[erlang-questions] Regular expression library (was Not an Erlang fan)
Wed Oct 3 23:51:48 CEST 2007
> Unfortunately at the moment is a little slower on simple regular
> expressions than the old regexp module. It seems like it is more
> difficult to optimise for the simple cases when you concentrate on
> the tough ones.
> But I'm working on it. Do the versions which use PCRE or other
> libraries work on Windows without a C compiler?
I do not know, and I don't have a Windows machine with me.
I'm in sunny Freiburg with my trusty MacBook, across the road from
the conference in the 'Design Hotel' Stadtgarten.
> At the moment that is all I have with no other development env than
> Erlang. It would be interesting to compare.
> On 01/10/2007, G Bulmer <> wrote: Robert
> Sorry for the tardy response. I've been enjoying Erlang too
> much ... :-)
> The results for your new version on pathological cases look
> How does this versions performance compare to the existing regexp for
> simpler matches (without back references)?
> G Bulmer
> PS - See y'all in Freiburg on Thursday & Friday
> > On 27/09/2007, G Bulmer wrote:
> > I guess it's the 'pathological' cases that worry me; "MY software
> > NEVER breaks on the easy cases" :-)
> > Seriously though, having a regexp with stable behaviour wins over
> > that gets the last 200% of performance *most of the time*, but is
> > unstable.
> > I did some tests using Russ Cox example comparing the old regexp
> > module (not a good comparison i know) and a new version I am
> > working on. The results confirmed his findings.
> > N 15 18 20 22
> > 25 30 40
> > regexp 40 360 1570 6900 59000
> > re 0.2 0.25 0.32 0.38 0.5
> > 0.73 1.4
> > All times in millisecs. The old regexp uses a backtracking
> > Which tends to show that we will have no problems with pathological
> > cases. :-) If people feel that it is too slow for the simpler
> > regexps and would prefer to use a C library then it is definitely
> > important to choose the *right* library.
> > Robert
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