/// <summary>
/// Adds a node before a specified node in the <see cref="DoublyLinkedList{T}"/>.
/// </summary>
/// <remarks>
/// This method is an O(1) operation.
/// </remarks>
/// <param name="node">The <see cref="DoublyLinkedListNode{T}"/> to add before.</param>
/// <param name="value">The value of the node to add after the specified node.</param>
public void AddBefore(DoublyLinkedListNode <T> node, T value)
{
ValidateAddArgs(node);
DoublyLinkedListNode <T> n = new DoublyLinkedListNode <T>(value);
// check if adding before _head node
if (node == m_head)
{
n.Next = m_head;
m_head.Previous = n;
m_head = n;
}
else
{
n.Next = node;
node.Previous.Next = n;
n.Previous = node.Previous;
node.Previous = n;
}
Count++;
}
/// <summary>
/// Adds a node after a specified node in the <see cref="DoublyLinkedList{T}"/>.
/// </summary>
/// <remarks>
/// This is an O(1) operation.
/// </remarks>
/// <param name="node">The <see cref="DoublyLinkedListNode{T}"/> to add after.</param>
/// <param name="value">The value of the node to add after the specified node.</param>
public void AddAfter(DoublyLinkedListNode <T> node, T value)
{
ValidateAddArgs(node);
DoublyLinkedListNode <T> n = new DoublyLinkedListNode <T>(value);
// check if adding after _tail node
if (node == m_tail)
{
n.Previous = m_tail;
m_tail.Next = n;
m_tail = n;
}
else
{
n.Next = node.Next;
n.Next.Previous = n;
node.Next = n;
n.Previous = node;
}
Count++;
}
/// <summary>
/// Method that validates the state of the DoublyLinkedListCollection(Of T) as well as if the node passed in is null.
/// This method is used by AddAfter, and AddBefore.
/// </summary>
/// <param name="node">Node to verify whether or not is null.</param>
private void ValidateAddArgs(DoublyLinkedListNode <T> node)
{
Guard.InvalidOperation(IsEmpty(), Resources.DoublyLinkedListEmpty);
Guard.ArgumentNull(node, "node");
}
/// <summary>
/// Resets the <see cref="DoublyLinkedList{T}"/> back to its default state.
/// </summary>
public override void Clear()
{
m_head = null;
m_tail = null;
Count = 0;
}