Search code examples
javajavacc

How to have a range for a number

I'm using javaCC to generate my parser. But I want to have a date with this format : "01/02" or "05/12" or "30/11"

TOKEN :
{
  < CONSTANT : (< DIGIT >)+ >
| < STRING : ( ["A"-"Z","a"-"z"] )+ >
| < #DIGIT : [ "0"-"9" ] >
| < SLASH: "/" >
}

I have something like that : 

(< CONSTANT > <SLASH > < CONSTANT >)

But it accept 999/888 ... How can i accept only 0-31 for the left side of slash, and 0-12 for the right side of slash

Thanks a lot for your help

Solution

  • I'd probably handle this in the parser roughly as follows

    void date() throws AnException : {
    Token t ;
    int m;
    int d ;
}{
    t=<CONSTANT>   { d = Integer.parse(t.image) ; }
    <SLASH>
    t=<CONSTANT>   { m = Integer.parse(t.image) ; }
    {   if( m > 12 ) throw AnException() ;
        if( d > 31 ) throw AnException() ;
    }
 }