Re: How detect cycle in grammar ?

Path	csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!nx01.iad01.newshosting.com!newshosting.com!198.186.194.249.MISMATCH!transit3.readnews.com!news-out.readnews.com!news-xxxfer.readnews.com!news.misty.com!news.iecc.com!nerds-end
From	Gene <gene.ressler@gmail.com>
Newsgroups	comp.compilers
Subject	Re: How detect cycle in grammar ?
Date	Sun, 27 Nov 2011 10:18:56 -0800 (PST)
Organization	Compilers Central
Lines	14
Sender	news@iecc.com
Approved	comp.compilers@iecc.com
Message-ID	<11-11-056@comp.compilers> (permalink)
References	<11-11-041@comp.compilers> <11-11-045@comp.compilers> <11-11-046@comp.compilers>
NNTP-Posting-Host	news.iecc.com
X-Trace	leila.iecc.com 1322426252 91585 64.57.183.58 (27 Nov 2011 20:37:32 GMT)
X-Complaints-To	abuse@iecc.com
NNTP-Posting-Date	Sun, 27 Nov 2011 20:37:32 +0000 (UTC)
Keywords	parse, theory
Posted-Date	27 Nov 2011 15:37:32 EST
X-submission-address	compilers@iecc.com
X-moderator-address	compilers-request@iecc.com
X-FAQ-and-archives	http://compilers.iecc.com
Xref	x330-a1.tempe.blueboxinc.net comp.compilers:358

Show key headers only | View raw

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.

Back to comp.compilers | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

How detect cycle in grammar ? Borneq <a.moderacja@gmail.com> - 2011-11-20 08:48 -0800
  Re: How detect cycle in grammar ? Hans Aberg <haberg-news@telia.com> - 2011-11-21 18:14 +0100
  Re: How detect cycle in grammar ? Gene <gene.ressler@gmail.com> - 2011-11-21 10:20 -0800
    Re: How detect cycle in grammar ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-11-22 15:20 +0000
      Re: How detect cycle in grammar ? Quinn Tyler Jackson <quinn_jackson2004@yahoo.ca> - 2011-11-25 22:28 -0800
      Re: How detect cycle in grammar ? Gene <gene.ressler@gmail.com> - 2011-11-27 10:18 -0800
    Re: How detect cycle in grammar ? Borneq <a.moderacja@gmail.com> - 2011-11-23 12:56 -0800
    Re: How detect cycle in grammar ? Borneq <a.moderacja@gmail.com> - 2011-11-24 09:24 -0800
      Re: How detect cycle in grammar ? Gene <gene.ressler@gmail.com> - 2011-11-27 10:27 -0800
        Re: How detect cycle in grammar ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-11-28 16:46 +0000
          Re: How detect cycle in grammar ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-11-29 07:31 +0000
            Re: How detect cycle in grammar ? Paul B Mann <paul@paulbmann.com> - 2011-12-01 02:46 -0800
              Re: How detect cycle in grammar ? Quinn Tyler Jackson <quinn_jackson2004@yahoo.ca> - 2011-12-02 09:20 -0800
          Re: How detect cycle in grammar ? Gene <gene.ressler@gmail.com> - 2011-12-07 06:29 -0800

csiph-web