Question

I have a simple antlr rule to catch a phrase like “running.exception=2.j=15” and I want to identify the value is initialized to which is 2 in this case.

However, ANTLR is looking at 2. as a float. Is there anyway to make it identify it as an int?

My rule:

exception
    :
    (
    ID*
    '.exception='
    INT
    '.'
    ID*
    );

Answer 1

Try something like this:

grammar T;

parse
 : (t=. {System.out.printf("\%-10s '\%s'\n", tokenNames[$t.type], $t.text);})* EOF
 ;

FLOAT
 : DIGIT+ ( ('.' DIGIT)=> '.' DIGIT+
          | {$type=INT;}
          )
 | '.' DIGIT+
 ;

DOT
 : '.'
 ;

SPACE
 : ' ' {skip();}
 ;

fragment DIGIT : '0'..'9';
fragment INT : ;

which would parse the input "0.12 .34 56. 78" like this:

FLOAT      '0.12'
FLOAT      '.34'
INT        '56'
DOT        '.'
INT        '78'