From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Case mapping of sharp s Date: Thu, 19 Nov 2009 23:20:38 -0500 Message-ID: References: <4B05A11F.5000700@gmx.de> <87iqd6gmpk.fsf@lola.goethe.zz> <87tywp7tir.fsf@uwakimon.sk.tsukuba.ac.jp> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1258690863 10029 80.91.229.12 (20 Nov 2009 04:21:03 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 20 Nov 2009 04:21:03 +0000 (UTC) Cc: David Kastrup , emacs-devel@gnu.org To: "Stephen J. Turnbull" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Nov 20 05:20:56 2009 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1NBKzO-0007LQ-Vm for ged-emacs-devel@m.gmane.org; Fri, 20 Nov 2009 05:20:55 +0100 Original-Received: from localhost ([127.0.0.1]:53898 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NBKzN-00063z-Vc for ged-emacs-devel@m.gmane.org; Thu, 19 Nov 2009 23:20:54 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NBKzI-00062G-Qc for emacs-devel@gnu.org; Thu, 19 Nov 2009 23:20:48 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NBKzD-0005yc-FK for emacs-devel@gnu.org; Thu, 19 Nov 2009 23:20:47 -0500 Original-Received: from [199.232.76.173] (port=33795 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NBKzD-0005yR-9q for emacs-devel@gnu.org; Thu, 19 Nov 2009 23:20:43 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:62258 helo=ironport2-out.pppoe.ca) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NBKzB-0003Qa-NZ; Thu, 19 Nov 2009 23:20:41 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApsEAHOoBUvO+IIa/2dsb2JhbACBTtQBhDsEiW8 X-IronPort-AV: E=Sophos;i="4.44,775,1249272000"; d="scan'208";a="49715023" Original-Received: from 206-248-130-26.dsl.teksavvy.com (HELO ceviche.home) ([206.248.130.26]) by ironport2-out.pppoe.ca with ESMTP; 19 Nov 2009 23:20:39 -0500 Original-Received: by ceviche.home (Postfix, from userid 20848) id 0E8AAB40C9; Thu, 19 Nov 2009 23:20:38 -0500 (EST) In-Reply-To: <87tywp7tir.fsf@uwakimon.sk.tsukuba.ac.jp> (Stephen J. Turnbull's message of "Fri, 20 Nov 2009 12:41:00 +0900") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.50 (gnu/linux) X-detected-operating-system: by monty-python.gnu.org: Genre and OS details not recognized. X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:117323 Archived-At: >> > But maybe we're doing something silly somewhere. >> The Emacs 22 multibyte scheme likely had worse properties for reverse >> searching. So maybe something might be simplified nowadays. > Nope. The basic nature of the representation and even algorithms are > the same. The main difference is that the leading-byte to character > length map in Mule coding is somewhat arbitrary, while in UTF-8 > there's an algorithm for computing it. In both cases, the sane > algorithm is to keep a 256-entry table of corresponding lengths and > use the octet as an index into that table. Actually, there is a significant difference when going backward, because of the special encoding used for eight-bit-graphics in Emacs-22 and the more regular and less space-efficient encoding used for eight-bit chars in Emacs-23. Stefan