Re: Parsing fully context-free grammars

haberg@math.su.se (Hans Aberg)
2 Oct 2005 02:50:07 -0400

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Parsing fully context-free grammars lowell@coasttocoastresearch.com (Lowell Thomas) (2005-09-17)
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Re: Parsing fully context-free grammars lowell@coasttocoastresearch.com (Lowell Thomas) (2005-09-22)
Re: Parsing fully context-free grammars haberg@math.su.se (2005-09-23)
Re: Parsing fully context-free grammars paul@parsetec.com (Paul Mann) (2005-10-02)
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Re: Parsing fully context-free grammars hannah@schlund.de (2005-10-06)
Re: Parsing fully context-free grammars drikosv@otenet.gr (Evangelos Drikos) (2005-10-07)
Re: Parsing fully context-free grammars lowell@coasttocoastresearch.com (lowell@coasttocoastresearch.com) (2005-10-20)
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From: haberg@math.su.se (Hans Aberg)
Newsgroups: comp.compilers
Date: 2 Oct 2005 02:50:07 -0400
Organization: Mathematics
References: 05-09-090 05-09-117
Keywords: parse
Posted-Date: 02 Oct 2005 02:50:07 EDT

haberg@math.su.se (Hans Aberg) wrote:


> When writing a compiler, one needs to have the parse tree built according
> to the grammar specification, due to the stuff put into the actions of the
> rules.


Actually, a situation where it is convenient using a different parse than
of the language grammar, is when one has a large number of operator
precedences (like in Prolog) which cannot be conveniently parsed via a
parser generated by a Yacc style static grammar parser generator. In the
parse, one puts the operators and values on a stack or compute the
semantic value as parenthesizes and operator precedences so require.


In article 05-09-067, "Lowell Thomas"
<lowell@coasttocoastresearch.com> wrote:


> It seems to me that this could be generalized to say, in effect, that
> any tree from the forest can be emulated by any other. Does anyone
> know of a contradiction to this?


So there are indeed situations where this is useful and used. But I do not
know of any general exploration of the topic.


--
    Hans Aberg



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