[antlr-interest] Re: another nondeterminism question

Adrian Sandor aditsu at yahoo.com
Wed Jul 16 11:25:44 PDT 2003


ok, I tried with the following grammar:

class l1 extends Lexer;
options{k=2;}
protected A: 'a' | "bb";
B: 'b';
S: (A)=>(A)+;

and I got:

ANTLR Parser Generator   Version 2.7.2   1989-2003 jGuru.com
t1.g: warning:lexical nondeterminism between rules B and S upon
t1.g:     k==1:'b'
t1.g:     k==2:<end-of-token>
t1.g:5: warning:Syntactic predicate ignored for single alternative


Adrian

--- In antlr-interest at yahoogroups.com, mzukowski at y... wrote:
> That's a weird bug you ran into, I think.  It should give warnings 
in both
> cases.  You could solve this with a syntactic predicate:
> 
> S: (A)=>(A)+;
> 
> -----Original Message-----
> From: Adrian Sandor [mailto:aditsu at y...] 
> Sent: Friday, July 11, 2003 9:54 AM
> To: antlr-interest at yahoogroups.com
> Subject: [antlr-interest] another nondeterminism question
> 
> 
> why do I get a nondeterminism warning for this grammar:
> 
> class l1 extends Lexer;
> options{k=2;}
> protected A: 'a' | "bb";
> B: 'b';
> S: (A)+;
> 
> but I don't get any warning when I change S to:
> 
> S: A (A)+;
> 
> and how can I solve it for the first case?
> I tried many things but to no avail...
> 
> thanks
> Adrian
> 
> 
>  
> 
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