// Bryan Chadwick
// Visit.java
// Container problem using DJ and Visitors

import edu.neu.ccs.demeter.dj.*;
import java.util.Stack;

public class Visit{
   public static void main(String[] args) {
       ClassGraph cg = new ClassGraph(true,false);

       Container con;
       con = new Container(18,new Item[]{new Element(4),
                                         new Container(8,new Item[]{new Element(4),
                                                                    new Element(3)}),
                                         new Element(1),
                                         new Container(5,new Item[]{new Element(6),
                                                                    new Element(1)})});
       Strategy s = new Strategy("from Container via Item to Element");
       TraversalGraph tg = new TraversalGraph(s, cg);

       ViolationVisitor vv = new ViolationVisitor();
       tg.traverse(con,vv);
       int i = ((Integer)(vv.getReturnValue())).intValue();

       System.out.println("Violations : "+i);
   }
}

interface Item{}

// Visitor that just collects the Weight
class WeightVisitor extends Visitor{
   int weight = 0;
   public void before(Element e){ weight += e.weight; }
   public Object getReturnValue(){ return new Integer(weight); }
}

// Visitor that collects Weight, and checks for capacity violations
class ViolationVisitor extends Visitor{
   int weight = 0;
   int violations = 0;
   Stack stack = new Stack();//<Integer> stack = new Stack<Integer>();

   public void before(Element e){ weight += e.weight; }
   public void before(Container c){ stack.push(new Integer(weight)); }
   public void after(Container c){
       if((weight - ((Integer)stack.pop()).intValue()) > c.capacity)
           violations++;
   }
   public Object getReturnValue(){ return new Integer(violations); }
}

// Represents something of Weight
class Element implements Item{
   public int weight;
   public Element(int w){ weight = w;}
}

// Represents a Weightless container, with a capacity
//   meening the only things with weight are Elements
//   and Containers that contain Elements...etc
class Container implements Item{
   public Item [] items;
   public int capacity;
   public Container(int c, Item[] i){items = i; capacity = c;}
}