// behavior

Container {
  traversal allWeights(
    CheckingVisitor cV,
    SummingVisitor sV,
    InitialVisitor iV
    ) {
    to Weight;}

  (@
// traverse while counting and summing
  int checkCapacity() throws Exception {
    // adaptive specification of objects using parsing
    SummingVisitor sV = SummingVisitor.parse("0");
    InitialVisitor iV = 
      new InitialVisitor(0, new Stack(), sV);
    CheckingVisitor cV = new CheckingVisitor(iV,0);
    this.allWeights(cV, sV, iV );
    return (cV.get_violations());
  }
  @)
}
SummingVisitor {
  before Weight (@ 
    total = total + host.get_i(); @)
}

CheckingVisitor {
  after  Container (@
    int initial = iV.get_initial();
    int cap = host.get_capacity().get_i();
    // violation of Law of Demeter
    // should use traversal
    int diff = iV.get_sV().get_total() - initial;
    if (diff > cap)
      { this.set_violations(get_violations() + 1);
	System.out.println(" total weight " + 
	diff + " but limit is = " + 
	cap + " OVER CAPACITY "); };
  @)
}

InitialVisitor {
// stack handling
  before Container (@ stack.push(
    new Integer(sV.get_total()));  @)
  after  Container (@ initial = 
    ((Integer) stack.pop()).intValue(); @)
}

Main {
(@
  static public void main(String args[]) throws Exception {
    Container a = Container.parse(System.in);
    int result = a.checkCapacity();
  }
@)
}

// solving the capacity checking problem from hw 2
// without modifying the host
// visitor has own stack to keep track of initial value

// class dictionary
(@
import java.util.*;
@)
Container = "(" 
  <contents> List(Item) <capacity> Capacity ")".
Item : Container | Simple.
List(S) ~ {S}.
Simple =  <name> Ident <w> Weight.
Capacity = <i> int.
Weight = <i> int.


CheckingVisitor = <iV> InitialVisitor <violations> int.
SummingVisitor = <total> int.
InitialVisitor = // takes care of computing initial value 
  <initial> int // result for communication
		    // with checking visitor
  <stack> Stack   
  <sV> SummingVisitor. 

Main = .

// input

( //begin container 1
apple 1 //item
  ( //begin container 2
  pencil 1 //item
    ( //begin container 3
    apple 1 //item
    1) //capacity
  orange 1
  1) //capacity
orange 1
kiwi 1
5) //capacity