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: efficient regular expression that never matches Date: Fri, 20 Nov 2015 10:13:11 -0500 Message-ID: References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1448032612 11387 80.91.229.3 (20 Nov 2015 15:16:52 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 20 Nov 2015 15:16:52 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Nov 20 16:16:44 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZznQI-0005NP-72 for geh-help-gnu-emacs@m.gmane.org; Fri, 20 Nov 2015 16:16:26 +0100 Original-Received: from localhost ([::1]:48017 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZznQH-0001dJ-Ox for geh-help-gnu-emacs@m.gmane.org; Fri, 20 Nov 2015 10:16:25 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:40853) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZznQ5-0001cq-Hc for help-gnu-emacs@gnu.org; Fri, 20 Nov 2015 10:16:14 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZznQ1-0006jD-GY for help-gnu-emacs@gnu.org; Fri, 20 Nov 2015 10:16:13 -0500 Original-Received: from plane.gmane.org ([80.91.229.3]:46887) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZznQ1-0006ic-4c for help-gnu-emacs@gnu.org; Fri, 20 Nov 2015 10:16:09 -0500 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZznOu-0003ig-Bu for help-gnu-emacs@gnu.org; Fri, 20 Nov 2015 16:15:00 +0100 Original-Received: from 23-91-153-239.cpe.pppoe.ca ([23.91.153.239]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 20 Nov 2015 16:15:00 +0100 Original-Received: from monnier by 23-91-153-239.cpe.pppoe.ca with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 20 Nov 2015 16:15:00 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 7 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 23-91-153-239.cpe.pppoe.ca User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) Cancel-Lock: sha1:Pe47kWUnNWC0i7FnTnTys6pC29Y= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:108167 Archived-At: > I'm thinking of "$a", but it should scan all the string until end > of the string, so it may not be efficient. IIRC I used something like "\\`\\'a". Stefan