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From: bobg+@andrew.cmu.edu (Robert Steven Glickstein)
Newsgroups: comp.lang.c,comp.unix.questions
Subject: Solved! (Re: Yacc probs w/ANSI-C)
Message-ID: <wYcaieq00VsnQB92FH@andrew.cmu.edu>
Date: 23 Jun 89 16:56:10 GMT
References: <UYbhqrq00Vsn43xmA3@andrew.cmu.edu>
Organization: Information Technology Center, Carnegie Mellon, Pittsburgh, PA
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In-Reply-To: <UYbhqrq00Vsn43xmA3@andrew.cmu.edu>

In: 21-Jun-89 Yacc probs w/ANSI-C, I wrote

> I've written a parser for ANSI-C using YACC (adhering strictly to the
> grammar given in K&R, second edition) that doesn't work.  Despite the
> claim in section A13 that "this grammar is acceptable to the YACC
> parser-generator"(modulo some changes, which I've made), it in fact is
not; it's not even LR(1).

My profuse apologies to Messrs. Kernighan and Ritchie.  I had failed to
follow the advice given in section A13 that tells the Yacc user to write
all rules containing optional subrules twice.  That is to say, I had
written

    foo: bar opt_baz bletch
        ;
    opt_baz:
        | baz
        ;

when I should have written

    foo: bar bletch
        | bar baz bletch
        ;

Converting everything to the latter form fixed my problems.  Thanks to
everyone who responded!


	Bob Glickstein