// Computer Science 367, Section 3, Fall 1997
// Instructor: Michael Siff (siff@cs.wisc.edu)
//
//
// FILE: queue.C
//
//
// A queue template class using a linked-list List template class.
//
//
// INVARIANT for Queue: 
//
// Keep the cursor of the underlying list at the head of the list and thus
// at the front of the queue. Dequeue will call reset, current, and
// remove. Enqueue will call append.


#include <assert.h>  // Provides assert
#include <stdlib.h>  // Provides size_t


// CONSTANT MEMBER FUNCTIONS
// -------------------------
  
template<class Item>
size_t Queue<Item>::size() const
{
  return (rep.length());
}


template<class Item>
bool Queue<Item>::isEmpty() const
{
  return(rep.isEmpty());
}


template<class Item>
bool Queue<Item>::isFull() const
{
  return(rep.isFull());
}


  
// MODIFICATION MEMBER FUNCTIONS
// -----------------------------

template<class Item>
void Queue<Item>::enqueue(const Item& it)
// Places it on the back of the queue.
{
  assert(!isFull());

  rep.append(it);
}


template<class Item>
Item Queue<Item>::dequeue()
// Removes and returns the item off the front of the queue.
{
  assert(!isEmpty());
  
  rep.reset(); // make sure the cursor is at the front 
  Item result = rep.current();
  rep.remove();
  return result;
}