git.meshlink.io Git - meshlink/blob - src/splay_tree.c

   1 /*
   2     splay_tree.c -- splay tree and linked list convenience
   3     Copyright (C) 2004-2013 Guus Sliepen <guus@tinc-vpn.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21
  22 #include "splay_tree.h"
  23 #include "xalloc.h"
  24
  25 /* Splay operation */
  26
  27 static splay_node_t *splay_top_down(splay_tree_t *tree, const void *data, int *result) {
  28         splay_node_t left = {NULL}, right = {NULL};
  29         splay_node_t *leftbottom = &left, *rightbottom = &right, *child, *grandchild;
  30         splay_node_t *root = tree->root;
  31         int c;
  32
  33         if(!root) {
  34                 if(result)
  35                         *result = 0;
  36                 return NULL;
  37         }
  38
  39         while((c = tree->compare(data, root->data))) {
  40                 if(c < 0 && (child = root->left)) {
  41                         c = tree->compare(data, child->data);
  42
  43                         if(c < 0 && (grandchild = child->left)) {
  44                                 rightbottom->left = child;
  45                                 child->parent = rightbottom;
  46                                 rightbottom = child;
  47
  48                                 if((root->left = child->right))
  49                                         child->right->parent = root;
  50
  51                                 child->right = root;
  52                                 root->parent = child;
  53
  54                                 child->left = NULL;
  55                                 grandchild->parent = NULL;
  56
  57                                 root = grandchild;
  58                         } else if (c > 0 && (grandchild = child->right)) {
  59                                 leftbottom->right = child;
  60                                 child->parent = leftbottom;
  61                                 leftbottom = child;
  62
  63                                 child->right = NULL;
  64                                 grandchild->parent = NULL;
  65
  66                                 rightbottom->left = root;
  67                                 root->parent = rightbottom;
  68                                 rightbottom = root;
  69
  70                                 root->left = NULL;
  71
  72                                 root = grandchild;
  73                         } else {
  74                                 rightbottom->left = root;
  75                                 root->parent = rightbottom;
  76                                 rightbottom = root;
  77
  78                                 root->left = NULL;
  79                                 child->parent = NULL;
  80
  81                                 root = child;
  82                                 break;
  83                         }
  84                 } else if(c > 0 && (child = root->right)) {
  85                         c = tree->compare(data, child->data);
  86
  87                         if(c > 0 && (grandchild = child->right)) {
  88                                 leftbottom->right = child;
  89                                 child->parent = leftbottom;
  90                                 leftbottom = child;
  91
  92                                 if((root->right = child->left))
  93                                         child->left->parent = root;
  94
  95                                 child->left = root;
  96                                 root->parent = child;
  97
  98                                 child->right = NULL;
  99                                 grandchild->parent = NULL;
 100
 101                                 root = grandchild;
 102                         } else if (c < 0 && (grandchild = child->left)) {
 103                                 rightbottom->left = child;
 104                                 child->parent = rightbottom;
 105                                 rightbottom = child;
 106
 107                                 child->left = NULL;
 108                                 grandchild->parent = NULL;
 109
 110                                 leftbottom->right = root;
 111                                 root->parent = leftbottom;
 112                                 leftbottom = root;
 113
 114                                 root->right = NULL;
 115
 116                                 root = grandchild;
 117                         } else {
 118                                 leftbottom->right = root;
 119                                 root->parent = leftbottom;
 120                                 leftbottom = root;
 121
 122                                 root->right = NULL;
 123                                 child->parent = NULL;
 124
 125                                 root = child;
 126                                 break;
 127                         }
 128                 } else {
 129                         break;
 130                 }
 131         }
 132
 133         /* Merge trees */
 134
 135         if(left.right) {
 136                 if(root->left) {
 137                         leftbottom->right = root->left;
 138                         root->left->parent = leftbottom;
 139                 }
 140                 root->left = left.right;
 141                 left.right->parent = root;
 142         }
 143
 144         if(right.left) {
 145                 if(root->right) {
 146                         rightbottom->left = root->right;
 147                         root->right->parent = rightbottom;
 148                 }
 149                 root->right = right.left;
 150                 right.left->parent = root;
 151         }
 152
 153         /* Return result */
 154
 155         tree->root = root;
 156         if(result)
 157                 *result = c;
 158
 159         return tree->root;
 160 }
 161
 162 static void splay_bottom_up(splay_tree_t *tree, splay_node_t *node) {
 163         splay_node_t *parent, *grandparent, *greatgrandparent;
 164
 165         while((parent = node->parent)) {
 166                 if(!(grandparent = parent->parent)) { /* zig */
 167                         if(node == parent->left) {
 168                                 if((parent->left = node->right))
 169                                         parent->left->parent = parent;
 170                                 node->right = parent;
 171                         } else {
 172                                 if((parent->right = node->left))
 173                                         parent->right->parent = parent;
 174                                 node->left = parent;
 175                         }
 176
 177                         parent->parent = node;
 178                         node->parent = NULL;
 179                 } else {
 180                         greatgrandparent = grandparent->parent;
 181
 182                         if(node == parent->left && parent == grandparent->left) { /* left zig-zig */
 183                                 if((grandparent->left = parent->right))
 184                                         grandparent->left->parent = grandparent;
 185                                 parent->right = grandparent;
 186                                 grandparent->parent = parent;
 187
 188                                 if((parent->left = node->right))
 189                                         parent->left->parent = parent;
 190                                 node->right = parent;
 191                                 parent->parent = node;
 192                         } else if(node == parent->right && parent == grandparent->right) { /* right zig-zig */
 193                                 if((grandparent->right = parent->left))
 194                                         grandparent->right->parent = grandparent;
 195                                 parent->left = grandparent;
 196                                 grandparent->parent = parent;
 197
 198                                 if((parent->right = node->left))
 199                                         parent->right->parent = parent;
 200                                 node->left = parent;
 201                                 parent->parent = node;
 202                         } else if(node == parent->right && parent == grandparent->left) { /* left-right zig-zag */
 203                                 if((parent->right = node->left))
 204                                         parent->right->parent = parent;
 205                                 node->left = parent;
 206                                 parent->parent = node;
 207
 208                                 if((grandparent->left = node->right))
 209                                         grandparent->left->parent = grandparent;
 210                                 node->right = grandparent;
 211                                 grandparent->parent = node;
 212                         } else { /* right-left zig-zag */
 213                                 if((parent->left = node->right))
 214                                         parent->left->parent = parent;
 215                                 node->right = parent;
 216                                 parent->parent = node;
 217
 218                                 if((grandparent->right = node->left))
 219                                         grandparent->right->parent = grandparent;
 220                                 node->left = grandparent;
 221                                 grandparent->parent = node;
 222                         }
 223
 224                         if((node->parent = greatgrandparent)) {
 225                                 if(grandparent == greatgrandparent->left)
 226                                         greatgrandparent->left = node;
 227                                 else
 228                                         greatgrandparent->right = node;
 229                         }
 230                 }
 231         }
 232
 233         tree->root = node;
 234 }
 235
 236 /* (De)constructors */
 237
 238 splay_tree_t *splay_alloc_tree(splay_compare_t compare, splay_action_t delete) {
 239         splay_tree_t *tree;
 240
 241         tree = xzalloc(sizeof(splay_tree_t));
 242         tree->compare = compare;
 243         tree->delete = delete;
 244
 245         return tree;
 246 }
 247
 248 void splay_free_tree(splay_tree_t *tree) {
 249         free(tree);
 250 }
 251
 252 splay_node_t *splay_alloc_node(void) {
 253         return xzalloc(sizeof(splay_node_t));
 254 }
 255
 256 void splay_free_node(splay_tree_t *tree, splay_node_t *node) {
 257         if(node->data && tree->delete)
 258                 tree->delete(node->data);
 259
 260         free(node);
 261 }
 262
 263 /* Searching */
 264
 265 void *splay_search(splay_tree_t *tree, const void *data) {
 266         splay_node_t *node;
 267
 268         node = splay_search_node(tree, data);
 269
 270         return node ? node->data : NULL;
 271 }
 272
 273 void *splay_search_closest(splay_tree_t *tree, const void *data, int *result) {
 274         splay_node_t *node;
 275
 276         node = splay_search_closest_node(tree, data, result);
 277
 278         return node ? node->data : NULL;
 279 }
 280
 281 void *splay_search_closest_smaller(splay_tree_t *tree, const void *data) {
 282         splay_node_t *node;
 283
 284         node = splay_search_closest_smaller_node(tree, data);
 285
 286         return node ? node->data : NULL;
 287 }
 288
 289 void *splay_search_closest_greater(splay_tree_t *tree, const void *data) {
 290         splay_node_t *node;
 291
 292         node = splay_search_closest_greater_node(tree, data);
 293
 294         return node ? node->data : NULL;
 295 }
 296
 297 splay_node_t *splay_search_node(splay_tree_t *tree, const void *data) {
 298         splay_node_t *node;
 299         int result;
 300
 301         node = splay_search_closest_node(tree, data, &result);
 302
 303         return result ? NULL : node;
 304 }
 305
 306 splay_node_t *splay_search_closest_node_nosplay(const splay_tree_t *tree, const void *data, int *result) {
 307         splay_node_t *node;
 308         int c;
 309
 310         node = tree->root;
 311
 312         if(!node) {
 313                 if(result)
 314                         *result = 0;
 315                 return NULL;
 316         }
 317
 318         for(;;) {
 319                 c = tree->compare(data, node->data);
 320
 321                 if(c < 0) {
 322                         if(node->left)
 323                                 node = node->left;
 324                         else
 325                                 break;
 326                 } else if(c > 0) {
 327                         if(node->right)
 328                                 node = node->right;
 329                         else
 330                                 break;
 331                 } else {
 332                         break;
 333                 }
 334         }
 335
 336         if(result)
 337                 *result = c;
 338         return node;
 339 }
 340
 341 splay_node_t *splay_search_closest_node(splay_tree_t *tree, const void *data, int *result) {
 342         return splay_top_down(tree, data, result);
 343 }
 344
 345 splay_node_t *splay_search_closest_smaller_node(splay_tree_t *tree, const void *data) {
 346         splay_node_t *node;
 347         int result;
 348
 349         node = splay_search_closest_node(tree, data, &result);
 350
 351         if(result < 0)
 352                 node = node->prev;
 353
 354         return node;
 355 }
 356
 357 splay_node_t *splay_search_closest_greater_node(splay_tree_t *tree, const void *data) {
 358         splay_node_t *node;
 359         int result;
 360
 361         node = splay_search_closest_node(tree, data, &result);
 362
 363         if(result > 0)
 364                 node = node->next;
 365
 366         return node;
 367 }
 368
 369 /* Insertion and deletion */
 370
 371 splay_node_t *splay_insert(splay_tree_t *tree, void *data) {
 372         splay_node_t *closest, *new;
 373         int result;
 374
 375         if(!tree->root) {
 376                 new = splay_alloc_node();
 377                 new->data = data;
 378                 splay_insert_top(tree, new);
 379         } else {
 380                 closest = splay_search_closest_node(tree, data, &result);
 381
 382                 if(!result)
 383                         return NULL;
 384
 385                 new = splay_alloc_node();
 386                 new->data = data;
 387
 388                 if(result < 0)
 389                         splay_insert_before(tree, closest, new);
 390                 else
 391                         splay_insert_after(tree, closest, new);
 392         }
 393
 394         return new;
 395 }
 396
 397 splay_node_t *splay_insert_node(splay_tree_t *tree, splay_node_t *node) {
 398         splay_node_t *closest;
 399         int result;
 400
 401         node->left = node->right = node->parent = node->next = node->prev = NULL;
 402
 403         if(!tree->root)
 404                 splay_insert_top(tree, node);
 405         else {
 406                 closest = splay_search_closest_node(tree, node->data, &result);
 407
 408                 if(!result)
 409                         return NULL;
 410
 411                 if(result < 0)
 412                         splay_insert_before(tree, closest, node);
 413                 else
 414                         splay_insert_after(tree, closest, node);
 415         }
 416
 417         return node;
 418 }
 419
 420 void splay_insert_top(splay_tree_t *tree, splay_node_t *node) {
 421         node->prev = node->next = node->left = node->right = node->parent = NULL;
 422         tree->head = tree->tail = tree->root = node;
 423         tree->count++;
 424 }
 425
 426 void splay_insert_before(splay_tree_t *tree, splay_node_t *before, splay_node_t *node) {
 427         if(!before) {
 428                 if(tree->tail)
 429                         splay_insert_after(tree, tree->tail, node);
 430                 else
 431                         splay_insert_top(tree, node);
 432                 return;
 433         }
 434
 435         node->next = before;
 436         if((node->prev = before->prev))
 437                 before->prev->next = node;
 438         else
 439                 tree->head = node;
 440         before->prev = node;
 441
 442         splay_bottom_up(tree, before);
 443
 444         node->right = before;
 445         before->parent = node;
 446         if((node->left = before->left))
 447                 before->left->parent = node;
 448         before->left = NULL;
 449
 450         node->parent = NULL;
 451         tree->root = node;
 452         tree->count++;
 453 }
 454
 455 void splay_insert_after(splay_tree_t *tree, splay_node_t *after, splay_node_t *node) {
 456         if(!after) {
 457                 if(tree->head)
 458                         splay_insert_before(tree, tree->head, node);
 459                 else
 460                         splay_insert_top(tree, node);
 461                 return;
 462         }
 463
 464         node->prev = after;
 465         if((node->next = after->next))
 466                 after->next->prev = node;
 467         else
 468                 tree->tail = node;
 469         after->next = node;
 470
 471         splay_bottom_up(tree, after);
 472
 473         node->left = after;
 474         after->parent = node;
 475         if((node->right = after->right))
 476                 after->right->parent = node;
 477         after->right = NULL;
 478
 479         node->parent = NULL;
 480         tree->root = node;
 481         tree->count++;
 482 }
 483
 484 splay_node_t *splay_unlink(splay_tree_t *tree, void *data) {
 485         splay_node_t *node;
 486
 487         node = splay_search_node(tree, data);
 488
 489         if(node)
 490                 splay_unlink_node(tree, node);
 491
 492         return node;
 493 }
 494
 495 void splay_unlink_node(splay_tree_t *tree, splay_node_t *node) {
 496         if(node->prev)
 497                 node->prev->next = node->next;
 498         else
 499                 tree->head = node->next;
 500
 501         if(node->next)
 502                 node->next->prev = node->prev;
 503         else
 504                 tree->tail = node->prev;
 505
 506         splay_bottom_up(tree, node);
 507
 508         if(node->prev) {
 509                 node->left->parent = NULL;
 510                 tree->root = node->left;
 511                 if((node->prev->right = node->right))
 512                         node->right->parent = node->prev;
 513         } else if(node->next) {
 514                 tree->root = node->right;
 515                 node->right->parent = NULL;
 516         } else {
 517                 tree->root = NULL;
 518         }
 519
 520         tree->count--;
 521 }
 522
 523 void splay_delete_node(splay_tree_t *tree, splay_node_t *node) {
 524         splay_unlink_node(tree, node);
 525         splay_free_node(tree, node);
 526 }
 527
 528 void splay_delete(splay_tree_t *tree, void *data) {
 529         splay_node_t *node;
 530
 531         node = splay_search_node(tree, data);
 532
 533         if(node)
 534                 splay_delete_node(tree, node);
 535 }
 536
 537 /* Fast tree cleanup */
 538
 539 void splay_delete_tree(splay_tree_t *tree) {
 540         for(splay_node_t *node = tree->head, *next; node; node = next) {
 541                 next = node->next;
 542                 splay_free_node(tree, node);
 543         }
 544
 545         splay_free_tree(tree);
 546 }
 547
 548 /* Tree walking */
 549
 550 void splay_foreach(const splay_tree_t *tree, splay_action_t action) {
 551         for(splay_node_t *node = tree->head, *next; node; node = next) {
 552                 next = node->next;
 553                 action(node->data);
 554         }
 555 }
 556
 557 void splay_foreach_node(const splay_tree_t *tree, splay_action_t action) {
 558         for(splay_node_t *node = tree->head, *next; node; node = next) {
 559                 next = node->next;
 560                 action(node);
 561         }
 562 }