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Re: C and Emacs Lisp code parts


From: Fabrice Popineau
Subject: Re: C and Emacs Lisp code parts
Date: Sat, 2 Jul 2016 16:41:05 +0000 (UTC)
User-agent: Loom/3.14 (http://gmane.org/)

Eli Zaretskii <eliz <at> gnu.org> writes:

> As for font-lock, its features are based on regular expression and
> syntax tables, both of which are implemented in C as well.

The fact that regexp are implemented in C is not a guarantee of 
the best speed.
Some years ago, when the Common Lisp CL-PPCRE library appeared, 
it was benchmarked 5-20 times faster than C regexp libraries, because
the automaton was compiled directly to machine code, whereas the C
counterpart had to do lookups into the table that describes the
automaton.

I am no specialist of the the current variants of regexp libraries
but some of them seem to make use of jit compiler.
(See http://sljit.sourceforge.net/regex_perf.html for example)
So isnt't there some response time to gain around regexps?
Because I don't see that src/regex.c is using a jit.

Fabrice








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