/*****************************************************************************************

    File

        objq.cpp

    Description

        Provides a definition of a class implementing a queue using 
        the underlying data structure of a List. The derivation is 
        'private' because class Queue inherents the implementation, 
        but not the interface of class List.

    Public Methods

        Queue::remove                        void
        Queue::insert                      ItemType i


       
*****************************************************************************************/



#include <iostream.h>
#include "objq.h"


/*****************************************************************************************

    Function

        Queue::remove

    Parameters

        None              

    Returns

        Returns the item removed from the head of the queue.

    Description

        Remove the item at the head of the queue.
        

    Change History

        06/19/98  (thh)  Initial Definition based on modifications
                         to code provided with Instructor's Manual to
                         accompany Programming Languages Paradigm and Practice,
                         2nd Edition by Doris Appleby and Julius J. VandeKopple,
                         McGraw Hill, 1997.

*****************************************************************************************/


ItemType Queue::remove()
{
	if (len <= 0) {
		cerr << "Attempt to remove an item from an empty queue" << endl;
		return 0;
	}
	--len;
	return List::RemoveFromFront();
}


/*****************************************************************************************

    Function

        Queue::insert

    Parameters

        i              (I)        ItemType

    Returns

        None

    Description

        Insert an item at the tail of the queue.
        

    Change History

        06/19/98  (thh)  Initial Definition based on modifications
                         to code provided with Instructor's Manual to
                         accompany Programming Languages Paradigm and Practice,
                         2nd Edition by Doris Appleby and Julius J. VandeKopple,
                         McGraw Hill, 1997.

*****************************************************************************************/


void Queue::insert(ItemType i)
{
	List::AddToEnd(i);
	++len;
}