#include <stdlib.h>  // Provides size_t
#include <assert.h>  // Provides assert
#include "link2.h"   // Template Version Linked list toolkit 

template <class Item>
class Queue
{
    public:
        Queue( );
        Queue(const Queue& source);
        ~Queue( );
        // MODIFICATION functions
        void insert(const Item& entry);
        Item get_front( );
        void operator =(const Queue& source);
        // CONSTANT functions
        size_t size( ) const { return count; }
        bool is_empty( ) const { return (count == 0); }
    private:
        Node<Item> *front_ptr;  // Points to front of queue
        Node<Item> *rear_ptr;   // Points to rear of queue
        size_t count;           // Total number of items in the queue
};

template <class Item>
Queue<Item>::Queue( )
{
    count = 0;
    front_ptr = NULL;
}

template <class Item>
Queue<Item>::Queue(const Queue<Item>& source)
{
    count = source.count;
    list_copy(source.front_ptr, front_ptr, rear_ptr);
}

template <class Item>
Queue<Item>::~Queue( )
{
    list_clear(front_ptr);
}

template <class Item>
void Queue<Item>::operator =(const Queue<Item>& source)
{
    if (source.front_ptr == front_ptr) // Handle self-assignment
        return;

    list_clear(front_ptr);
    count = source.count;
    list_copy(source.front_ptr, front_ptr, rear_ptr);
}

template <class Item>
void Queue<Item>::insert(const Item& entry)
{
    if (is_empty( ))
    {   // Insert first entry
        list_head_insert(front_ptr, entry);
        rear_ptr = front_ptr;
    }
    else
    {
        list_insert(rear_ptr, entry);
        rear_ptr = rear_ptr->link;
    }
    count++;
}

template <class Item>
Item Queue<Item>::get_front( )
{
    Item answer;

    assert(!is_empty( ));
    answer = front_ptr->data;
    list_head_remove(front_ptr);
    count--;    
    return answer;
}