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//Copyright Dr. Marek A. Suchenek, 2015
//All rights reserved

package split;

/**
 *
 * @author suchenek
 */
public class QUEUE1<E>
{
	List<E> front; // points to "dummy" header
                       // it never changes
	List<E> rear; // points to the last element

// Both variables (above) point one position ahead
//        in order to facilitate enqueue and dequeue

	public QUEUE1()
//constructs the empty QUEUE consisting of "dummy" header
	{
		cnt.incr();
                List<E> temp = new List<E>();
		temp.head = null; //never used
		temp.tail = null;
		front = temp;
		rear = temp; // rear = front;
	}

	public void enqueue(E x)
	{
		cnt.incr();
                List<E> temp = new List<E>();
		temp.head = x;
		temp.tail = null;
		rear.tail = temp;
                rear = temp; // rear = rear.tail;
	}

	public E dequeue()
	{
		cnt.incr();
                if (front == rear) return null;
                E toReturn = front.tail.head;
                if(front.tail==rear) rear = front; // dequeue the only element
		front.tail = front.tail.tail;
                return toReturn;
	}


        public Boolean isEmpty()
    {
            return front == rear;
        }

            public void dump()
            {
                List i = front;
                System.out.print("Dump:");
                while (i!=rear)
                {
                    System.out.print(i.tail.head + " ");
                    i = i.tail;
               }
                System.out.println(" End Dump");
            }

        public QUEUE1<E> cloneAbstract()
//      Deep clone
	{
            QUEUE1<E> toReturn = new QUEUE1<E>();
            for (List<E> p = front; p !=rear; p = p.tail)
            {
                toReturn.enqueue(p.tail.head);
            }
            return toReturn;
        }

        public QUEUE1<E> clone()
//      Deep clone
	{
            QUEUE1<E> toReturn = new QUEUE1<E>();
            for (List<E> p = front; p != rear; p = p.tail)
            {
                List<E> temp = new List<E> ();
                temp.head = p.tail.head;
                temp.tail = null;
                toReturn.rear.tail = temp;
                toReturn.rear = temp;
            }
            return toReturn;
        }

}