From: Juri Linkov <juri@linkov.net>
To: Dmitry Gutov <dgutov@yandex.ru>
Cc: emacs-devel@gnu.org
Subject: Re: Looking at function
Date: Mon, 11 Jul 2022 22:14:48 +0300 [thread overview]
Message-ID: <86y1wzv4uv.fsf@mail.linkov.net> (raw)
In-Reply-To: <b41fa083-3536-bc1f-067f-b0dfcc92854e@yandex.ru> (Dmitry Gutov's message of "Mon, 11 Jul 2022 04:26:15 +0300")
>> 1. Replace ‘looking-at’ with a call to the search function,
>> but keep it at point by prepending ‘\\=’ to the regexp.
>> Can it break a complex regexp?
>
> I suppose it can. Even a simple one (that has \\| inside without
> a grouping).
This is what the fix for xref successfully uses in bug#53758
with changes in perform-replace from bug#14013. (However,
none of these variants is suitable for replacing another call
of looking-at in isearch-search-and-update.)
> Do we have a clear understanding of the idea behind this looking-at call?
>
> The comment says:
>
> ;; Otherwise, if matching a regular expression, do the next
> ;; match now, since the replacement for this match may
> ;; affect whether the next match is adjacent to this one.
> ;; If that match is empty, don't use it.
>
> What happens if there are multiple adjacent matches in a row, not just 2?
> I suppose the replacement could be performed for the first one, then the
> next one is "popped" becoming the current and looking-at is called again
> near its end?
>
> If so, perhaps a good alternative is to stop caring about whether those
> matches are adjacent and always store the latest two matches, whether they
> are next to each other or not.
The sole purpose of this "do the next match now" hack
is to handle a special use case that is tested
in test/lisp/replace-tests.el:
;; Test case from commit 5632eb272c7
("a a a " "C-M-% \\ba SPC RET c RET !" "ccc") ; not "ca c"
;; Test case from commit 5632eb272c7
("a a a " "\\ba " "c" nil t nil nil nil nil nil nil nil "ccc") ; not "ca c"
next prev parent reply other threads:[~2022-07-11 19:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 18:01 Looking at function Juri Linkov
2022-06-28 19:22 ` Stefan Monnier
2022-07-01 15:49 ` Juri Linkov
2022-07-11 1:26 ` Dmitry Gutov
2022-07-11 19:14 ` Juri Linkov [this message]
2022-07-12 0:19 ` Dmitry Gutov
2022-07-12 0:29 ` Stefan Monnier
2022-08-17 0:23 ` Dmitry Gutov
2022-07-12 7:50 ` Juri Linkov
2022-08-17 0:27 ` Dmitry Gutov
2022-08-21 16:09 ` Juri Linkov
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