From: Robert Klemme <shortcutter@...>
Date: 2007-04-18T01:10:07+09:00
Subject: Re: Slow ruby regexes

On 17.04.2007 17:44, MenTaLguY wrote:
> On Tue, 17 Apr 2007 23:10:11 +0900, Robert Klemme <shortcutter@googlemail.com> wrote:
>> LOL - now I'm confused, too. :-)  I was looking for something like (made
>> up fake): "To prioritize branches of an alternative in sed you do sed -e
>> 's/foo(!2bar|!1baz)/yummy\1/g'."  Of course this does not work with sed
>> (at least no implementation of sed that I know).  Are there other tools
>> that allow to embed something into a RX that will do this prioritization?
> 
> OHHHHHHHH.

I hope it doesn't hurt too much. ;-)

> | is a deterministic choice operator, so the branches are prioritized by default -- earlier alternatives take precedence over later ones.  Just write your RX alternatives from highest to lowest priority.
> 
> Does that answer your question?

Maybe. :-)

I was under the impression that this precisely is a point of difference 
between NFA and DFA based engines: sed is DFA based and for all I know 
order in an alternative does not matter while it does matter for the 
typical NFA engine.  Did I get this wrong?

Kind regards

	robert