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bug#19873: Ill-formed regular expression is constructed in forward-parag
From: |
Lars Ingebrigtsen |
Subject: |
bug#19873: Ill-formed regular expression is constructed in forward-paragraph. |
Date: |
Thu, 02 Dec 2021 11:39:51 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
Alan Mackenzie <acm@muc.de> writes:
> I think this idea is workable, but you'll have to check for one or both
> of paragraph-s{tart,eparate} starting with "[ \t]+". A good strategy
> here might be to begin the target regexp with "^[ \t]*", then begin one
> or both components with "[ \t]" (without the "*").
>
> There may be other gotchas which I haven't thought about yet.
>
> One needs a twisted mind to do this sort of thing properly, so I offer my
> services to review your upcoming patch. ;-)
The problem seems rather intractable to me. Is there really any way to
examine a regexp to determine "does this in practice match [ \t]*"?
I wonder whether instead of trying to construct a better overall regexp
could rewrite the loop. That is, instead of searching for sp-parstart,
search for parstart "\\|" parsep, and then check whether
(match-beginning 0) of that comes after "^[ \t]*". Or something along
those lines.
But I don't know whether that'd be any faster in practice.
Do you have a test case that demonstrates the slowness? In that case I
could try to see whether there's any alternate approach here that's
faster.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#19873: Ill-formed regular expression is constructed in forward-paragraph.,
Lars Ingebrigtsen <=