//
//   This file contains the C# code from Program 6.16 of
//   "Data Structures and Algorithms
//    with Object-Oriented Design Patterns in C#"
//   by Bruno R. Preiss.
//
//   Copyright (c) 2001--2002 by Bruno R. Preiss, P.Eng.  All rights reserved.
//
//   http://www.brpreiss.com/books/opus6/programs/pgm06_16.txt
//
public class QueueAsArray : AbstractContainer, Queue
{
    protected object[] array;
    protected int head;
    protected int tail;

    public object Head
    {
	get
	{
	    if (count == 0)
		throw new ContainerEmptyException();
	    return array[head];
	}
    }

    public void Enqueue(object obj)
    {
	if (count == array.Length)
	    throw new ContainerFullException();
	if (++tail == array.Length)
	    tail = 0;
	array[tail] = obj;
	++count;
    }

    public object Dequeue()
    {
	if (count == 0)
	    throw new ContainerEmptyException();
	object result = array[head];
	array[head] = null;
	if (++head == array.Length)
	    head = 0;
	--count;
	return result;
    }
    // ...
}