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bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string'
From: |
Lars Ingebrigtsen |
Subject: |
bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string' |
Date: |
Thu, 26 Nov 2020 15:03:30 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Mattias Engdegård <mattiase@acm.org> writes:
> Probably, but that would be a pure performance improvement. Most of
> the time is currently consumed in primitives (string-match,
> replace-match, substring, concat) so don't expect huge savings unless
> a substantially different approach is taken.
Yeah, perhaps there's isn't a lot to be gained there, unless a lot of
the re-checking of all the arguments (etc.) (which is unnecessary once
we've ascertained that everything is, indeed, a string) can be done by
refactoring some of the underlying primitives.
> (Dmitry Gutov asked for a C implementation in bug#20273 for improving
> the speed of json encoding; is that still relevant?)
No, probably not, since it's now done by Jansson? So I'm closing that
one.
> A bigger saving yet would be to use the much faster string-replace
> wherever possible. A little sweeping refactoring project perhaps? It
> would also improve readability -- no regexp quoting, fewer mysterious
> arguments like LITERAL and FIXEDCASE to worry about, etc.
I started looking at that, and there's a huge pile of calls like
(replace-regexp-in-string ":" ";" string)
that can be rewritten to use string-replace. But! Every single case
requires careful analysis, exactly because replace-regexp-in-string sets
the match data. Perhaps five lines later, there's a reference to
(match-string 0 string)? Perhaps the reference is in the function that
called this function?
So most changes are fraught with possible unforeseen breakages, the code
is super-duper straightforward like
(setq string (replace-regexp-in-string ":" ";" string))
(setq string (replace-regexp-in-string "a" "b" string))
Then you know that you can replace the first one without any danger.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Shigeru Fukaya, 2020/11/24
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Mattias Engdegård, 2020/11/25
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Mattias Engdegård, 2020/11/25
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Stefan Kangas, 2020/11/25
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Mattias Engdegård, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Lars Ingebrigtsen, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Mattias Engdegård, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string',
Lars Ingebrigtsen <=
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Mattias Engdegård, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Basil L. Contovounesios, 2020/11/29
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Stefan Kangas, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Lars Ingebrigtsen, 2020/11/26
- bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string', Eli Zaretskii, 2020/11/26