// Get first node in sequence by value.
private DoubleLinkedListNode <T> GetNodeByValue(T value)
{
DoubleLinkedListNode <T> nodeToBeFind = _head;
while (nodeToBeFind != null)
{
if (nodeToBeFind.Data.Equals(value))
{
return(nodeToBeFind);
}
nodeToBeFind = nodeToBeFind.Next;
}
if (nodeToBeFind.Equals(_head))
{
nodeToBeFind = null;
}
return(nodeToBeFind);
}
// Comparing who stands first in the list - first or second node.
private DoubleLinkedListNode <T> GetFirstNodeByOrder(DoubleLinkedListNode <T> firstNode, DoubleLinkedListNode <T> secondNode)
{
DoubleLinkedListNode <T> firstFacedNode = _head;
while (firstFacedNode != null)
{
if (firstFacedNode.Equals(firstNode))
{
firstFacedNode = firstNode;
break;
}
else if (firstFacedNode.Equals(secondNode))
{
firstFacedNode = secondNode;
break;
}
firstFacedNode = firstFacedNode.Next;
}
return(firstFacedNode);
}
/// <summary>
/// Insert value at the begining of the list.
/// </summary>
/// <param name="value">value to be inserted.</param>
public void AddFirst(T value)
{
if (_head == null)
{
_head = new DoubleLinkedListNode <T>(value);
_tail = _head;
}
else if (_head != null && _head.Equals(_tail))
{
_head = new DoubleLinkedListNode <T>(value);
_head.Next = _tail;
_tail.Prev = _head;
}
else
{
var head = _head;
var nodeAfterHead = _head.Next;
_head = new DoubleLinkedListNode <T>(value);
_head.Next = head;
head.Prev = _head;
}
Count++;
}