public RBTreeNode <T> InsertSuccessor(RBTreeNode <T> node, T successorData)
{
var successor = new RBTreeNode <T> {
Data = successorData
};
RBTreeNode <T> parent;
if (node != null)
{
//insert new node between node and its successor
successor.Previous = node;
successor.Next = node.Next;
if (node.Next != null)
{
node.Next.Previous = successor;
}
node.Next = successor;
//insert successor into the tree
if (node.Right != null)
{
node = GetFirst(node.Right);
node.Left = successor;
}
else
{
node.Right = successor;
}
parent = node;
}
else if (Root != null)
{
//if the node is null, successor must be inserted
//into the left most part of the tree
node = GetFirst(Root);
//successor.Previous = null;
successor.Next = node;
node.Previous = successor;
node.Left = successor;
parent = node;
}
else
{
//first insert
//successor.Previous = successor.Next = null;
Root = successor;
parent = null;
}
//successor.Left = successor.Right = null;
successor.Parent = parent;
successor.Red = true;
//the magic of the red black tree
RBTreeNode <T> grandma;
RBTreeNode <T> aunt;
node = successor;
while (parent != null && parent.Red)
{
grandma = parent.Parent;
if (parent == grandma.Left)
{
aunt = grandma.Right;
if (aunt != null && aunt.Red)
{
parent.Red = false;
aunt.Red = false;
grandma.Red = true;
node = grandma;
}
else
{
if (node == parent.Right)
{
RotateLeft(parent);
node = parent;
parent = node.Parent;
}
parent.Red = false;
grandma.Red = true;
RotateRight(grandma);
}
}
else
{
aunt = grandma.Left;
if (aunt != null && aunt.Red)
{
parent.Red = false;
aunt.Red = false;
grandma.Red = true;
node = grandma;
}
else
{
if (node == parent.Left)
{
RotateRight(parent);
node = parent;
parent = node.Parent;
}
parent.Red = false;
grandma.Red = true;
RotateLeft(grandma);
}
}
parent = node.Parent;
}
Root.Red = false;
return(successor);
}
//TODO: Clean this up
public void RemoveNode(RBTreeNode <T> node)
{
//fix up linked list structure
if (node.Next != null)
{
node.Next.Previous = node.Previous;
}
if (node.Previous != null)
{
node.Previous.Next = node.Next;
}
//replace the node
var original = node;
var parent = node.Parent;
var left = node.Left;
var right = node.Right;
RBTreeNode <T> next;
//figure out what to replace this node with
if (left == null)
{
next = right;
}
else if (right == null)
{
next = left;
}
else
{
next = GetFirst(right);
}
//fix up the parent relation
if (parent != null)
{
if (parent.Left == node)
{
parent.Left = next;
}
else
{
parent.Right = next;
}
}
else
{
Root = next;
}
bool red;
if (left != null && right != null)
{
red = next.Red;
next.Red = node.Red;
next.Left = left;
left.Parent = next;
// if we reached down the tree
if (next != right)
{
parent = next.Parent;
next.Parent = node.Parent;
node = next.Right;
parent.Left = node;
next.Right = right;
right.Parent = next;
}
else
{
// the direct right will replace the node
next.Parent = parent;
parent = next;
node = next.Right;
}
}
else
{
red = node.Red;
node = next;
}
if (node != null)
{
node.Parent = parent;
}
if (red)
{
return;
}
if (node != null && node.Red)
{
node.Red = false;
return;
}
//node is null or black
// fair warning this code gets nasty
//how do we guarantee sibling is not null
RBTreeNode <T> sibling = null;
do
{
if (node == Root)
{
break;
}
if (node == parent.Left)
{
sibling = parent.Right;
if (sibling.Red)
{
sibling.Red = false;
parent.Red = true;
RotateLeft(parent);
sibling = parent.Right;
}
if ((sibling.Left != null && sibling.Left.Red) || (sibling.Right != null && sibling.Right.Red))
{
//pretty sure this can be sibling.Left!= null && sibling.Left.Red
if (sibling.Right == null || !sibling.Right.Red)
{
sibling.Left.Red = false;
sibling.Red = true;
RotateRight(sibling);
sibling = parent.Right;
}
sibling.Red = parent.Red;
parent.Red = sibling.Right.Red = false;
RotateLeft(parent);
node = Root;
break;
}
}
else
{
sibling = parent.Left;
if (sibling.Red)
{
sibling.Red = false;
parent.Red = true;
RotateRight(parent);
sibling = parent.Left;
}
if ((sibling.Left != null && sibling.Left.Red) || (sibling.Right != null && sibling.Right.Red))
{
if (sibling.Left == null || !sibling.Left.Red)
{
sibling.Right.Red = false;
sibling.Red = true;
RotateLeft(sibling);
sibling = parent.Left;
}
sibling.Red = parent.Red;
parent.Red = sibling.Left.Red = false;
RotateRight(parent);
node = Root;
break;
}
}
sibling.Red = true;
node = parent;
parent = parent.Parent;
} while (!node.Red);
if (node != null)
{
node.Red = false;
}
}