From: Lars Ingebrigtsen <larsi@gnus.org>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Christian Johansson <christian@cvj.se>, 53680@debbugs.gnu.org
Subject: bug#53680: Endless loop in peculiar case of string-match and string-match-p 27.02 and 28.0.50
Date: Tue, 01 Feb 2022 13:16:30 +0100 [thread overview]
Message-ID: <87sft2vl29.fsf@gnus.org> (raw)
In-Reply-To: <87pmo63kio.fsf@igel.home> (Andreas Schwab's message of "Tue, 01 Feb 2022 12:15:43 +0100")
Andreas Schwab <schwab@linux-m68k.org> writes:
> It sure is. The nesting of the + operator without proper anchoring
> makes the search space explode.
Yup. So something like
(string-match
"[\r\t ]*implements\\([\r\t ]+[\\a-zA-Z_0-9_]+,?\\)+[\r\t ]*{$"
"ariable implements \\Magento\\Framework\\Event\\OberserverInterface\r{\r public function __construct()\r ")
won't have the same explosion (and indeed finished immediately).
So I don't think this is an Emacs bug, just a very tough regexp to
match. There's been some talk about replacing Emacs' regexp motor with
something that has better backtracking characteristics, but I don't
recall if anybody has actually made any moves to make that happen.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2022-02-01 12:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 7:37 bug#53680: Endless loop in peculiar case of string-match and string-match-p 27.02 and 28.0.50 Christian Johansson
2022-02-01 11:00 ` Lars Ingebrigtsen
2022-02-01 11:08 ` Lars Ingebrigtsen
2022-02-01 11:25 ` Andreas Schwab
2022-02-01 11:15 ` Andreas Schwab
2022-02-01 12:16 ` Lars Ingebrigtsen [this message]
2022-02-01 12:56 ` Mattias Engdegård
2022-02-01 13:12 ` Christian Johansson
[not found] ` <AB866492-4CC0-418A-8C9E-CAAB2C522CDA@acm.org>
2022-02-01 16:23 ` Christian Johansson
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