From: Robert Klemme <bob.news@...>
Date: 2004-08-13T04:41:10+09:00
Subject: Re: Implementation ideas?  Flexible string matching


"Kirk Haines" <khaines@enigo.com> schrieb im Newsbeitrag
news:20040812173551.M70191@enigo.com...
> On Fri, 13 Aug 2004 01:41:10 +0900, Martin DeMello wrote
> > Kirk Haines <khaines@enigo.com> wrote:
> >
> > > The only idea that I have come up with is to put the literal matches
in
> a
> > > hash, and then have the regular expressions in an array.  If there
isn't
> a
> > > literal match, then one has to accept the time consuming process of
> > > iterating through each regexp and checking it.  Can anyone think of
any
> > > other approaches that might be faster?
> >
> > If you only need to know that there is a match, rather than what
> > matched, how about combining all the regexps into one big regexp using
> > ((re1)|(re2)|...)?
>
> Hmmm.  Interesting idea.  I'll have to give it a try and see if there is a
> performance difference when doing that.

I was going to suggest the same: hash and a combined regexp.  You could even
create a single regexp that coevers all - if that doesn't blow up the regexp
engine.  I once made a script that takes a list of strings and creates a
single regexp from them that is supposedly matched fast (i.e. doesn't need
backtracking).  If you're interested I can check at work tomorrow - I'm
quite sure I still have it somewhere (please email as reminder).

Kind regards

    robert