[antlr-interest] Using Own classes to recolect or parse the data withing the grammar

[Victor Giordano]

Hi all!. Hope good again!! (And not tired... of me xD)
Above a paste and example of what i am looking towards to parse.
A linear Expression. That is simply a succession of linear terms.
A linear terms is something like : Constants Var | Var.
Based on the example of _the definitive guide to ANTLR_ with math 
expression, a procced to re adapt this to capture the data into my own
expression of the program.
So basically, for now, i only wanted to put all the linear terms in and 
list (specifically: an Arraylist) and have it in that strcuture because 
later i throw it in a simplex resolver to compute answer to linear 
optimization problems.
So... the thing, is that i do this (pasted above).
If you want, just copy and paste and debug this example with: 2x + 3y + 4z
You will see some output like this: 2.0 * x + 3.0 * y + 4.0 * z  (The 
resutl of invoke the toString over my custom class inner of the parser).

The question is: How i can do this, without definig the class inside the 
@menbers section. That class, in fact, is one of my program.. so i only 
want to reuse that.
Jim Idle say to me, days before, that for this kind of things are not 
simple and required the help of maven.... but i really hope someone know 
some easier way to archieve this.

Thanks!!.


------------------------------------------------------------------------
grammar LinearExpression;

options
{
     output=AST;
}


tokens
{
     PLUS     = '+';
     MINUS     = '-';
     MUL        = '*';
     DIV        = '/';
}

@members
{
     public static class LinearExpr
     {
         ArrayList<LinearTerm> terms;

         public LinearExpr()
         {
             terms = new ArrayList<LinearTerm>();
         }

         public void add(LinearTerm lt)
         {
             terms.add(lt);
         }

         @Override
         public String toString()
         {
             StringBuilder res = new StringBuilder(50);
             for (LinearTerm lt : terms)
             {
                 res.append(lt.toString()).append(" + ");
             }
             return res.substring(0,res.lastIndexOf("+"));
         }
     }


     public static class LinearTerm
     {
         String var;
         float cofactor;

         public LinearTerm()
         {
             this.var = "";
             this.cofactor = 1;
         }

         @Override
         public String toString()
         {
             return this.cofactor + " * " +  this.var;
         }
     }
}


expr returns [LinearExpr ret]
@init
{
     $ret = new LinearExpr();
}
@after
{
     System.out.println ($ret);
}
     : e=term {$ret.add($e.ret);}
     ( PLUS e=term {$ret.add($e.ret);}
     | MINUS e=term {$ret.add($e.ret);}
     )*;


term returns [LinearTerm ret]
@init
{
     $ret = new LinearTerm ();
}
     :
     (FLOAT {$ret.cofactor = Float.parseFloat($FLOAT.text);}
     |INT {$ret.cofactor = Integer.parseInt($INT.text);}
     )?
     ID {$ret.var = $ID.text;};

ID  :    ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*;

INT :    '0'..'9'+ ;

FLOAT
     :   ('0'..'9')+ '.' ('0'..'9')* EXPONENT?
     |   '.' ('0'..'9')+ EXPONENT?
     |   ('0'..'9')+ EXPONENT
     ;

fragment EXPONENT : ('e'|'E') ('+'|'-')? ('0'..'9')+ ;