private void AddData(T value, DoubleLinkedListNode <T> currentNode)
{
if (currentNode.Next == null)
{
currentNode.Next = new DoubleLinkedListNode <T>(value);
currentNode.Next.Prev = currentNode;
_tail = currentNode.Next;
Count++;
}
else
{
AddData(value, currentNode.Next);
}
}
// Update links of nodes that stands nearby and update their neighboring nodes links.
private void UpdateNearbyNodesLinks(DoubleLinkedListNode <T> firstNode, DoubleLinkedListNode <T> secondNode, DoubleLinkedListNode <T> prefirstNode, DoubleLinkedListNode <T> postSecondNode)
{
firstNode.Prev = secondNode;
firstNode.Next = postSecondNode;
secondNode.Prev = prefirstNode;
secondNode.Next = firstNode;
if (prefirstNode != null)
{
prefirstNode.Next = secondNode;
}
if (postSecondNode != null)
{
postSecondNode.Prev = firstNode;
}
}
// Update links of common nodes and their neighboring nodes.
private void UpdateCommonNodesLinks(DoubleLinkedListNode <T> firstNode, DoubleLinkedListNode <T> secondNode, DoubleLinkedListNode <T> preFirstNode,
DoubleLinkedListNode <T> postFirstNode, DoubleLinkedListNode <T> preSecondNode, DoubleLinkedListNode <T> postSecondNode)
{
firstNode.Prev = preSecondNode;
firstNode.Next = postSecondNode;
secondNode.Prev = preFirstNode;
secondNode.Next = postFirstNode;
if (preFirstNode != null)
{
preFirstNode.Next = secondNode;
}
postFirstNode.Prev = secondNode;
preSecondNode.Next = firstNode;
if (postSecondNode != null)
{
postSecondNode.Prev = firstNode;
}
}
private void Check(T value, DoubleLinkedListNode <T> currentNode)
{
if (currentNode == null)
{
_contains = false;
return;
}
if (currentNode.Data.Equals(value))
{
_contains = true;
return;
}
else
{
Check(value, currentNode.Next);
}
}
private void RemoveData(T value, DoubleLinkedListNode <T> currentNode)
{
if (currentNode == null)
{
throw new ArgumentNullException("Can't find any value");
}
if (currentNode.Data.Equals(value))
{
// Deleting only one element - head and tail
if (currentNode.Prev == null && currentNode.Next == null)
{
_head = null;
_tail = null;
}
// Deleting first node.
else if (currentNode.Prev == null && currentNode.Next != null)
{
currentNode.Next.Prev = null;
_head = currentNode.Next;
}
// Deleting node in the middle.
else if (currentNode.Next != null && currentNode.Prev != null)
{
currentNode.Prev.Next = currentNode.Next;
currentNode.Next.Prev = currentNode.Prev;
}
// Deleting last node.
else
{
currentNode.Prev.Next = null;
_tail = currentNode.Prev;
}
currentNode = null;
Count--;
}
else
{
RemoveData(value, currentNode.Next);
}
}
/// <summary>
/// Performs swap between elements.
/// </summary>
/// <param name="firstValue">first value to be swaped.</param>
/// <param name="secondValue">second value to be swaped.</param>
public bool Swap(T firstValue, T secondValue)
{
if (!Contains(firstValue))
{
return(false);
}
if (!Contains(secondValue))
{
return(false);
}
// Find nodes that contains that values. Since nodes already exists, don't check result.
DoubleLinkedListNode <T> firstNode = GetNodeByValue(firstValue);
DoubleLinkedListNode <T> secondNode = GetNodeByValue(secondValue);
// Check if nodes stands nearby
if (firstNode.Next != null && firstNode.Next.Equals(secondNode))
{
SwapNearbyNodes(firstNode, secondNode);
}
else if (secondNode.Next != null && secondNode.Next.Equals(firstNode))
{
SwapNearbyNodes(secondNode, firstNode);
}
else
{
// Check if first node before second, otherwise reverse params passed to method.
var firstNodeByOrder = GetFirstNodeByOrder(firstNode, secondNode);
// Swap values depending on their order.
if (firstNodeByOrder.Equals(firstNode))
{
SwapCommonNodes(firstNode, secondNode);
}
else
{
SwapCommonNodes(secondNode, firstNode);
}
}
return(true);
}
private void UpdateHeadAndTail(DoubleLinkedListNode <T> preFirstNode, DoubleLinkedListNode <T> firstNode, DoubleLinkedListNode <T> secondNode, DoubleLinkedListNode <T> postSecondNode)
{
// Swap head and tail.
if (preFirstNode == null && postSecondNode == null)
{
_head = secondNode;
_tail = firstNode;
}
// Swap head with common element.
else if (preFirstNode == null)
{
_head = secondNode;
}
// Swap tail with common element.
else if (postSecondNode == null)
{
_tail = firstNode;
}
}
// 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++;
}
