/// <summary>
/// Time complexity: O(1).
/// </summary>
internal void Union(DoublyLinkedList <T> newList)
{
if (Head == null)
{
Head = newList.Head;
Tail = newList.Tail;
return;
}
if (newList.Head == null)
{
return;
}
Head.Previous = newList.Tail;
newList.Tail.Next = Head;
Head = newList.Head;
}
public bool MoveNext()
{
if (headNode == null)
{
return(false);
}
if (currentNode == null)
{
currentNode = headNode;
return(true);
}
if (currentNode.Next != null)
{
currentNode = currentNode.Next;
return(true);
}
return(false);
}
/// <summary>
/// Time complexity: O(1).
/// </summary>
/// <returns>The new node.</returns>
public DoublyLinkedListNode <T> InsertFirst(T data)
{
var newNode = new DoublyLinkedListNode <T>(data);
if (Head != null)
{
Head.Previous = newNode;
}
newNode.Next = Head;
newNode.Previous = null;
Head = newNode;
if (Tail == null)
{
Tail = Head;
}
return(newNode);
}
/// <summary>
/// Insert right after this node.
/// Time complexity: O(1).
/// </summary>
public DoublyLinkedListNode <T> InsertAfter(DoublyLinkedListNode <T> node, DoublyLinkedListNode <T> data)
{
if (node == null)
{
throw new Exception("Empty reference node");
}
if (node == Head && node == Tail)
{
node.Next = data;
node.Previous = null;
data.Previous = node;
data.Next = null;
Head = node;
Tail = data;
return(data);
}
if (node != Tail)
{
data.Previous = node;
data.Next = node.Next;
node.Next.Previous = data;
node.Next = data;
}
else
{
data.Previous = node;
data.Next = null;
node.Next = data;
Tail = data;
}
return(data);
}
/// <summary>
/// Insert right before this node.
/// Time complexity:O(1).
/// </summary>
public DoublyLinkedListNode <T> InsertBefore(DoublyLinkedListNode <T> node, DoublyLinkedListNode <T> data)
{
if (node == null)
{
throw new Exception("Empty node");
}
if (node == Head && node == Tail)
{
node.Previous = data;
node.Next = null;
Tail = node;
data.Previous = null;
data.Next = node;
Head = data;
return(data);
}
if (node == Head)
{
data.Previous = null;
data.Next = node;
node.Previous = data;
Head = data;
}
else
{
data.Previous = node.Previous;
data.Next = node;
node.Previous.Next = data;
node.Previous = data;
}
return(data);
}
/// <summary>
/// Delete tail node.
/// Time complexity: O(1)
/// </summary>
///
public T DeleteLast()
{
if (Tail == null)
{
throw new Exception("Empty list");
}
var tailData = Tail.Data;
if (Tail == Head)
{
Head = null;
Tail = null;
}
else
{
Tail.Previous.Next = null;
Tail = Tail.Previous;
}
return(tailData);
}
/// <summary>
/// Time complexity: O(1).
/// </summary>
public T DeleteFirst()
{
if (Head == null)
{
throw new Exception("Empty list");
}
var headData = Head.Data;
if (Head == Tail)
{
Head = null;
Tail = null;
}
else
{
Head.Next.Previous = null;
Head = Head.Next;
}
return(headData);
}
public void Dispose()
{
headNode = null;
currentNode = null;
}
public void Reset()
{
currentNode = headNode;
}
internal DoublyLinkedListEnumerator(ref DoublyLinkedListNode <T> headNode)
{
this.headNode = headNode;
}