Re: How detect cycle in grammar ?

Gene <gene.ressler@gmail.com>
Sun, 27 Nov 2011 10:18:56 -0800 (PST)

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From: Gene <gene.ressler@gmail.com>
Newsgroups: comp.compilers
Date: Sun, 27 Nov 2011 10:18:56 -0800 (PST)
Organization: Compilers Central
References: 11-11-041 11-11-045 11-11-046
Keywords: parse, theory
Posted-Date: 27 Nov 2011 15:37:32 EST

On Nov 22, 10:20 am, an...@mips.complang.tuwien.ac.at (Anton Ertl)
wrote:
> Gene <gene.ress...@gmail.com> writes:
> >Nonterminals that can never derive a terminal string are the
> >problem.
>
> Is it really? Since they cannot derive a terminal, they have no
> influence on the language described by the grammar. They might just
> as well not be there. Are they really a problem (except for certain
> implementation techniques)?


The algorithm is commonly used to print warnings in parser
generators. Check recent releases of bison, for example.



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