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Re: Problems with syntax-ppss
From: |
Stefan Monnier |
Subject: |
Re: Problems with syntax-ppss |
Date: |
Sat, 05 Apr 2008 14:37:39 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) |
>> >I strongly recommend to always call syntax-ppss in a widened buffer.
>> ... and with match-data saved.
> Er, your replies don't exactly radiate an aura of confidence about
> syntax-ppss. ;-(
> I think you (Stefan) 're saying that the function isn't 100% defined for
> a narrowed buffer.
Indeed.
> Will calling s-ppss on a narrowed buffer corrupt the
> cache at all, for example?
Yes it can. Similarly the cache does not keep track of the syntax-table
so if you switch syntax-table between calls you may get unexpected results.
> As a matter of interest, are there any benchmark figures for s-ppss?
I did time it in various circumstances when writing it (so as to tune
its algorithm).
> Like, how many characters do you have to scan more than, before s-ppss
> (an interpreted lisp function) starts being faster than
> (parse-partial-sexp 1 (point)) (a fast function written in C)?
I can't remember exactly, but syntax-ppss-max-span was set based on
these measurements, so it gives you an idea. Note that there are two
different caches: there's syntax-ppss-cache which is affected by
syntax-ppss-max-span and is only really useful for large buffers, and
there's syntax-ppss-last which benefit from spatial locality.
Stefan
- Problems with syntax-ppss, Alan Mackenzie, 2008/04/04
- Re: Problems with syntax-ppss, Lennart Borgman (gmail), 2008/04/04
- Re: Problems with syntax-ppss, Stefan Monnier, 2008/04/04
- Re: Problems with syntax-ppss, martin rudalics, 2008/04/04
- Re: Problems with syntax-ppss, Alan Mackenzie, 2008/04/05
- Re: Problems with syntax-ppss,
Stefan Monnier <=
- Re: Problems with syntax-ppss, Alan Mackenzie, 2008/04/06
- Re: Problems with syntax-ppss, Stefan Monnier, 2008/04/07
- Re: Problems with syntax-ppss, Lennart Borgman (gmail), 2008/04/07
- Re: Problems with syntax-ppss, Stefan Monnier, 2008/04/07
- Re: Problems with syntax-ppss, Stefan Monnier, 2008/04/07