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Path: utzoo!utcsrgv!utai!uthub!thomson
From: thomson@uthub.UUCP (Brian Thomson)
Newsgroups: net.lang.c
Subject: Re: 2 b lalr(1)
Message-ID: <164@uthub.UUCP>
Date: Wed, 23-May-84 14:05:55 EDT
Article-I.D.: uthub.164
Posted: Wed May 23 14:05:55 1984
Date-Received: Wed, 23-May-84 18:41:42 EDT
References: <19533@wivax.UUCP>
Organization: CSRG, University of Toronto
Lines: 20

wivax!mckeeman states:
   Even more interesting, reserved words are not necessary for
   LALR(1).  One can put in a rule
   <ident> ::= IF | THEN | DO ...
   which will turn the reserved word back into <ident> into a
   grammar and still get the LALR(1) tables in most cases.

Actually, I believe this would fail in most cases, at least for
the IF keyword.  If your grammar contains

   <statement> ::= IF <expression> THEN ....
   <ident>     ::= IF

and an <expression> may begin with a left parenthesis
it will fail to be LALR(1) because of the resulting shift-reduce conflict.
'IF (' is a prefix of a valid procedure call.
I don't know of any way to resolve the conflict, do you?
-- 
		    Brian Thomson,	    CSRG Univ. of Toronto
		    {linus,ihnp4,uw-beaver,floyd,utzoo}!utcsrgv!uthub!thomson