// BEHAVIOR
//========================================================================

// A simple DJ program for checking capacity 
// constraints for recursive containers.
// Three behavioral concerns: Checking, Summing, Difference
// abbreviated C S I
// Two generic concerns: traversal, behavior modification (visitor)
// count transition points, except in formal or actual parameters

Container {
{{
// ordering of visitors is important
// difference must be initalized before it is used
// after methods are called in reverse order of appearance
// it is important that DifferenceVisitor is after CheckingVisitor
// could also use: CheckingVisitorDJ DifferenceVisitorDJ SummingVisitorDJ ordering

// traverse while counting and summing
  int checkCapacityDJ(TraversalGraph whereToGo) {

    CheckingVisitorDJ cV = new CheckingVisitorDJ();		//1
    SummingVisitorDJ sV = new SummingVisitorDJ();		//1
    DifferenceVisitorDJ iV = new DifferenceVisitorDJ();		//1

    cV.set_iV(iV);					//2
    iV.set_sV(sV);					//2

    // old version
    // Visitor[] visitors = new Visitor[3];
    // visitors[0]=(Visitor) iV;
    // visitors[1]=(Visitor) sV;
    // visitors[2]=(Visitor) cV;
    // System.out.println("visitors prepared");
    // Integer res = (Integer) whereToGo.traverse(this, visitors);
    Integer res = (Integer) whereToGo.traverse(this, 
      new Visitor[] { iV, sV, cV });
    return res.intValue();
  }
}}
}
							//1
CheckingVisitorDJ {
{{
  public void start() { violations=0; System.out.println("begin"); }
  public void before(Container o) {
    System.out.println(" start new container ");}

  public void after(Container host) {
    int cap = host.get_capacity().get_i().intValue();
    int diff = ((Integer) iV.getReturnValue()).intValue();
    if (diff > cap)
      { this.set_violations(get_violations() + 1);
	System.out.println(" total weight " + 
	diff + " but limit is = " + cap + " OVER CAPACITY "); };
    System.out.println(" end container "); 
  }
  public Object getReturnValue() {return new Integer(violations);}
}}
}
							//1
// it is better to return difference
DifferenceVisitorDJ {
{{
// stack handling
  public void start() { stack = new Stack(); }
  public void before(Container o) {
    stack.push(sV.getReturnValue()); }

  public void after(Container o) {
     difference = ((Integer) sV.getReturnValue()).intValue() -
       ((Integer) stack.pop()).intValue(); }
  public Object getReturnValue() {return new Integer(difference);}
}}
}