From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Ugly regexps Date: Wed, 03 Mar 2021 10:48:33 -0500 Message-ID: References: <79673252-c43d-6916-69d9-a46207137c85@yandex.ru> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="17342"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: Dmitry Gutov Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Mar 03 16:49:15 2021 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 1lHTkQ-0004PU-T4 for ged-emacs-devel@m.gmane-mx.org; Wed, 03 Mar 2021 16:49:14 +0100 Original-Received: from localhost ([::1]:33398 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lHTkP-0007Kj-Vh for ged-emacs-devel@m.gmane-mx.org; Wed, 03 Mar 2021 10:49:13 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:56994) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lHTjr-0006fN-Fw for emacs-devel@gnu.org; Wed, 03 Mar 2021 10:48:39 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:1268) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lHTjp-0005i2-S6 for emacs-devel@gnu.org; Wed, 03 Mar 2021 10:48:39 -0500 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id BF46E80B6D; Wed, 3 Mar 2021 10:48:36 -0500 (EST) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 3216280618; Wed, 3 Mar 2021 10:48:35 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1614786515; bh=3GYshEBT26DqBcdLCpws+2e81WCgnzoc4VqjJhBOMiY=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=bdkyOed9lIF5F57HhoYmpIVdQBR8caiZ8cDX+f4fZIQLl1o98M9TlnUJF9QNkD8xR LntE9dGXSnvD15rcv1WlaGqpehw4XHUUWOl9FTs179ArkotundYWjpn7LqrSR3Ue5K WBn7Y3o03XDj6JRuoMXpM2Rp+u8ePL32QayT6HUkbuieNdvJAd5Knw9aj3hC8Q3YpR Vpd0geYLa3NuiMQBttge/w5Nnk9jNEVrepV4+tGWUWVWJCXBPZfL57knMp5LFcY9mY vYeqi+LJLTiKQjRo6n54KDKhsTKCAAFxPeXbT25KowDtzmiHmIHCvGeG29u0asjKgY PP7RkxSyXwhFA== Original-Received: from alfajor (unknown [216.154.41.47]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id CA66D1202C1; Wed, 3 Mar 2021 10:48:34 -0500 (EST) In-Reply-To: <79673252-c43d-6916-69d9-a46207137c85@yandex.ru> (Dmitry Gutov's message of "Wed, 3 Mar 2021 14:17:39 +0200") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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:265889 Archived-At: >> (defun ere (re) >> "Convert an ERE-style regexp RE to an Emacs-style regexp." >> (let ((pos 0) >> (last 0) >> (chunks '())) >> (while (string-match "\\\\.\\|[{}()|]" re pos) >> (let ((beg (match-beginning 0)) >> (end (match-end 0))) >> (when (subregexp-context-p re beg) >> (cond >> ;; A normal paren: add a backslash. >> ((= (1+ beg) end) >> (push (substring re last beg) chunks) (setq last beg) >> (push "\\" chunks)) >> ;; A grouping paren: skip the backslash. >> ((memq (aref re (1+ beg)) '(?\( ?\) ?\{ ?\} ?\|)) >> (push (substring re last beg) chunks) >> (setq last (1+ beg))))) >> (setq pos end))) >> (mapconcat #'identity (nreverse (cons (substring re last) chunks)) ""))) > > See also xref--regexp-to-extended, my last attempt at RE->ERE conversion, > though woefully lacking in tests. Oh, thanks for the pointer. > Its goal was to move in the other direction, but (unless I'm missing > something about the syntax differences) this function is reversible. Indeed it is, Stefan