// L-12 MCS 360 Mon 20 Sep 2010 : mcs360_double_list.tc

/* This file defines the member function of the templated class List
   in the namespace mcs360_double_list. */

#include <iostream>

namespace mcs360_double_list
{
   template <typename T>
   List<T>::List()
   {
      first = NULL;
      last = NULL;
   }

   template <typename T>
   List<T>::List(T item)
   {
      first = new Node(item);
      last = first;
   }

   template <typename T>
   void List<T>::append(T item)
   {
      if(first == NULL)
      {
         first = new Node(item);
         last = first;
      } 
      else if(first == last)
      {
         first->next = new Node(item);
         first->next->prev = first;
         last = first->next;
      }
      else
      {
         last->next = new Node(item);
         last->next->prev = last;
         last = last->next;
      }
   }

   template <typename T>
   void List<T>::write_forward()
   {
      Node *ptr = first;
      while(ptr != NULL)
      {
         std::cout << "->" << ptr->data;
         ptr = ptr->next;
      }
   }

   template <typename T>
   void List<T>::write_backward()
   {
      Node *ptr = last;
      while(ptr != NULL)
      {
         std::cout << "->" << ptr->data;
         ptr = ptr->prev;
      }
   }
}