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bug#31584: 27.0.50; Document again what match re-search-backward finds


From: Michael Heerdegen
Subject: bug#31584: 27.0.50; Document again what match re-search-backward finds
Date: Fri, 25 May 2018 00:47:49 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)

Noam Postavsky <address@hidden> writes:

> The docstring should definitely be clarified, but technically it can
> still be answered, if you read very carefully:
>
>     (re-search-backward REGEXP &optional BOUND NOERROR COUNT)
>
>     Search backward from point for regular expression REGEXP.
>     This function is almost identical to ‘re-search-forward’, except that
>     by default it searches backward instead of forward, and the sign of
>     COUNT also indicates exactly the opposite searching direction.
>
>     (re-search-forward REGEXP &optional BOUND NOERROR COUNT)
>
>     [...]
>     With COUNT positive/negative, the match found is [...] located
>       entirely after/before the origin of the search.

You mean the sentence about the COUNT arg?  Yes, _very_ carefully.

> It is greedy:
>
> (with-temp-buffer
>   (insert "xxxxyyyy")
>   (and (re-search-backward "x+y*" nil t)
>        (match-string 0))) ;=> "xyyyy"
>
> Non-greedy wouldn't match any "y"s.  It's a bit tricky to explain both
> correctly and clearly...

Ok, good example.  You convinced me that the sentence we once had was
actually quite good.


Michael.





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