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Re: Regexps and strings once again

From: Daniel Colascione
Subject: Re: Regexps and strings once again
Date: Sun, 14 Sep 2014 17:50:12 -0700
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On 09/14/2014 04:27 PM, Lars Magne Ingebrigtsen wrote:
> (dom-by-id dom (regexp "I \\(couldn't\\)?haz new syntax"))
> It would basically just put a text property on the string, and functions
> like `dom-by-id' would just do
> (if (regexp-p match)
>     (string-match match id)
>   (string= match id))
> Of course, both `regexp' and the proposed new syntax could compile the
> regexp and return a regexp object and stuff if we wanted to be more
> efficient...  But the regexp cache is already quite efficient, isn't it?

I've been working on an NFA combinator facility lately. The basic idea
is that you don't work in terms of regular expressions per se, but in
terms of state-matching machines (like the ones Ragel has) that you can
combine using the standard union, repeat, negative, and intersection
operators. You'd then build a matcher from an NFA-representation object
when you needed to build a recognizer. Stefan has something similar in
ELPA --- lex.el --- except his code seems to do the conversion in one
shot instead of supporting the incremental building of matching machines.

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