[antlr-interest] nondeterminism problem

[Jack Hong]

Terence,

Thank you so much.

I tried that way before, but somehow it didn't work well.

This is the parser rule I declared in the parser before:
//---------------------------------------------
boolean_literal returns [Boolean b]
{
        b = null;
}
        :       "TRUE" { b = new Boolean(true); }
        |       "FALSE" { b = new Boolean(false); }
        ;
//---------------------------------------------

It looks good, but always returns null.  So I added a token
BOOLEAN_LITERAL in the lexer, after that my parser can retrieve the
correct value, but another problem raised -- nondeterminism.


Jack


-----Original Message-----
From: Terence Parr [mailto:parrt at jguru.com]
Sent: October 12, 2002 12:11 AM
To: antlr-interest at yahoogroups.com
Subject: Re: [antlr-interest] nondeterminism problem


Hi.  Just reference "TRUE" and "FALSE" in the parser and the lexer will
automatically test for them :)

Terence

On Friday, October 11, 2002, at 05:51  PM, Jack Hong wrote:

> Hi all,
>  
> I get following warning messages when I run ANTLR:
>  
> warning: lexical nondeterminism between rules IDENT and
> BOOLEAN_LITERAL upon
> petal.g:0:  k==1:'F','T'
> petal.g:0:  k==2:'A','R'
> petal.g:0:  k==3:'L','U'
>  
> related token definitions in my grammar file:
>  
> BOOLEAN_LITERAL
>     :    "TRUE"
>     |    "FALSE"
>     ;
>  
> IDENT
>     :    ( 'a'..'z' | 'A'..'Z' | '_') ( 'a'..'z' | 'A'..'Z' | '_' |
> '0'..'9')*
>     ;
>  
>  
> Any idea of how to fix these two nondeterministic tokens will be
> greatly appreciated.
>  
>  
> Thanks
> Jack
>  
>
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--
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Creator, ANTLR Parser Generator: http://www.antlr.org
Lecturer in Comp. Sci., University of San Francisco




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