgrim) on Sep 12, 2006 at 18:26 UTC
I'd also be interested in seeing the benchmarks. I can add one thing: the last Regex isn't the same as the others because the `[^\n]` character class is (accidently) a negated character class. Rearranging it to `[\n^]` should fix that. Hays	[reply] [d/l] [select]
Re^3: Inexplicably slow regex by Anonymous Monk on Sep 12, 2006 at 18:52 UTC
Nothing accidental about the negation of that character class. I'm using it with a negative look-behind assertion. It's supposed to mean: "If it's not true that the preceding character is not a linebreak". So it's either a linebreak or there's nothing there at all (beginning of string). Processing a file approximately 0.5MB in size, using gettimeofday for timing, I get First version: 0.7 seconds Second version: 0.003 seconds Third version: 0.03 seconds My actual regexes are slightly more complicated than the examples given so I see little speed difference between #2 and #3.	[reply]
Re^4: Inexplicably slow regex by Anonymous Monk on Sep 12, 2006 at 20:55 UTC
You may wish to show your actual regex, as that's the likely source of the issue.	[reply]
Re^5: Inexplicably slow regex by Anonymous Monk on Sep 12, 2006 at 22:37 UTC