132
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1 /*
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2 File: RBCell.d
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3
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4 Originally written by Doug Lea and released into the public domain.
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5 Thanks for the assistance and support of Sun Microsystems Labs, Agorics
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6 Inc, Loral, and everyone contributing, testing, and using this code.
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7
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8 History:
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9 Date Who What
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10 24Sep95 dl@cs.oswego.edu Create from tango.util.collection.d working file
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11
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12 */
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13
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14
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15 module tango.util.collection.impl.RBCell;
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16
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17 private import tango.util.collection.impl.Cell;
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18
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19 private import tango.util.collection.model.Iterator,
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20 tango.util.collection.model.Comparator;
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21
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22 /**
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23 * RBCell implements basic capabilities of Red-Black trees,
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24 * an efficient kind of balanced binary tree. The particular
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25 * algorithms used are adaptations of those in Corman,
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26 * Lieserson, and Rivest's <EM>Introduction to Algorithms</EM>.
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27 * This class was inspired by (and code cross-checked with) a
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28 * similar class by Chuck McManis. The implementations of
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29 * rebalancings during insertion and deletion are
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30 * a little trickier than those versions since they
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31 * don't swap Cell contents or use special dummy nilnodes.
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32 * <P>
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33 * It is a pure implementation class. For harnesses, see:
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34 * See_Also: RBTree
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35 * Authors: Doug Lea
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36 **/
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37
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38
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39
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40
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41 public class RBCell(T) : Cell!(T)
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42 {
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43 static bool RED = false;
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44 static bool BLACK = true;
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45
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46 /**
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47 * The node color (RED, BLACK)
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48 **/
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49
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50 package bool color_;
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51
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52 /**
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53 * Pointer to left child
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54 **/
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55
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56 package RBCell left_;
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57
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58 /**
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59 * Pointer to right child
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60 **/
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61
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62 package RBCell right_;
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63
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64 /**
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65 * Pointer to parent (null if root)
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66 **/
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67
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68 private RBCell parent_;
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69
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70 /**
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71 * Make a new Cell with given element, null links, and BLACK color.
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72 * Normally only called to establish a new root.
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73 **/
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74
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75 public this (T element)
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76 {
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77 super(element);
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78 left_ = null;
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79 right_ = null;
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80 parent_ = null;
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81 color_ = BLACK;
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82 }
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83
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84 /**
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85 * Return a new RBCell with same element and color as self,
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86 * but with null links. (Since it is never OK to have
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87 * multiple identical links in a RB tree.)
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88 **/
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89
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90 protected RBCell duplicate()
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91 {
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92 RBCell t = new RBCell(element());
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93 t.color_ = color_;
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94 return t;
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95 }
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96
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97
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98 /**
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99 * Return left child (or null)
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100 **/
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101
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102 public final RBCell left()
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103 {
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104 return left_;
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105 }
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106
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107 /**
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108 * Return right child (or null)
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109 **/
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110
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111 public final RBCell right()
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112 {
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113 return right_;
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114 }
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115
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116 /**
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117 * Return parent (or null)
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118 **/
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119 public final RBCell parent()
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120 {
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121 return parent_;
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122 }
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123
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124
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125 /**
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126 * See_Also: tango.util.collection.model.View.View.checkImplementation.
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127 **/
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128 public void checkImplementation()
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129 {
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130
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131 // It's too hard to check the property that every simple
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132 // path from node to leaf has same number of black nodes.
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133 // So restrict to the following
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134
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135 assert(parent_ is null ||
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136 this is parent_.left_ ||
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137 this is parent_.right_);
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138
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139 assert(left_ is null ||
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140 this is left_.parent_);
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141
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142 assert(right_ is null ||
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143 this is right_.parent_);
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144
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145 assert(color_ is BLACK ||
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146 (colorOf(left_) is BLACK) && (colorOf(right_) is BLACK));
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147
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148 if (left_ !is null)
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149 left_.checkImplementation();
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150 if (right_ !is null)
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151 right_.checkImplementation();
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152 }
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153
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154 /+
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155 public final void assert(bool pred)
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156 {
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157 ImplementationError.assert(this, pred);
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158 }
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159 +/
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160
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161 /**
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162 * Return the minimum element of the current (sub)tree
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163 **/
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164
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165 public final RBCell leftmost()
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166 {
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167 auto p = this;
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168 for ( ; p.left_ !is null; p = p.left_)
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169 {}
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170 return p;
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171 }
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172
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173 /**
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174 * Return the maximum element of the current (sub)tree
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175 **/
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176 public final RBCell rightmost()
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177 {
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178 auto p = this;
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179 for ( ; p.right_ !is null; p = p.right_)
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180 {}
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181 return p;
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182 }
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183
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184 /**
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185 * Return the root (parentless node) of the tree
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186 **/
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187 public final RBCell root()
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188 {
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189 auto p = this;
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190 for ( ; p.parent_ !is null; p = p.parent_)
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191 {}
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192 return p;
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193 }
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194
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195 /**
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196 * Return true if node is a root (i.e., has a null parent)
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197 **/
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198
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199 public final bool isRoot()
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200 {
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201 return parent_ is null;
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202 }
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203
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204
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205 /**
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206 * Return the inorder successor, or null if no such
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207 **/
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208
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209 public final RBCell successor()
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210 {
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211 if (right_ !is null)
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212 return right_.leftmost();
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213 else
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214 {
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215 auto p = parent_;
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216 auto ch = this;
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217 while (p !is null && ch is p.right_)
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218 {
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219 ch = p;
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220 p = p.parent_;
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221 }
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222 return p;
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223 }
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224 }
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225
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226 /**
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227 * Return the inorder predecessor, or null if no such
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228 **/
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229
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230 public final RBCell predecessor()
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231 {
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232 if (left_ !is null)
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233 return left_.rightmost();
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234 else
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235 {
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236 auto p = parent_;
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237 auto ch = this;
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238 while (p !is null && ch is p.left_)
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239 {
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240 ch = p;
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241 p = p.parent_;
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242 }
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243 return p;
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244 }
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245 }
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246
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247 /**
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248 * Return the number of nodes in the subtree
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249 **/
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250 public final int size()
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251 {
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252 int c = 1;
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253 if (left_ !is null)
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254 c += left_.size();
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255 if (right_ !is null)
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256 c += right_.size();
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257 return c;
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258 }
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259
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260
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261 /**
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262 * Return node of current subtree containing element as element(),
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263 * if it exists, else null.
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264 * Uses Comparator cmp to find and to check equality.
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265 **/
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266
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267 public RBCell find(T element, Comparator!(T) cmp)
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268 {
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269 auto t = this;
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270 for (;;)
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271 {
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272 int diff = cmp.compare(element, t.element());
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273 if (diff is 0)
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274 return t;
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275 else
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276 if (diff < 0)
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277 t = t.left_;
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278 else
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279 t = t.right_;
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280 if (t is null)
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281 break;
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282 }
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283 return null;
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284 }
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285
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286
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287 /**
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288 * Return number of nodes of current subtree containing element.
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289 * Uses Comparator cmp to find and to check equality.
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290 **/
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291 public int count(T element, Comparator!(T) cmp)
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292 {
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293 int c = 0;
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294 auto t = this;
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295 while (t !is null)
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296 {
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297 int diff = cmp.compare(element, t.element());
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298 if (diff is 0)
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299 {
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300 ++c;
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301 if (t.left_ is null)
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302 t = t.right_;
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303 else
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304 if (t.right_ is null)
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305 t = t.left_;
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306 else
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307 {
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308 c += t.right_.count(element, cmp);
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309 t = t.left_;
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310 }
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311 }
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312 else
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313 if (diff < 0)
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314 t = t.left_;
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315 else
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316 t = t.right_;
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317 }
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318 return c;
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319 }
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320
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321
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322
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323
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324 /**
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325 * Return a new subtree containing each element of current subtree
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326 **/
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327
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328 public final RBCell copyTree()
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329 {
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330 auto t = cast(RBCell)(duplicate());
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331
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332 if (left_ !is null)
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333 {
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334 t.left_ = left_.copyTree();
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335 t.left_.parent_ = t;
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336 }
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337 if (right_ !is null)
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338 {
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339 t.right_ = right_.copyTree();
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340 t.right_.parent_ = t;
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341 }
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342 return t;
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343 }
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344
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345
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346 /**
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347 * There's no generic element insertion. Instead find the
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348 * place you want to add a node and then invoke insertLeft
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349 * or insertRight.
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350 * <P>
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351 * Insert Cell as the left child of current node, and then
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352 * rebalance the tree it is in.
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353 * @param Cell the Cell to add
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354 * @param root, the root of the current tree
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355 * Returns: the new root of the current tree. (Rebalancing
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356 * can change the root!)
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357 **/
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358
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359
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360 public final RBCell insertLeft(RBCell Cell, RBCell root)
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361 {
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362 left_ = Cell;
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363 Cell.parent_ = this;
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364 return Cell.fixAfterInsertion(root);
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365 }
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366
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367 /**
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368 * Insert Cell as the right child of current node, and then
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369 * rebalance the tree it is in.
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370 * @param Cell the Cell to add
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371 * @param root, the root of the current tree
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372 * Returns: the new root of the current tree. (Rebalancing
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373 * can change the root!)
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374 **/
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375
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376 public final RBCell insertRight(RBCell Cell, RBCell root)
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377 {
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378 right_ = Cell;
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379 Cell.parent_ = this;
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380 return Cell.fixAfterInsertion(root);
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381 }
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382
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383
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384 /**
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385 * Delete the current node, and then rebalance the tree it is in
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386 * @param root the root of the current tree
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387 * Returns: the new root of the current tree. (Rebalancing
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388 * can change the root!)
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389 **/
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390
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391
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392 public final RBCell remove (RBCell root)
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393 {
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394
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395 // handle case where we are only node
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396 if (left_ is null && right_ is null && parent_ is null)
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397 return null;
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398
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399 // if strictly internal, swap places with a successor
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400 if (left_ !is null && right_ !is null)
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401 {
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402 auto s = successor();
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403 // To work nicely with arbitrary subclasses of RBCell, we don't want to
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404 // just copy successor's fields. since we don't know what
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405 // they are. Instead we swap positions _in the tree.
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406 root = swapPosition(this, s, root);
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407 }
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408
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409 // Start fixup at replacement node (normally a child).
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410 // But if no children, fake it by using self
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411
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412 if (left_ is null && right_ is null)
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413 {
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414
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415 if (color_ is BLACK)
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416 root = this.fixAfterDeletion(root);
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417
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418 // Unlink (Couldn't before since fixAfterDeletion needs parent ptr)
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419
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420 if (parent_ !is null)
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421 {
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422 if (this is parent_.left_)
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423 parent_.left_ = null;
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424 else
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425 if (this is parent_.right_)
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426 parent_.right_ = null;
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427 parent_ = null;
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428 }
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429
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430 }
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431 else
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432 {
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433 auto replacement = left_;
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434 if (replacement is null)
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435 replacement = right_;
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436
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437 // link replacement to parent
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438 replacement.parent_ = parent_;
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439
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440 if (parent_ is null)
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441 root = replacement;
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442 else
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443 if (this is parent_.left_)
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444 parent_.left_ = replacement;
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445 else
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446 parent_.right_ = replacement;
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447
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448 left_ = null;
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449 right_ = null;
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450 parent_ = null;
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451
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452 // fix replacement
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453 if (color_ is BLACK)
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454 root = replacement.fixAfterDeletion(root);
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455
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456 }
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457
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458 return root;
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459 }
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460
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461 /**
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462 * Swap the linkages of two nodes in a tree.
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463 * Return new root, in case it changed.
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464 **/
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465
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466 static final RBCell swapPosition(RBCell x, RBCell y, RBCell root)
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467 {
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468
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469 /* Too messy. TODO: find sequence of assigments that are always OK */
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470
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471 auto px = x.parent_;
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472 bool xpl = px !is null && x is px.left_;
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473 auto lx = x.left_;
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474 auto rx = x.right_;
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475
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476 auto py = y.parent_;
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477 bool ypl = py !is null && y is py.left_;
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478 auto ly = y.left_;
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479 auto ry = y.right_;
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480
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481 if (x is py)
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482 {
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483 y.parent_ = px;
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484 if (px !is null)
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485 if (xpl)
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486 px.left_ = y;
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487 else
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488 px.right_ = y;
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489 x.parent_ = y;
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490 if (ypl)
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491 {
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492 y.left_ = x;
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493 y.right_ = rx;
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494 if (rx !is null)
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495 rx.parent_ = y;
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496 }
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497 else
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498 {
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499 y.right_ = x;
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500 y.left_ = lx;
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501 if (lx !is null)
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502 lx.parent_ = y;
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503 }
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504 x.left_ = ly;
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505 if (ly !is null)
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506 ly.parent_ = x;
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507 x.right_ = ry;
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508 if (ry !is null)
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509 ry.parent_ = x;
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510 }
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511 else
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512 if (y is px)
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513 {
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514 x.parent_ = py;
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515 if (py !is null)
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516 if (ypl)
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517 py.left_ = x;
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518 else
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519 py.right_ = x;
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520 y.parent_ = x;
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521 if (xpl)
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522 {
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523 x.left_ = y;
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524 x.right_ = ry;
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525 if (ry !is null)
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526 ry.parent_ = x;
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527 }
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528 else
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529 {
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530 x.right_ = y;
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531 x.left_ = ly;
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532 if (ly !is null)
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533 ly.parent_ = x;
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534 }
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535 y.left_ = lx;
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536 if (lx !is null)
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537 lx.parent_ = y;
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538 y.right_ = rx;
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539 if (rx !is null)
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540 rx.parent_ = y;
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541 }
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542 else
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543 {
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544 x.parent_ = py;
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545 if (py !is null)
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546 if (ypl)
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547 py.left_ = x;
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548 else
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549 py.right_ = x;
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550 x.left_ = ly;
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551 if (ly !is null)
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552 ly.parent_ = x;
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553 x.right_ = ry;
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554 if (ry !is null)
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555 ry.parent_ = x;
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556
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557 y.parent_ = px;
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558 if (px !is null)
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559 if (xpl)
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560 px.left_ = y;
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561 else
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562 px.right_ = y;
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563 y.left_ = lx;
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564 if (lx !is null)
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565 lx.parent_ = y;
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566 y.right_ = rx;
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567 if (rx !is null)
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568 rx.parent_ = y;
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569 }
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570
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571 bool c = x.color_;
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572 x.color_ = y.color_;
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573 y.color_ = c;
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574
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575 if (root is x)
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576 root = y;
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577 else
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578 if (root is y)
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579 root = x;
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580 return root;
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581 }
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582
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583
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584
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585 /**
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586 * Return color of node p, or BLACK if p is null
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587 * (In the CLR version, they use
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588 * a special dummy `nil' node for such purposes, but that doesn't
|
|
589 * work well here, since it could lead to creating one such special
|
|
590 * node per real node.)
|
|
591 *
|
|
592 **/
|
|
593
|
|
594 static final bool colorOf(RBCell p)
|
|
595 {
|
|
596 return (p is null) ? BLACK : p.color_;
|
|
597 }
|
|
598
|
|
599 /**
|
|
600 * return parent of node p, or null if p is null
|
|
601 **/
|
|
602 static final RBCell parentOf(RBCell p)
|
|
603 {
|
|
604 return (p is null) ? null : p.parent_;
|
|
605 }
|
|
606
|
|
607 /**
|
|
608 * Set the color of node p, or do nothing if p is null
|
|
609 **/
|
|
610
|
|
611 static final void setColor(RBCell p, bool c)
|
|
612 {
|
|
613 if (p !is null)
|
|
614 p.color_ = c;
|
|
615 }
|
|
616
|
|
617 /**
|
|
618 * return left child of node p, or null if p is null
|
|
619 **/
|
|
620
|
|
621 static final RBCell leftOf(RBCell p)
|
|
622 {
|
|
623 return (p is null) ? null : p.left_;
|
|
624 }
|
|
625
|
|
626 /**
|
|
627 * return right child of node p, or null if p is null
|
|
628 **/
|
|
629
|
|
630 static final RBCell rightOf(RBCell p)
|
|
631 {
|
|
632 return (p is null) ? null : p.right_;
|
|
633 }
|
|
634
|
|
635
|
|
636 /** From CLR **/
|
|
637 protected final RBCell rotateLeft(RBCell root)
|
|
638 {
|
|
639 auto r = right_;
|
|
640 right_ = r.left_;
|
|
641 if (r.left_ !is null)
|
|
642 r.left_.parent_ = this;
|
|
643 r.parent_ = parent_;
|
|
644 if (parent_ is null)
|
|
645 root = r;
|
|
646 else
|
|
647 if (parent_.left_ is this)
|
|
648 parent_.left_ = r;
|
|
649 else
|
|
650 parent_.right_ = r;
|
|
651 r.left_ = this;
|
|
652 parent_ = r;
|
|
653 return root;
|
|
654 }
|
|
655
|
|
656 /** From CLR **/
|
|
657 protected final RBCell rotateRight(RBCell root)
|
|
658 {
|
|
659 auto l = left_;
|
|
660 left_ = l.right_;
|
|
661 if (l.right_ !is null)
|
|
662 l.right_.parent_ = this;
|
|
663 l.parent_ = parent_;
|
|
664 if (parent_ is null)
|
|
665 root = l;
|
|
666 else
|
|
667 if (parent_.right_ is this)
|
|
668 parent_.right_ = l;
|
|
669 else
|
|
670 parent_.left_ = l;
|
|
671 l.right_ = this;
|
|
672 parent_ = l;
|
|
673 return root;
|
|
674 }
|
|
675
|
|
676
|
|
677 /** From CLR **/
|
|
678 protected final RBCell fixAfterInsertion(RBCell root)
|
|
679 {
|
|
680 color_ = RED;
|
|
681 auto x = this;
|
|
682
|
|
683 while (x !is null && x !is root && x.parent_.color_ is RED)
|
|
684 {
|
|
685 if (parentOf(x) is leftOf(parentOf(parentOf(x))))
|
|
686 {
|
|
687 auto y = rightOf(parentOf(parentOf(x)));
|
|
688 if (colorOf(y) is RED)
|
|
689 {
|
|
690 setColor(parentOf(x), BLACK);
|
|
691 setColor(y, BLACK);
|
|
692 setColor(parentOf(parentOf(x)), RED);
|
|
693 x = parentOf(parentOf(x));
|
|
694 }
|
|
695 else
|
|
696 {
|
|
697 if (x is rightOf(parentOf(x)))
|
|
698 {
|
|
699 x = parentOf(x);
|
|
700 root = x.rotateLeft(root);
|
|
701 }
|
|
702 setColor(parentOf(x), BLACK);
|
|
703 setColor(parentOf(parentOf(x)), RED);
|
|
704 if (parentOf(parentOf(x)) !is null)
|
|
705 root = parentOf(parentOf(x)).rotateRight(root);
|
|
706 }
|
|
707 }
|
|
708 else
|
|
709 {
|
|
710 auto y = leftOf(parentOf(parentOf(x)));
|
|
711 if (colorOf(y) is RED)
|
|
712 {
|
|
713 setColor(parentOf(x), BLACK);
|
|
714 setColor(y, BLACK);
|
|
715 setColor(parentOf(parentOf(x)), RED);
|
|
716 x = parentOf(parentOf(x));
|
|
717 }
|
|
718 else
|
|
719 {
|
|
720 if (x is leftOf(parentOf(x)))
|
|
721 {
|
|
722 x = parentOf(x);
|
|
723 root = x.rotateRight(root);
|
|
724 }
|
|
725 setColor(parentOf(x), BLACK);
|
|
726 setColor(parentOf(parentOf(x)), RED);
|
|
727 if (parentOf(parentOf(x)) !is null)
|
|
728 root = parentOf(parentOf(x)).rotateLeft(root);
|
|
729 }
|
|
730 }
|
|
731 }
|
|
732 root.color_ = BLACK;
|
|
733 return root;
|
|
734 }
|
|
735
|
|
736
|
|
737
|
|
738 /** From CLR **/
|
|
739 protected final RBCell fixAfterDeletion(RBCell root)
|
|
740 {
|
|
741 auto x = this;
|
|
742 while (x !is root && colorOf(x) is BLACK)
|
|
743 {
|
|
744 if (x is leftOf(parentOf(x)))
|
|
745 {
|
|
746 auto sib = rightOf(parentOf(x));
|
|
747 if (colorOf(sib) is RED)
|
|
748 {
|
|
749 setColor(sib, BLACK);
|
|
750 setColor(parentOf(x), RED);
|
|
751 root = parentOf(x).rotateLeft(root);
|
|
752 sib = rightOf(parentOf(x));
|
|
753 }
|
|
754 if (colorOf(leftOf(sib)) is BLACK && colorOf(rightOf(sib)) is BLACK)
|
|
755 {
|
|
756 setColor(sib, RED);
|
|
757 x = parentOf(x);
|
|
758 }
|
|
759 else
|
|
760 {
|
|
761 if (colorOf(rightOf(sib)) is BLACK)
|
|
762 {
|
|
763 setColor(leftOf(sib), BLACK);
|
|
764 setColor(sib, RED);
|
|
765 root = sib.rotateRight(root);
|
|
766 sib = rightOf(parentOf(x));
|
|
767 }
|
|
768 setColor(sib, colorOf(parentOf(x)));
|
|
769 setColor(parentOf(x), BLACK);
|
|
770 setColor(rightOf(sib), BLACK);
|
|
771 root = parentOf(x).rotateLeft(root);
|
|
772 x = root;
|
|
773 }
|
|
774 }
|
|
775 else
|
|
776 {
|
|
777 auto sib = leftOf(parentOf(x));
|
|
778 if (colorOf(sib) is RED)
|
|
779 {
|
|
780 setColor(sib, BLACK);
|
|
781 setColor(parentOf(x), RED);
|
|
782 root = parentOf(x).rotateRight(root);
|
|
783 sib = leftOf(parentOf(x));
|
|
784 }
|
|
785 if (colorOf(rightOf(sib)) is BLACK && colorOf(leftOf(sib)) is BLACK)
|
|
786 {
|
|
787 setColor(sib, RED);
|
|
788 x = parentOf(x);
|
|
789 }
|
|
790 else
|
|
791 {
|
|
792 if (colorOf(leftOf(sib)) is BLACK)
|
|
793 {
|
|
794 setColor(rightOf(sib), BLACK);
|
|
795 setColor(sib, RED);
|
|
796 root = sib.rotateLeft(root);
|
|
797 sib = leftOf(parentOf(x));
|
|
798 }
|
|
799 setColor(sib, colorOf(parentOf(x)));
|
|
800 setColor(parentOf(x), BLACK);
|
|
801 setColor(leftOf(sib), BLACK);
|
|
802 root = parentOf(x).rotateRight(root);
|
|
803 x = root;
|
|
804 }
|
|
805 }
|
|
806 }
|
|
807 setColor(x, BLACK);
|
|
808 return root;
|
|
809 }
|
|
810 }
|
|
811
|