From: Tim Landscheidt <tim@tim-landscheidt.de>
To: help-gnu-emacs@gnu.org
Subject: Re: does emacs regular expression support (?!expression)
Date: Thu, 02 Feb 2012 22:11:27 +0000 [thread overview]
Message-ID: <m3pqdwlwc0.fsf@passepartout.tim-landscheidt.de> (raw)
In-Reply-To: 87ipjo52qn.fsf@thinkpad.tsdh.de
Tassilo Horn <tassilo@member.fsf.org> wrote:
> [...]
>>> matches "foo19" or "bar23", but doesn't capture foo or bar, so that
>>> (match-string 1) is the number.
>> In Perl, "(?!pattern)" is a zero-width negative look-ahead
>> assertion. Emacs does not support these AFAIK.
> I see. So when you do /foo(?!bar)/ in Perl, you'd need to do
> "foo\\(?:[^b][^a][^r]\\)" in elisp.
You have to account for possible end-of-buffer as well so
usually it's "easier" to use two matches ('(while (and
(search-forward-regexp "foo") (not (looking-at "bar"))))'
(untested)) - that's why I (still :-)) think these features
should be implemented in Emacs as well.
Tim
next prev parent reply other threads:[~2012-02-02 22:11 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 14:02 does emacs regular expression support (?!expression) 土星五号
2012-02-02 18:56 ` Tassilo Horn
2012-02-02 21:14 ` Tim Landscheidt
2012-02-02 21:45 ` Tassilo Horn
2012-02-02 22:11 ` Tim Landscheidt [this message]
2012-02-02 22:17 ` Tim Landscheidt
2012-02-03 0:37 ` Kevin Rodgers
2012-02-03 2:12 ` 土星五号
2012-02-03 8:30 ` Thien-Thi Nguyen
2012-02-03 11:17 ` Tim Landscheidt
2012-02-03 11:48 ` Thien-Thi Nguyen
2012-02-04 10:12 ` Tim Landscheidt
2012-02-04 12:16 ` 土星五号
2012-02-04 15:26 ` Thien-Thi Nguyen
2012-02-05 11:57 ` Tim Landscheidt
2012-02-02 22:09 ` Glenn Morris
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