tinc-vpn.org Git - tinc/blob - src/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 along
  19     with this program; if not, write to the Free Software Foundation, Inc.,
  20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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
  33 #include "system.h"
  34
  35 #include "avl_tree.h"
  36 #include "xalloc.h"
  37
  38 #ifdef AVL_COUNT
  39 #define AVL_NODE_COUNT(n)  ((n) ? (n)->count : 0)
  40 #define AVL_L_COUNT(n)     (AVL_NODE_COUNT((n)->left))
  41 #define AVL_R_COUNT(n)     (AVL_NODE_COUNT((n)->right))
  42 #define AVL_CALC_COUNT(n)  (AVL_L_COUNT(n) + AVL_R_COUNT(n) + 1)
  43 #endif
  44
  45 #ifdef AVL_DEPTH
  46 #define AVL_NODE_DEPTH(n)  ((n) ? (n)->depth : 0)
  47 #define L_AVL_DEPTH(n)     (AVL_NODE_DEPTH((n)->left))
  48 #define R_AVL_DEPTH(n)     (AVL_NODE_DEPTH((n)->right))
  49 #define AVL_CALC_DEPTH(n)  ((L_AVL_DEPTH(n)>R_AVL_DEPTH(n)?L_AVL_DEPTH(n):R_AVL_DEPTH(n)) + 1)
  50 #endif
  51
  52 #ifndef AVL_DEPTH
  53 static int lg(unsigned int u) __attribute__ ((__const__));
  54
  55 static int lg(unsigned int u)
  56 {
  57         int r = 1;
  58
  59         if(!u)
  60                 return 0;
  61
  62         if(u & 0xffff0000) {
  63                 u >>= 16;
  64                 r += 16;
  65         }
  66
  67         if(u & 0x0000ff00) {
  68                 u >>= 8;
  69                 r += 8;
  70         }
  71
  72         if(u & 0x000000f0) {
  73                 u >>= 4;
  74                 r += 4;
  75         }
  76
  77         if(u & 0x0000000c) {
  78                 u >>= 2;
  79                 r += 2;
  80         }
  81
  82         if(u & 0x00000002)
  83                 r++;
  84
  85         return r;
  86 }
  87 #endif
  88
  89 /* Internal helper functions */
  90
  91 static int avl_check_balance(const avl_node_t *node)
  92 {
  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 {
 121         avl_node_t *child;
 122         avl_node_t *gchild;
 123         avl_node_t *parent;
 124         avl_node_t **superparent;
 125
 126         parent = node;
 127
 128         while(node) {
 129                 parent = node->parent;
 130
 131                 superparent =
 132                         parent ? node ==
 133                         parent->left ? &parent->left : &parent->right : &tree->root;
 134
 135                 switch (avl_check_balance(node)) {
 136                         case -1:
 137                                 child = node->left;
 138 #ifdef AVL_DEPTH
 139                                 if(L_AVL_DEPTH(child) >= R_AVL_DEPTH(child)) {
 140 #else
 141                                 if(AVL_L_COUNT(child) >= AVL_R_COUNT(child)) {
 142 #endif
 143                                         node->left = child->right;
 144                                         if(node->left)
 145                                                 node->left->parent = node;
 146
 147                                         child->right = node;
 148                                         node->parent = child;
 149                                         *superparent = child;
 150                                         child->parent = parent;
 151 #ifdef AVL_COUNT
 152                                         node->count = AVL_CALC_COUNT(node);
 153                                         child->count = AVL_CALC_COUNT(child);
 154 #endif
 155 #ifdef AVL_DEPTH
 156                                         node->depth = AVL_CALC_DEPTH(node);
 157                                         child->depth = AVL_CALC_DEPTH(child);
 158 #endif
 159                                 } else {
 160                                         gchild = child->right;
 161                                         node->left = gchild->right;
 162
 163                                         if(node->left)
 164                                                 node->left->parent = node;
 165                                         child->right = gchild->left;
 166
 167                                         if(child->right)
 168                                                 child->right->parent = child;
 169                                         gchild->right = node;
 170
 171                                         if(gchild->right)
 172                                                 gchild->right->parent = gchild;
 173                                         gchild->left = child;
 174
 175                                         if(gchild->left)
 176                                                 gchild->left->parent = gchild;
 177                                         *superparent = gchild;
 178
 179                                         gchild->parent = parent;
 180 #ifdef AVL_COUNT
 181                                         node->count = AVL_CALC_COUNT(node);
 182                                         child->count = AVL_CALC_COUNT(child);
 183                                         gchild->count = AVL_CALC_COUNT(gchild);
 184 #endif
 185 #ifdef AVL_DEPTH
 186                                         node->depth = AVL_CALC_DEPTH(node);
 187                                         child->depth = AVL_CALC_DEPTH(child);
 188                                         gchild->depth = AVL_CALC_DEPTH(gchild);
 189 #endif
 190                                 }
 191                                 break;
 192
 193                         case 1:
 194                                 child = node->right;
 195 #ifdef AVL_DEPTH
 196                                 if(R_AVL_DEPTH(child) >= L_AVL_DEPTH(child)) {
 197 #else
 198                                 if(AVL_R_COUNT(child) >= AVL_L_COUNT(child)) {
 199 #endif
 200                                         node->right = child->left;
 201                                         if(node->right)
 202                                                 node->right->parent = node;
 203                                         child->left = node;
 204                                         node->parent = child;
 205                                         *superparent = child;
 206                                         child->parent = parent;
 207 #ifdef AVL_COUNT
 208                                         node->count = AVL_CALC_COUNT(node);
 209                                         child->count = AVL_CALC_COUNT(child);
 210 #endif
 211 #ifdef AVL_DEPTH
 212                                         node->depth = AVL_CALC_DEPTH(node);
 213                                         child->depth = AVL_CALC_DEPTH(child);
 214 #endif
 215                                 } else {
 216                                         gchild = child->left;
 217                                         node->right = gchild->left;
 218
 219                                         if(node->right)
 220                                                 node->right->parent = node;
 221                                         child->left = gchild->right;
 222
 223                                         if(child->left)
 224                                                 child->left->parent = child;
 225                                         gchild->left = node;
 226
 227                                         if(gchild->left)
 228                                                 gchild->left->parent = gchild;
 229                                         gchild->right = child;
 230
 231                                         if(gchild->right)
 232                                                 gchild->right->parent = gchild;
 233
 234                                         *superparent = gchild;
 235                                         gchild->parent = parent;
 236 #ifdef AVL_COUNT
 237                                         node->count = AVL_CALC_COUNT(node);
 238                                         child->count = AVL_CALC_COUNT(child);
 239                                         gchild->count = AVL_CALC_COUNT(gchild);
 240 #endif
 241 #ifdef AVL_DEPTH
 242                                         node->depth = AVL_CALC_DEPTH(node);
 243                                         child->depth = AVL_CALC_DEPTH(child);
 244                                         gchild->depth = AVL_CALC_DEPTH(gchild);
 245 #endif
 246                                 }
 247                                 break;
 248
 249                         default:
 250 #ifdef AVL_COUNT
 251                                 node->count = AVL_CALC_COUNT(node);
 252 #endif
 253 #ifdef AVL_DEPTH
 254                                 node->depth = AVL_CALC_DEPTH(node);
 255 #endif
 256                 }
 257                 node = parent;
 258         }
 259 }
 260
 261 /* (De)constructors */
 262
 263 avl_tree_t *avl_alloc_tree(avl_compare_t compare, avl_action_t delete)
 264 {
 265         avl_tree_t *tree;
 266
 267         tree = xmalloc_and_zero(sizeof(avl_tree_t));
 268         tree->compare = compare;
 269         tree->delete = delete;
 270
 271         return tree;
 272 }
 273
 274 void avl_free_tree(avl_tree_t *tree)
 275 {
 276         free(tree);
 277 }
 278
 279 avl_node_t *avl_alloc_node(void)
 280 {
 281         return xmalloc_and_zero(sizeof(avl_node_t));
 282 }
 283
 284 void avl_free_node(avl_tree_t *tree, avl_node_t *node)
 285 {
 286         if(node->data && tree->delete)
 287                 tree->delete(node->data);
 288
 289         free(node);
 290 }
 291
 292 /* Searching */
 293
 294 void *avl_search(const avl_tree_t *tree, const void *data)
 295 {
 296         avl_node_t *node;
 297
 298         node = avl_search_node(tree, data);
 299
 300         return node ? node->data : NULL;
 301 }
 302
 303 void *avl_search_closest(const avl_tree_t *tree, const void *data, int *result)
 304 {
 305         avl_node_t *node;
 306
 307         node = avl_search_closest_node(tree, data, result);
 308
 309         return node ? node->data : NULL;
 310 }
 311
 312 void *avl_search_closest_smaller(const avl_tree_t *tree, const void *data)
 313 {
 314         avl_node_t *node;
 315
 316         node = avl_search_closest_smaller_node(tree, data);
 317
 318         return node ? node->data : NULL;
 319 }
 320
 321 void *avl_search_closest_greater(const avl_tree_t *tree, const void *data)
 322 {
 323         avl_node_t *node;
 324
 325         node = avl_search_closest_greater_node(tree, data);
 326
 327         return node ? node->data : NULL;
 328 }
 329
 330 avl_node_t *avl_search_node(const avl_tree_t *tree, const void *data)
 331 {
 332         avl_node_t *node;
 333         int result;
 334
 335         node = avl_search_closest_node(tree, data, &result);
 336
 337         return result ? NULL : node;
 338 }
 339
 340 avl_node_t *avl_search_closest_node(const avl_tree_t *tree, const void *data,
 341                                                                         int *result)
 342 {
 343         avl_node_t *node;
 344         int c;
 345
 346         node = tree->root;
 347
 348         if(!node) {
 349                 if(result)
 350                         *result = 0;
 351                 return NULL;
 352         }
 353
 354         for(;;) {
 355                 c = tree->compare(data, node->data);
 356
 357                 if(c < 0) {
 358                         if(node->left)
 359                                 node = node->left;
 360                         else {
 361                                 if(result)
 362                                         *result = -1;
 363                                 break;
 364                         }
 365                 } else if(c > 0) {
 366                         if(node->right)
 367                                 node = node->right;
 368                         else {
 369                                 if(result)
 370                                         *result = 1;
 371                                 break;
 372                         }
 373                 } else {
 374                         if(result)
 375                                 *result = 0;
 376                         break;
 377                 }
 378         }
 379
 380         return node;
 381 }
 382
 383 avl_node_t *avl_search_closest_smaller_node(const avl_tree_t *tree,
 384                                                                                         const void *data)
 385 {
 386         avl_node_t *node;
 387         int result;
 388
 389         node = avl_search_closest_node(tree, data, &result);
 390
 391         if(result < 0)
 392                 node = node->prev;
 393
 394         return node;
 395 }
 396
 397 avl_node_t *avl_search_closest_greater_node(const avl_tree_t *tree,
 398                                                                                         const void *data)
 399 {
 400         avl_node_t *node;
 401         int result;
 402
 403         node = avl_search_closest_node(tree, data, &result);
 404
 405         if(result > 0)
 406                 node = node->next;
 407
 408         return node;
 409 }
 410
 411 /* Insertion and deletion */
 412
 413 avl_node_t *avl_insert(avl_tree_t *tree, void *data)
 414 {
 415         avl_node_t *closest, *new;
 416         int result;
 417
 418         if(!tree->root) {
 419                 new = avl_alloc_node();
 420                 new->data = data;
 421                 avl_insert_top(tree, new);
 422         } else {
 423                 closest = avl_search_closest_node(tree, data, &result);
 424
 425                 switch (result) {
 426                         case -1:
 427                                 new = avl_alloc_node();
 428                                 new->data = data;
 429                                 avl_insert_before(tree, closest, new);
 430                                 break;
 431
 432                         case 1:
 433                                 new = avl_alloc_node();
 434                                 new->data = data;
 435                                 avl_insert_after(tree, closest, new);
 436                                 break;
 437
 438                         default:
 439                                 return NULL;
 440                 }
 441         }
 442
 443 #ifdef AVL_COUNT
 444         new->count = 1;
 445 #endif
 446 #ifdef AVL_DEPTH
 447         new->depth = 1;
 448 #endif
 449
 450         return new;
 451 }
 452
 453 avl_node_t *avl_insert_node(avl_tree_t *tree, avl_node_t *node)
 454 {
 455         avl_node_t *closest;
 456         int result;
 457
 458         if(!tree->root)
 459                 avl_insert_top(tree, node);
 460         else {
 461                 closest = avl_search_closest_node(tree, node->data, &result);
 462
 463                 switch (result) {
 464                         case -1:
 465                                 avl_insert_before(tree, closest, node);
 466                                 break;
 467
 468                         case 1:
 469                                 avl_insert_after(tree, closest, node);
 470                                 break;
 471
 472                         case 0:
 473                                 return NULL;
 474                 }
 475         }
 476
 477 #ifdef AVL_COUNT
 478         node->count = 1;
 479 #endif
 480 #ifdef AVL_DEPTH
 481         node->depth = 1;
 482 #endif
 483
 484         return node;
 485 }
 486
 487 void avl_insert_top(avl_tree_t *tree, avl_node_t *node)
 488 {
 489         node->prev = node->next = node->parent = NULL;
 490         tree->head = tree->tail = tree->root = node;
 491 }
 492
 493 void avl_insert_before(avl_tree_t *tree, avl_node_t *before,
 494                                            avl_node_t *node)
 495 {
 496         if(!before) {
 497                 if(tree->tail)
 498                         avl_insert_after(tree, tree->tail, node);
 499                 else
 500                         avl_insert_top(tree, node);
 501                 return;
 502         }
 503
 504         node->next = before;
 505         node->parent = before;
 506         node->prev = before->prev;
 507
 508         if(before->left) {
 509                 avl_insert_after(tree, before->prev, node);
 510                 return;
 511         }
 512
 513         if(before->prev)
 514                 before->prev->next = node;
 515         else
 516                 tree->head = node;
 517
 518         before->prev = node;
 519         before->left = node;
 520
 521         avl_rebalance(tree, before);
 522 }
 523
 524 void avl_insert_after(avl_tree_t *tree, avl_node_t *after, avl_node_t *node)
 525 {
 526         if(!after) {
 527                 if(tree->head)
 528                         avl_insert_before(tree, tree->head, node);
 529                 else
 530                         avl_insert_top(tree, node);
 531                 return;
 532         }
 533
 534         if(after->right) {
 535                 avl_insert_before(tree, after->next, node);
 536                 return;
 537         }
 538
 539         node->prev = after;
 540         node->parent = after;
 541         node->next = after->next;
 542
 543         if(after->next)
 544                 after->next->prev = node;
 545         else
 546                 tree->tail = node;
 547
 548         after->next = node;
 549         after->right = node;
 550
 551         avl_rebalance(tree, after);
 552 }
 553
 554 avl_node_t *avl_unlink(avl_tree_t *tree, void *data)
 555 {
 556         avl_node_t *node;
 557
 558         node = avl_search_node(tree, data);
 559
 560         if(node)
 561                 avl_unlink_node(tree, node);
 562
 563         return node;
 564 }
 565
 566 void avl_unlink_node(avl_tree_t *tree, avl_node_t *node)
 567 {
 568         avl_node_t *parent;
 569         avl_node_t **superparent;
 570         avl_node_t *subst, *left, *right;
 571         avl_node_t *balnode;
 572
 573         if(node->prev)
 574                 node->prev->next = node->next;
 575         else
 576                 tree->head = node->next;
 577         if(node->next)
 578                 node->next->prev = node->prev;
 579         else
 580                 tree->tail = node->prev;
 581
 582         parent = node->parent;
 583
 584         superparent =
 585                 parent ? node ==
 586                 parent->left ? &parent->left : &parent->right : &tree->root;
 587
 588         left = node->left;
 589         right = node->right;
 590         if(!left) {
 591                 *superparent = right;
 592
 593                 if(right)
 594                         right->parent = parent;
 595
 596                 balnode = parent;
 597         } else if(!right) {
 598                 *superparent = left;
 599                 left->parent = parent;
 600                 balnode = parent;
 601         } else {
 602                 subst = node->prev;
 603
 604                 if(subst == left) {
 605                         balnode = subst;
 606                 } else {
 607                         balnode = subst->parent;
 608                         balnode->right = subst->left;
 609
 610                         if(balnode->right)
 611                                 balnode->right->parent = balnode;
 612
 613                         subst->left = left;
 614                         left->parent = subst;
 615                 }
 616
 617                 subst->right = right;
 618                 subst->parent = parent;
 619                 right->parent = subst;
 620                 *superparent = subst;
 621         }
 622
 623         avl_rebalance(tree, balnode);
 624
 625         node->next = node->prev = node->parent = node->left = node->right = NULL;
 626
 627 #ifdef AVL_COUNT
 628         node->count = 0;
 629 #endif
 630 #ifdef AVL_DEPTH
 631         node->depth = 0;
 632 #endif
 633 }
 634
 635 void avl_delete_node(avl_tree_t *tree, avl_node_t *node)
 636 {
 637         avl_unlink_node(tree, node);
 638         avl_free_node(tree, node);
 639 }
 640
 641 void avl_delete(avl_tree_t *tree, void *data)
 642 {
 643         avl_node_t *node;
 644
 645         node = avl_search_node(tree, data);
 646
 647         if(node)
 648                 avl_delete_node(tree, node);
 649 }
 650
 651 /* Fast tree cleanup */
 652
 653 void avl_delete_tree(avl_tree_t *tree)
 654 {
 655         avl_node_t *node, *next;
 656
 657         for(node = tree->head; node; node = next) {
 658                 next = node->next;
 659                 avl_free_node(tree, node);
 660         }
 661
 662         avl_free_tree(tree);
 663 }
 664
 665 /* Tree walking */
 666
 667 void avl_foreach(const avl_tree_t *tree, avl_action_t action)
 668 {
 669         avl_node_t *node, *next;
 670
 671         for(node = tree->head; node; node = next) {
 672                 next = node->next;
 673                 action(node->data);
 674         }
 675 }
 676
 677 void avl_foreach_node(const avl_tree_t *tree, avl_action_t action)
 678 {
 679         avl_node_t *node, *next;
 680
 681         for(node = tree->head; node; node = next) {
 682                 next = node->next;
 683                 action(node);
 684         }
 685 }
 686
 687 /* Indexing */
 688
 689 #ifdef AVL_COUNT
 690 unsigned int avl_count(const avl_tree_t *tree)
 691 {
 692         return AVL_NODE_COUNT(tree->root);
 693 }
 694
 695 avl_node_t *avl_get_node(const avl_tree_t *tree, unsigned int index)
 696 {
 697         avl_node_t *node;
 698         unsigned int c;
 699
 700         node = tree->root;
 701
 702         while(node) {
 703                 c = AVL_L_COUNT(node);
 704
 705                 if(index < c) {
 706                         node = node->left;
 707                 } else if(index > c) {
 708                         node = node->right;
 709                         index -= c + 1;
 710                 } else {
 711                         return node;
 712                 }
 713         }
 714
 715         return NULL;
 716 }
 717
 718 unsigned int avl_index(const avl_node_t *node)
 719 {
 720         avl_node_t *next;
 721         unsigned int index;
 722
 723         index = AVL_L_COUNT(node);
 724
 725         while((next = node->parent)) {
 726                 if(node == next->right)
 727                         index += AVL_L_COUNT(next) + 1;
 728                 node = next;
 729         }
 730
 731         return index;
 732 }
 733 #endif
 734 #ifdef AVL_DEPTH
 735 unsigned int avl_depth(const avl_tree_t *tree)
 736 {
 737         return AVL_NODE_DEPTH(tree->root);
 738 }
 739 #endif