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

    File
 
        objlist.h

    Description

        Provides a definition of class List. List is a class that 
        defines a list that allows insertions and deletions from both 
        the front and end the data structure is a singly-linked list 
        with pointers to the first and last elements.  Insertions at
        either end are easy. Deleting the element at the front of the 
        list is also easy, but deleting the element at the end of the list
        requires traversing the entire list.

    Include File Dependencies

        vehicle.h
        mystring.h

    Change History

        06/19/98  (distribution disk)  Initial Definition from 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.
                         
       
*****************************************************************************************/


#ifndef OBJLIST_H_INCLUDED
#define OBJLIST_H_INCLUDED

#include "vehicle.h"
#include "Mystring.h"

typedef Vehicle *ItemType;


class List {
	public:
      List() : ListFront(0), ListEnd(0) {} // initialize pointers to zero
		~List();
		int is_empty() const { return ListFront == 0; }
		void AddToFront(ItemType);
		void AddToEnd(ItemType);
		ItemType RemoveFromFront();
		ItemType RemoveFromEnd();
	private:
		struct Node {
			Node(ItemType i, Node *n) : item(i), next(n) {};
			ItemType item;
			Node *next;
		};
		Node *ListFront;	// pointer to first element of the list
		Node *ListEnd;		// pointer to the last element
};

#endif