// *********************************************************
// Excerpts from the implementation file ListT.cpp.
// *********************************************************
#include "ListT.h"   // header file
#include <stddef.h>  // for NULL

template <class T> 
struct listNode
{
   T            Item;
   listNode<T>* Next;
   listNode();  //constructor
};  // end struct

template <class T> 
listNode<T>::listNode(): Next(NULL)
{
}  // end default constructor

template <class T> 
listClass<T>::listClass(): Size(0), Head(NULL)
{
}  // end default constructor

template <class T> 
void listClass<T>::ListInsert(int NewPosition, T NewItem,
                              bool& Success)
{
   int NewLength = ListLength() + 1;

   Success = bool( (NewPosition >= 1) && 
                  (NewPosition <= NewLength) );

   if (Success)
   {  Size = NewLength;

 // create new node and place NewItem in it
      listNode<T>* NewPtr = new listNode<T>;
      Success = bool(NewPtr != NULL);

      if (Success)
      {  NewPtr->Item = NewItem;

         // attach new node to list
         if (NewPosition == 1)
         {  // insert new node at beginning of list
            NewPtr->Next = Head;
            Head = NewPtr;
         }

         else
         {  listNode<T>* Prev = PtrTo(NewPosition-1);
            // insert new node after node 
            // to which Prev points
            NewPtr->Next = Prev->Next;
            Prev->Next = NewPtr;
         }  // end if
      }  // end if
   }  // end if
} // end ListInsert

template <class T> 
listNode<T>* listClass<T>::PtrTo(int Position)
{
   if ( (Position < 1) || (Position > ListLength()) )
    return NULL;

   else  // count from the beginning of the list
   {  listNode<T>* Trav = Head;
      for (int Skip = 1; Skip < Position; ++Skip)
         Trav = Trav->Next;
      return Trav;
   }
}  // end PtrTo