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Re: strange regexp behavior
From: |
Thomas Weber |
Subject: |
Re: strange regexp behavior |
Date: |
Thu, 18 Sep 2008 11:30:04 +0200 |
Am Donnerstag, den 18.09.2008, 11:02 +0200 schrieb David Bateman:
> G.. wrote:
> > David Bateman wrote:
> >
> >> Do you know what restrictions the dfa version implies?
> >>
> >>
> >
> > No. I don't know much about regexp internals. The PCRE list seems the place
> > to go.
> >
> > G.
> >
> >
> Ok reading the man page pcrematching it appears that there are several
> restrictions that will impact the use of the DFA algorithm
>
> * It can't tell the difference between a greedy and non-greedy match and
> so this feature of Octave's regexp function can't be used.
>
> * It can't keep back references and so lookbehind can't be implemented.
>
> * Its slower...
>
> I'd therefore suggest keeping the standard pcre_exec function in Octave,
> and how the PCRE people fix this eventually for your test string in
> future versions of PCRE.
I'm currently discussing this with PCRE developers on their list,
http://lists.exim.org/lurker/message/20080915.202357.7f71f452.en.html
I already learned that this innocent looking pattern is a bad citizen :)
Thomas
- strange regexp behavior, G.., 2008/09/12
- Re: strange regexp behavior, Sergei Steshenko, 2008/09/12
- Re: strange regexp behavior, dbateman, 2008/09/13
- Re: strange regexp behavior, Thomas Weber, 2008/09/14
- Re: strange regexp behavior, G.., 2008/09/18
- Re: strange regexp behavior, David Bateman, 2008/09/18
- Re: strange regexp behavior, G.., 2008/09/18
- Re: strange regexp behavior, David Bateman, 2008/09/18
- Re: strange regexp behavior,
Thomas Weber <=
- Re: strange regexp behavior, David Bateman, 2008/09/18
- Re: strange regexp behavior, Thomas Weber, 2008/09/21
- Re: strange regexp behavior, David Bateman, 2008/09/23
- Message not available
- Re: strange regexp behavior, David Bateman, 2008/09/23
- Re: strange regexp behavior, John W. Eaton, 2008/09/24
- Re: strange regexp behavior, Jaroslav Hajek, 2008/09/29