From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Juri Linkov Newsgroups: gmane.emacs.devel Subject: Re: Make regexp handling more regular Date: Thu, 03 Dec 2020 23:02:10 +0200 Organization: LINKOV.NET Message-ID: <87wnxya9il.fsf@mail.linkov.net> References: <87lfeg60iy.fsf@gnus.org> <87a6uv7vp1.fsf@mail.linkov.net> <87360nz3gl.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="26086"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (x86_64-pc-linux-gnu) Cc: Lars Ingebrigtsen , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Dec 03 22:40:23 2020 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kkwKs-0006fg-Sp for ged-emacs-devel@m.gmane-mx.org; Thu, 03 Dec 2020 22:40:22 +0100 Original-Received: from localhost ([::1]:54112 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kkwKr-0004zq-Sg for ged-emacs-devel@m.gmane-mx.org; Thu, 03 Dec 2020 16:40:21 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:58464) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kkwJX-0004DU-Hf for emacs-devel@gnu.org; Thu, 03 Dec 2020 16:38:59 -0500 Original-Received: from relay11.mail.gandi.net ([217.70.178.231]:36967) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kkwJV-0008GZ-9d for emacs-devel@gnu.org; Thu, 03 Dec 2020 16:38:59 -0500 Original-Received: from mail.gandi.net (m91-129-99-98.cust.tele2.ee [91.129.99.98]) (Authenticated sender: juri@linkov.net) by relay11.mail.gandi.net (Postfix) with ESMTPSA id 17CF7100003; Thu, 3 Dec 2020 21:38:50 +0000 (UTC) In-Reply-To: (Stefan Monnier's message of "Thu, 03 Dec 2020 10:00:24 -0500") Received-SPF: pass client-ip=217.70.178.231; envelope-from=juri@linkov.net; helo=relay11.mail.gandi.net X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:260251 Archived-At: >>> Currently the match data is like a dynamically bound variable accessible >>> to the callee. But maybe the match data should be only lexically-bound? >>> (This is just a vague idea, I don't know how to implement this.) >> Yes, I wondered whether one could use some lexical magic here, but I >> didn't quite see what that would look like. > > Actually, currently the match-data is *not* like a dynamically-scoped > var, but like a global var. And we don't really need it to be lexically > scoped, we would be already well-served with a dynamically-scoped var. Notably in Ruby e.g. /(.)(.)(.)/.match("foo") returns a MatchData object: # Shouldn't a function like string-match (or rather some new function) return a # object too? Or the current list returned by the function 'match-data' is sufficient? Binding it to a variable will avoid the need to have global data (unless global data is a requirement for performance). Then: (let ((match-data (string-match regexp string))) (list (match-beginning subexp match-data) (match-end subexp match-data))) with an additional arg MATCH-DATA added to match-processing functions: (match-beginning SUBEXP &optional MATCH-DATA) (match-end SUBEXP &optional MATCH-DATA) (match-string NUM &optional STRING MATCH-DATA)