Thread: Need help abstracting my linked list.

Okay, so here is my current code:
I don't want the Linked_List class to be an actual link in the linked list. Why should the links have functions to add more links?

Code:

#include <string>
#include <iostream>
using namespace std;

template< typename T_ >
class Linked_List
{
public:

	Linked_List<T_>()
	{
		start_ptr = NULL;
		current = NULL;
	}

	T_ data;
    Linked_List<T_> * nxt;// Pointer to next node

	void add_node(T_ & t)
	{
		Linked_List<T_> *temp, *temp2;   // Temporary pointers
		// Reserve space for new node and fill it with data
		temp = new Linked_List<T_>;
		temp->data = t;
		temp->nxt = NULL;
		// Set up link to this node
		if (start_ptr == NULL)
		{
			start_ptr = temp;
			current = start_ptr;
		}
		else
		{
			temp2 = start_ptr;
			// We know this is not NULL - list not empty!
		    while (temp2->nxt != NULL)
			{
				temp2 = temp2->nxt;
                // Move to next link in chain
            }
			temp2->nxt = temp;
		}
	}

	void display_list()
	{
		Linked_List<T_> *temp;
		temp = start_ptr;
		cout << endl;
		if (temp == NULL)
			cout << "The list is empty!" << endl;
		else
		{
			while (temp != NULL)
			{
				// Display details for what temp points to
				cout << temp->data;
				if (temp == current)
					cout << " <-- Current node";
				cout << endl;
				temp = temp->nxt;
			}
		}
	}

	void delete_start_node()
	{
		Linked_List<T_> *temp;
		temp = start_ptr;
		start_ptr = start_ptr->nxt;
		delete temp;
	}

	void delete_end_node()
	{ 
		Linked_List<T_>  *temp1, *temp2;
		if (start_ptr == NULL)
			cout << "The list is empty!" << endl;
		else
		{ 
			temp1 = start_ptr;
			if (temp1->nxt == NULL)
			{
				delete temp1;
				start_ptr = NULL;
            }
			else
			{
				while (temp1->nxt != NULL)
				{
					temp2 = temp1;
					temp1 = temp1->nxt;
                }
				delete temp1;
                temp2->nxt = NULL;
			}
		}
	}
	 
	void move_current_on ()
	{
		if (current->nxt == NULL)
			current = start_ptr;
		else
			current = current->nxt;
    }

	void move_current_back ()
	{ 
		if (current == start_ptr)
			cout << "You are at the start of the list" << endl;
		else
		{ 
			 node *previous;     // Declare the pointer
			 previous = start_ptr;
			 while (previous->nxt != current)
			 {
				 previous = previous->nxt;
			 }
			 current = previous;
		 }
	 }

	 Linked_List<T_> * start_ptr;
	 Linked_List<T_> *current;		 // Used to move along the list
};

Here is a picture telling you what I want to do with it:

http://img.photobucket.com/albums/v1...ewhatimean.jpg

Basically, I want to make the Linked_List class more or less just a controller and entry point of the actual linked list.

I want to have an abstract node class that I can add functions to and derive those functions into subclasses.

By doing this I hope to accomplish a system where I can automatically and recursively update the data held in the links. Which should all be derivations of type link.

Does this make sense?

Code:

template< typename T_ >
struct listnode
{
  T_ data;
  listnode< T_ >* next;
};

template< typename T_ >
class linkedlist
{
  // ...
};

I can see cleeearly now the rain is gonee... Thanks :d