From lojban+bncCLr6ktCfBBCon5vqBBoEnbjwYg@googlegroups.com Mon Jan 31 07:05:30 2011 Received: from mail-yx0-f189.google.com ([209.85.213.189]) by chain.digitalkingdom.org with esmtp (Exim 4.72) (envelope-from ) id 1PjvJl-0007ed-09; Mon, 31 Jan 2011 07:05:29 -0800 Received: by yxn35 with SMTP id 35sf3778193yxn.16 for ; Mon, 31 Jan 2011 07:05:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=beta; h=domainkey-signature:x-beenthere:received-spf:date:from:to:subject :message-id:mail-followup-to:mime-version:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type:content-disposition; bh=OEiScMmJjFRlgz1EtpWfozzbfa0oCoKHC/St9UIOIZo=; b=xxR0Z1weqweZx8kqCZabmFzBpoTZo6R9Yxe0lzc77sSek1fjXkLm7qQMY55+2L38e3 8nYgiDHP/nurZMZfhMtqSeJJIRQek8xt9I7aoOId2Mjm2nGm6gW1j8FiIf4TJ2Ur68zK Gtqh3YaTfMIAdWlnIOb2KLZ4iMDDEQKVfvCWY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlegroups.com; s=beta; h=x-beenthere:received-spf:date:from:to:subject:message-id :mail-followup-to:mime-version:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type:content-disposition; b=PAG3KI6bu2Aat247EvVk1w9WJRc3Igb4SrPKYCVdLENxr6cDoLYRGlH7XGT/eOHMYb m9LsVfrG2WHVhqfpAntYubs3qvmnzQYHCqWy9qbu06tLZuGzEOCNciUxoD8A8dPvB3Iy QlZDXff0oVPpFyhmIDXtQxl/90ruIpn9ni3XA= Received: by 10.90.99.20 with SMTP id w20mr478687agb.34.1296486312221; Mon, 31 Jan 2011 07:05:12 -0800 (PST) X-BeenThere: lojban@googlegroups.com Received: by 10.90.138.2 with SMTP id l2ls1012881agd.4.p; Mon, 31 Jan 2011 07:05:11 -0800 (PST) Received: by 10.90.63.4 with SMTP id l4mr926633aga.26.1296486311243; Mon, 31 Jan 2011 07:05:11 -0800 (PST) Received: by 10.90.63.4 with SMTP id l4mr926632aga.26.1296486311185; Mon, 31 Jan 2011 07:05:11 -0800 (PST) Received: from mail-yw0-f49.google.com (mail-yw0-f49.google.com [209.85.213.49]) by gmr-mx.google.com with ESMTPS id e31si7705324ana.11.2011.01.31.07.05.11 (version=TLSv1/SSLv3 cipher=RC4-MD5); Mon, 31 Jan 2011 07:05:11 -0800 (PST) Received-SPF: neutral (google.com: 209.85.213.49 is neither permitted nor denied by best guess record for domain of alanpost@sunflowerriver.org) client-ip=209.85.213.49; Received: by ywf7 with SMTP id 7so2079539ywf.36 for ; Mon, 31 Jan 2011 07:05:11 -0800 (PST) Received: by 10.236.108.178 with SMTP id q38mr12875045yhg.81.1296486310942; Mon, 31 Jan 2011 07:05:10 -0800 (PST) Received: from sunflowerriver.org (173-10-243-253-Albuquerque.hfc.comcastbusiness.net [173.10.243.253]) by mx.google.com with ESMTPS id j3sm4531566yha.7.2011.01.31.07.05.08 (version=TLSv1/SSLv3 cipher=RC4-MD5); Mon, 31 Jan 2011 07:05:09 -0800 (PST) Date: Mon, 31 Jan 2011 08:05:04 -0700 From: ".alyn.post." To: Lojban List Subject: [lojban] confusion over FUhE-post PEG grammar rule Message-ID: <20110131150504.GA49994@alice.local> Mail-Followup-To: Lojban List Mime-Version: 1.0 X-Original-Sender: alyn.post@lodockikumazvati.org X-Original-Authentication-Results: gmr-mx.google.com; spf=neutral (google.com: 209.85.213.49 is neither permitted nor denied by best guess record for domain of alanpost@sunflowerriver.org) smtp.mail=alanpost@sunflowerriver.org Reply-To: lojban@googlegroups.com Precedence: list Mailing-list: list lojban@googlegroups.com; contact lojban+owners@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: Sender: lojban@googlegroups.com List-Subscribe: , List-Unsubscribe: , Content-Type: text/plain; charset=ISO-8859-1 Content-Disposition: inline I'm confused over the intent of the FUhE-post production in the PEG grammar: FUhE-clause <- FUhE-pre FUhE-post FUhE-pre <- pre-clause FUhE spaces? FUhE-post <- !BU-clause spaces? !ZEI-clause !BU-clause The ! predicate does not advance the input, so if you walk through each rule in the FUhE-post production, you try to: * not match BU-clause. If we find one, we no-match immediately and stop checking. The input isn't advanced if we non-match it. * the spaces? production will always match the empty string, as FUhE-post only appears in FUhE-clause, and FUhE-pre, the rule before it, ends with a spaces? * not match ZEI-clause. If we find ZEI-clause, we immediately stop checking. If we don't find one, the input is not advanced. * not match BU-clause. This is where I get confused. We haven't advanced the token stream, and we've already checked for a BU-clause earlier. The final !BU-clause is either: * redundant * should be something like !(ZEI-clause BU-clause) Anything I missed? -Alan -- .i ko djuno fi le do sevzi -- You received this message because you are subscribed to the Google Groups "lojban" group. 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