//---------------------------------------------------------------------
// File: queue.h
// Name: Sharon M. Tuttle
// last modified: 4-01-05
//
// Class name: queue
//
// Description: a collection of items such that entries can be
//    inserted at one end (called the rear) and removed at the
//    other end (called the front).
//    This version does NOT have a fixed capacity.
//
//---------------------------------------------------------------------

#ifndef QUEUE_H
#define QUEUE_H

#include <cstdlib>	// provides NULL
#include "node.h"
using namespace std;

template <typename Item>
class queue
{
    public:
        /****************************************************/
        /* TYPEDEFS and MEMBER CONSTANTS                    */
        /****************************************************/

        typedef Item value_type;

        /*****************************************************/
        /* CONSTRUCTORS and DESTRUCTORS                      */
        /*****************************************************/

        // postcondition: creates an empty queue instance 
        //
        queue();

        // copy constructor
        //
        queue(const queue& source);

        // destructor
        //
        ~queue( );

        /*************************************************************/
        /* ACCESSORS and other constant member functions (observers) */
        /*************************************************************/

        // postcondition: returns true if queue is empty, and 
        //    returns false otherwise 
        //
        bool is_empty( ) const;

        // precondition: is_empty() == false 
        //
        // postcondition: returns the value of the front item of the 
        //    queue, BUT the queue is unchanged. 
        //
        value_type get_front( ) const;

        /*****************************************************/
        /* MODIFIERS and other modifying member functions    */
        /*****************************************************/

        // postcondition: a new copy of entry has been inserted 
        //    at the rear of the queue 
        //
        void enqueue(const value_type& entry);

        // precondition: is_empty() == false 
        //
        // postcondition: the front item of the queue has been 
        //    removed and is returned
        //
	value_type dequeue( );

    private:

        /*****************************************************/
        /* DATA FIELDS                                       */
        /*****************************************************/
        node<Item>* front;   // pointer to node containing front
                             //    of queue
        node<Item>* rear ;   // pointer to node containing rear
                             //    of queue
	int used;	     // how many items are in the queue
};

#include "queue.template"

#endif