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bug#24801: 25.1; Reverse regexp search highlighting
From: |
Eli Zaretskii |
Subject: |
bug#24801: 25.1; Reverse regexp search highlighting |
Date: |
Thu, 27 Oct 2016 05:33:52 +0300 |
> From: npostavs@users.sourceforge.net
> Date: Wed, 26 Oct 2016 18:42:20 -0400
> Cc: 24801@debbugs.gnu.org
>
> > I see this behavior in Emacs 23 and later, but not in Emacs 22 and
> > before, so I'm guessing this change is maybe intentional. But it's not
> > clear to me why it would be.
>
> `(elisp) Regexp Search', under `re-search-backward' says:
>
> This function is analogous to `re-search-forward', but they are not
> simple mirror images. `re-search-forward' finds the match whose
> beginning is as close as possible to the starting point. If
> `re-search-backward' were a perfect mirror image, it would find the
> match whose end is as close as possible. However, in fact it
> finds the match whose beginning is as close as possible (and yet
> ends before the starting point). The reason for this is that
> matching a regular expression at a given spot always works from
> beginning to end, and starts at a specified beginning position.
>
> A true mirror-image of `re-search-forward' would require a special
> feature for matching regular expressions from end to beginning.
> It's not worth the trouble of implementing that.
>
> And the texi source says the same at tag emacs-22.1; I've only built
> Emacs back to 23.4 though, so I can't test it.
I see the same behavior in all versions, including 22.x and 21.4.