precedence have both ways

jgk@panix.com (Joe keane)
Thu, 30 May 2013 23:21:41 -0400 (EDT)

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Re: Articles/books that discuss separating the context-free part of a anton@mips.complang.tuwien.ac.at (2013-05-20)
precedence have both ways jgk@panix.com (2013-05-30)
Re: precedence have both ways gah@ugcs.caltech.edu (glen herrmannsfeldt) (2013-05-31)
Re: precedence have both ways anton@mips.complang.tuwien.ac.at (2013-05-31)
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From: jgk@panix.com (Joe keane)
Newsgroups: comp.compilers
Date: Thu, 30 May 2013 23:21:41 -0400 (EDT)
Organization: Public Access Networks Corp.
References: 13-05-010 13-05-018
Keywords: parse, theory
Posted-Date: 30 May 2013 23:21:41 EDT

Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>a<3 AND b<3


This reminds me of a question.


One person designs a language 'C1' with precedence:


        [higher]
        ...
        |
        &
        <, <=, >, <=
        ==, !=
        ...
        [lower]


Some other person designs a language 'C2' with precedence:


        [higher]
        ...
        <, <=, >, <=
        ==, !=
        |
        &
        ...
        [lower]


They're the same besides that.


To compromise, they make a new language 'C3' such that a program is
valid C3 if it is valid C1 and valid C2 -and- both ways mean the same.


Is there some good way to do this -in the grammar-?


[I see gcc has warnings like this.]


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