591 lines
16 KiB
C#
591 lines
16 KiB
C#
// <file>
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// <copyright see="prj:///doc/copyright.txt"/>
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// <license see="prj:///doc/license.txt"/>
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// <owner name="Daniel Grunwald" email="daniel@danielgrunwald.de"/>
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// <version>$Revision$</version>
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// </file>
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using System;
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using System.Text;
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using System.Diagnostics;
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using System.Collections.Generic;
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namespace ICSharpCode.TextEditor.Util
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{
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internal sealed class RedBlackTreeNode<T>
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{
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internal RedBlackTreeNode<T> left, right, parent;
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internal T val;
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internal bool color;
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internal RedBlackTreeNode(T val)
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{
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this.val = val;
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}
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internal RedBlackTreeNode<T> LeftMost {
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get {
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RedBlackTreeNode<T> node = this;
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while (node.left != null)
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node = node.left;
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return node;
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}
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}
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internal RedBlackTreeNode<T> RightMost {
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get {
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RedBlackTreeNode<T> node = this;
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while (node.right != null)
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node = node.right;
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return node;
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}
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}
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}
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internal interface IRedBlackTreeHost<T> : IComparer<T>
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{
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bool Equals(T a, T b);
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void UpdateAfterChildrenChange(RedBlackTreeNode<T> node);
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void UpdateAfterRotateLeft(RedBlackTreeNode<T> node);
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void UpdateAfterRotateRight(RedBlackTreeNode<T> node);
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}
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/// <summary>
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/// Description of RedBlackTree.
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/// </summary>
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internal sealed class AugmentableRedBlackTree<T, Host> : ICollection<T> where Host : IRedBlackTreeHost<T>
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{
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readonly Host host;
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int count;
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internal RedBlackTreeNode<T> root;
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public AugmentableRedBlackTree(Host host)
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{
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if (host == null) throw new ArgumentNullException("host");
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this.host = host;
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}
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public int Count {
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get { return count; }
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}
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public void Clear()
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{
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root = null;
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count = 0;
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}
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#region Debugging code
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#if DEBUG
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/// <summary>
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/// Check tree for consistency and being balanced.
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/// </summary>
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[Conditional("DATACONSISTENCYTEST")]
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void CheckProperties()
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{
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int blackCount = -1;
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CheckNodeProperties(root, null, RED, 0, ref blackCount);
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int nodeCount = 0;
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foreach (T val in this) {
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nodeCount++;
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}
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Debug.Assert(count == nodeCount);
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}
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/*
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1. A node is either red or black.
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2. The root is black.
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3. All leaves are black. (The leaves are the NIL children.)
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4. Both children of every red node are black. (So every red node must have a black parent.)
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5. Every simple path from a node to a descendant leaf contains the same number of black nodes. (Not counting the leaf node.)
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*/
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void CheckNodeProperties(RedBlackTreeNode<T> node, RedBlackTreeNode<T> parentNode, bool parentColor, int blackCount, ref int expectedBlackCount)
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{
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if (node == null) return;
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Debug.Assert(node.parent == parentNode);
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if (parentColor == RED) {
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Debug.Assert(node.color == BLACK);
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}
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if (node.color == BLACK) {
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blackCount++;
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}
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if (node.left == null && node.right == null) {
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// node is a leaf node:
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if (expectedBlackCount == -1)
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expectedBlackCount = blackCount;
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else
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Debug.Assert(expectedBlackCount == blackCount);
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}
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CheckNodeProperties(node.left, node, node.color, blackCount, ref expectedBlackCount);
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CheckNodeProperties(node.right, node, node.color, blackCount, ref expectedBlackCount);
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}
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public string GetTreeAsString()
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{
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StringBuilder b = new StringBuilder();
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AppendTreeToString(root, b, 0);
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return b.ToString();
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}
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static void AppendTreeToString(RedBlackTreeNode<T> node, StringBuilder b, int indent)
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{
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if (node.color == RED)
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b.Append("RED ");
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else
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b.Append("BLACK ");
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b.AppendLine(node.val.ToString());
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indent += 2;
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if (node.left != null) {
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b.Append(' ', indent);
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b.Append("L: ");
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AppendTreeToString(node.left, b, indent);
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}
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if (node.right != null) {
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b.Append(' ', indent);
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b.Append("R: ");
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AppendTreeToString(node.right, b, indent);
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}
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}
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#endif
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#endregion
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#region Add
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public void Add(T item)
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{
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AddInternal(new RedBlackTreeNode<T>(item));
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#if DEBUG
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CheckProperties();
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#endif
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}
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void AddInternal(RedBlackTreeNode<T> newNode)
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{
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Debug.Assert(newNode.color == BLACK);
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if (root == null) {
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count = 1;
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root = newNode;
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return;
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}
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// Insert into the tree
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RedBlackTreeNode<T> parentNode = root;
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while (true) {
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if (host.Compare(newNode.val, parentNode.val) <= 0) {
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if (parentNode.left == null) {
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InsertAsLeft(parentNode, newNode);
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return;
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}
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parentNode = parentNode.left;
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} else {
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if (parentNode.right == null) {
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InsertAsRight(parentNode, newNode);
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return;
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}
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parentNode = parentNode.right;
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}
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}
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}
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internal void InsertAsLeft(RedBlackTreeNode<T> parentNode, RedBlackTreeNode<T> newNode)
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{
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Debug.Assert(parentNode.left == null);
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parentNode.left = newNode;
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newNode.parent = parentNode;
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newNode.color = RED;
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host.UpdateAfterChildrenChange(parentNode);
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FixTreeOnInsert(newNode);
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count++;
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}
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internal void InsertAsRight(RedBlackTreeNode<T> parentNode, RedBlackTreeNode<T> newNode)
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{
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Debug.Assert(parentNode.right == null);
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parentNode.right = newNode;
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newNode.parent = parentNode;
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newNode.color = RED;
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host.UpdateAfterChildrenChange(parentNode);
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FixTreeOnInsert(newNode);
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count++;
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}
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void FixTreeOnInsert(RedBlackTreeNode<T> node)
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{
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Debug.Assert(node != null);
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Debug.Assert(node.color == RED);
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Debug.Assert(node.left == null || node.left.color == BLACK);
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Debug.Assert(node.right == null || node.right.color == BLACK);
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RedBlackTreeNode<T> parentNode = node.parent;
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if (parentNode == null) {
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// we inserted in the root -> the node must be black
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// since this is a root node, making the node black increments the number of black nodes
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// on all paths by one, so it is still the same for all paths.
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node.color = BLACK;
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return;
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}
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if (parentNode.color == BLACK) {
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// if the parent node where we inserted was black, our red node is placed correctly.
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// since we inserted a red node, the number of black nodes on each path is unchanged
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// -> the tree is still balanced
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return;
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}
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// parentNode is red, so there is a conflict here!
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// because the root is black, parentNode is not the root -> there is a grandparent node
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RedBlackTreeNode<T> grandparentNode = parentNode.parent;
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RedBlackTreeNode<T> uncleNode = Sibling(parentNode);
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if (uncleNode != null && uncleNode.color == RED) {
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parentNode.color = BLACK;
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uncleNode.color = BLACK;
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grandparentNode.color = RED;
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FixTreeOnInsert(grandparentNode);
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return;
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}
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// now we know: parent is red but uncle is black
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// First rotation:
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if (node == parentNode.right && parentNode == grandparentNode.left) {
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RotateLeft(parentNode);
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node = node.left;
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} else if (node == parentNode.left && parentNode == grandparentNode.right) {
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RotateRight(parentNode);
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node = node.right;
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}
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// because node might have changed, reassign variables:
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parentNode = node.parent;
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grandparentNode = parentNode.parent;
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// Now recolor a bit:
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parentNode.color = BLACK;
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grandparentNode.color = RED;
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// Second rotation:
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if (node == parentNode.left && parentNode == grandparentNode.left) {
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RotateRight(grandparentNode);
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} else {
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// because of the first rotation, this is guaranteed:
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Debug.Assert(node == parentNode.right && parentNode == grandparentNode.right);
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RotateLeft(grandparentNode);
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}
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}
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void ReplaceNode(RedBlackTreeNode<T> replacedNode, RedBlackTreeNode<T> newNode)
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{
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if (replacedNode.parent == null) {
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Debug.Assert(replacedNode == root);
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root = newNode;
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} else {
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if (replacedNode.parent.left == replacedNode)
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replacedNode.parent.left = newNode;
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else
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replacedNode.parent.right = newNode;
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}
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if (newNode != null) {
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newNode.parent = replacedNode.parent;
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}
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replacedNode.parent = null;
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}
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void RotateLeft(RedBlackTreeNode<T> p)
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{
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// let q be p's right child
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RedBlackTreeNode<T> q = p.right;
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Debug.Assert(q != null);
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Debug.Assert(q.parent == p);
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// set q to be the new root
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ReplaceNode(p, q);
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// set p's right child to be q's left child
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p.right = q.left;
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if (p.right != null) p.right.parent = p;
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// set q's left child to be p
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q.left = p;
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p.parent = q;
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host.UpdateAfterRotateLeft(p);
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}
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void RotateRight(RedBlackTreeNode<T> p)
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{
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// let q be p's left child
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RedBlackTreeNode<T> q = p.left;
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Debug.Assert(q != null);
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Debug.Assert(q.parent == p);
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// set q to be the new root
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ReplaceNode(p, q);
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// set p's left child to be q's right child
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p.left = q.right;
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if (p.left != null) p.left.parent = p;
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// set q's right child to be p
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q.right = p;
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p.parent = q;
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host.UpdateAfterRotateRight(p);
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}
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RedBlackTreeNode<T> Sibling(RedBlackTreeNode<T> node)
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{
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if (node == node.parent.left)
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return node.parent.right;
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else
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return node.parent.left;
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}
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#endregion
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#region Remove
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public void RemoveAt(RedBlackTreeIterator<T> iterator)
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{
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RedBlackTreeNode<T> node = iterator.node;
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if (node == null)
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throw new ArgumentException("Invalid iterator");
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while (node.parent != null)
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node = node.parent;
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if (node != root)
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throw new ArgumentException("Iterator does not belong to this tree");
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RemoveNode(iterator.node);
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#if DEBUG
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CheckProperties();
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#endif
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}
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internal void RemoveNode(RedBlackTreeNode<T> removedNode)
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{
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if (removedNode.left != null && removedNode.right != null) {
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// replace removedNode with it's in-order successor
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RedBlackTreeNode<T> leftMost = removedNode.right.LeftMost;
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RemoveNode(leftMost); // remove leftMost from its current location
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// and overwrite the removedNode with it
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ReplaceNode(removedNode, leftMost);
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leftMost.left = removedNode.left;
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if (leftMost.left != null) leftMost.left.parent = leftMost;
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leftMost.right = removedNode.right;
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if (leftMost.right != null) leftMost.right.parent = leftMost;
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leftMost.color = removedNode.color;
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host.UpdateAfterChildrenChange(leftMost);
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if (leftMost.parent != null) host.UpdateAfterChildrenChange(leftMost.parent);
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return;
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}
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count--;
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// now either removedNode.left or removedNode.right is null
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// get the remaining child
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RedBlackTreeNode<T> parentNode = removedNode.parent;
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RedBlackTreeNode<T> childNode = removedNode.left ?? removedNode.right;
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ReplaceNode(removedNode, childNode);
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if (parentNode != null) host.UpdateAfterChildrenChange(parentNode);
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if (removedNode.color == BLACK) {
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if (childNode != null && childNode.color == RED) {
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childNode.color = BLACK;
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} else {
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FixTreeOnDelete(childNode, parentNode);
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}
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}
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}
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static RedBlackTreeNode<T> Sibling(RedBlackTreeNode<T> node, RedBlackTreeNode<T> parentNode)
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{
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Debug.Assert(node == null || node.parent == parentNode);
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if (node == parentNode.left)
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return parentNode.right;
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else
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return parentNode.left;
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}
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const bool RED = true;
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const bool BLACK = false;
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static bool GetColor(RedBlackTreeNode<T> node)
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{
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return node != null ? node.color : BLACK;
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}
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void FixTreeOnDelete(RedBlackTreeNode<T> node, RedBlackTreeNode<T> parentNode)
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{
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Debug.Assert(node == null || node.parent == parentNode);
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if (parentNode == null)
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return;
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// warning: node may be null
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RedBlackTreeNode<T> sibling = Sibling(node, parentNode);
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if (sibling.color == RED) {
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parentNode.color = RED;
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sibling.color = BLACK;
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if (node == parentNode.left) {
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RotateLeft(parentNode);
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} else {
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RotateRight(parentNode);
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}
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sibling = Sibling(node, parentNode); // update value of sibling after rotation
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}
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if (parentNode.color == BLACK
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&& sibling.color == BLACK
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&& GetColor(sibling.left) == BLACK
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&& GetColor(sibling.right) == BLACK)
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{
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sibling.color = RED;
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FixTreeOnDelete(parentNode, parentNode.parent);
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return;
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}
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if (parentNode.color == RED
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&& sibling.color == BLACK
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&& GetColor(sibling.left) == BLACK
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&& GetColor(sibling.right) == BLACK)
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{
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sibling.color = RED;
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parentNode.color = BLACK;
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return;
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}
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if (node == parentNode.left &&
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sibling.color == BLACK &&
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GetColor(sibling.left) == RED &&
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GetColor(sibling.right) == BLACK)
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{
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sibling.color = RED;
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sibling.left.color = BLACK;
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RotateRight(sibling);
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}
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else if (node == parentNode.right &&
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sibling.color == BLACK &&
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GetColor(sibling.right) == RED &&
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GetColor(sibling.left) == BLACK)
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{
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sibling.color = RED;
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sibling.right.color = BLACK;
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RotateLeft(sibling);
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}
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sibling = Sibling(node, parentNode); // update value of sibling after rotation
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sibling.color = parentNode.color;
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parentNode.color = BLACK;
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if (node == parentNode.left) {
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if (sibling.right != null) {
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Debug.Assert(sibling.right.color == RED);
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sibling.right.color = BLACK;
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}
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RotateLeft(parentNode);
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} else {
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if (sibling.left != null) {
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Debug.Assert(sibling.left.color == RED);
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sibling.left.color = BLACK;
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}
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RotateRight(parentNode);
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}
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}
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#endregion
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#region Find/LowerBound/UpperBound/GetEnumerator
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/// <summary>
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/// Returns the iterator pointing to the specified item, or an iterator in End state if the item is not found.
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/// </summary>
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public RedBlackTreeIterator<T> Find(T item)
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{
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RedBlackTreeIterator<T> it = LowerBound(item);
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while (it.IsValid && host.Compare(it.Current, item) == 0) {
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if (host.Equals(it.Current, item))
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return it;
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it.MoveNext();
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}
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return default(RedBlackTreeIterator<T>);
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}
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/// <summary>
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/// Returns the iterator pointing to the first item greater or equal to <paramref name="item"/>.
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/// </summary>
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public RedBlackTreeIterator<T> LowerBound(T item)
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{
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RedBlackTreeNode<T> node = root;
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RedBlackTreeNode<T> resultNode = null;
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while (node != null) {
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if (host.Compare(node.val, item) < 0) {
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node = node.right;
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} else {
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resultNode = node;
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node = node.left;
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}
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}
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return new RedBlackTreeIterator<T>(resultNode);
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}
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/// <summary>
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/// Returns the iterator pointing to the first item greater than <paramref name="item"/>.
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/// </summary>
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public RedBlackTreeIterator<T> UpperBound(T item)
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{
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RedBlackTreeIterator<T> it = LowerBound(item);
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while (it.IsValid && host.Compare(it.Current, item) == 0) {
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it.MoveNext();
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}
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return it;
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}
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/// <summary>
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/// Gets a tree iterator that starts on the first node.
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/// </summary>
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public RedBlackTreeIterator<T> Begin()
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{
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if (root == null) return default(RedBlackTreeIterator<T>);
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return new RedBlackTreeIterator<T>(root.LeftMost);
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}
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/// <summary>
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/// Gets a tree iterator that starts one node before the first node.
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/// </summary>
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public RedBlackTreeIterator<T> GetEnumerator()
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{
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if (root == null) return default(RedBlackTreeIterator<T>);
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RedBlackTreeNode<T> dummyNode = new RedBlackTreeNode<T>(default(T));
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dummyNode.right = root;
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return new RedBlackTreeIterator<T>(dummyNode);
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|
}
|
|
#endregion
|
|
|
|
#region ICollection members
|
|
public bool Contains(T item)
|
|
{
|
|
return Find(item).IsValid;
|
|
}
|
|
|
|
public bool Remove(T item)
|
|
{
|
|
RedBlackTreeIterator<T> it = Find(item);
|
|
if (!it.IsValid) {
|
|
return false;
|
|
} else {
|
|
RemoveAt(it);
|
|
return true;
|
|
}
|
|
}
|
|
|
|
IEnumerator<T> IEnumerable<T>.GetEnumerator()
|
|
{
|
|
return GetEnumerator();
|
|
}
|
|
|
|
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
|
|
{
|
|
return GetEnumerator();
|
|
}
|
|
|
|
bool ICollection<T>.IsReadOnly {
|
|
get { return false; }
|
|
}
|
|
|
|
public void CopyTo(T[] array, int arrayIndex)
|
|
{
|
|
if (array == null) throw new ArgumentNullException("array");
|
|
foreach (T val in this) {
|
|
array[arrayIndex++] = val;
|
|
}
|
|
}
|
|
#endregion
|
|
}
|
|
}
|