Re: Grammar for optional elements

Chris F Clark <cfc@shell01.TheWorld.com>
Mon, 02 Jul 2007 13:55:22 -0400

          From comp.compilers

Related articles
[10 earlier articles]
Re: Grammar for optional elements lowell@coasttocoastresearch.com (Lowell Thomas) (2007-06-19)
Re: Grammar for optional elements dot@dotat.at (Tony Finch) (2007-06-20)
Re: Grammar for optional elements Meyer-Eltz@t-online.de (Detlef Meyer-Eltz) (2007-06-20)
Re: Grammar for optional elements cfc@shell01.TheWorld.com (Chris F Clark) (2007-06-21)
Re: Grammar for optional elements dot@dotat.at (Tony Finch) (2007-06-21)
Re: Grammar for optional elements lowell@coasttocoastresearch.com (Lowell Thomas) (2007-06-22)
Re: Grammar for optional elements cfc@shell01.TheWorld.com (Chris F Clark) (2007-07-02)
| List of all articles for this month |

From: Chris F Clark <cfc@shell01.TheWorld.com>
Newsgroups: comp.compilers
Date: Mon, 02 Jul 2007 13:55:22 -0400
Organization: The World Public Access UNIX, Brookline, MA
References: 07-06-019 07-06-038 07-06-042 07-06-053 07-06-054
Keywords: syntax

Tony Finch <dot@dotat.at> writes:


> Interesting. Do you have any examples or citations? Ford's paper on the
> formal properties of PEGs says that it is an open question whether there
> are context-free languages that cannot be described with PEGs, and I
> wonder if ordered choice is relevant.


I've been trying to track down where I read about ordered choice using
google and haven't had any luck yet. I can't find the exact reference
yet, but I recall the point was that you were using a "global ordering
of the parsing elements to make local decisions". There is a similar
issue with the precedence and ambiguity operators ala yacc. If I find
the reference, I will try to post it. Otherwise, perhaps the author
of the paper/web page I was reading will happen to read this,
recognize that I am refering to them, and chime in.


Sorry I can't be more specific yet,
-Chris


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