public DoublyLinkedListNode <T> Find(T item)
{
DoublyLinkedListNode <T> current = Head;
while (current != null)
{
// Head -> 3 -> 5 -> 7
// Value: 5
if (current.Value.Equals(item))
{
return(current);
}
current = current.Next;
}
return(null);
}
/// <summary>
/// Removes the first occurance of the item from the list (searching
/// from Head to Tail).
/// </summary>
/// <param name="item">The item to remove</param>
/// <returns>True if the item was found and removed, false otherwise</returns>
public bool Remove(T item)
{
DoublyLinkedListNode <T> found = Find(item);
if (found == null)
{
return(false);
}
DoublyLinkedListNode <T> previous = found.Previous;
DoublyLinkedListNode <T> next = found.Next;
if (previous == null)
{
// we're removing the head node
Head = next;
if (Head != null)
{
Head.Previous = null;
}
}
else
{
previous.Next = next;
}
if (next == null)
{
// we're removing the tail
Tail = previous;
if (Tail != null)
{
Tail.Next = null;
}
}
else
{
next.Previous = previous;
}
Count--;
return(true);
}
/// <summary>
/// Add the node to the end of the list
/// </summary>
/// <param name="node">The node to add</param>
public void AddTail(DoublyLinkedListNode <T> node)
{
if (Count == 0)
{
Head = node;
}
else
{
Tail.Next = node;
// Before: Head -> 3 <-> 5 -> null
// After: Head -> 3 <-> 5 <-> 7 -> null
// 7.Previous = 5
node.Previous = Tail;
}
Tail = node;
Count++;
}
/// <summary>
/// Removes the last node from the list
/// </summary>
public void RemoveTail()
{
if (Count != 0)
{
if (Count == 1)
{
Head = null;
Tail = null;
}
else
{
// Before: Head --> 3 --> 5 --> 7
// Tail = 7
// After: Head --> 3 --> 5 --> null
// Tail = 5
// Null out 5's Next pointer
Tail.Previous.Next = null;
Tail = Tail.Previous;
}
Count--;
}
}
/// <summary>
/// Removes the first node from the list.
/// </summary>
public void RemoveHead()
{
if (Count != 0)
{
// Before: Head -> 3 <-> 5
// After: Head -------> 5
// Head -> 3 -> null
// Head ------> null
Head = Head.Next;
Count--;
if (Count == 0)
{
Tail = null;
}
else
{
// 5.Previous was 3, now null
Head.Previous = null;
}
}
}