GNU bug report logs - #44861
27.1; [PATCH] signal in `replace-regexp-in-string'

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#44861: closed (27.1; [PATCH] signal in `replace-regexp-in-string')
Date: Thu, 26 Nov 2020 13:40:02 +0000

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Your message dated Thu, 26 Nov 2020 14:39:01 +0100
with message-id <C136B0DC-1CC5-499E-8BBD-14EAF9E2A4EB <at> acm.org>
and subject line Re: bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string'
has caused the debbugs.gnu.org bug report #44861,
regarding 27.1; [PATCH] signal in `replace-regexp-in-string'
to be marked as done.

(If you believe you have received this mail in error, please contact
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44861: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=44861
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From: Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 27.1; [PATCH] signal in `replace-regexp-in-string'
Date: Wed, 25 Nov 2020 13:02:11 +0900

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`replace-regexp-in-string' sometimes signals an error when REGEXP
contains some bondary sequence.  Difference of searches between
against an original passed string and against an extracted substring
causes the incident.


(replace-regexp-in-string-simple "a\\B" "A" "a aaaa")
	error --> cons: Args out of range: 2, 3
    expected
	==> "a AAAa"

(replace-regexp-in-string "\\Ba" "A" "a aaaa")
	error --> cons: Args out of range: 3, 4
    expected
	==> "a aAAA"

--
Shigeru

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From: Mattias Engdegård <mattiase <at> acm.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: Dmitry Gutov <dgutov <at> yandex.ru>, 44861-done <at> debbugs.gnu.org,
 Stefan Kangas <stefankangas <at> gmail.com>,
 Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
Subject: Re: bug#44861: 27.1; [PATCH] signal in `replace-regexp-in-string'
Date: Thu, 26 Nov 2020 14:39:01 +0100

26 nov. 2020 kl. 14.12 skrev Lars Ingebrigtsen <larsi <at> gnus.org>:

> I'm all for speeding up replace-regexp-in-string (which is used all over
> the place), so your change looks reasonable to me.

Thank you! Pushed to master.

> But I wonder -- would it make sense to move the entire
> replace-regexp-in-string function to C?

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.

(Dmitry Gutov asked for a C implementation in bug#20273 for improving the speed of json encoding; is that still relevant?)

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.

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