private void DeleteCase1(IRbNode n)
{
if (n.Parent == null)
return;
DeleteCase2(n);
}
//-----------------------------------
private void InsertCase2(IRbNode n)
{
if (NodeColor(n.Parent) == Color.Black)
return; // Tree is still valid
InsertCase3(n);
}
public void Delete(IRbNode template, out IRbNode deletedAlt)
{
deletedAlt = null;
var n = LookupNode(template);
if (n == null)
{
return; // Key not found, do nothing
}
if (n.Left != null && n.Right != null)
{
// Copy key/value from predecessor and then delete it instead
var pred = MaximumNode(n.Left);
pred.AssignValueTo(n);
n = pred;
deletedAlt = pred;
}
//assert n.left == null || n.right == null;
var child = n.Right ?? n.Left;
if (NodeColor(n) == Color.Black)
{
n.Color = NodeColor(child);
DeleteCase1(n);
}
ReplaceNode(n, child);
if (NodeColor(Root) == Color.Red)
{
Root.Color = Color.Black;
}
}
private static void PrintHelper(IRbNode n, int indent)
{
if (n == null)
{
Trace.WriteLine("<empty tree>");
return;
}
if (n.Left != null)
{
PrintHelper(n.Left, indent + _indentStep);
}
for (var i = 0; i < indent; i++)
{
Trace.Write(" ");
}
if (n.Color == Color.Black)
{
Trace.WriteLine(" " + n + " ");
}
else
{
Trace.WriteLine("<" + n + ">");
}
if (n.Right != null)
{
PrintHelper(n.Right, indent + _indentStep);
}
}
//------------------------------------
private void InsertCase1(IRbNode n)
{
if (n.Parent == null)
n.Color = Color.Black;
else
InsertCase2(n);
}
internal void FireNodeOperation(IRbNode node, NodeOperation operation)
{
if (NodeOperation != null)
{
NodeOperation(node, operation);
}
}
private static IRbNode MaximumNode(IRbNode n)
{
//assert n != null;
while (n.Right != null)
{
n = n.Right;
}
return(n);
}
private static void VerifyProperty1(IRbNode n)
{
Assert.IsTrue(NodeColor(n) == Color.Red || NodeColor(n) == Color.Black);
if (n == null)
{
return;
}
VerifyProperty1(n.Left);
VerifyProperty1(n.Right);
}
public bool TryLookup(IRbNode template, out IRbNode val)
{
var n = LookupNode(template);
if (n == null)
{
val = null;
return(false);
}
val = n;
return(true);
}
public void Insert(IRbNode newNode)
{
newNode.Color = Color.Red;
var insertedNode = newNode;
if (Root == null)
{
Root = insertedNode;
}
else
{
var n = Root;
while (true)
{
var compResult = newNode.CompareTo(n);
if (compResult == 0)
{
throw new RbTreeDuplicatedItemException(
"RBNode " + newNode + " already present in tree");
}
if (compResult < 0)
{
if (n.Left == null)
{
n.Left = insertedNode;
break;
}
n = n.Left;
}
else
{
//assert compResult > 0;
if (n.Right == null)
{
n.Right = insertedNode;
break;
}
n = n.Right;
}
}
insertedNode.Parent = n;
}
InsertCase1(insertedNode);
NodeInserted?.Invoke(insertedNode);
}
private void DeleteCase4(IRbNode n)
{
if (NodeColor(n.Parent) == Color.Red &&
NodeColor(n.Sibling()) == Color.Black &&
NodeColor(n.Sibling().Left) == Color.Black &&
NodeColor(n.Sibling().Right) == Color.Black)
{
n.Sibling().Color = Color.Red;
n.Parent.Color = Color.Black;
}
else
DeleteCase5(n);
}
private void RotateLeft(IRbNode n)
{
var r = n.Right;
ReplaceNode(n, r);
n.Right = r.Left;
if (r.Left != null)
{
r.Left.Parent = n;
}
r.Left = n;
n.Parent = r;
}
//----------------------------
private void InsertCase3(IRbNode n)
{
if (NodeColor(n.Uncle()) == Color.Red)
{
n.Parent.Color = Color.Black;
n.Uncle().Color = Color.Black;
n.Grandparent().Color = Color.Red;
InsertCase1(n.Grandparent());
}
else
{
InsertCase4(n);
}
}
private static void DoVisitTreeNodes(Action <IRbNode> action, IRbNode walker)
{
if (walker.Left != null)
{
DoVisitTreeNodes(action, walker.Left);
}
action?.Invoke(walker);
if (walker.Right != null)
{
DoVisitTreeNodes(action, walker.Right);
}
}
//----------------------------
private void InsertCase5(IRbNode n)
{
n.Parent.Color = Color.Black;
n.Grandparent().Color = Color.Red;
if (Equals(n, n.Parent.Left) && Equals(n.Parent, n.Grandparent().Left))
{
RotateRight(n.Grandparent());
}
else
{
//assert n == n.parent.right && n.parent == n.grandparent().right;
RotateLeft(n.Grandparent());
}
}
private void DeleteCase3(IRbNode n)
{
if (NodeColor(n.Parent) == Color.Black &&
NodeColor(n.Sibling()) == Color.Black &&
NodeColor(n.Sibling().Left) == Color.Black &&
NodeColor(n.Sibling().Right) == Color.Black)
{
n.Sibling().Color = Color.Red;
DeleteCase1(n.Parent);
}
else
{
DeleteCase4(n);
}
}
private void RotateRight(IRbNode n)
{
var l = n.Left;
ReplaceNode(n, l);
n.Left = l.Right;
if (l.Right != null)
{
l.Right.Parent = n;
}
l.Right = n;
n.Parent = l;
}
//----------------------------
private void InsertCase4(IRbNode n)
{
if (Equals(n, n.Parent.Right) && Equals(n.Parent, n.Grandparent().Left))
{
RotateLeft(n.Parent);
n = n.Left;
}
else if (Equals(n, n.Parent.Left) && Equals(n.Parent, n.Grandparent().Right))
{
RotateRight(n.Parent);
n = n.Right;
}
InsertCase5(n);
}
private void DeleteCase2(IRbNode n)
{
if (NodeColor(n.Sibling()) == Color.Red)
{
n.Parent.Color = Color.Red;
n.Sibling().Color = Color.Black;
if (Equals(n, n.Parent.Left))
RotateLeft(n.Parent);
else
RotateRight(n.Parent);
}
DeleteCase3(n);
}
private static void VerifyProperty4(IRbNode n)
{
if (NodeColor(n) == Color.Red)
{
Assert.IsTrue((NodeColor(n.Left) == Color.Black));
Assert.IsTrue((NodeColor(n.Right) == Color.Black));
Assert.IsTrue((NodeColor(n.Parent) == Color.Black));
}
if (n == null)
{
return;
}
VerifyProperty4(n.Left);
VerifyProperty4(n.Right);
}
private IRbNode LookupNode(IRbNode template)
{
var n = Root;
while (n != null)
{
var compResult = template.CompareTo(n);
if (compResult == 0)
{
return(n);
}
n = compResult < 0 ? n.Left : n.Right;
}
return(null);
}
private void DeleteCase6(IRbNode n)
{
n.Sibling().Color = NodeColor(n.Parent);
n.Parent.Color = Color.Black;
if (Equals(n, n.Parent.Left))
{
//assert nodeColor(n.sibling().right) == Color.RED;
n.Sibling().Right.Color = Color.Black;
RotateLeft(n.Parent);
}
else
{
//assert nodeColor(n.sibling().left) == Color.RED;
n.Sibling().Left.Color = Color.Black;
RotateRight(n.Parent);
}
}
private void ReplaceNode(IRbNode oldn, IRbNode newn)
{
if (oldn.Parent == null)
{
Root = newn;
}
else
{
if (Equals(oldn, oldn.Parent.Left))
oldn.Parent.Left = newn;
else
oldn.Parent.Right = newn;
}
if (newn != null)
{
newn.Parent = oldn.Parent;
}
}
private void DeleteCase5(IRbNode n)
{
if (Equals(n, n.Parent.Left) &&
NodeColor(n.Sibling()) == Color.Black &&
NodeColor(n.Sibling().Left) == Color.Red &&
NodeColor(n.Sibling().Right) == Color.Black)
{
n.Sibling().Color = Color.Red;
n.Sibling().Left.Color = Color.Black;
RotateRight(n.Sibling());
}
else if (Equals(n, n.Parent.Right) &&
NodeColor(n.Sibling()) == Color.Black &&
NodeColor(n.Sibling().Right) == Color.Red &&
NodeColor(n.Sibling().Left) == Color.Black)
{
n.Sibling().Color = Color.Red;
n.Sibling().Right.Color = Color.Black;
RotateLeft(n.Sibling());
}
DeleteCase6(n);
}
private static int VerifyProperty5Helper(IRbNode n, int blackCount, int pathBlackCount)
{
if (NodeColor(n) == Color.Black)
{
blackCount++;
}
if (n == null)
{
if (pathBlackCount == -1)
{
pathBlackCount = blackCount;
}
else
{
Assert.IsTrue(blackCount == pathBlackCount);
}
return(pathBlackCount);
}
pathBlackCount = VerifyProperty5Helper(n.Left, blackCount, pathBlackCount);
pathBlackCount = VerifyProperty5Helper(n.Right, blackCount, pathBlackCount);
return(pathBlackCount);
}
private static void VerifyProperty5(IRbNode root)
{
VerifyProperty5Helper(root, 0, -1);
}
private static Color NodeColor(IRbNode n)
{
return(n == null ? Color.Black : n.Color);
}
private static void VerifyProperty2(IRbNode root)
{
Assert.IsTrue(NodeColor(root) == Color.Black);
}
public RbTree(IRbNode root)
{
Root = root;
}