/*
 * Aresh Saharkhiz
 * saharkiz@gmail.com
 * Associate Professor / Mapua Institute of Technology / Philippines
 */

using System.Collections;
using System;

// Introduction to Software Testing
// Authors: Paul Ammann & Jeff Offutt
// Chapter 2, section 2.5, page 86

public class Queue
{ // Overview:  a Queue is a mutable, bounded FIFO data structure
    // of fixed size  (size is 2, for this exercise).
    // A typical Queue is [], [o1], or [o1, o2], where neither o1 nor o2
    // are ever null.  Older elements are listed before newer ones.
    private object[] elements;
    private int size, front, back;
    private const int capacity = 2;

    public Queue()
    {
        elements = new object[capacity];
        size = 0;
        front = 0;
        back = 0;
    }

    //JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
    //ORIGINAL LINE: public void enqueue(Object o) throws NullPointerException, IllegalStateException
    public virtual void enqueue(object o)
    { // Modifies: this
        // Effects:   If argument is null throw NullPointerException
        // else if this is full, throw IllegalStateException,
        // else make o the newest element of this
        if (o == null)
        {
            throw new System.NullReferenceException("Queue.enqueue");
        }
        else if (size == capacity)
        {
            throw new InvalidOperationException("Queue.enqueue");
        }
        else
        {
            size++;
            elements[back] = o;
            back = (back + 1) % capacity;
        }
    }

    //JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
    //ORIGINAL LINE: public Object dequeue() throws IllegalStateException
    public virtual object dequeue()
    { // Modifies: this
        // Effects:   If queue is empty, throw IllegalStateException,
        // else remove and return oldest element of this

        if (size == 0)
        {
            throw new InvalidOperationException("Queue.dequeue");
        }
        else
        {
            size--;
            object o = elements[(front % capacity)];
            elements[front] = null;
            front = (front + 1) % capacity;
            return o;
        }
    }

    public virtual bool Empty
    {
        get
        {
            return (size == 0);
        }
    }
    public virtual bool Full
    {
        get
        {
            return (size == capacity);
        }
    }

    public override string ToString()
    {
        string result = "[";
        for (int i = 0; i < size; i++)
        {
            result += elements[(front + i) % capacity].ToString();
            if (i < size - 1)
            {
                result += ", ";
            }
        }
        result += "]";
        return result;
    }
    public static void Main(string[] args)
    { }
}