For use with CMSC-341, Spring 99,  Project 2

Here is the definition of the DlNode class. 
Copy it to your DlNode.H file. 

Remember:
 -- implement the inline method(s)
 -- guard the file
 -- complete the documentation
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version:  28 February 1999
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// forward references for template classes
template <class T> class LinkedList;
template <class T> class LinkedListIterator;

template<class T>
class DlNode 
{
  friend class LinkedList<T>;
  friend class LinkedListIterator<T>;
private:
  T _data;              // datum stored at node
  DlNode<T>* _prev;     // ptr to previous node
  DlNode<T>* _next;     // ptr to next node

  // Constructor for node with unspecified datum, 
  // null previous and next pointers
  DlNode();

  // Constructor for node with specified datum,
  // null previous and next pointers
  DlNode(const T& datum);

  virtual ~DlNode();

protected:
  // Accessor for this node's datum
  // Returns: reference to datum stored at this node
  inline T& GetData();

  // Accessor for this nodes' previous node
  // Returns: pointer to the 'previous' node
  inline DlNode<T> * GetPrev();

  // Accessor for this node's next node
  // Returns: pointer to the 'next' node
  inline DlNode<T> * GetNext();

  // Mutator for this node's previous node.
  // Param: n the node to become this node's prev.
  inline virtual void SetPrev(DlNode<T> * n);

  // Mutator for this node's next node.
  // Param: n the node to become this node's next.
  inline void SetNext(DlNode<T> * n);

  // Mutator for this node's datum.
  // Param: d the datum to store at this node.
  inline void SetData(const T& d);
};