From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: [RFC/PATCH 0/3] git log --pretty=lua Date: Mon, 24 Sep 2012 20:23:25 -0400 Message-ID: <20120925002325.GA19560@sigill.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Tue Sep 25 02:24:03 2012 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TGIwU-0007gv-KP for gcvg-git-2@plane.gmane.org; Tue, 25 Sep 2012 02:24:02 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751874Ab2IYAXe (ORCPT ); Mon, 24 Sep 2012 20:23:34 -0400 Received: from 75-15-5-89.uvs.iplsin.sbcglobal.net ([75.15.5.89]:57440 "EHLO peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751521Ab2IYAXb (ORCPT ); Mon, 24 Sep 2012 20:23:31 -0400 Received: (qmail 7315 invoked by uid 107); 25 Sep 2012 00:23:58 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) (smtp-auth username relayok, mechanism cram-md5) by peff.net (qpsmtpd/0.84) with ESMTPA; Mon, 24 Sep 2012 20:23:58 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Mon, 24 Sep 2012 20:23:25 -0400 Content-Disposition: inline Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: We've talked off and on about extending the --pretty=format specifiers to something more flexible. There's also been talk recently of more flexible commit-filtering (e.g., grepping individual notes). Rather than invent a new Turing-complete language, I thought I'd try building on somebody else's work by embedding an existing language. Why Lua? I don't especially like it as a language. But it's designed for this purpose, which makes it very lightweight and relatively simple to embed. Here are timing results for a few log commands (best-of-five, warm cache): $ git log --oneline >/dev/null real 0m1.042s user 0m0.660s sys 0m0.372s $ git log --tformat:"%h %s" >/dev/null real 0m1.039s user 0m0.624s sys 0m0.396s $ git log --pretty=lua:'return abbrev(hash()) .. " " .. subject()' real 0m1.112s user 0m0.716s sys 0m0.388s So you can see that we're a little bit slower than the existing format, but not too much. There may well be some optimizations we can do, too. This is the first time I've ever played with embedding Lua, so I would not be surprised if I got something wrong or suboptimal. The syntax, on the other hand...yuck. One thing that makes Lua horrible for this use is that it does not have interpolated strings. However, there are template libraries for Lua, so maybe there's something there. The patches are: [1/3]: pretty: make some commit-parsing helpers more public [2/3]: add basic lua infrastructure [3/3]: add a "lua" pretty format And a "4/3" patch would probably add "--lua-filter" as a revision option for limiting commits. The patches are very rough and not meant to be applied. For me, this was a bit of an experiment. I'm not sure if I like it or not. It seems like a cool direction to go, but to be perfectly honest, I do not generally feel like git's existing filtering or output are inadequate (sure, it's slower to pipe --pretty=raw out to a separate perl filter and then do fancy formatting, but it's usually fast enough, and it's very flexible). So I don't have plans to work on it more any time soon, but I thought I'd share in case anybody is interested. And if somebody wants to pick up the topic and run with it, I'd be happy to help. -Peff