EquationSystem{
  (@
  void f() {
    V1 v1 = new V1(null, new Integer(0));
    t1(v1);
    int result = v1.get_c().intValue();
if(result == 4) {
System.out.println("SUCCESS");
} else {
System.out.println("FAILURE");
}                          
  }
  @)
  (@
  void g(Variable w) {
    // creates a new visitor object for each call
    // better would be
    // V2 v2 = Visitors.v2;
    // v2.set_var(w);
    V2 v2 = new V2(new Equation(), w);
    t2(v2);
  }
  @)
  traversal t1(V1 v1) {
      bypassing Exp
    to Variable;} 
  traversal t2(V2 v2) {
    // the following shoul also work, but doesn't. A bug?
    bypassing {-> *,var,*}
    // bypassing {-> Equation,var,Variable}
    to Variable;}
}

V1{
  before EquationSystem (@ e = host; @)
  before Variable (@ 
    this.set_c(new Integer(this.get_c().intValue() + 1));
    // find out where used
    System.out.println(" V1 " + host.get_variableName().toString());
    e.g(host);
  @)
}

V2{
  before * (@ System.out.println("V2 is in " +host.getClass().toString()); @)
  before Equation (@ equation = host; @)
  before Variable (@
    System.out.println(" V2 variable " + host.get_variableName().toString()); 
    if (host.get_variableName().equals(variable.get_variableName())) {
       System.out.println(" V2 " + host.get_variableName().toString() 
       + " is used in an equation"); 
    }  
  @)
}

Main {
(@
  static public void main(String args[]) throws Exception {
      EquationSystem e = EquationSystem.parse(System.in);
      e.f();

      System.out.println("done: ");
}
@)
}