From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Daniel Colascione 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 07:46:01 -0700 Message-ID: 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=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1529419457 19928 195.159.176.226 (19 Jun 2018 14:44:17 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 19 Jun 2018 14:44:17 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 Cc: Stefan Monnier , emacs-devel@gnu.org To: "Perry E. Metzger" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Jun 19 16:44:13 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 1fVHrf-00053v-JT for ged-emacs-devel@m.gmane.org; Tue, 19 Jun 2018 16:44:11 +0200 Original-Received: from localhost ([::1]:43079 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVHtm-00055b-NK for ged-emacs-devel@m.gmane.org; Tue, 19 Jun 2018 10:46:22 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:46613) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVHta-000553-QW for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:46:11 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fVHtZ-0005Df-Nj for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:46:10 -0400 Original-Received: from dancol.org ([2600:3c01::f03c:91ff:fedf:adf3]:54304) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fVHtZ-0005CX-Ba for emacs-devel@gnu.org; Tue, 19 Jun 2018 10:46:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=dancol.org; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=XGHtfojYp+HaD7eethPr38d5NATpM1b2vUate5q0cQQ=; b=QxP95xDv3OHsJnebOEGSnp18Ax2oqrylzcFkRx8bqaA1Yb2Hirvijr9Bo6o6u2JQwfMRkKH0tOlEeiURBPKCVa4/o/leUoUuXLNVKsSMe4XshZJlsY0wIzNzYt5WjGrE7OKCgtn9fMm5pxUvywFXRGXFiVpfrXw7b62YIOLE75zv2Txwdn+umyXvSXYVjhzts3/VM/ioCm7C0LMWj06z6cDuWx1e+wQhueEJGVa1PLuDKPctfF4vHAb9MHaSj0qyDoZMsJt0QT+yImN3pqpMmsWJ7uLm1dYfvWwu6OO1Dc5IdO6GkyB2Y5eXSPyMFgyeKZweJe+fqk7sXnYn5dlNrQ==; Original-Received: from [2604:4080:1321:8c20:d991:ea76:d225:59a1] by dancol.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1fVHtX-0002R4-AT; Tue, 19 Jun 2018 07:46:07 -0700 In-Reply-To: <20180619103002.4f000018@jabberwock.cb.piermont.com> Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2600:3c01::f03c:91ff:fedf:adf3 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:226508 Archived-At: On 06/19/2018 07:30 AM, Perry E. Metzger wrote: > On Tue, 19 Jun 2018 06:49:03 -0700 Daniel Colascione > wrote: >> On 06/19/2018 06:44 AM, Perry E. Metzger wrote: >>> On Tue, 19 Jun 2018 09:40:05 -0400 "Perry E. Metzger" >>> wrote: >>>> On Mon, 18 Jun 2018 10:49:46 -0700 "Daniel Colascione" >>>> wrote: >>>>>> I think the right thing would be to use TRE if we could get >>>>>> Ville Laurikari to let someone else be the maintainer. Sadly >>>>>> right now it seems unmaintained and has been for years, but >>>>>> it's fast, complete, and has the ability to handle things like >>>>>> gap buffers. >>>>> >>>>> Last time I looked, many years ago, there were several bugs (or >>>>> differences between TRE and POSIX anyway) >>>> >>>> Bugs yes, but the POSIX conformance was pretty strict. As I >>>> said, he seemed to have abandoned the thing, but the bones are >>>> pretty good. Someone could just fork it and implement all the >>>> patches people have been contributing that have been languishing >>>> in the github issue trackers. >>> >>> 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 Sure, but the DFA and non-DFA engines can vary independently so long as they understand the same language, modulo backreference support. IMHO, back reference support is an old unix mistake. I can't think of a time when I've wanted to actually use them, but their theoretical use is still a hindrance. One option would be to just deprecate them.