public void Add(IComparable key, object data)
{
if (key == null || data == null)
{
throw new RedBlackException("RedBlackNode key and value must not be null");
}
RedBlackNode node = new RedBlackNode(key, data);
RedBlackNode returnedNode = (RedBlackNode)base.Add(node);
returnedNode.Left = SentinelNode;
returnedNode.Right = SentinelNode;
if (returnedNode.Parent == null)
{
returnedNode.Color = Color.BLACK;
}
this.RestoreAfterInsert(returnedNode);
}
private void RestoreAfterDelete(RedBlackNode node)
{
RedBlackNode workingNode;
while (node != this.Root && node.Color == Color.BLACK)
{
// determine from parent which sub tree we're examining
if (node == node.Parent.Left)
{
// on the left sub tree
workingNode = node.Parent.Right; // workingNode is node's sibling
if (workingNode.Color == Color.RED)
{
// node is black, workingNode is red - make both black and rotate
workingNode.Color = Color.BLACK;
node.Parent.Color = Color.RED;
this.RotateLeft(node.Parent);
workingNode = node.Parent.Right;
}
if (workingNode.Left.Color == Color.BLACK &&
workingNode.Right.Color == Color.BLACK)
{
// node's sibling's children are both black
workingNode.Color = Color.RED; // change sibling to red
node = node.Parent; // move up the tree
}
else
{
// node's sibling has at least one red child
if (workingNode.Right.Color == Color.BLACK)
{
workingNode.Left.Color = Color.BLACK;
workingNode.Color = Color.RED;
this.RotateRight(workingNode);
workingNode = node.Parent.Right;
}
workingNode.Color = node.Parent.Color;
node.Parent.Color = Color.BLACK;
workingNode.Right.Color = Color.BLACK;
this.RotateLeft(node.Parent);
node = this.Root;
}
}
else
{
// on the right sub tree
// mirror left case
workingNode = node.Parent.Left;
if (workingNode.Color == Color.RED)
{
workingNode.Color = Color.BLACK;
node.Parent.Color = Color.RED;
this.RotateRight(node.Parent);
workingNode = node.Parent.Left;
}
if (workingNode.Right.Color == Color.BLACK &&
workingNode.Left.Color == Color.BLACK)
{
workingNode.Color = Color.RED;
node = node.Parent;
}
else
{
if (workingNode.Left.Color == Color.BLACK)
{
workingNode.Right.Color = Color.BLACK;
workingNode.Color = Color.RED;
this.RotateLeft(workingNode);
workingNode = node.Parent.Left;
}
workingNode.Color = node.Parent.Color;
node.Parent.Color = Color.BLACK;
workingNode.Left.Color = Color.BLACK;
this.RotateRight(node.Parent);
node = this.Root;
}
}
}
node.Color = Color.BLACK;
}
private void RestoreAfterInsert(RedBlackNode insertedNode)
{
RedBlackNode uncle;
while (insertedNode != this.Root && insertedNode.Parent.Color == Color.RED)
{
// Parent is RED;
if (insertedNode.Parent == insertedNode.Parent.Parent.Left)
{
// traversing Left subtree
uncle = insertedNode.Parent.Parent.Right; // get uncle
if (uncle != null && uncle.Color == Color.RED)
{
// uncle is RED - repaint
insertedNode.Parent.Color = Color.BLACK;
uncle.Color = Color.BLACK;
insertedNode.Parent.Parent.Color = Color.RED;
insertedNode = insertedNode.Parent.Parent; // continue loop with grandparent
}
else
{
// uncle is BLACK (don't be racist)
if (insertedNode == insertedNode.Parent.Right)
{
// insertedNode is on the right of it's parent
insertedNode = insertedNode.Parent;
this.RotateLeft(insertedNode);
}
// insertedNode is on the left of it's parent
// repaint
insertedNode.Parent.Color = Color.BLACK;
insertedNode.Parent.Parent.Color = Color.RED;
// rotate right
this.RotateRight(insertedNode.Parent.Parent);
}
}
else
{
// traversing Right subtree
// mirror to traversing Left subtree
uncle = insertedNode.Parent.Parent.Left;
if (uncle != null && uncle.Color == Color.RED)
{
insertedNode.Parent.Color = Color.BLACK;
uncle.Color = Color.BLACK;
insertedNode.Parent.Parent.Color = Color.RED;
insertedNode = insertedNode.Parent.Parent;
}
else
{
if (insertedNode == insertedNode.Parent.Left)
{
insertedNode = insertedNode.Parent;
this.RotateRight(insertedNode);
}
insertedNode.Parent.Color = Color.BLACK;
insertedNode.Parent.Parent.Color = Color.RED;
this.RotateLeft(insertedNode.Parent.Parent);
}
}
}
// root is always black
this.Root.Color = Color.BLACK;
}
