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: [PATCH] add compiled regexp primitive lisp object Date: Tue, 24 Dec 2024 00:37:15 -0500 Message-ID: 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33689"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Eli Zaretskii , 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: Ihor Radchenko Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Dec 24 06:38:18 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 1tPxcX-0008dd-Cf for ged-emacs-devel@m.gmane-mx.org; Tue, 24 Dec 2024 06:38:17 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tPxbs-0003M7-Su; Tue, 24 Dec 2024 00:37:36 -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 1tPxbj-0003Kg-JP for emacs-devel@gnu.org; Tue, 24 Dec 2024 00:37:30 -0500 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 1tPxbh-0005N6-08; Tue, 24 Dec 2024 00:37:27 -0500 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 88C50804E6; Tue, 24 Dec 2024 00:37:21 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1735018636; bh=JBgWk+Ar8V0R6Ifv9JPisfr3rNz8WKR7siyPF+/gd6c=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MNswcdHnpPZ0SSynErYiqNAtY5g3wbcw8ino7RmisTTNq0JN4C7z+4aXK6U6BEjcQ sOCPZHSWrFz639IZowKP9l940IHHGlucDR/Td7mBYQSsgnYZHI+5DNNqUCVqyRT/FK iEj4H2AH0a3WQwbGrxIvedaDDfhX7YRtlO5YzI20U8ZfN+K+vivhGrDrpU+42Mr1ql /Rr1vOxAZz5lYryrUHzWiziTxxJqSDMd3WG02cGfWHtIn5UPfRD7cax9km4/zN8Hr7 wMqIv9sRW/YQfHxlOlUoYzW7st8PM7akKyohYP3sF2Khrcr6Hg90fe8F5pGCNdBm6u W+c8AqnlVbupg== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 58BBE800C4; Tue, 24 Dec 2024 00:37:16 -0500 (EST) Original-Received: from pastel (104-195-225-43.cpe.teksavvy.com [104.195.225.43]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id EDE6712068E; Tue, 24 Dec 2024 00:37:15 -0500 (EST) In-Reply-To: <87y106jr4i.fsf@localhost> (Ihor Radchenko's message of "Mon, 23 Dec 2024 16:33:49 +0000") 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, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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: 2.1.29 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:326962 Archived-At: > Having compiler regexp object exposed to Elisp would open the > following extra opportunities: Nitpick: there are various ways to "Add compiled regexp primitive lisp object", and not all of them would really expose those objects in ways would allow the following points. > 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. You can now/already use `re--describe-compiled` to inspect the compiled regexps used by Emacs's regexp engine. > 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. Definitely. And since it would be one in ELisp, there could be dozens of specialized compilers in ELPA packages to choose from. =F0=9F=99=82 Eli wrote: > If we can optimize them from Lisp, we should be able to do the same > in C. `re_compile_pattern` is not terribly easy to improve. Among other things because it needs to be fast, single pass, etc... If regexp objects are exposed in such a way that we can build them from ELisp and write them to `.elc` files, then anyone can write their own regexp compiler for their own regexp flavor, which can be as slow as they like because it won't slow down anyone else. > 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. If we want to be able to compile regexps to a DFA-style compiled form, we'll need to extend the regexp bytecode, of course, but it would either require we implement that compilation in C (which could be a fair bit of work) or it would require changing `re_compile_pattern` to recognize new elements in the regexp-string corresponding to those new bytecode instructions. I have the impression it would be simpler to expose the bytecode vectors to ELisp (so as to be able to build them and print+read them) and do the rest in ELisp. Or course, we'd still want to keep `re_compile_pattern` to handle the cases where we can't (or can't be bothered to) pre-compile the regexp and hence where the compilation to bytecode needs to be as fast as possible. Stefan