[antlr-interest] How to define a FLOAT number

[Bernardo Elayda]

Hi,

My solution for recognizing a float is a little different:

REAL
     :(
     (NATURAL+ PERIOD)=>NATURAL+ PERIOD {++n;} NATURAL* {n==1}?
     |
     (PERIOD NATURAL+)=>PERIOD {++n;} NATURAL+ {n==1}?
      )
     {
            System.out.println("n is: " + n);
     }
     ;

fragment PERIOD : '.' ;
fragment NATURAL: '0'..'9' ;

I found that it was necessary to use syntax predicate and a validating
semantic check.  Without the validating semantic check, a value of
1.2.3would be recognized as a float.

regards,
Bernie Elayda
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20080228/8b1b2204/attachment.html