Factoring a Grammar for Predictive Parsers ?

Vimal <j.vimal@gmail.com>
Thu, 16 Aug 2007 23:10:11 +0530

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Factoring a Grammar for Predictive Parsers ? j.vimal@gmail.com (Vimal) (2007-08-16)
Re: Factoring a Grammar for Predictive Parsers ? j.vimal@gmail.com (Vimal) (2007-08-17)
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From: Vimal <j.vimal@gmail.com>
Newsgroups: comp.compilers
Date: Thu, 16 Aug 2007 23:10:11 +0530
Organization: Compilers Central
Keywords: parse, question

Hi
I have a grammar G generating a language L. To write predictive parsers
for the grammar, I would like to convert the grammar G into an equivalent
grammar G' such that it is easy to "predictively" parse the input and test
for membership.
Q: Is it always possible to do such a conversion?
Q: If possible, I would like to know how to convert this grammar
to help predictive parsers.


S -> {L} | {}
L -> E | E,L
E -> { | } | ,


The grammar generates valid expressions to represent sets. But
its difficult to parse, because, the set can contain { or } or , as an
element. So, this confuses me :(


The predictive parser I would be using (not code one), is Haskell's Parsec.


Thanks!


Vimal
Department of Computer Science and Engineering
Indian Institute of Technology Madras
PS: To the editor: I am not sure if this question is valid in your forum!
I just hope it is not misunderstood as a "Solve my homework" type question :)
I really broke my head on this one, so, some help required!


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