From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <maril_manson@yahoo.de>
X-Original-To: caml-list@yquem.inria.fr
Delivered-To: caml-list@yquem.inria.fr
Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78])
	by yquem.inria.fr (Postfix) with ESMTP id 7075ABB9C
	for <caml-list@yquem.inria.fr>; Sun,  4 Dec 2005 16:04:23 +0100 (CET)
Received: from mailout09.sul.t-online.com (mailout09.sul.t-online.com [194.25.134.84])
	by nez-perce.inria.fr (8.13.0/8.13.0) with ESMTP id jB4F4NkR027540
	for <caml-list@yquem.inria.fr>; Sun, 4 Dec 2005 16:04:23 +0100
Received: from fwd30.aul.t-online.de 
	by mailout09.sul.t-online.com with smtp 
	id 1EivPa-0006xQ-01; Sun, 04 Dec 2005 16:04:22 +0100
Received: from fibonacci.home.krausn.de (EwP3KvZ-QeTHLl6Pz2R1dpwUsV25vN1rL5mC9L11VyzHszmnyBK1k9@[84.145.218.47]) by fwd30.sul.t-online.de
	with esmtp id 1EivPS-1oRtzs0; Sun, 4 Dec 2005 16:04:14 +0100
Received: from serialm.homelinux.org (unknown [IPv6:2001:1a50:5057::1])
	by fibonacci.home.krausn.de (Postfix) with ESMTP id F191730C2CB
	for <caml-list@yquem.inria.fr>; Sun,  4 Dec 2005 16:04:12 +0100 (CET)
Received: from waltraud.manson.mm (waltraud.manson.mm [IPv6:2001:1a50:5057:1:2e0:81ff:fe26:71fc])
	by serialm.homelinux.org (8.13.5/8.13.4) with ESMTP id jB4F3erI022869
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK)
	for <caml-list@yquem.inria.fr>; Sun, 4 Dec 2005 16:03:40 +0100 (CET)
Received: from waltraud.manson.mm (mary@localhost.localdomain [127.0.0.1])
	by waltraud.manson.mm (8.13.4/8.13.4) with ESMTP id jB4F3d71013329
	for <caml-list@yquem.inria.fr>; Sun, 4 Dec 2005 16:03:39 +0100
Received: (from mary@localhost)
	by waltraud.manson.mm (8.13.4/8.13.4/Submit) id jB4F3dGd013328
	for caml-list@yquem.inria.fr; Sun, 4 Dec 2005 16:03:39 +0100
Date: Sun, 4 Dec 2005 16:03:39 +0100
From: "Robert W." <slrn_robert@yahoo.de>
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] yacc question
Message-ID: <20051204150339.GA10618@waltraud.manson.mm>
Mail-Followup-To: caml-list@yquem.inria.fr
References: <1133705740.11050.14.camel@rosella>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1133705740.11050.14.camel@rosella>
User-Agent: Mutt/1.5.11
X-ID: EwP3KvZ-QeTHLl6Pz2R1dpwUsV25vN1rL5mC9L11VyzHszmnyBK1k9@t-dialin.net
X-TOI-MSGID: 314a23ea-0d34-47c2-a083-603af2437129
X-Miltered: at nez-perce with ID 43930577.001 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)!
X-Spam: no; 0.00; caml-list:01 parser:01 expr:01 buffer:01 ocamlyacc:01 parses:01 lexer:01 token:01 expr:01 token:01 trailing:01 buffer:01 parser:01 wrote:01 integer:01 
X-Spam-Checker-Version: SpamAssassin 3.0.3 (2005-04-27) on yquem.inria.fr
X-Spam-Level: 
X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=disabled 
	version=3.0.3

On Mon, Dec 05, 2005 at 01:15:40AM +1100, skaller wrote:
> I have the 'usual' kind of parser for expressions, with two
> nonterminals 'expr' and 'atom', the latter including ( expr ) 
> and INTEGER of course.
> 
> When I have input like
> 
> 1;
> 1 + 2 ;
> (1 + 2) ;
> 
> none of the case parse as expressions, the first and
> last do parse as atoms (leaving the ; in the buffer).
> 
> What I want is to parse the longest possible match.
> The only way I can think of doing this is:
> 

ocamlyacc parses longest match by default.
Your rule for atoms seem to complex or you lexer isn't able to extract
the token for atoms correctly from the line.

>   | expr token_not_allowed_in_expressions
> 
> and then 'put back' the trailing token into the buffer.
> Is there another way?
> 
This shouldn't be necessary, normally you can redesign your parser
rules to avoid this.

-- 

	Robert...