/// <summary>
/// Returns true if the list contains the specified item,
/// false otherwise.
/// </summary>
/// <param name="item">The item to search for</param>
/// <returns>True if the item is found, false otherwise.</returns>
public bool Contains(T item)
{
DoublyLinkedListNode <T> current = Head;
while (current != null)
{
// Head -> 3 -> 5 -> 7
// Value: 5
if (current.Value.Equals(item))
{
return(true);
}
current = current.Next;
}
return(false);
}
public void Add(T item)
{
var nodeToAdd = new DoublyLinkedListNode <T>(item);
if (Tail == null)
{
Head = Tail = nodeToAdd;
}
else
{
Tail.Next = nodeToAdd;
nodeToAdd.Previous = Tail;
Tail = nodeToAdd;
}
++Count;
}
/// <summary>
/// Add the node to the end of the list
/// </summary>
/// <param name="value">The node to add</param>
public void AddLast(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++;
}
public bool Remove(T item)
{
var current = Head;
while (current != null)
{
if (current.Value.CompareTo(item) == 0)
{
//are we at head
if (current.Previous == null)
{
//is head and tail same
if (current.Next == null)
{
Clear();
return(true);
}
Head = current;
Head.Previous = null;
}
// are we at tail
else if (current.Next == null)
{
Tail = current.Previous;
Tail.Next = null;
}
else
{
current.Previous.Next = current.Next;
current.Next.Previous = current.Previous;
}
--Count;
return(true);
}
current = current.Next;
}
return(false);
}
/// <summary>
/// Removes the last node from the list
/// </summary>
public void RemoveLast()
{
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 RemoveFirst()
{
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;
}
}
}
public void Clear()
{
Head = null;
Tail = null;
Count = 0;
}
