// ********************************************************
// Implementation file QueueA.cpp for the ADT queue.
// Circular array-based implementation.
// The array has indexes to the front and back of the
// queue. A counter tracks the number of items currently
// in the queue.
// ********************************************************
#include "QueueA.h"  // header file

Queue::Queue():front(0), count(0)
{
}  // end default constructor

Queue::~Queue()
{
  dequeueAll();
}

bool Queue::isEmpty() const
{
   return (count == 0);
}  // end isEmpty

void Queue::enqueue(Object* newItem) throw(QueueException)
{
   if (count == MAX_QUEUE)
      throw QueueException("QueueException: queue full on enqueue");
   else
   {  // queue is not full; insert item
      items[(front+count) % MAX_QUEUE] = newItem;
      ++count;
   }  // end if
}  // end enqueue

Object* Queue::dequeue() throw(QueueException)
{
   if (isEmpty())
      throw QueueException("QueueException: empty queue, cannot dequeue");
   else
   {  // queue is not empty; remove front
      Object* toBeReturned = items[front];
      front = (front+1) % MAX_QUEUE;
      --count;
      return toBeReturned;
   }  // end if
}  // end dequeue

void Queue::dequeueAll()
{
   while (!isEmpty())
   {  // queue is not empty; delete and remove front element
      delete items[front];
      front = (front+1) % MAX_QUEUE;
      --count;
   }  // end if
}  // end dequeue

const Object* Queue::peek() const throw(QueueException)
{
   if (isEmpty())
      throw QueueException("QueueException: empty queue, cannot getFront");
   else
      // queue is not empty; retrieve front
      return items[front];
}  // end getFront
// End of implementation file.