From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Ihor Radchenko Newsgroups: gmane.emacs.devel Subject: Re: [PATCH] add compiled regexp primitive lisp object Date: Mon, 23 Dec 2024 17:10:34 +0000 Message-ID: <87seqejpf9.fsf@localhost> References: <87mslxxddk.fsf@protonmail.com> <5He97LtsyeyQoTLU7d91oP2CLO8s_2afdgcNxozsFjzu8qGbB_7nXmsZL5O6Ej7K-tuEmngCcPKJpDAjxeKz4jk1DvqSUbdOLpw5U1vo1SY=@hypnicjerk.ai> <87le1avopk.fsf@protonmail.com> <2LOLmIp1X8w4CGbqq3qDrzmKVA0KzYNL1N9lBtWdB-MtEv9oCuYgJMYprG170wMPjYxeQImAmWOPatGTTl4KxZMlptNo9A9hnHt84vdN9EA=@hypnicjerk.ai> <87ttfxtszi.fsf@protonmail.com> <86r0b1o5sr.fsf@gnu.org> <868qx8o83w.fsf@gnu.org> <875xscec62.fsf@gmail.com> <87o764sb6y.fsf@gmail.com> <87a5cn7cnu.fsf@localhost> <86cyhj5xmc.fsf@gnu.org> <87ttavlc50.fsf@localhost> <86a5cn5v1n.fsf@gnu.org> <87r05zlas8.fsf@localhost> <8634ie60jd.fsf@gnu.org> <87y106jr4i.fsf@localhost> <868qs64a65.fsf@gnu.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="25571"; mail-complaints-to="usenet@ciao.gmane.io" Cc: monnier@iro.umontreal.ca, mattiase@acm.org, arstoffel@gmail.com, eller.helmut@gmail.com, dmcc2@hypnicjerk.ai, pipcet@protonmail.com, emacs-devel@gnu.org, acorallo@gnu.org, stefankangas@gmail.com To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Dec 23 18:10:11 2024 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 1tPlwY-0006VT-Om for ged-emacs-devel@m.gmane-mx.org; Mon, 23 Dec 2024 18:10:10 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tPlvg-0006cj-LA; Mon, 23 Dec 2024 12:09:18 -0500 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 1tPlva-0006bX-6d for emacs-devel@gnu.org; Mon, 23 Dec 2024 12:09:10 -0500 Original-Received: from mout02.posteo.de ([185.67.36.66]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tPlvX-0000m9-1v for emacs-devel@gnu.org; Mon, 23 Dec 2024 12:09:09 -0500 Original-Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 5C0E3240101 for ; Mon, 23 Dec 2024 18:09:03 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1734973745; bh=M+IOuvQ9zIBJvCNGvtsMvbY/JafsPXXzbEPzVHE0Lv8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type: From; b=L8yiNPyC9qRZshKqqIoOg02sRRtby46JeH+hJMvRKeye04Q8TO9yHxe/0TbikKmG2 g6DkB+F6Uiw620wRH/IXlmcac+B3X+QzkYcLCpA0kpg0JZAD+o2PacA0QFboWHX8Bw v9A2LrCINp+7Y56KOuIr+SFm4s55Xazm5iVH0hwYt0zTKZP1+s7vcTbOBTnqMHNeTv qrP22OYtJ0E+xRojc2GR19SdQE1OAGd9EBP8rAQExrglJjcp0hTbY9/qOL3GMve7pX PFaHThUyJ0NsP+zilPZtD8AN5z41gMIUSr6RuqQZTntxFdwsUrMp//cC2EO+uVsgra Ac5UN25neZdIw== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4YH4Hg1FfCz6tyv; Mon, 23 Dec 2024 18:09:02 +0100 (CET) In-Reply-To: <868qs64a65.fsf@gnu.org> Received-SPF: pass client-ip=185.67.36.66; envelope-from=yantar92@posteo.net; helo=mout02.posteo.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:326923 Archived-At: Eli Zaretskii writes: >> 1. They could be inspected from Elisp, and hopefully optimized >> better. For now, there is simply no way to detect which parts of >> regexps are slow and which are not. > > If we can optimize them from Lisp, we should be able to do the same in > C. If you explain what kind of optimization opportunities you had in > mind, we could discuss how to implement that. In any case, adding > APIs for regexp optimizations doesn't require to have compiled regexp > objects. What I had in mind is some kind of profiler for regexps. I cannot imagine such a profiler without having access to the state machine instructions emitted by regexp compiler - there will be no easy mapping between regexp itself and the resulting compiled instructions (that mapping will depend on the specifics of Emacs compiler) >> 2. They could maybe even be constructed from Elisp, opening >> opportunities for custom regexp compilers that can be tailored to >> specific application needs rather than having to stick to hard-coded >> generic tradeoffs Emacs has to do without knowing the purpose of a >> regexp. > > How will this help making matching faster, and why does this have to > be via compiled regexp objects? My motivation is https://burntsushi.net/regex-internals/#literal-extraction that explains how regexp compilation depends on certain heuristics. For example, when searching for "\\(foo\\|bar\\)[a-z]+", heuristics invoking simple string literal search for "foo" and "bar" first before using heavy regexp automata is justified. Not so much when the prefix is simply " " that usually occurs very frequently in text. However, for specially structures texts (e.g. in parsers), additional knowledge about structure is available and can be utilized to fine-tune the regexp compilation. Ultimately, an ability to construct instructions from scratch can be useful - this may allow going beyond what Emacs regexp syntax provides; and faster. -- Ihor Radchenko // yantar92, Org mode maintainer, Learn more about Org mode at . Support Org development at , or support my work at