void ReplaceNode(HeightTreeNode replacedNode, HeightTreeNode newNode)
{
if (replacedNode.parent == null)
{
Debug.Assert(replacedNode == root);
root = newNode;
}
else
{
if (replacedNode.parent.left == replacedNode)
{
replacedNode.parent.left = newNode;
}
else
{
replacedNode.parent.right = newNode;
}
}
if (newNode != null)
{
newNode.parent = replacedNode.parent;
}
replacedNode.parent = null;
}
static void UpdateAfterChildrenChange(HeightTreeNode node)
{
UpdateAugmentedData(node, UpdateAfterChildrenChangeRecursionMode.IfRequired);
}
static bool GetColor(HeightTreeNode node)
{
return(node != null ? node.color : BLACK);
}
void FixTreeOnDelete(HeightTreeNode node, HeightTreeNode parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (parentNode == null)
{
return;
}
// warning: node may be null
HeightTreeNode sibling = Sibling(node, parentNode);
if (sibling.color == RED)
{
parentNode.color = RED;
sibling.color = BLACK;
if (node == parentNode.left)
{
RotateLeft(parentNode);
}
else
{
RotateRight(parentNode);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
}
if (parentNode.color == BLACK &&
sibling.color == BLACK &&
GetColor(sibling.left) == BLACK &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
FixTreeOnDelete(parentNode, parentNode.parent);
return;
}
if (parentNode.color == RED &&
sibling.color == BLACK &&
GetColor(sibling.left) == BLACK &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
parentNode.color = BLACK;
return;
}
if (node == parentNode.left &&
sibling.color == BLACK &&
GetColor(sibling.left) == RED &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
sibling.left.color = BLACK;
RotateRight(sibling);
}
else if (node == parentNode.right &&
sibling.color == BLACK &&
GetColor(sibling.right) == RED &&
GetColor(sibling.left) == BLACK)
{
sibling.color = RED;
sibling.right.color = BLACK;
RotateLeft(sibling);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
sibling.color = parentNode.color;
parentNode.color = BLACK;
if (node == parentNode.left)
{
if (sibling.right != null)
{
Debug.Assert(sibling.right.color == RED);
sibling.right.color = BLACK;
}
RotateLeft(parentNode);
}
else
{
if (sibling.left != null)
{
Debug.Assert(sibling.left.color == RED);
sibling.left.color = BLACK;
}
RotateRight(parentNode);
}
}
void UpdateAfterRotateRight(HeightTreeNode node)
{
// node = old parent
// node.parent = pivot, new parent
var collapsedP = node.parent.collapsedSections;
var collapsedQ = node.collapsedSections;
// move collapsedSections from old parent to new parent
node.parent.collapsedSections = collapsedQ;
node.collapsedSections = null;
// split the collapsedSections from the new parent into its old children:
if (collapsedP != null) {
foreach (CollapsedLineSection cs in collapsedP) {
if (node.parent.left != null)
node.parent.left.AddDirectlyCollapsed(cs);
node.parent.lineNode.AddDirectlyCollapsed(cs);
if (node.left != null)
node.left.AddDirectlyCollapsed(cs);
}
}
MergeCollapsedSectionsIfPossible(node);
UpdateAfterChildrenChange(node);
// not required: rotations only happen on insertions/deletions
// -> totalCount changes -> the parent is always updated
//UpdateAfterChildrenChange(node.parent);
}
void ReplaceNode(HeightTreeNode replacedNode, HeightTreeNode newNode)
{
if (replacedNode.parent == null) {
Debug.Assert(replacedNode == root);
root = newNode;
} else {
if (replacedNode.parent.left == replacedNode)
replacedNode.parent.left = newNode;
else
replacedNode.parent.right = newNode;
}
if (newNode != null) {
newNode.parent = replacedNode.parent;
}
replacedNode.parent = null;
}
void MergeCollapsedSectionsIfPossible(HeightTreeNode node)
{
Debug.Assert(node != null);
if (inRemoval) {
nodesToCheckForMerging.Add(node);
return;
}
// now check if we need to merge collapsedSections together
bool merged = false;
var collapsedL = node.lineNode.collapsedSections;
if (collapsedL != null) {
for (int i = collapsedL.Count - 1; i >= 0; i--) {
CollapsedLineSection cs = collapsedL[i];
if (cs.Start == node.documentLine || cs.End == node.documentLine)
continue;
if (node.left == null
|| (node.left.collapsedSections != null && node.left.collapsedSections.Contains(cs)))
{
if (node.right == null
|| (node.right.collapsedSections != null && node.right.collapsedSections.Contains(cs)))
{
// all children of node contain cs: -> merge!
if (node.left != null) node.left.RemoveDirectlyCollapsed(cs);
if (node.right != null) node.right.RemoveDirectlyCollapsed(cs);
collapsedL.RemoveAt(i);
node.AddDirectlyCollapsed(cs);
merged = true;
}
}
}
if (collapsedL.Count == 0)
node.lineNode.collapsedSections = null;
}
if (merged && node.parent != null) {
MergeCollapsedSectionsIfPossible(node.parent);
}
}
HeightTreeNode InsertAfter(HeightTreeNode node, DocumentLine newLine)
{
HeightTreeNode newNode = new HeightTreeNode(newLine, defaultLineHeight);
if (node.right == null) {
if (node.lineNode.collapsedSections != null) {
// we are inserting directly after node - so copy all collapsedSections
// that do not end at node.
foreach (CollapsedLineSection cs in node.lineNode.collapsedSections) {
if (cs.End != node.documentLine)
newNode.AddDirectlyCollapsed(cs);
}
}
InsertAsRight(node, newNode);
} else {
node = node.right.LeftMost;
if (node.lineNode.collapsedSections != null) {
// we are inserting directly before node - so copy all collapsedSections
// that do not start at node.
foreach (CollapsedLineSection cs in node.lineNode.collapsedSections) {
if (cs.Start != node.documentLine)
newNode.AddDirectlyCollapsed(cs);
}
}
InsertAsLeft(node, newNode);
}
return newNode;
}
static double GetVisualPositionFromNode(HeightTreeNode node)
{
double position = (node.left != null) ? node.left.totalHeight : 0;
while (node.parent != null) {
if (node.IsDirectlyCollapsed)
position = 0;
if (node == node.parent.right) {
if (node.parent.left != null)
position += node.parent.left.totalHeight;
position += node.parent.lineNode.TotalHeight;
}
node = node.parent;
}
return position;
}
static bool GetIsCollapedFromNode(HeightTreeNode node)
{
while (node != null) {
if (node.IsDirectlyCollapsed)
return true;
node = node.parent;
}
return false;
}
static bool GetColor(HeightTreeNode node)
{
return node != null ? node.color : BLACK;
}
static void AddRemoveCollapsedSectionDown(CollapsedLineSection section, HeightTreeNode node, int sectionLength, bool add)
{
while (true) {
if (node.left != null) {
if (node.left.totalCount < sectionLength) {
// mark left subtree
if (add)
node.left.AddDirectlyCollapsed(section);
else
node.left.RemoveDirectlyCollapsed(section);
sectionLength -= node.left.totalCount;
} else {
// mark only inside the left subtree
node = node.left;
Debug.Assert(node != null);
continue;
}
}
if (add)
node.lineNode.AddDirectlyCollapsed(section);
else
node.lineNode.RemoveDirectlyCollapsed(section);
sectionLength -= 1;
if (sectionLength == 0) {
// done!
Debug.Assert(node.documentLine == section.End);
break;
}
// mark inside right subtree:
node = node.right;
Debug.Assert(node != null);
}
}
/// <summary>
/// Rebuild the tree, in O(n).
/// </summary>
public void RebuildDocument()
{
foreach (CollapsedLineSection s in GetAllCollapsedSections()) {
s.Start = null;
s.End = null;
}
HeightTreeNode[] nodes = new HeightTreeNode[document.LineCount];
int lineNumber = 0;
foreach (DocumentLine ls in document.Lines) {
nodes[lineNumber++] = new HeightTreeNode(ls, defaultLineHeight);
}
Debug.Assert(nodes.Length > 0);
// now build the corresponding balanced tree
int height = DocumentLineTree.GetTreeHeight(nodes.Length);
Debug.WriteLine("HeightTree will have height: " + height);
root = BuildTree(nodes, 0, nodes.Length, height);
root.color = BLACK;
#if DEBUG
CheckProperties();
#endif
}
public void Dispose()
{
if (weakLineTracker != null)
weakLineTracker.Deregister();
this.root = null;
this.weakLineTracker = null;
}
void CheckProperties(HeightTreeNode node)
{
int totalCount = 1;
double totalHeight = node.lineNode.TotalHeight;
if (node.lineNode.IsDirectlyCollapsed)
Debug.Assert(node.lineNode.collapsedSections.Count > 0);
if (node.left != null) {
CheckProperties(node.left);
totalCount += node.left.totalCount;
totalHeight += node.left.totalHeight;
CheckAllContainedIn(node.left.collapsedSections, node.lineNode.collapsedSections);
}
if (node.right != null) {
CheckProperties(node.right);
totalCount += node.right.totalCount;
totalHeight += node.right.totalHeight;
CheckAllContainedIn(node.right.collapsedSections, node.lineNode.collapsedSections);
}
if (node.left != null && node.right != null) {
if (node.left.collapsedSections != null && node.right.collapsedSections != null) {
var intersection = System.Linq.Enumerable.Intersect(node.left.collapsedSections, node.right.collapsedSections);
Debug.Assert(System.Linq.Enumerable.Count(intersection) == 0);
}
}
if (node.IsDirectlyCollapsed) {
Debug.Assert(node.collapsedSections.Count > 0);
totalHeight = 0;
}
Debug.Assert(node.totalCount == totalCount);
Debug.Assert(node.totalHeight.IsClose(totalHeight));
}
void FixTreeOnInsert(HeightTreeNode node)
{
Debug.Assert(node != null);
Debug.Assert(node.color == RED);
Debug.Assert(node.left == null || node.left.color == BLACK);
Debug.Assert(node.right == null || node.right.color == BLACK);
HeightTreeNode parentNode = node.parent;
if (parentNode == null) {
// we inserted in the root -> the node must be black
// since this is a root node, making the node black increments the number of black nodes
// on all paths by one, so it is still the same for all paths.
node.color = BLACK;
return;
}
if (parentNode.color == BLACK) {
// if the parent node where we inserted was black, our red node is placed correctly.
// since we inserted a red node, the number of black nodes on each path is unchanged
// -> the tree is still balanced
return;
}
// parentNode is red, so there is a conflict here!
// because the root is black, parentNode is not the root -> there is a grandparent node
HeightTreeNode grandparentNode = parentNode.parent;
HeightTreeNode uncleNode = Sibling(parentNode);
if (uncleNode != null && uncleNode.color == RED) {
parentNode.color = BLACK;
uncleNode.color = BLACK;
grandparentNode.color = RED;
FixTreeOnInsert(grandparentNode);
return;
}
// now we know: parent is red but uncle is black
// First rotation:
if (node == parentNode.right && parentNode == grandparentNode.left) {
RotateLeft(parentNode);
node = node.left;
} else if (node == parentNode.left && parentNode == grandparentNode.right) {
RotateRight(parentNode);
node = node.right;
}
// because node might have changed, reassign variables:
parentNode = node.parent;
grandparentNode = parentNode.parent;
// Now recolor a bit:
parentNode.color = BLACK;
grandparentNode.color = RED;
// Second rotation:
if (node == parentNode.left && parentNode == grandparentNode.left) {
RotateRight(grandparentNode);
} else {
// because of the first rotation, this is guaranteed:
Debug.Assert(node == parentNode.right && parentNode == grandparentNode.right);
RotateLeft(grandparentNode);
}
}
static HeightTreeNode Sibling(HeightTreeNode node)
{
if (node == node.parent.left)
return node.parent.right;
else
return node.parent.left;
}
void InsertAsRight(HeightTreeNode parentNode, HeightTreeNode newNode)
{
Debug.Assert(parentNode.right == null);
parentNode.right = newNode;
newNode.parent = parentNode;
newNode.color = RED;
UpdateAfterChildrenChange(parentNode);
FixTreeOnInsert(newNode);
}
static HeightTreeNode Sibling(HeightTreeNode node, HeightTreeNode parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (node == parentNode.left)
return parentNode.right;
else
return parentNode.left;
}
void RemoveNode(HeightTreeNode removedNode)
{
if (removedNode.left != null && removedNode.right != null) {
// replace removedNode with it's in-order successor
HeightTreeNode leftMost = removedNode.right.LeftMost;
HeightTreeNode parentOfLeftMost = leftMost.parent;
RemoveNode(leftMost); // remove leftMost from its current location
BeforeNodeReplace(removedNode, leftMost, parentOfLeftMost);
// and overwrite the removedNode with it
ReplaceNode(removedNode, leftMost);
leftMost.left = removedNode.left;
if (leftMost.left != null) leftMost.left.parent = leftMost;
leftMost.right = removedNode.right;
if (leftMost.right != null) leftMost.right.parent = leftMost;
leftMost.color = removedNode.color;
UpdateAfterChildrenChange(leftMost);
if (leftMost.parent != null) UpdateAfterChildrenChange(leftMost.parent);
return;
}
// now either removedNode.left or removedNode.right is null
// get the remaining child
HeightTreeNode parentNode = removedNode.parent;
HeightTreeNode childNode = removedNode.left ?? removedNode.right;
BeforeNodeRemove(removedNode);
ReplaceNode(removedNode, childNode);
if (parentNode != null) UpdateAfterChildrenChange(parentNode);
if (removedNode.color == BLACK) {
if (childNode != null && childNode.color == RED) {
childNode.color = BLACK;
} else {
FixTreeOnDelete(childNode, parentNode);
}
}
}
static void UpdateAfterChildrenChange(HeightTreeNode node)
{
UpdateAugmentedData(node, UpdateAfterChildrenChangeRecursionMode.IfRequired);
}
void RotateRight(HeightTreeNode p)
{
// let q be p's left child
HeightTreeNode q = p.left;
Debug.Assert(q != null);
Debug.Assert(q.parent == p);
// set q to be the new root
ReplaceNode(p, q);
// set p's left child to be q's right child
p.left = q.right;
if (p.left != null) p.left.parent = p;
// set q's right child to be p
q.right = p;
p.parent = q;
UpdateAfterRotateRight(p);
}
static void UpdateAugmentedData(HeightTreeNode node, UpdateAfterChildrenChangeRecursionMode mode)
{
int totalCount = 1;
double totalHeight = node.lineNode.TotalHeight;
if (node.left != null) {
totalCount += node.left.totalCount;
totalHeight += node.left.totalHeight;
}
if (node.right != null) {
totalCount += node.right.totalCount;
totalHeight += node.right.totalHeight;
}
if (node.IsDirectlyCollapsed)
totalHeight = 0;
if (totalCount != node.totalCount
|| !totalHeight.IsClose(node.totalHeight)
|| mode == UpdateAfterChildrenChangeRecursionMode.WholeBranch)
{
node.totalCount = totalCount;
node.totalHeight = totalHeight;
if (node.parent != null && mode != UpdateAfterChildrenChangeRecursionMode.None)
UpdateAugmentedData(node.parent, mode);
}
}
// TODO: Optimize this. This tree takes alot of memory.
// (56 bytes for HeightTreeNode
// We should try to get rid of the dictionary and find height nodes per index. (DONE!)
// And we might do much better by compressing lines with the same height into a single node.
// That would also improve load times because we would always start with just a single node.
/* Idea:
class NewHeightTreeNode {
int totalCount; // =count+left.count+right.count
int count; // one node can represent multiple lines
double height; // height of each line in this node
double totalHeight; // =(collapsedSections!=null?0:height*count) + left.totalHeight + right.totalHeight
List<CollapsedSection> collapsedSections; // sections holding this line collapsed
// no "nodeCollapsedSections"/"totalCollapsedSections":
NewHeightTreeNode left, right, parent;
bool color;
}
totalCollapsedSections: are hard to update and not worth the effort. O(n log n) isn't too bad for
collapsing/uncollapsing, especially when compression reduces the n.
*/
#endregion Other
#if DEBUG
static void AppendTreeToString(HeightTreeNode node, StringBuilder b, int indent)
{
if (node.color == RED)
b.Append("RED ");
else
b.Append("BLACK ");
b.AppendLine(node.ToString());
indent += 2;
if (node.left != null) {
b.Append(' ', indent);
b.Append("L: ");
AppendTreeToString(node.left, b, indent);
}
if (node.right != null) {
b.Append(' ', indent);
b.Append("R: ");
AppendTreeToString(node.right, b, indent);
}
}
// node removal:
// a node in the middle of the tree is removed as following:
// its successor is removed
// it is replaced with its successor
void BeforeNodeRemove(HeightTreeNode removedNode)
{
Debug.Assert(removedNode.left == null || removedNode.right == null);
var collapsed = removedNode.collapsedSections;
if (collapsed != null) {
HeightTreeNode childNode = removedNode.left ?? removedNode.right;
if (childNode != null) {
foreach (CollapsedLineSection cs in collapsed)
childNode.AddDirectlyCollapsed(cs);
}
}
if (removedNode.parent != null)
MergeCollapsedSectionsIfPossible(removedNode.parent);
}
void BeforeNodeReplace(HeightTreeNode removedNode, HeightTreeNode newNode, HeightTreeNode newNodeOldParent)
{
Debug.Assert(removedNode != null);
Debug.Assert(newNode != null);
while (newNodeOldParent != removedNode) {
if (newNodeOldParent.collapsedSections != null) {
foreach (CollapsedLineSection cs in newNodeOldParent.collapsedSections) {
newNode.lineNode.AddDirectlyCollapsed(cs);
}
}
newNodeOldParent = newNodeOldParent.parent;
}
if (newNode.collapsedSections != null) {
foreach (CollapsedLineSection cs in newNode.collapsedSections) {
newNode.lineNode.AddDirectlyCollapsed(cs);
}
}
newNode.collapsedSections = removedNode.collapsedSections;
MergeCollapsedSectionsIfPossible(newNode);
}
/// <summary>
/// build a tree from a list of nodes
/// </summary>
HeightTreeNode BuildTree(HeightTreeNode[] nodes, int start, int end, int subtreeHeight)
{
Debug.Assert(start <= end);
if (start == end) {
return null;
}
int middle = (start + end) / 2;
HeightTreeNode node = nodes[middle];
node.left = BuildTree(nodes, start, middle, subtreeHeight - 1);
node.right = BuildTree(nodes, middle + 1, end, subtreeHeight - 1);
if (node.left != null) node.left.parent = node;
if (node.right != null) node.right.parent = node;
if (subtreeHeight == 1)
node.color = RED;
UpdateAugmentedData(node, UpdateAfterChildrenChangeRecursionMode.None);
return node;
}
void AddRemoveCollapsedSection(CollapsedLineSection section, int sectionLength, bool add)
{
Debug.Assert(sectionLength > 0);
HeightTreeNode node = GetNode(section.Start);
// Go up in the tree.
while (true)
{
// Mark all middle nodes as collapsed
if (add)
{
node.lineNode.AddDirectlyCollapsed(section);
}
else
{
node.lineNode.RemoveDirectlyCollapsed(section);
}
sectionLength -= 1;
if (sectionLength == 0)
{
// we are done!
Debug.Assert(node.documentLine == section.End);
break;
}
// Mark all right subtrees as collapsed.
if (node.right != null)
{
if (node.right.totalCount < sectionLength)
{
if (add)
{
node.right.AddDirectlyCollapsed(section);
}
else
{
node.right.RemoveDirectlyCollapsed(section);
}
sectionLength -= node.right.totalCount;
}
else
{
// mark partially into the right subtree: go down the right subtree.
AddRemoveCollapsedSectionDown(section, node.right, sectionLength, add);
break;
}
}
// go up to the next node
HeightTreeNode parentNode = node.parent;
Debug.Assert(parentNode != null);
while (parentNode.right == node)
{
node = parentNode;
parentNode = node.parent;
Debug.Assert(parentNode != null);
}
node = parentNode;
}
UpdateAugmentedData(GetNode(section.Start), UpdateAfterChildrenChangeRecursionMode.WholeBranch);
UpdateAugmentedData(GetNode(section.End), UpdateAfterChildrenChangeRecursionMode.WholeBranch);
}
void FixTreeOnDelete(HeightTreeNode node, HeightTreeNode parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (parentNode == null)
return;
// warning: node may be null
HeightTreeNode sibling = Sibling(node, parentNode);
if (sibling.color == RED) {
parentNode.color = RED;
sibling.color = BLACK;
if (node == parentNode.left) {
RotateLeft(parentNode);
} else {
RotateRight(parentNode);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
}
if (parentNode.color == BLACK
&& sibling.color == BLACK
&& GetColor(sibling.left) == BLACK
&& GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
FixTreeOnDelete(parentNode, parentNode.parent);
return;
}
if (parentNode.color == RED
&& sibling.color == BLACK
&& GetColor(sibling.left) == BLACK
&& GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
parentNode.color = BLACK;
return;
}
if (node == parentNode.left &&
sibling.color == BLACK &&
GetColor(sibling.left) == RED &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
sibling.left.color = BLACK;
RotateRight(sibling);
}
else if (node == parentNode.right &&
sibling.color == BLACK &&
GetColor(sibling.right) == RED &&
GetColor(sibling.left) == BLACK)
{
sibling.color = RED;
sibling.right.color = BLACK;
RotateLeft(sibling);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
sibling.color = parentNode.color;
parentNode.color = BLACK;
if (node == parentNode.left) {
if (sibling.right != null) {
Debug.Assert(sibling.right.color == RED);
sibling.right.color = BLACK;
}
RotateLeft(parentNode);
} else {
if (sibling.left != null) {
Debug.Assert(sibling.left.color == RED);
sibling.left.color = BLACK;
}
RotateRight(parentNode);
}
}
void FixTreeOnInsert(HeightTreeNode node)
{
Debug.Assert(node != null);
Debug.Assert(node.color == RED);
Debug.Assert(node.left == null || node.left.color == BLACK);
Debug.Assert(node.right == null || node.right.color == BLACK);
HeightTreeNode parentNode = node.parent;
if (parentNode == null)
{
// we inserted in the root -> the node must be black
// since this is a root node, making the node black increments the number of black nodes
// on all paths by one, so it is still the same for all paths.
node.color = BLACK;
return;
}
if (parentNode.color == BLACK)
{
// if the parent node where we inserted was black, our red node is placed correctly.
// since we inserted a red node, the number of black nodes on each path is unchanged
// -> the tree is still balanced
return;
}
// parentNode is red, so there is a conflict here!
// because the root is black, parentNode is not the root -> there is a grandparent node
HeightTreeNode grandparentNode = parentNode.parent;
HeightTreeNode uncleNode = Sibling(parentNode);
if (uncleNode != null && uncleNode.color == RED)
{
parentNode.color = BLACK;
uncleNode.color = BLACK;
grandparentNode.color = RED;
FixTreeOnInsert(grandparentNode);
return;
}
// now we know: parent is red but uncle is black
// First rotation:
if (node == parentNode.right && parentNode == grandparentNode.left)
{
RotateLeft(parentNode);
node = node.left;
}
else if (node == parentNode.left && parentNode == grandparentNode.right)
{
RotateRight(parentNode);
node = node.right;
}
// because node might have changed, reassign variables:
parentNode = node.parent;
grandparentNode = parentNode.parent;
// Now recolor a bit:
parentNode.color = BLACK;
grandparentNode.color = RED;
// Second rotation:
if (node == parentNode.left && parentNode == grandparentNode.left)
{
RotateRight(grandparentNode);
}
else
{
// because of the first rotation, this is guaranteed:
Debug.Assert(node == parentNode.right && parentNode == grandparentNode.right);
RotateLeft(grandparentNode);
}
}
/*
1. A node is either red or black.
2. The root is black.
3. All leaves are black. (The leaves are the NIL children.)
4. Both children of every red node are black. (So every red node must have a black parent.)
5. Every simple path from a node to a descendant leaf contains the same number of black nodes. (Not counting the leaf node.)
*/
void CheckNodeProperties(HeightTreeNode node, HeightTreeNode parentNode, bool parentColor, int blackCount, ref int expectedBlackCount)
{
if (node == null) return;
Debug.Assert(node.parent == parentNode);
if (parentColor == RED) {
Debug.Assert(node.color == BLACK);
}
if (node.color == BLACK) {
blackCount++;
}
if (node.left == null && node.right == null) {
// node is a leaf node:
if (expectedBlackCount == -1)
expectedBlackCount = blackCount;
else
Debug.Assert(expectedBlackCount == blackCount);
}
CheckNodeProperties(node.left, node, node.color, blackCount, ref expectedBlackCount);
CheckNodeProperties(node.right, node, node.color, blackCount, ref expectedBlackCount);
}