From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: "Perry E. Metzger" Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; update syntax during match Date: Tue, 19 Jun 2018 10:33:25 -0400 Message-ID: <20180619103325.7d79befb@jabberwock.cb.piermont.com> References: <20180616204650.8423.73499@vcs0.savannah.gnu.org> <20180616204653.86AFC203CB@vcs0.savannah.gnu.org> <04e89d2beffedcc102b811863910c1ec.squirrel@dancol.org> <20180618115941.4f22a9d3@jabberwock.cb.piermont.com> <1de38eca2662563e9e08006c88a6d2e5.squirrel@dancol.org> <20180619094005.11465a87@jabberwock.cb.piermont.com> <20180619094442.41287e4b@jabberwock.cb.piermont.com> <20180619103002.4f000018@jabberwock.cb.piermont.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1529418821 6384 195.159.176.226 (19 Jun 2018 14:33:41 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 19 Jun 2018 14:33:41 +0000 (UTC) Cc: Stefan Monnier , emacs-devel@gnu.org To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Jun 19 16:33:36 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fVHhQ-0001Yq-EA for ged-emacs-devel@m.gmane.org; Tue, 19 Jun 2018 16:33:36 +0200 Original-Received: from localhost ([::1]:43021 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVHjX-0007Dj-PS for ged-emacs-devel@m.gmane.org; Tue, 19 Jun 2018 10:35:47 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:42964) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVHhH-0005km-2u for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:33:32 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fVHhG-0004v4-9b for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:33:27 -0400 Original-Received: from hacklheber.piermont.com ([2001:470:30:84:e276:63ff:fe62:3400]:54844) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fVHhG-0004uK-4k for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:33:26 -0400 Original-Received: from snark.cb.piermont.com (localhost [127.0.0.1]) by hacklheber.piermont.com (Postfix) with ESMTP id 7D3C719F; Tue, 19 Jun 2018 10:33:25 -0400 (EDT) Original-Received: from jabberwock.cb.piermont.com (jabberwock.cb.piermont.com [10.160.2.107]) by snark.cb.piermont.com (Postfix) with ESMTP id 6FB472DEC76; Tue, 19 Jun 2018 10:33:25 -0400 (EDT) In-Reply-To: <20180619103002.4f000018@jabberwock.cb.piermont.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:470:30:84:e276:63ff:fe62:3400 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:226507 Archived-At: On Tue, 19 Jun 2018 10:30:02 -0400 "Perry E. Metzger" wrote: > > > Oh, and re2 isn't built for POSIX compliance. It has no > > > constructs that require backtracking etc. > > > > No DFA engine can do backtracking. > > Correct, but there are regexp libraries that will switch between DFA > and non-DFA implementations depending on whether the regexp has > constructs in it that require backtracking. Just to be explicit: TRE does this, IIRC. It certainly implements backreferences, which re2 does not. (And, it has provisions in its API for handling things like gap buffers. The main problem is it is unmaintained.) Perry -- Perry E. Metzger perry@piermont.com