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From: Drew Adams <drew.adams@oracle.com>
To: Tassilo Horn <tsdh@gnu.org>
Cc: Michael Heerdegen <michael_heerdegen@web.de>, help-gnu-emacs@gnu.org
Subject: RE: `looking-back' strange warning
Date: Fri, 2 Oct 2015 14:35:03 -0700 (PDT)	[thread overview]
Message-ID: <785d8be4-1024-4635-83ff-7bc51dd4b5bf@default> (raw)
In-Reply-To: <87lhblrnpe.fsf@gnu.org>

> This version is about 6 times faster in the t case and a still a bit
> faster in the nil case where the char before point is already different
> (which is the best case for your function).
> 
> (defun chars-before (chars)
>   "Return non-nil if the literal string CHARS is right before point.
> This is more efficient that `looking-back' for this use case."
>   (let ((beg (- (point) (length chars))))
>     (unless (< beg 0)
>       (save-excursion
> 	  (goto-char beg)
> 	  (looking-at (regexp-quote chars))))))

OK.  Good to know.

See also bug #17284,
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=17284,
where this has been discussed and I and others proposed
code for this.

You are welcome to contribute to that (short) bug thread,
or to otherwise try to get such a function added to Emacs.



  reply	other threads:[~2015-10-02 21:35 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-30  8:25 `looking-back' strange warning Andreas Röhler
2015-10-01  6:20 ` Michael Heerdegen
2015-10-01  6:25 ` Tassilo Horn
2015-10-01  6:50 ` Dmitry Gutov
2015-10-01  7:49   ` Andreas Röhler
2015-10-01  8:20     ` Tassilo Horn
2015-10-01  8:46       ` Andreas Röhler
2015-10-01  9:29         ` Tassilo Horn
2015-10-02  0:10       ` Stefan Monnier
2015-10-02 15:21         ` Tassilo Horn
2015-10-01 16:00   ` Drew Adams
2015-10-01 17:56     ` Dmitry Gutov
2015-10-01 18:24       ` Andreas Röhler
2015-10-01 18:59         ` Dmitry Gutov
2015-10-01 19:55           ` Andreas Röhler
2015-10-01 20:26             ` Dmitry Gutov
2015-10-02  0:15             ` Stefan Monnier
2015-10-02  1:18               ` Michael Heerdegen
2015-10-02  5:13                 ` Drew Adams
2015-10-02 20:28                   ` Drew Adams
2015-10-02 20:59                     ` Tassilo Horn
2015-10-02 21:35                       ` Drew Adams [this message]
2015-10-03  6:26                         ` Tassilo Horn
2015-10-03  6:45                           ` Andreas Röhler
2015-10-03 15:20                             ` Drew Adams
2015-10-03 15:17                           ` Drew Adams
2015-10-02  1:19               ` Michael Heerdegen
2015-10-02  5:12               ` Drew Adams
2015-10-02  6:16                 ` Andreas Röhler
2015-10-02  6:36                   ` Michael Heerdegen
2015-10-02 12:46                 ` Stefan Monnier
2015-10-02 15:02                   ` Drew Adams
2015-10-02 19:08               ` Tom Tromey
2015-10-02 19:33                 ` Stefan Monnier
2015-10-03 18:11                   ` Stefan Monnier
     [not found]   ` <mailman.176.1443721449.16064.help-gnu-emacs@gnu.org>
2015-10-01 18:50     ` Barry Margolin
     [not found]     ` <<barmar-D40496.14502501102015@88-209-239-213.giganet.hu>
2015-10-01 23:42       ` Drew Adams
2015-10-02  0:12         ` Stefan Monnier
2015-10-02  5:10           ` Drew Adams
2015-10-02 12:48             ` Stefan Monnier
2015-10-02 15:03               ` Drew Adams
2015-10-02 15:21                 ` Stefan Monnier
2015-10-02 15:24                   ` Drew Adams
2015-10-02 19:28                     ` Stefan Monnier
2015-10-01 12:35 ` Artur Malabarba
     [not found] <<560B9C7F.2060301@easy-emacs.de>

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