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: A function to take the regexp-matched subsring directly Date: Sun, 30 Oct 2022 11:52:19 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="20685"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: daanturo Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Oct 30 16:53:12 2022 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 1opAcZ-0005DH-MM for ged-emacs-devel@m.gmane-mx.org; Sun, 30 Oct 2022 16:53:11 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1opAbt-0007ww-Fz; Sun, 30 Oct 2022 11:52:29 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1opAbr-0007te-I6 for emacs-devel@gnu.org; Sun, 30 Oct 2022 11:52:27 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1opAbp-0001o6-QG for emacs-devel@gnu.org; Sun, 30 Oct 2022 11:52:27 -0400 Original-Received: from pmg1.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 864FE100142; Sun, 30 Oct 2022 11:52:23 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 329F31000E6; Sun, 30 Oct 2022 11:52:22 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1667145142; bh=Wcp0hNEFLqC1PO9Q/d83V+DGZD2lDinB5LTJSKp45sA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=CLbg05/FXqnNUYrV7dWaCs+gNIC9NOXfDrjgujC4d6rbINxKWRUV6SrD9ieRplMEq 30itjYLr/daaegNaEWJilcwU0xJVBy7WS1cVmUo3gHzu50jgVqQBo7n/w+v/vDY0AU fMZdmzPdFq0PMEYHZN5lnJQV3XFUWlEE6am58695avksNULSozwSQ6z/dZbRAQqOTi bxTY83SFL3w57oP/J+7X5v+MJna/jqceZwin1Mhnzj3MPsHM4h741IoOAkPoowob6L ssFhsWXWp23QrhLz7GfXhwtdwXdZEzUzEBX7+Y38INRSwfnaPhjcdDJvnwqSKMwfyx b+g9jMgH7ekQw== Original-Received: from pastel (65-110-220-202.cpe.pppoe.ca [65.110.220.202]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id E41A4120B1C; Sun, 30 Oct 2022 11:52:21 -0400 (EDT) In-Reply-To: (daanturo@gmail.com's message of "Sun, 30 Oct 2022 22:17:00 +0700") 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: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: "Emacs-devel" Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:298823 Archived-At: > +;;;###autoload > +(defun regexp-match (regexp string &optional n) > + "Return the N -th matched substring for REGEXP in STRING. > +N defaults to 0 (the whole match). > + > +This function does not change the match data." > + (declare (pure t) (side-effect-free t)) > + (let ((n (or n 0))) > + (save-match-data > + (when (string-match regexp string) > + (match-string n string))))) `save-match-data` is costly and extremely rarely needed. So I'd much rather not save it here. > + (save-match-data > + (when (string-match regexp string) > + (let ((match-index (1- (/ (length (match-data)) 2))) > + matches) > + (while (<=3D 0 match-index) > + (push (match-string match-index string) matches) > + (setq match-index (1- match-index))) > + matches)))) I suspect it'd be more efficient to iterate directly on the `match-data` ra= ther than on an integer (which suffers from an O(N=B2) complexity). Stefan