src/rbtree.c

   1 /*
   2  * nao-ulib
   3  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>
   4  * Subject to the GPL.
   5  * Nao-Team HTWK,
   6  * Faculty of Computer Science, Mathematics and Natural Sciences,
   7  * Leipzig University of Applied Sciences (HTWK Leipzig)
   8  */
   9
  10 /*
  11  * Red Black Trees
  12  * (C) 1999  Andrea Arcangeli <andrea@suse.de>
  13  * (C) 2002  David Woodhouse <dwmw2@infradead.org>
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  28  *
  29  * linux/lib/rbtree.c
  30  */
  31
  32 #include <stdio.h>
  33
  34 #include "rbtree.h"
  35
  36 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
  37 {
  38         struct rb_node *right = node->rb_right;
  39         struct rb_node *parent = rb_parent(node);
  40
  41         if ((node->rb_right = right->rb_left))
  42                 rb_set_parent(right->rb_left, node);
  43         right->rb_left = node;
  44
  45         rb_set_parent(right, parent);
  46
  47         if (parent)
  48         {
  49                 if (node == parent->rb_left)
  50                         parent->rb_left = right;
  51                 else
  52                         parent->rb_right = right;
  53         }
  54         else
  55                 root->rb_node = right;
  56         rb_set_parent(node, right);
  57 }
  58
  59 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
  60 {
  61         struct rb_node *left = node->rb_left;
  62         struct rb_node *parent = rb_parent(node);
  63
  64         if ((node->rb_left = left->rb_right))
  65                 rb_set_parent(left->rb_right, node);
  66         left->rb_right = node;
  67
  68         rb_set_parent(left, parent);
  69
  70         if (parent)
  71         {
  72                 if (node == parent->rb_right)
  73                         parent->rb_right = left;
  74                 else
  75                         parent->rb_left = left;
  76         }
  77         else
  78                 root->rb_node = left;
  79         rb_set_parent(node, left);
  80 }
  81
  82 void rb_insert_color(struct rb_node *node, struct rb_root *root)
  83 {
  84         struct rb_node *parent, *gparent;
  85
  86         while ((parent = rb_parent(node)) && rb_is_red(parent))
  87         {
  88                 gparent = rb_parent(parent);
  89
  90                 if (parent == gparent->rb_left)
  91                 {
  92                         {
  93                                 register struct rb_node *uncle = gparent->rb_right;
  94                                 if (uncle && rb_is_red(uncle))
  95                                 {
  96                                         rb_set_black(uncle);
  97                                         rb_set_black(parent);
  98                                         rb_set_red(gparent);
  99                                         node = gparent;
 100                                         continue;
 101                                 }
 102                         }
 103
 104                         if (parent->rb_right == node)
 105                         {
 106                                 register struct rb_node *tmp;
 107                                 __rb_rotate_left(parent, root);
 108                                 tmp = parent;
 109                                 parent = node;
 110                                 node = tmp;
 111                         }
 112
 113                         rb_set_black(parent);
 114                         rb_set_red(gparent);
 115                         __rb_rotate_right(gparent, root);
 116                 } else {
 117                         {
 118                                 register struct rb_node *uncle = gparent->rb_left;
 119                                 if (uncle && rb_is_red(uncle))
 120                                 {
 121                                         rb_set_black(uncle);
 122                                         rb_set_black(parent);
 123                                         rb_set_red(gparent);
 124                                         node = gparent;
 125                                         continue;
 126                                 }
 127                         }
 128
 129                         if (parent->rb_left == node)
 130                         {
 131                                 register struct rb_node *tmp;
 132                                 __rb_rotate_right(parent, root);
 133                                 tmp = parent;
 134                                 parent = node;
 135                                 node = tmp;
 136                         }
 137
 138                         rb_set_black(parent);
 139                         rb_set_red(gparent);
 140                         __rb_rotate_left(gparent, root);
 141                 }
 142         }
 143
 144         rb_set_black(root->rb_node);
 145 }
 146
 147 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
 148                              struct rb_root *root)
 149 {
 150         struct rb_node *other;
 151
 152         while ((!node || rb_is_black(node)) && node != root->rb_node)
 153         {
 154                 if (parent->rb_left == node)
 155                 {
 156                         other = parent->rb_right;
 157                         if (rb_is_red(other))
 158                         {
 159                                 rb_set_black(other);
 160                                 rb_set_red(parent);
 161                                 __rb_rotate_left(parent, root);
 162                                 other = parent->rb_right;
 163                         }
 164                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
 165                             (!other->rb_right || rb_is_black(other->rb_right)))
 166                         {
 167                                 rb_set_red(other);
 168                                 node = parent;
 169                                 parent = rb_parent(node);
 170                         }
 171                         else
 172                         {
 173                                 if (!other->rb_right || rb_is_black(other->rb_right))
 174                                 {
 175                                         struct rb_node *o_left;
 176                                         if ((o_left = other->rb_left))
 177                                                 rb_set_black(o_left);
 178                                         rb_set_red(other);
 179                                         __rb_rotate_right(other, root);
 180                                         other = parent->rb_right;
 181                                 }
 182                                 rb_set_color(other, rb_color(parent));
 183                                 rb_set_black(parent);
 184                                 if (other->rb_right)
 185                                         rb_set_black(other->rb_right);
 186                                 __rb_rotate_left(parent, root);
 187                                 node = root->rb_node;
 188                                 break;
 189                         }
 190                 }
 191                 else
 192                 {
 193                         other = parent->rb_left;
 194                         if (rb_is_red(other))
 195                         {
 196                                 rb_set_black(other);
 197                                 rb_set_red(parent);
 198                                 __rb_rotate_right(parent, root);
 199                                 other = parent->rb_left;
 200                         }
 201                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
 202                             (!other->rb_right || rb_is_black(other->rb_right)))
 203                         {
 204                                 rb_set_red(other);
 205                                 node = parent;
 206                                 parent = rb_parent(node);
 207                         }
 208                         else
 209                         {
 210                                 if (!other->rb_left || rb_is_black(other->rb_left))
 211                                 {
 212                                         register struct rb_node *o_right;
 213                                         if ((o_right = other->rb_right))
 214                                                 rb_set_black(o_right);
 215                                         rb_set_red(other);
 216                                         __rb_rotate_left(other, root);
 217                                         other = parent->rb_left;
 218                                 }
 219                                 rb_set_color(other, rb_color(parent));
 220                                 rb_set_black(parent);
 221                                 if (other->rb_left)
 222                                         rb_set_black(other->rb_left);
 223                                 __rb_rotate_right(parent, root);
 224                                 node = root->rb_node;
 225                                 break;
 226                         }
 227                 }
 228         }
 229         if (node)
 230                 rb_set_black(node);
 231 }
 232
 233 void rb_erase(struct rb_node *node, struct rb_root *root)
 234 {
 235         struct rb_node *child, *parent;
 236         int color;
 237
 238         if (!node->rb_left)
 239                 child = node->rb_right;
 240         else if (!node->rb_right)
 241                 child = node->rb_left;
 242         else
 243         {
 244                 struct rb_node *old = node, *left;
 245
 246                 node = node->rb_right;
 247                 while ((left = node->rb_left) != NULL)
 248                         node = left;
 249                 child = node->rb_right;
 250                 parent = rb_parent(node);
 251                 color = rb_color(node);
 252
 253                 if (child)
 254                         rb_set_parent(child, parent);
 255                 if (parent == old) {
 256                         parent->rb_right = child;
 257                         parent = node;
 258                 } else
 259                         parent->rb_left = child;
 260
 261                 node->rb_parent_color = old->rb_parent_color;
 262                 node->rb_right = old->rb_right;
 263                 node->rb_left = old->rb_left;
 264
 265                 if (rb_parent(old))
 266                 {
 267                         if (rb_parent(old)->rb_left == old)
 268                                 rb_parent(old)->rb_left = node;
 269                         else
 270                                 rb_parent(old)->rb_right = node;
 271                 } else
 272                         root->rb_node = node;
 273
 274                 rb_set_parent(old->rb_left, node);
 275                 if (old->rb_right)
 276                         rb_set_parent(old->rb_right, node);
 277                 goto color;
 278         }
 279
 280         parent = rb_parent(node);
 281         color = rb_color(node);
 282
 283         if (child)
 284                 rb_set_parent(child, parent);
 285         if (parent)
 286         {
 287                 if (parent->rb_left == node)
 288                         parent->rb_left = child;
 289                 else
 290                         parent->rb_right = child;
 291         }
 292         else
 293                 root->rb_node = child;
 294
 295  color:
 296         if (color == RB_BLACK)
 297                 __rb_erase_color(child, parent, root);
 298 }
 299
 300 /*
 301  * This function returns the first node (in sort order) of the tree.
 302  */
 303 struct rb_node *rb_first(struct rb_root *root)
 304 {
 305         struct rb_node  *n;
 306
 307         n = root->rb_node;
 308         if (!n)
 309                 return NULL;
 310         while (n->rb_left)
 311                 n = n->rb_left;
 312         return n;
 313 }
 314
 315 struct rb_node *rb_last(struct rb_root *root)
 316 {
 317         struct rb_node  *n;
 318
 319         n = root->rb_node;
 320         if (!n)
 321                 return NULL;
 322         while (n->rb_right)
 323                 n = n->rb_right;
 324         return n;
 325 }
 326
 327 struct rb_node *rb_next(struct rb_node *node)
 328 {
 329         struct rb_node *parent;
 330
 331         if (rb_parent(node) == node)
 332                 return NULL;
 333
 334         /* If we have a right-hand child, go down and then left as far
 335            as we can. */
 336         if (node->rb_right) {
 337                 node = node->rb_right;
 338                 while (node->rb_left)
 339                         node=node->rb_left;
 340                 return node;
 341         }
 342
 343         /* No right-hand children.  Everything down and left is
 344            smaller than us, so any 'next' node must be in the general
 345            direction of our parent. Go up the tree; any time the
 346            ancestor is a right-hand child of its parent, keep going
 347            up. First time it's a left-hand child of its parent, said
 348            parent is our 'next' node. */
 349         while ((parent = rb_parent(node)) && node == parent->rb_right)
 350                 node = parent;
 351
 352         return parent;
 353 }
 354
 355 struct rb_node *rb_prev(struct rb_node *node)
 356 {
 357         struct rb_node *parent;
 358
 359         if (rb_parent(node) == node)
 360                 return NULL;
 361
 362         /* If we have a left-hand child, go down and then right as far
 363            as we can. */
 364         if (node->rb_left) {
 365                 node = node->rb_left;
 366                 while (node->rb_right)
 367                         node=node->rb_right;
 368                 return node;
 369         }
 370
 371         /* No left-hand children. Go up till we find an ancestor which
 372            is a right-hand child of its parent */
 373         while ((parent = rb_parent(node)) && node == parent->rb_left)
 374                 node = parent;
 375
 376         return parent;
 377 }
 378
 379 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 380                      struct rb_root *root)
 381 {
 382         struct rb_node *parent = rb_parent(victim);
 383
 384         /* Set the surrounding nodes to point to the replacement */
 385         if (parent) {
 386                 if (victim == parent->rb_left)
 387                         parent->rb_left = new;
 388                 else
 389                         parent->rb_right = new;
 390         } else {
 391                 root->rb_node = new;
 392         }
 393         if (victim->rb_left)
 394                 rb_set_parent(victim->rb_left, new);
 395         if (victim->rb_right)
 396                 rb_set_parent(victim->rb_right, new);
 397
 398         /* Copy the pointers/colour from the victim to the replacement */
 399         *new = *victim;
 400 }