tinc-vpn.org Git - tinc/blob - lib/avl_tree.c

   1 /*
   2     avl_tree.c -- avl_ tree and linked list convenience
   3     Copyright (C) 1998 Michael H. Buselli
   4                   2000-2005 Ivo Timmermans,
   5                   2000-2006 Guus Sliepen <guus@tinc-vpn.org>
   6                   2000-2005 Wessel Dankers <wsl@tinc-vpn.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21
  22     Original AVL tree library by Michael H. Buselli <cosine@cosine.org>.
  23
  24     Modified 2000-11-28 by Wessel Dankers <wsl@tinc-vpn.org> to use counts
  25     instead of depths, to add the ->next and ->prev and to generally obfuscate
  26     the code. Mail me if you found a bug.
  27
  28     Cleaned up and incorporated some of the ideas from the red-black tree
  29     library for inclusion into tinc (http://www.tinc-vpn.org/) by
  30     Guus Sliepen <guus@tinc-vpn.org>.
  31
  32     $Id$
  33 */
  34
  35 #include "system.h"
  36
  37 #include "avl_tree.h"
  38 #include "xalloc.h"
  39
  40 #ifdef AVL_COUNT
  41 #define AVL_NODE_COUNT(n)  ((n) ? (n)->count : 0)
  42 #define AVL_L_COUNT(n)     (AVL_NODE_COUNT((n)->left))
  43 #define AVL_R_COUNT(n)     (AVL_NODE_COUNT((n)->right))
  44 #define AVL_CALC_COUNT(n)  (AVL_L_COUNT(n) + AVL_R_COUNT(n) + 1)
  45 #endif
  46
  47 #ifdef AVL_DEPTH
  48 #define AVL_NODE_DEPTH(n)  ((n) ? (n)->depth : 0)
  49 #define L_AVL_DEPTH(n)     (AVL_NODE_DEPTH((n)->left))
  50 #define R_AVL_DEPTH(n)     (AVL_NODE_DEPTH((n)->right))
  51 #define AVL_CALC_DEPTH(n)  ((L_AVL_DEPTH(n)>R_AVL_DEPTH(n)?L_AVL_DEPTH(n):R_AVL_DEPTH(n)) + 1)
  52 #endif
  53
  54 #ifndef AVL_DEPTH
  55 static int lg(unsigned int u) __attribute__ ((__const__));
  56
  57 static int lg(unsigned int u) {
  58         int r = 1;
  59
  60         if(!u)
  61                 return 0;
  62
  63         if(u & 0xffff0000) {
  64                 u >>= 16;
  65                 r += 16;
  66         }
  67
  68         if(u & 0x0000ff00) {
  69                 u >>= 8;
  70                 r += 8;
  71         }
  72
  73         if(u & 0x000000f0) {
  74                 u >>= 4;
  75                 r += 4;
  76         }
  77
  78         if(u & 0x0000000c) {
  79                 u >>= 2;
  80                 r += 2;
  81         }
  82
  83         if(u & 0x00000002)
  84                 r++;
  85
  86         return r;
  87 }
  88 #endif
  89
  90 /* Internal helper functions */
  91
  92 static int avl_check_balance(const avl_node_t *node) {
  93 #ifdef AVL_DEPTH
  94         int d;
  95
  96         d = R_AVL_DEPTH(node) - L_AVL_DEPTH(node);
  97
  98         return d < -1 ? -1 : d > 1 ? 1 : 0;
  99 #else
 100 /*      int d;
 101  *      d = lg(AVL_R_COUNT(node)) - lg(AVL_L_COUNT(node));
 102  *      d = d<-1?-1:d>1?1:0;
 103  */
 104         int pl, r;
 105
 106         pl = lg(AVL_L_COUNT(node));
 107         r = AVL_R_COUNT(node);
 108
 109         if(r >> pl + 1)
 110                 return 1;
 111
 112         if(pl < 2 || r >> pl - 2)
 113                 return 0;
 114
 115         return -1;
 116 #endif
 117 }
 118
 119 static void avl_rebalance(avl_tree_t *tree, avl_node_t *node) {
 120         avl_node_t *child;
 121         avl_node_t *gchild;
 122         avl_node_t *parent;
 123         avl_node_t **superparent;
 124
 125         parent = node;
 126
 127         while(node) {
 128                 parent = node->parent;
 129
 130                 superparent =
 131                         parent ? node ==
 132                         parent->left ? &parent->left : &parent->right : &tree->root;
 133
 134                 switch (avl_check_balance(node)) {
 135                         case -1:
 136                                 child = node->left;
 137 #ifdef AVL_DEPTH
 138                                 if(L_AVL_DEPTH(child) >= R_AVL_DEPTH(child)) {
 139 #else
 140                                 if(AVL_L_COUNT(child) >= AVL_R_COUNT(child)) {
 141 #endif
 142                                         node->left = child->right;
 143                                         if(node->left)
 144                                                 node->left->parent = node;
 145
 146                                         child->right = node;
 147                                         node->parent = child;
 148                                         *superparent = child;
 149                                         child->parent = parent;
 150 #ifdef AVL_COUNT
 151                                         node->count = AVL_CALC_COUNT(node);
 152                                         child->count = AVL_CALC_COUNT(child);
 153 #endif
 154 #ifdef AVL_DEPTH
 155                                         node->depth = AVL_CALC_DEPTH(node);
 156                                         child->depth = AVL_CALC_DEPTH(child);
 157 #endif
 158                                 } else {
 159                                         gchild = child->right;
 160                                         node->left = gchild->right;
 161
 162                                         if(node->left)
 163                                                 node->left->parent = node;
 164                                         child->right = gchild->left;
 165
 166                                         if(child->right)
 167                                                 child->right->parent = child;
 168                                         gchild->right = node;
 169
 170                                         if(gchild->right)
 171                                                 gchild->right->parent = gchild;
 172                                         gchild->left = child;
 173
 174                                         if(gchild->left)
 175                                                 gchild->left->parent = gchild;
 176                                         *superparent = gchild;
 177
 178                                         gchild->parent = parent;
 179 #ifdef AVL_COUNT
 180                                         node->count = AVL_CALC_COUNT(node);
 181                                         child->count = AVL_CALC_COUNT(child);
 182                                         gchild->count = AVL_CALC_COUNT(gchild);
 183 #endif
 184 #ifdef AVL_DEPTH
 185                                         node->depth = AVL_CALC_DEPTH(node);
 186                                         child->depth = AVL_CALC_DEPTH(child);
 187                                         gchild->depth = AVL_CALC_DEPTH(gchild);
 188 #endif
 189                                 }
 190                                 break;
 191
 192                         case 1:
 193                                 child = node->right;
 194 #ifdef AVL_DEPTH
 195                                 if(R_AVL_DEPTH(child) >= L_AVL_DEPTH(child)) {
 196 #else
 197                                 if(AVL_R_COUNT(child) >= AVL_L_COUNT(child)) {
 198 #endif
 199                                         node->right = child->left;
 200                                         if(node->right)
 201                                                 node->right->parent = node;
 202                                         child->left = node;
 203                                         node->parent = child;
 204                                         *superparent = child;
 205                                         child->parent = parent;
 206 #ifdef AVL_COUNT
 207                                         node->count = AVL_CALC_COUNT(node);
 208                                         child->count = AVL_CALC_COUNT(child);
 209 #endif
 210 #ifdef AVL_DEPTH
 211                                         node->depth = AVL_CALC_DEPTH(node);
 212                                         child->depth = AVL_CALC_DEPTH(child);
 213 #endif
 214                                 } else {
 215                                         gchild = child->left;
 216                                         node->right = gchild->left;
 217
 218                                         if(node->right)
 219                                                 node->right->parent = node;
 220                                         child->left = gchild->right;
 221
 222                                         if(child->left)
 223                                                 child->left->parent = child;
 224                                         gchild->left = node;
 225
 226                                         if(gchild->left)
 227                                                 gchild->left->parent = gchild;
 228                                         gchild->right = child;
 229
 230                                         if(gchild->right)
 231                                                 gchild->right->parent = gchild;
 232
 233                                         *superparent = gchild;
 234                                         gchild->parent = parent;
 235 #ifdef AVL_COUNT
 236                                         node->count = AVL_CALC_COUNT(node);
 237                                         child->count = AVL_CALC_COUNT(child);
 238                                         gchild->count = AVL_CALC_COUNT(gchild);
 239 #endif
 240 #ifdef AVL_DEPTH
 241                                         node->depth = AVL_CALC_DEPTH(node);
 242                                         child->depth = AVL_CALC_DEPTH(child);
 243                                         gchild->depth = AVL_CALC_DEPTH(gchild);
 244 #endif
 245                                 }
 246                                 break;
 247
 248                         default:
 249 #ifdef AVL_COUNT
 250                                 node->count = AVL_CALC_COUNT(node);
 251 #endif
 252 #ifdef AVL_DEPTH
 253                                 node->depth = AVL_CALC_DEPTH(node);
 254 #endif
 255                 }
 256                 node = parent;
 257         }
 258 }
 259
 260 /* (De)constructors */
 261
 262 avl_tree_t *avl_alloc_tree(avl_compare_t compare, avl_action_t delete) {
 263         avl_tree_t *tree;
 264
 265         tree = xmalloc_and_zero(sizeof(avl_tree_t));
 266         tree->compare = compare;
 267         tree->delete = delete;
 268
 269         return tree;
 270 }
 271
 272 void avl_free_tree(avl_tree_t *tree) {
 273         free(tree);
 274 }
 275
 276 avl_node_t *avl_alloc_node(void) {
 277         return xmalloc_and_zero(sizeof(avl_node_t));
 278 }
 279
 280 void avl_free_node(avl_tree_t *tree, avl_node_t *node) {
 281         if(node->data && tree->delete)
 282                 tree->delete(node->data);
 283
 284         free(node);
 285 }
 286
 287 /* Searching */
 288
 289 void *avl_search(const avl_tree_t *tree, const void *data) {
 290         avl_node_t *node;
 291
 292         node = avl_search_node(tree, data);
 293
 294         return node ? node->data : NULL;
 295 }
 296
 297 void *avl_search_closest(const avl_tree_t *tree, const void *data, int *result) {
 298         avl_node_t *node;
 299
 300         node = avl_search_closest_node(tree, data, result);
 301
 302         return node ? node->data : NULL;
 303 }
 304
 305 void *avl_search_closest_smaller(const avl_tree_t *tree, const void *data) {
 306         avl_node_t *node;
 307
 308         node = avl_search_closest_smaller_node(tree, data);
 309
 310         return node ? node->data : NULL;
 311 }
 312
 313 void *avl_search_closest_greater(const avl_tree_t *tree, const void *data) {
 314         avl_node_t *node;
 315
 316         node = avl_search_closest_greater_node(tree, data);
 317
 318         return node ? node->data : NULL;
 319 }
 320
 321 avl_node_t *avl_search_node(const avl_tree_t *tree, const void *data) {
 322         avl_node_t *node;
 323         int result;
 324
 325         node = avl_search_closest_node(tree, data, &result);
 326
 327         return result ? NULL : node;
 328 }
 329
 330 avl_node_t *avl_search_closest_node(const avl_tree_t *tree, const void *data,
 331                                                                         int *result) {
 332         avl_node_t *node;
 333         int c;
 334
 335         node = tree->root;
 336
 337         if(!node) {
 338                 if(result)
 339                         *result = 0;
 340                 return NULL;
 341         }
 342
 343         for(;;) {
 344                 c = tree->compare(data, node->data);
 345
 346                 if(c < 0) {
 347                         if(node->left)
 348                                 node = node->left;
 349                         else {
 350                                 if(result)
 351                                         *result = -1;
 352                                 break;
 353                         }
 354                 } else if(c > 0) {
 355                         if(node->right)
 356                                 node = node->right;
 357                         else {
 358                                 if(result)
 359                                         *result = 1;
 360                                 break;
 361                         }
 362                 } else {
 363                         if(result)
 364                                 *result = 0;
 365                         break;
 366                 }
 367         }
 368
 369         return node;
 370 }
 371
 372 avl_node_t *avl_search_closest_smaller_node(const avl_tree_t *tree,
 373                                                                                         const void *data) {
 374         avl_node_t *node;
 375         int result;
 376
 377         node = avl_search_closest_node(tree, data, &result);
 378
 379         if(result < 0)
 380                 node = node->prev;
 381
 382         return node;
 383 }
 384
 385 avl_node_t *avl_search_closest_greater_node(const avl_tree_t *tree,
 386                                                                                         const void *data) {
 387         avl_node_t *node;
 388         int result;
 389
 390         node = avl_search_closest_node(tree, data, &result);
 391
 392         if(result > 0)
 393                 node = node->next;
 394
 395         return node;
 396 }
 397
 398 /* Insertion and deletion */
 399
 400 avl_node_t *avl_insert(avl_tree_t *tree, void *data) {
 401         avl_node_t *closest, *new;
 402         int result;
 403
 404         if(!tree->root) {
 405                 new = avl_alloc_node();
 406                 new->data = data;
 407                 avl_insert_top(tree, new);
 408         } else {
 409                 closest = avl_search_closest_node(tree, data, &result);
 410
 411                 switch (result) {
 412                         case -1:
 413                                 new = avl_alloc_node();
 414                                 new->data = data;
 415                                 avl_insert_before(tree, closest, new);
 416                                 break;
 417
 418                         case 1:
 419                                 new = avl_alloc_node();
 420                                 new->data = data;
 421                                 avl_insert_after(tree, closest, new);
 422                                 break;
 423
 424                         default:
 425                                 return NULL;
 426                 }
 427         }
 428
 429 #ifdef AVL_COUNT
 430         new->count = 1;
 431 #endif
 432 #ifdef AVL_DEPTH
 433         new->depth = 1;
 434 #endif
 435
 436         return new;
 437 }
 438
 439 avl_node_t *avl_insert_node(avl_tree_t *tree, avl_node_t *node) {
 440         avl_node_t *closest;
 441         int result;
 442
 443         if(!tree->root)
 444                 avl_insert_top(tree, node);
 445         else {
 446                 closest = avl_search_closest_node(tree, node->data, &result);
 447
 448                 switch (result) {
 449                         case -1:
 450                                 avl_insert_before(tree, closest, node);
 451                                 break;
 452
 453                         case 1:
 454                                 avl_insert_after(tree, closest, node);
 455                                 break;
 456
 457                         case 0:
 458                                 return NULL;
 459                 }
 460         }
 461
 462 #ifdef AVL_COUNT
 463         node->count = 1;
 464 #endif
 465 #ifdef AVL_DEPTH
 466         node->depth = 1;
 467 #endif
 468
 469         return node;
 470 }
 471
 472 void avl_insert_top(avl_tree_t *tree, avl_node_t *node) {
 473         node->prev = node->next = node->parent = NULL;
 474         tree->head = tree->tail = tree->root = node;
 475 }
 476
 477 void avl_insert_before(avl_tree_t *tree, avl_node_t *before,
 478                                            avl_node_t *node) {
 479         if(!before) {
 480                 if(tree->tail)
 481                         avl_insert_after(tree, tree->tail, node);
 482                 else
 483                         avl_insert_top(tree, node);
 484                 return;
 485         }
 486
 487         node->next = before;
 488         node->parent = before;
 489         node->prev = before->prev;
 490
 491         if(before->left) {
 492                 avl_insert_after(tree, before->prev, node);
 493                 return;
 494         }
 495
 496         if(before->prev)
 497                 before->prev->next = node;
 498         else
 499                 tree->head = node;
 500
 501         before->prev = node;
 502         before->left = node;
 503
 504         avl_rebalance(tree, before);
 505 }
 506
 507 void avl_insert_after(avl_tree_t *tree, avl_node_t *after, avl_node_t *node) {
 508         if(!after) {
 509                 if(tree->head)
 510                         avl_insert_before(tree, tree->head, node);
 511                 else
 512                         avl_insert_top(tree, node);
 513                 return;
 514         }
 515
 516         if(after->right) {
 517                 avl_insert_before(tree, after->next, node);
 518                 return;
 519         }
 520
 521         node->prev = after;
 522         node->parent = after;
 523         node->next = after->next;
 524
 525         if(after->next)
 526                 after->next->prev = node;
 527         else
 528                 tree->tail = node;
 529
 530         after->next = node;
 531         after->right = node;
 532
 533         avl_rebalance(tree, after);
 534 }
 535
 536 avl_node_t *avl_unlink(avl_tree_t *tree, void *data) {
 537         avl_node_t *node;
 538
 539         node = avl_search_node(tree, data);
 540
 541         if(node)
 542                 avl_unlink_node(tree, node);
 543
 544         return node;
 545 }
 546
 547 void avl_unlink_node(avl_tree_t *tree, avl_node_t *node) {
 548         avl_node_t *parent;
 549         avl_node_t **superparent;
 550         avl_node_t *subst, *left, *right;
 551         avl_node_t *balnode;
 552
 553         if(node->prev)
 554                 node->prev->next = node->next;
 555         else
 556                 tree->head = node->next;
 557         if(node->next)
 558                 node->next->prev = node->prev;
 559         else
 560                 tree->tail = node->prev;
 561
 562         parent = node->parent;
 563
 564         superparent =
 565                 parent ? node ==
 566                 parent->left ? &parent->left : &parent->right : &tree->root;
 567
 568         left = node->left;
 569         right = node->right;
 570         if(!left) {
 571                 *superparent = right;
 572
 573                 if(right)
 574                         right->parent = parent;
 575
 576                 balnode = parent;
 577         } else if(!right) {
 578                 *superparent = left;
 579                 left->parent = parent;
 580                 balnode = parent;
 581         } else {
 582                 subst = node->prev;
 583
 584                 if(subst == left) {
 585                         balnode = subst;
 586                 } else {
 587                         balnode = subst->parent;
 588                         balnode->right = subst->left;
 589
 590                         if(balnode->right)
 591                                 balnode->right->parent = balnode;
 592
 593                         subst->left = left;
 594                         left->parent = subst;
 595                 }
 596
 597                 subst->right = right;
 598                 subst->parent = parent;
 599                 right->parent = subst;
 600                 *superparent = subst;
 601         }
 602
 603         avl_rebalance(tree, balnode);
 604
 605         node->next = node->prev = node->parent = node->left = node->right = NULL;
 606
 607 #ifdef AVL_COUNT
 608         node->count = 0;
 609 #endif
 610 #ifdef AVL_DEPTH
 611         node->depth = 0;
 612 #endif
 613 }
 614
 615 void avl_delete_node(avl_tree_t *tree, avl_node_t *node) {
 616         avl_unlink_node(tree, node);
 617         avl_free_node(tree, node);
 618 }
 619
 620 void avl_delete(avl_tree_t *tree, void *data) {
 621         avl_node_t *node;
 622
 623         node = avl_search_node(tree, data);
 624
 625         if(node)
 626                 avl_delete_node(tree, node);
 627 }
 628
 629 /* Fast tree cleanup */
 630
 631 void avl_delete_tree(avl_tree_t *tree) {
 632         avl_node_t *node, *next;
 633
 634         for(node = tree->head; node; node = next) {
 635                 next = node->next;
 636                 avl_free_node(tree, node);
 637         }
 638
 639         avl_free_tree(tree);
 640 }
 641
 642 /* Tree walking */
 643
 644 void avl_foreach(const avl_tree_t *tree, avl_action_t action) {
 645         avl_node_t *node, *next;
 646
 647         for(node = tree->head; node; node = next) {
 648                 next = node->next;
 649                 action(node->data);
 650         }
 651 }
 652
 653 void avl_foreach_node(const avl_tree_t *tree, avl_action_t action) {
 654         avl_node_t *node, *next;
 655
 656         for(node = tree->head; node; node = next) {
 657                 next = node->next;
 658                 action(node);
 659         }
 660 }
 661
 662 /* Indexing */
 663
 664 #ifdef AVL_COUNT
 665 unsigned int avl_count(const avl_tree_t *tree) {
 666         return AVL_NODE_COUNT(tree->root);
 667 }
 668
 669 avl_node_t *avl_get_node(const avl_tree_t *tree, unsigned int index) {
 670         avl_node_t *node;
 671         unsigned int c;
 672
 673         node = tree->root;
 674
 675         while(node) {
 676                 c = AVL_L_COUNT(node);
 677
 678                 if(index < c) {
 679                         node = node->left;
 680                 } else if(index > c) {
 681                         node = node->right;
 682                         index -= c + 1;
 683                 } else {
 684                         return node;
 685                 }
 686         }
 687
 688         return NULL;
 689 }
 690
 691 unsigned int avl_index(const avl_node_t *node) {
 692         avl_node_t *next;
 693         unsigned int index;
 694
 695         index = AVL_L_COUNT(node);
 696
 697         while((next = node->parent)) {
 698                 if(node == next->right)
 699                         index += AVL_L_COUNT(next) + 1;
 700                 node = next;
 701         }
 702
 703         return index;
 704 }
 705 #endif
 706 #ifdef AVL_DEPTH
 707 unsigned int avl_depth(const avl_tree_t *tree) {
 708         return AVL_NODE_DEPTH(tree->root);
 709 }
 710 #endif