[regex-coach] Feature request: Regexp performance indicator/steps used

[Morten Hattesen]

I realize that a "step count" is not necessarily a true indication of 
performance of a regular expression, but it would be a valuable tool, and 
could provide valid performance indication when comparing two different 
regular expression approaches on a given target string.
 I hope you'll keep it in mind, when you get around to extending/maintaining 
Regex Coach some time in the future.
 rgds,
 Morten
 On 5/2/05, Edi Weitz <edi at agharta.de> wrote: 
> 
> On Mon, 2 May 2005 16:05:46 +0200, Morten Hattesen <
> morten.hattesen at gmail.com> wrote:
> 
> > I really appreciate what Regex Coach has done for honing my Regular
> > Expressions skills, and assisting debugging of complex expressions.
> >
> > I frequently wish to optimize regular expressions (mainly by
> > reducing possible backtracking
> > http://www.regular-expressions.info/atomic.html), but lack a way to
> > test the relative performance between different regular expressions.
> >
> > To measure performance of a given regexp, I would really like the
> > possibility of having Regex Coach count the total number of steps
> > used by the underlying regexp engine for a given regexp search, or
> > some other meaningful performance indicator.
> >
> > This could possibly be displayed when pressing the ">>" (show next
> > match) button (regardless of whether a match was found or not). This
> > way, you can quickly try out different matching approaches, and get
> > an indication of the relative performance.
> 
> Hi Morten!
> 
> I see a couple of problems here:
> 
> 1. As you mentioned yourself already the number of "steps" used is not
> necessarily a good measure for the efficiency of a regular
> expression.
> 
> 2. The efficiency of a regular expression might depend heavily on the
> target strings it's used with - a regex that's pretty good for a
> certain subset of all possible strings might be particularly bad
> for another subset.
> 
> 3. Plus, the efficiency of a regular expression will also depend on
> the underlying implementation - even if, say, Perl and PHP use the
> same regex syntax they use different engines which employ different
> optimization strategies.
> 
> Having said that, even if I had a good idea how to give performance
> hints I wouldn't be able to add this to Regex Coach in the near future
> because I'm very busy with other projects.
> 
> Cheers,
> Edi.
> 



-- 
Morten Hattesen
Almindingen 56
DK-2870 Dyssegaard
Denmark
Tel: +45 3969 2212
Mobile: +45 2524 2114
mailto:morten.hattesen at gmail.com
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