public void AddLast(T item)
{
// if head is null, then this will be the first item
if (head == null)
{
this.AddFirstItem(item);
}
else
{
DoublyLinkedListNode <T> newNode = new DoublyLinkedListNode <T>(item);
tail.Next = newNode;
newNode.Next = head;
newNode.Previous = tail;
tail = newNode;
head.Previous = tail;
}
++count;
}
public void CopyTo(T[] array, int arrayIndex)
{
if (array == null)
{
throw new ArgumentNullException("array");
}
if (arrayIndex < 0 || arrayIndex > array.Length)
{
throw new ArgumentOutOfRangeException("arrayIndex");
}
DoublyLinkedListNode <T> node = this.head;
do
{
array[arrayIndex++] = node.Value;
node = node.Next;
} while (node != head);
}
public DoublyLinkedListNode <T> this[int index]
{
get
{
if (index >= count || index < 0)
{
throw new ArgumentOutOfRangeException("index");
}
else
{
DoublyLinkedListNode <T> node = this.head;
for (int i = 0; i < index; i++)
{
node = node.Next;
}
return(node);
}
}
}
bool RemoveNode(DoublyLinkedListNode <T> nodeToRemove)
{
DoublyLinkedListNode <T> previous = nodeToRemove.Previous;
previous.Next = nodeToRemove.Next;
nodeToRemove.Next.Previous = nodeToRemove.Previous;
// if this is head, we need to update the head reference
if (head == nodeToRemove)
{
head = nodeToRemove.Next;
}
else if (tail == nodeToRemove)
{
tail = tail.Previous;
}
--count;
return(true);
}
public T RemoveLast()
{
//Case 1 - List is empty
if (_head == null)
{
return(default(T));
}
//Case 2 - list has single element
if (_head == _tail)
{
return(RemoveFirst());
}
//Case 3 - list has more than one element
T result = _tail.Value;
_tail = _tail.Previous;
_tail.Next = null;
_count--;
return(result);
}
public T RemoveFirst()
{
//Case 1 - List is empty
if (_head == null)
{
return(default(T));
}
T result = _head.Value;
//Case 2 - list has one element
if (_head == _tail)
{
_head = _tail = null;
}
//Case 3 - list has multiple elements
else
{
_head = _head.Next;
_head.Previous = null;
}
_count--;
return(result);
}
public void Clear()
{
head = null;
tail = null;
count = 0;
}
public DoublyLinkedListNode <T> Find(T item)
{
DoublyLinkedListNode <T> node = FindNode(head, item);
return(node);
}
public DoublyLinkedList()
{
_head = null;
_tail = null;
_count = 0;
}
private void AddFirstItem(T item)
{
_head = _tail = new DoublyLinkedListNode <T>(item);
}
