[Pharo-users] Non-greedy RegEx?

Manuel Leuenberger leuenberger at inf.unibe.ch
Tue Feb 5 09:49:54 EST 2019


I am not advocating for PCRE in particular, I just need a regex engine that is just as powerful. I guess re2 serves that purpose, although I haven't used it myself (knowingly).

Looking at https://github.com/google/re2/wiki/WhyRE2 <https://github.com/google/re2/wiki/WhyRE2>, re2 actually seems to be a good target. "match time is linear in the length of the input string", sounds like a really nice property.

> On 5 Feb 2019, at 12:26, Richard O'Keefe <raoknz at gmail.com> wrote:
> 
> Please DON'T move to PCRE.
> "Outside world standards"?  There are so many.
> There are two important things to know about
> PCRE: (1) it is a popular open source regexp
> library for Perl-style regexps, (2) because of
> that, it is prone to truly horrendous performance
> problems.  There are alternatives, such as re2,
> https://github.com/google/re2 <https://github.com/google/re2> ,
> which are not subject to PCRE's intrinsic
> performance pathologies.  As it happens, re2
> supports *? +? and ??.
> 
> On Tue, 5 Feb 2019 at 20:34, Esteban Lorenzano <estebanlm at gmail.com <mailto:estebanlm at gmail.com>> wrote:
> Hi,
> 
> Yes, Pharo regex implementation is very naive. 
> We will be moving to a PCRE binding to match outside world standards but we have not had the time to work on it :(
> 
> Esteban
> 
> > On 5 Feb 2019, at 00:27, Manuel Leuenberger <leuenberger at inf.unibe.ch <mailto:leuenberger at inf.unibe.ch>> wrote:
> > 
> > Hi,
> > 
> > I just noticed that the Pharo regexes do not understand non-greedy matches. A regex engine to be PCRE is kind of essential, not having '.*?' to be a parseable and working regex is a bummer. Are there any more powerful regex engines around for Pharo? I could not find any.
> > 
> > Cheers,
> > Manuel
> > 
> > 
> 
> 

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