From mboxrd@z Thu Jan 1 00:00:00 1970 From: Davide Libenzi Subject: Re: weird diff output? Date: Thu, 14 Apr 2016 06:56:39 -0700 (PDT) Message-ID: References:

<20160330045554.GA11007@sigill.intra.peff.net> <20160331134750.GA29790@sigill.intra.peff.net>

Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Jacob Keller , davidel@xmailserver.org, Jeff King , Junio C Hamano , Git mailing list , Jens Lehmann To: Stefan Beller X-From: git-owner@vger.kernel.org Thu Apr 14 16:04:58 2016 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 1aqhtB-0006Z1-1n for gcvg-git-2@plane.gmane.org; Thu, 14 Apr 2016 16:04:57 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753910AbcDNOEw (ORCPT ); Thu, 14 Apr 2016 10:04:52 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:38774 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753110AbcDNOEw (ORCPT ); Thu, 14 Apr 2016 10:04:52 -0400 X-Greylist: delayed 491 seconds by postgrey-1.27 at vger.kernel.org; Thu, 14 Apr 2016 10:04:52 EDT X-AuthUser: davidel@xmailserver.org Received: from zino by x35.xmailserver.org with [XMail 1.27 ESMTP Server] id for from ; Thu, 14 Apr 2016 09:56:18 -0400 X-X-Sender: davide@zino In-Reply-To: User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Tue, 12 Apr 2016, Stefan Beller wrote: > On Wed, Apr 6, 2016 at 10:47 AM, Jacob Keller wrote: > > > > I started attempting to implement this heuristic within xdiff, but I > > am at a loss as to how xdiff actually works. I suspect this would go > > in xdi_change_compact or after it, but I really don't understand how > > xdiff represents the diffs at all... > > I agree that this seems like the right place. > > On the off chance that David, the author of xdiff remembers that > part, I cc'd him. (The whole discussion on better diffs is found at > http://thread.gmane.org/gmane.comp.version-control.git/290093) That was a zillions of years ago :) , but from a quick look at email thread, if you want to do it within xdiff, xdi_change_compact would be the place. The issue is knowing in which situations one diff look better than another, and embedding an if-tis-do-tat logic deep into the core diff machinery. In theory one could implement the same thing higher up, working with the unified diff text format, where maybe a user can provide its own diff post-process hook script. In any case, that still leaves open the issue on what to shift in the diff chunks, and in which cases. Which is likely going to be language/format dependent. IMHO, it gets nasty pretty quickly.