From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Perl, etc has these "?"-prefix modifiers/codes/whatever. Precisely which does emacs have (and NOT have)? Date: Wed, 24 Feb 2010 14:54:14 -0500 Message-ID: References: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: dough.gmane.org 1267044111 18910 80.91.229.12 (24 Feb 2010 20:41:51 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 24 Feb 2010 20:41:51 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Feb 24 21:41:47 2010 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1NkO3D-0006Yv-9T for geh-help-gnu-emacs@m.gmane.org; Wed, 24 Feb 2010 21:41:43 +0100 Original-Received: from localhost ([127.0.0.1]:48493 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NkO3C-0007rr-QL for geh-help-gnu-emacs@m.gmane.org; Wed, 24 Feb 2010 15:41:42 -0500 Original-Path: news.stanford.edu!usenet.stanford.edu!postnews.google.com!news2.google.com!npeer02.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!post01.iad.highwinds-media.com!newsfe09.iad.POSTED!7564ea0f!not-for-mail Original-Newsgroups: gnu.emacs.help User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.92 (gnu/linux) Cancel-Lock: sha1:JzR7DLbLxMR4TbGIMtis0YW4B4M= Original-Lines: 23 Original-X-Complaints-To: abuse@UsenetServer.com Original-NNTP-Posting-Date: Wed, 24 Feb 2010 19:54:15 UTC Original-Xref: news.stanford.edu gnu.emacs.help:177072 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:72111 Archived-At: > Please, someone, make an ascii or html table or even plain text > list of all these neat "new" non-standard ops that perl and > even php and ruby etc seem to have now, comparing them > to what Emacs has or don't have. As mentioned, Emacs regexps are fairly well described in the Emacs manual and the Elisp manual. Indeed Emacs regexps don't support all the fancy additions present in things like Perl. IIRC someone provided a patch for the look-ahead and look-behind features, but it got lost somewhere along the way. Emacs likes regexps, so it makes sense to support these things. At the same time, I've known them for a long time but have rarely found a need for them in my Emacs experience. Personally I'd like to add a DFA-based regex engine to Emacs, so as to get rid of the exponential backtracking problem that shows up every once in a while (it also has a few other advantages, such as the ability to do the regexp matching a chunk at a time). Stefan