[antlr-interest] literals.

Oliver Zeigermann oliver at zeigermann.de
Tue Dec 9 23:37:30 PST 2003


cesar octavio lopez nataren wrote:
> On Wed, 2003-12-10 at 01:00, Oliver Zeigermann wrote:
> If I erase that and add the lexical rule
> 
> IN: "in";
> 
> I get: 
> 
> jscript.g: warning:lexical nondeterminism between rules IDENTIFIER and
> IN upon
> jscript-lexer-parser.g:     k==1:'i'
> jscript-lexer-parser.g:     k==2:'n'
> jscript-lexer-parser.g:     k==3:<end-of-token>
> 
> The definition of IDENTIFIER  that I have is:
> 
> IDENTIFIER
> options { testLiterals = true; }
>         : ('a'..'z' | 'A'..'Z') ('a'..'z' | 'A'..'Z' | '0'..'9')*
>         ;

Ah, I see now. This looks like a real nondeterminism. If you were really 
correct - I think nobody actually does this, this is just to make me 
point clear - you would have to omit the string "in" from your 
IDENTIFIER rule. Of course you should not do this, but simply put the IN 
rule before the IDENTIFIER which gives preceedence of IN over IDENTIFIER 
and ignore the warning.

Oliver



 

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