[antlr-interest] Lexer rules for numbers and intervals

[beckersheinzsb]

Hello

I have the following rules in my lexer:

protected
DOT     :   '.'        ;

protected
DIGIT   :   '0'..'9'   ;

NUMBER  : (DOT (DIGIT)+)
        | (DIGIT)+ (DOT (DIGIT)*)?;


This piece works fine but now i want to add intervals, e.g. 5..9
If I try to define a rule like

INTERVAL_SIGN  : DOT DOT ;

I get a nondeterminism.

I see that it is difficult to distinguish between the second subrule 
of NUMBER and an interval 5..9 (NUMBER INTERVAL_SIGN NUMBER). Do I 
have to left-factor? 
Or is there a possibility to achieve that the lexer recognizes two 
following dots as an interval sign at all?

Could you please give me a hint

thanks a lot
greets

heinz





 
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