[Phoenix-pm] Fwd: Re: A christmas wish: simple notation for ratcheting (non-backtrack) regex

Scott Walters scott at illogics.org
Tue Dec 26 10:35:28 PST 2006

Hi all,

In Perl 5.10, + in a pattern after another qualifier means "don't back up past
this point if you've matched this much".  Yay =)


----- Forwarded message from Rafael Garcia-Suarez <rgarciasuarez at gmail.com> -----

From: Rafael Garcia-Suarez <rgarciasuarez at gmail.com>
To: "Randal L. Schwartz" <merlyn at stonehenge.com>
Subject: Re: A christmas wish: simple notation for ratcheting (non-backtrack) regex

On 25 Dec 2006 21:39:29 -0800, Randal L. Schwartz <merlyn at stonehenge.com> 
>>>>>> "mark" == mark  <mark at mark.mielke.cc> writes:
>mark> Are you asking for the same thing as the Java "possessive 
>mark> They use "+" to mean this already.
>Yeah, OK.  I didn't think I was totally making this up. :)
>But it's even more interesting if it's to be compatible with other
>regex engines.  Cool.

bleadperl has possessive quantifiers, thanks to Yves.
>From perlre:

Possessive quantifiers are equivalent to putting the item they are applied
to inside of one of these constructs. The following equivalences apply:

   Quantifier Form     Bracketing Form
   ---------------     ---------------
   PAT*+               (?>PAT*)
   PAT++               (?>PAT+)
   PAT?+               (?>PAT?)
   PAT{min,max}+       (?>PAT{min,max})

----- End forwarded message -----

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