/**
  * Bloch's Generic Stack example
  * SWE 619
  */

import java.util.*;

public class Stack <E> {

   private E[] elements;
   private int size = 0;
   private static final int DEFAULT_CAPACITY = 16;


   @SuppressWarnings("unchecked") // All items in elements[] are of type E
   public Stack() {   
      // this.elements = new E[DEFAULT_CAPACITY];  // doesn't compile
      this.elements = (E[]) new Object[DEFAULT_CAPACITY];
   }

   public void push (E e) {
     ensureCapacity();
     elements[size++] = e;
   }

   public E pop () {
     if (size == 0) throw new IllegalStateException("Stack.pop");
     E result = elements[--size];
     elements[size] = null;
     return result;
   }

   public boolean isEmpty() {
      return size == 0;
   }

   // public void pushAll(Iterable<E> src) {   // doesn't compile
   public void pushAll(Iterable<? extends E> src) {
      for (E e: src) {
         push(e);
      }
   }

   // public void popAll(Collection<E> dst) {  // doesn't compile
   public void popAll(Collection<? super E> dst) { 
      while (!isEmpty()) {
         dst.add(pop());
      }
   }

   @SuppressWarnings("unchecked") // All items in elements[] are of type E
   private void ensureCapacity() {
      if (elements.length == size) {
         Object oldElements[] = elements;
         // elements = new E[2*size + 1];   // doesn't compile
         elements = (E[]) new Object[2*size + 1];
         System.arraycopy(oldElements, 0, elements, 0, size);
      }
   }


  public static void main(String[] args) {
     // Simple exercise to push/pop cmd line args
     Stack <String> s = new Stack <String>();
     for (String arg : args)
        s.push(arg);
     while (!s.isEmpty() )
        System.out.println(s.pop().toUpperCase());

     // Exercise for pushAll, popAll
     Stack <Number> s1 = new Stack<Number>();
     Integer i = 1;   s1.push(i);
     i = 2; s1.push(i);

     Collection<Integer> integers = new HashSet<Integer> ();
     integers.add(2);
     integers.add(3);
     s1.pushAll(integers);

     Collection<Object> result = new ArrayList<Object> ();
     s1.popAll(result);


     for (Object n : result) 
        System.out.println(n);
  }

}