package esercizi;

import exceptions.EmptyStackException;
import queue.NodeQueue;
import stack.Stack;

/**
 * Created with MONSTER.
 * User: xgiovio
 * Date: 13/04/2014
 * Time: 23:48
 */

// emulate a stack with a queue
public class QStack<E> implements Stack<E> {

    NodeQueue<E> a = new NodeQueue<E>();

    @Override
    public void push(E element) {
        a.enqueue(element);
    }

    @Override
    public E top() throws EmptyStackException {
        if (a.isEmpty()){
            throw new EmptyStackException();
        }else {
            E t;
            for (int i = 0 ;i<a.size() - 1;i++){
                a.enqueue(a.dequeue());
            }
            t = a.front();
            a.enqueue(a.dequeue());
            return t;
        }
    }

    @Override
    public E pop() throws EmptyStackException {
        if (a.isEmpty()){
            throw new EmptyStackException();
        }else {
            for (int i = 0 ;i<a.size() - 1;i++){
                a.enqueue(a.dequeue());
            }
            return a.dequeue();
        }
    }

    @Override
    public boolean isEmpty() {
        return a.isEmpty();
    }

    @Override
    public int size() {
        return a.size();
    }

    @Override
    public String toString() {
        return a.toString();
    }
}