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.