public bool TryAdd(T x)
{
if (_items.ContainsKey(x))
{
return(false);
}
var item = new DoublyLinkedItem <T>(x);
_items.Add(x, item);
if (FirstItem == null)
{
AddAtBegin(item);
return(true);
}
if (item.Value.CompareTo(FirstItem.Value) >= 0)
{
AddAtBegin(item);
}
else
{
AddAtEnd(item);
AdjustPosition(item);
}
return(true);
}
public void AddAtEnd(T x)
{
if (_items.ContainsKey(x))
{
return;
}
var item = new DoublyLinkedItem <T>(x);
_items.Add(x, item);
AddAtEnd(item);
AdjustPosition(item);
}
private void AddAtBegin(DoublyLinkedItem <T> item)
{
Count++;
if (FirstItem == null)
{
FirstItem = item;
LastItem = item;
return;
}
item.Right = FirstItem;
FirstItem.Left = item;
FirstItem = item;
}
private void Remove(DoublyLinkedItem <T> item)
{
if (item == FirstItem)
{
ExtractFirstItem();
return;
}
if (item == LastItem)
{
ExtractLastItem();
return;
}
Count--;
var left = item.Left;
var right = item.Right;
left.Right = right;
right.Left = left;
}
private void AdjustPosition(DoublyLinkedItem <T> item)
{
while (item.Right != null && item.Value.CompareTo(item.Right.Value) < 0)
{
if (item.Right == null)
{
return;
}
var right = item.Right;
var left = item.Left;
if (FirstItem == item)
{
FirstItem = right;
}
item.Right = right.Right;
item.Left = right;
if (item.Right != null)
{
item.Right.Left = item;
}
right.Right = item;
right.Left = left;
if (left != null)
{
left.Right = right;
}
if (item.Right == null)
{
LastItem = item;
}
}
while (item.Left != null && item.Value.CompareTo(item.Left.Value) > 0)
{
var right = item.Right;
var left = item.Left;
if (LastItem == item)
{
LastItem = left;
}
item.Right = left;
item.Left = left.Left;
if (left.Left != null)
{
left.Left.Right = item;
}
left.Right = right;
left.Left = item;
if (right != null)
{
right.Left = left;
}
if (item.Left == null)
{
FirstItem = item;
}
}
}
public DoublyLinkedItem(T value)
{
Value = value;
Left = null;
Right = null;
}
