///////////////////////////////////////////////////////
// Deque.java
// 
// Written By Geoff Knagge (9806135)
// last modified 14/8/1999
//
// interface required for implementing a deque
///////////////////////////////////////////////////////

public interface Deque 
{
	public int size();
	public boolean isEmpty();
	public void insertFirst(Object O);
	public void insertLast(Object O);
	public Object removeFirst() throws EmptyDequeException;
	public Object removeLast() throws EmptyDequeException;
	public Object firstElement() throws EmptyDequeException;
	public Object lastElement() throws EmptyDequeException;
}