From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: Bug #25608 and the comment-cache branch
Date: Tue, 14 Feb 2017 11:38:06 -0500 [thread overview]
Message-ID: <jwv4lzwn46i.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: 424e6409-029c-d15d-421c-4fb90594329c@yandex.ru
> What is "it"? I would imagine that to be sure that point is not
> e.g. inside a string, the patch would have to consult the cache (or call
> syntax-ppss) at least once per forward-comment call.
Like all the sexp movement functions, `forward-comment` is allowed to
assume that the starting position is outside of comments/strings, so it
doesn't need to consult the cache to see if it's within a string.
In the case we do scan forward (e.g. the case where we end up using
parse-partial-sexp (or syntax-ppss in my patch)), we actually manually
re-introduce that behavior: if the forward parse says that the
end-comment-marker in inside a string (or inside another comment), we
re-parse from the beginning of that string (or comment) to try and see
if that end-comment-marker could be considered to close a comment nested
within the string (or the other comment).
> From there, I don't really see a real need for backward comment scanning.
> So if you rewrote some code to use forward scanning, that approach should be
> applicable on top of the AP as well.
Calling syntax-ppss every time back_comment is invoked would probably
result in bad performance currently: when parsing backward
(e.g. backward-sexp), the syntax-ppss-last optimization is ineffective,
so we'd fallback on syntax-ppss-cache which ends up scanning on the
average syntax-ppss-max-span/2 (i.e. 10K) chars. When \n is a comment
ender (i.e. in most programming language modes), it would imply
a forward scan of 10K for every line.
IOW, for such an approach to work, we'd have to rework syntax-ppss to be
faster when scanning backward (e.g. reduce syntax-ppss-max-span, which
would have other repercussions).
>> That sounds like you've decided you want to use syntax-ppss no matter
There's no alternative to syntax-ppss on the table, AFAIK.
>> what, and the bugs this will cause will just be relabeled as features.
Care to back up this claim?
Where/when have we claimed that what you consider as a syntax-ppss bug
is a feature?
Stefan
next prev parent reply other threads:[~2017-02-14 16:38 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-02 20:24 Bug #25608 and the comment-cache branch Alan Mackenzie
2017-02-02 20:47 ` Eli Zaretskii
2017-02-02 21:51 ` Alan Mackenzie
2017-02-02 22:15 ` Dmitry Gutov
2017-02-03 7:41 ` Eli Zaretskii
2017-02-03 17:29 ` Alan Mackenzie
2017-02-03 22:08 ` Dmitry Gutov
2017-02-04 10:24 ` Alan Mackenzie
2017-02-06 2:09 ` Dmitry Gutov
2017-02-06 19:24 ` Alan Mackenzie
2017-02-07 1:42 ` Dmitry Gutov
2017-02-07 19:21 ` Alan Mackenzie
2017-02-14 15:28 ` Dmitry Gutov
2017-02-14 16:38 ` Stefan Monnier [this message]
2017-02-22 2:25 ` Dmitry Gutov
2017-02-22 3:53 ` Stefan Monnier
2017-02-23 14:23 ` Dmitry Gutov
2017-02-23 14:48 ` Stefan Monnier
2017-02-24 7:46 ` Tom Tromey
2017-02-14 21:14 ` Alan Mackenzie
2017-02-16 14:10 ` Stefan Monnier
2017-02-18 10:44 ` Alan Mackenzie
2017-02-18 13:49 ` Stefan Monnier
2017-02-12 2:53 ` John Wiegley
2017-02-12 8:20 ` Elias Mårtenson
2017-02-12 10:47 ` Alan Mackenzie
2017-02-12 11:14 ` martin rudalics
2017-02-12 15:05 ` Andreas Röhler
2017-02-12 15:39 ` Eli Zaretskii
2017-02-05 22:00 ` Alan Mackenzie
2017-02-06 1:12 ` Stefan Monnier
2017-02-06 18:37 ` Alan Mackenzie
2017-02-08 17:20 ` Eli Zaretskii
2017-02-11 23:25 ` Alan Mackenzie
2017-02-12 0:55 ` Stefan Monnier
2017-02-12 12:05 ` Alan Mackenzie
2017-02-12 13:13 ` Juanma Barranquero
2017-02-12 15:57 ` Dmitry Gutov
2017-02-12 17:29 ` Alan Mackenzie
2017-02-12 20:35 ` Dmitry Gutov
2017-02-13 1:47 ` zhanghj
2017-02-13 5:50 ` Stefan Monnier
2017-02-13 6:45 ` zhanghj
2017-02-13 7:24 ` Stefan Monnier
2017-02-13 7:59 ` zhanghj
2017-02-13 9:25 ` Stefan Monnier
2017-02-13 16:14 ` Drew Adams
2017-02-13 7:05 ` zhanghj
2017-02-13 7:16 ` zhanghj
2017-02-13 14:57 ` Dmitry Gutov
2017-02-12 17:49 ` Stefan Monnier
2017-02-13 18:09 ` Alan Mackenzie
2017-02-13 19:34 ` Eli Zaretskii
2017-02-13 21:21 ` Stefan Monnier
2017-02-02 22:14 ` Dmitry Gutov
2017-02-03 16:44 ` Alan Mackenzie
2017-02-03 21:53 ` Dmitry Gutov
2017-02-04 11:02 ` Alan Mackenzie
2017-02-06 1:28 ` Dmitry Gutov
2017-02-06 19:37 ` Alan Mackenzie
2017-02-06 2:08 ` Stefan Monnier
2017-02-06 20:01 ` Alan Mackenzie
2017-02-06 22:33 ` Stefan Monnier
2017-02-07 21:24 ` Alan Mackenzie
2017-02-08 12:54 ` Stefan Monnier
2017-02-07 15:29 ` Eli Zaretskii
2017-02-07 21:09 ` Alan Mackenzie
2017-02-08 17:28 ` Eli Zaretskii
2017-02-02 23:57 ` Stefan Monnier
2017-02-03 16:19 ` Alan Mackenzie
2017-02-04 9:06 ` Andreas Röhler
2017-02-04 18:18 ` Stefan Monnier
2017-02-04 18:28 ` Alan Mackenzie
2017-02-03 7:49 ` Yuri Khan
2017-02-03 18:30 ` Andreas Röhler
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