From nobody@digitalkingdom.org Wed Oct 31 06:30:52 2007 Received: with ECARTIS (v1.0.0; list lojban-list); Wed, 31 Oct 2007 06:30:53 -0700 (PDT) Received: from nobody by chain.digitalkingdom.org with local (Exim 4.67) (envelope-from ) id 1InDel-00022a-Cr for lojban-list-real@lojban.org; Wed, 31 Oct 2007 06:30:51 -0700 Received: from nf-out-0910.google.com ([64.233.182.185]) by chain.digitalkingdom.org with esmtp (Exim 4.67) (envelope-from ) id 1InDeg-000223-Di for lojban-list@lojban.org; Wed, 31 Oct 2007 06:30:48 -0700 Received: by nf-out-0910.google.com with SMTP id 4so100838nfv for ; Wed, 31 Oct 2007 06:30:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=TZXl3hdQVQKI4Ekf+rLOqF6LqnQtiV+3Lrot9EPnWH4=; b=pC0kFn7miHJpXAHYcyf9Dvk7CRxK/7Jce5I0ot9y2CUS4te2pyQiU57zYjPfCGY+agPow8AHVYwJv+dzJvlf04U3mf/BrjLFa/O2K/wsSzIeKAo3sOasJC0wcXOsp1nhl+01B0JvDrfdjb+g6KQf2+NFza8TtyI2Egewx15ulqw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=E04GHsELx9E869F8cPMJJg+g66A7xReOLoTaqwqVKGmYpI+0j5u1/y9GKM+hpWAGB6ZM3iRiN38ZqCaGNy+SF0EapQ/UKf+CivZfhzg8AjL6k6n87oC0tXwI5WkGn/XOVs8NEtCbl9Hw/B4vp/HpQ/RrLAazHkSF02PvH8D33Ks= Received: by 10.86.79.19 with SMTP id c19mr6588449fgb.1193837440165; Wed, 31 Oct 2007 06:30:40 -0700 (PDT) Received: by 10.86.86.13 with HTTP; Wed, 31 Oct 2007 06:30:40 -0700 (PDT) Message-ID: <925d17560710310630te45f3dbs210159dcc8143a6d@mail.gmail.com> Date: Wed, 31 Oct 2007 10:30:40 -0300 From: "=?ISO-8859-1?Q?Jorge_Llamb=EDas?=" To: lojban-list@lojban.org Subject: [lojban] Re: PEG left recursive definitions In-Reply-To: <737b61f30710301744x530646c8q748ccb5190ec3eee@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <737b61f30710301744x530646c8q748ccb5190ec3eee@mail.gmail.com> X-Spam-Score: 0.0 X-Spam-Score-Int: 0 X-Spam-Bar: / X-archive-position: 13890 X-ecartis-version: Ecartis v1.0.0 Sender: lojban-list-bounce@lojban.org Errors-to: lojban-list-bounce@lojban.org X-original-sender: jjllambias@gmail.com Precedence: bulk Reply-to: lojban-list@lojban.org X-list: lojban-list On 10/30/07, Chris Capel wrote: > Does the PEG currently use left recursive definitions? Left associativity is handled by rules such as: selbri-3 <- selbri-4+ or: sumti-2 <- sumti-3 (joik-ek sumti-3)* so it is left implicit. > If not, would it be helpful if it could? It would be helpful if the parse tree is to show left associativity explicitly. > For instance. Example input: > > x ? x : x > > To parse this, we could write > > expr <- tri-cond / x > tri-cond <- expr '?' expr ':' expr > x <- 'x' That's equivalent to: expr <- expr '?' expr ':' expr / 'x' which would not be allowed in PEG. > This would be translated to > > expr-1 <- x > tri-cond <- expr-1 '?' expr ':' expr / expr-1 > expr <- tri-cond / expr-1 > x <- 'x' This one is equivalent to: expr <- 'x' '?' expr ':' expr / 'x' Which is allowed, but does not have an explicitly left associative parse tree. mu'o mi'e xorxes To unsubscribe from this list, send mail to lojban-list-request@lojban.org with the subject unsubscribe, or go to http://www.lojban.org/lsg2/, or if you're really stuck, send mail to secretary@lojban.org for help.