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   1 /*
   2     splay_tree.c -- splay tree and linked list convenience
   3     Copyright (C) 2004 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
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19     $Id: splay_tree.c 1374 2004-03-21 14:21:22Z guus $
  20 */
  21
  22 #include "system.h"
  23
  24 #include "splay_tree.h"
  25 #include "xalloc.h"
  26
  27 /* Splay operation */
  28
  29 static splay_node_t *splay_top_down(splay_tree_t *tree, const void *data, int *result) {
  30         splay_node_t left = {0}, right = {0};
  31         splay_node_t *leftbottom = &left, *rightbottom = &right, *child;
  32         splay_node_t *node = tree->root;
  33         int c;
  34
  35         while((c = tree->compare(data, node->data))) {
  36                 if(c < 0) {
  37                         child = node->left;
  38
  39                         if(child) {
  40                                 c = tree->compare(data, child->data);
  41
  42                                 if(c < 0) {
  43                                         rightbottom->left = child;
  44                                         child->parent = rightbottom;
  45                                         rightbottom = child;
  46
  47                                         node->left = child->right;
  48                                         child->right = node;
  49                                         node->parent = child;
  50                                         node = child->left;
  51                                         child->left = NULL;
  52                                 } else if (c > 0) {
  53                                         if(!child->right)
  54                                                 break;
  55
  56                                         leftbottom->right = child;
  57                                         child->parent = leftbottom;
  58                                         leftbottom = child;
  59
  60                                         rightbottom->left = node;
  61                                         node->parent = rightbottom;
  62                                         rightbottom = node;
  63
  64                                         node->left = NULL;
  65                                         node = child->right;
  66                                         child->right = NULL;
  67                                 } else {
  68                                         rightbottom->left = node;
  69                                         node->parent = rightbottom;
  70                                         rightbottom = node;
  71
  72                                         node->left = NULL;
  73                                         child->parent = NULL;
  74                                         node = child;
  75                                         break;
  76                                 }
  77                         } else {
  78                                 break;
  79                         }
  80                 } else {
  81                         child = node->right;
  82
  83                         if(child) {
  84                                 c = tree->compare(data, child->data);
  85
  86                                 if(c > 0) {
  87                                         leftbottom->right = child;
  88                                         child->parent = leftbottom;
  89                                         leftbottom = child;
  90
  91                                         node->right = child->left;
  92                                         child->left = node;
  93                                         node->parent = child;
  94                                         node = child->right;
  95                                         child->right = NULL;
  96                                 } else if (c < 0) {
  97                                         if(!child->left)
  98                                                 break;
  99
 100                                         rightbottom->left = child;
 101                                         child->parent = rightbottom;
 102                                         rightbottom = child;
 103
 104                                         leftbottom->right = node;
 105                                         node->parent = leftbottom;
 106                                         leftbottom = node;
 107
 108                                         node->right = NULL;
 109                                         node = child->left;
 110                                         child->left = NULL;
 111                                 } else {
 112                                         leftbottom->right = node;
 113                                         node->parent = leftbottom;
 114                                         leftbottom = node;
 115
 116                                         node->right = NULL;
 117                                         child->parent = NULL;
 118                                         node = child;
 119                                         break;
 120                                 }
 121                         } else {
 122                                 break;
 123                         }
 124                 }
 125         }
 126
 127         tree->root = node;
 128
 129         /* Merge trees */
 130
 131         if(left.right) {
 132                 if(node->left) {
 133                         leftbottom->right = node->left;
 134                         node->left->parent = leftbottom;
 135                 }
 136                 node->left = left.right;
 137                 left.right->parent = node;
 138         }
 139
 140         if(right.left) {
 141                 if(node->right) {
 142                         rightbottom->left = node->right;
 143                         node->right->parent = rightbottom;
 144                 }
 145                 node->right = right.left;
 146                 right.left->parent = node;
 147         }
 148
 149         if(result)
 150                 *result = c;
 151
 152         return node;
 153 }
 154
 155
 156 static void splay_bottom_up(splay_tree_t *tree, splay_node_t *node) {
 157         splay_node_t *parent, *grandparent;
 158
 159         while(node->parent) {
 160                 parent = node->parent;
 161                 grandparent = node->parent->parent;
 162
 163                 if(!grandparent) { /* zig */
 164                         if(node == parent->left) {
 165                                 parent->left = node->right;
 166                                 node->right = parent;
 167                         } else {
 168                                 parent->right = node->left;
 169                                 node->left = parent;
 170                         }
 171
 172                         parent->parent = node;
 173                         node->parent = NULL;
 174                 } else {
 175                         if(node == grandparent->left->left) { /* left zig-zig */
 176                                 grandparent->left = parent->right;
 177                                 parent->right = grandparent;
 178                                 grandparent->parent = parent;
 179
 180                                 parent->left = node->right;
 181                                 node->right = parent;
 182                                 parent->parent = node;
 183
 184                         } else if(node == grandparent->right->right) { /* right zig-zig */
 185                                 grandparent->right = parent->left;
 186                                 parent->left = grandparent;
 187                                 grandparent->parent = parent;
 188
 189                                 parent->right = node->left;
 190                                 node->left = parent;
 191                                 parent->parent = node;
 192
 193                         } else if(node == grandparent->left->right) { /* left-right zig-zag */
 194                                 parent->right = node->left;
 195                                 node->left = parent;
 196                                 parent->parent = node;
 197
 198                                 grandparent->left = node->right;
 199                                 node->right = grandparent;
 200                                 grandparent->parent = node;
 201
 202                         } else { /* right-left zig-zag */
 203                                 parent->left = node->right;
 204                                 node->right = parent;
 205                                 parent->parent = node;
 206
 207                                 grandparent->right = node->left;
 208                                 node->left = grandparent;
 209                                 grandparent->parent = node;
 210                         }
 211
 212                         node->parent = grandparent->parent;
 213
 214                         if(node->parent) {
 215                                 if(grandparent == node->parent->left)
 216                                         node->parent->left = node;
 217                                 else
 218                                         node->parent->right = node;
 219                         }
 220                 }
 221         }
 222
 223         tree->root = node;
 224 }
 225
 226 /* (De)constructors */
 227
 228 splay_tree_t *splay_alloc_tree(splay_compare_t compare, splay_action_t delete) {
 229         splay_tree_t *tree;
 230
 231         tree = xmalloc_and_zero(sizeof(splay_tree_t));
 232         tree->compare = compare;
 233         tree->delete = delete;
 234
 235         return tree;
 236 }
 237
 238 void splay_free_tree(splay_tree_t *tree) {
 239         free(tree);
 240 }
 241
 242 splay_node_t *splay_alloc_node(void) {
 243         return xmalloc_and_zero(sizeof(splay_node_t));
 244 }
 245
 246 void splay_free_node(splay_tree_t *tree, splay_node_t *node) {
 247         if(node->data && tree->delete)
 248                 tree->delete(node->data);
 249
 250         free(node);
 251 }
 252
 253 /* Searching */
 254
 255 void *splay_search(splay_tree_t *tree, const void *data) {
 256         splay_node_t *node;
 257
 258         node = splay_search_node(tree, data);
 259
 260         return node ? node->data : NULL;
 261 }
 262
 263 void *splay_search_closest(splay_tree_t *tree, const void *data, int *result) {
 264         splay_node_t *node;
 265
 266         node = splay_search_closest_node(tree, data, result);
 267
 268         return node ? node->data : NULL;
 269 }
 270
 271 void *splay_search_closest_smaller(splay_tree_t *tree, const void *data) {
 272         splay_node_t *node;
 273
 274         node = splay_search_closest_smaller_node(tree, data);
 275
 276         return node ? node->data : NULL;
 277 }
 278
 279 void *splay_search_closest_greater(splay_tree_t *tree, const void *data) {
 280         splay_node_t *node;
 281
 282         node = splay_search_closest_greater_node(tree, data);
 283
 284         return node ? node->data : NULL;
 285 }
 286
 287 splay_node_t *splay_search_node(splay_tree_t *tree, const void *data) {
 288         splay_node_t *node;
 289         int result;
 290
 291         node = splay_search_closest_node(tree, data, &result);
 292
 293         return result ? NULL : node;
 294 }
 295
 296 splay_node_t *splay_search_closest_node_nosplay(const splay_tree_t *tree, const void *data, int *result) {
 297         splay_node_t *node;
 298         int c;
 299
 300         node = tree->root;
 301
 302         if(!node) {
 303                 if(result)
 304                         *result = 0;
 305                 return NULL;
 306         }
 307
 308         for(;;) {
 309                 c = tree->compare(data, node->data);
 310
 311                 if(c < 0) {
 312                         if(node->left)
 313                                 node = node->left;
 314                         else {
 315                                 if(result)
 316                                         *result = -1;
 317                                 break;
 318                         }
 319                 } else if(c > 0) {
 320                         if(node->right)
 321                                 node = node->right;
 322                         else {
 323                                 if(result)
 324                                         *result = 1;
 325                                 break;
 326                         }
 327                 } else {
 328                         if(result)
 329                                 *result = 0;
 330                         break;
 331                 }
 332         }
 333
 334         return node;
 335 }
 336
 337 splay_node_t *splay_search_closest_node(splay_tree_t *tree, const void *data, int *result) {
 338         return splay_top_down(tree, data, result);
 339 }
 340
 341 splay_node_t *splay_search_closest_smaller_node(splay_tree_t *tree, const void *data) {
 342         splay_node_t *node;
 343         int result;
 344
 345         node = splay_search_closest_node(tree, data, &result);
 346
 347         if(result < 0)
 348                 node = node->prev;
 349
 350         return node;
 351 }
 352
 353 splay_node_t *splay_search_closest_greater_node(splay_tree_t *tree, const void *data) {
 354         splay_node_t *node;
 355         int result;
 356
 357         node = splay_search_closest_node(tree, data, &result);
 358
 359         if(result > 0)
 360                 node = node->next;
 361
 362         return node;
 363 }
 364
 365 /* Insertion and deletion */
 366
 367 splay_node_t *splay_insert(splay_tree_t *tree, void *data) {
 368         splay_node_t *closest, *new;
 369         int result;
 370
 371         if(!tree->root) {
 372                 new = splay_alloc_node();
 373                 new->data = data;
 374                 splay_insert_top(tree, new);
 375         } else {
 376                 closest = splay_search_closest_node_nosplay(tree, data, &result);
 377
 378                 if(!result)
 379                         return NULL;
 380
 381                 new = splay_alloc_node();
 382                 new->data = data;
 383
 384                 if(result < 0)
 385                         splay_insert_before(tree, closest, new);
 386                 else
 387                         splay_insert_after(tree, closest, new);
 388         }
 389
 390         return new;
 391 }
 392
 393 splay_node_t *splay_insert_node(splay_tree_t *tree, splay_node_t *node) {
 394         splay_node_t *closest;
 395         int result;
 396
 397         if(!tree->root)
 398                 splay_insert_top(tree, node);
 399         else {
 400                 closest = splay_search_closest_node_nosplay(tree, node->data, &result);
 401
 402                 if(!result)
 403                         return NULL;
 404
 405                 if(result < 0)
 406                         splay_insert_before(tree, closest, node);
 407                 else
 408                         splay_insert_after(tree, closest, node);
 409         }
 410
 411         return node;
 412 }
 413
 414 void splay_insert_top(splay_tree_t *tree, splay_node_t *node) {
 415         node->prev = node->next = node->parent = NULL;
 416         tree->head = tree->tail = tree->root = node;
 417 }
 418
 419 void splay_insert_before(splay_tree_t *tree, splay_node_t *before, splay_node_t *node) {
 420         if(!before) {
 421                 if(tree->tail)
 422                         splay_insert_after(tree, tree->tail, node);
 423                 else
 424                         splay_insert_top(tree, node);
 425                 return;
 426         }
 427
 428         node->next = before;
 429         node->parent = before;
 430         node->prev = before->prev;
 431
 432         if(before->left) {
 433                 splay_insert_after(tree, before->prev, node);
 434                 return;
 435         }
 436
 437         if(before->prev)
 438                 before->prev->next = node;
 439         else
 440                 tree->head = node;
 441
 442         before->prev = node;
 443         before->left = node;
 444
 445         splay_bottom_up(tree, node);
 446 }
 447
 448 void splay_insert_after(splay_tree_t *tree, splay_node_t *after, splay_node_t *node) {
 449         if(!after) {
 450                 if(tree->head)
 451                         splay_insert_before(tree, tree->head, node);
 452                 else
 453                         splay_insert_top(tree, node);
 454                 return;
 455         }
 456
 457         if(after->right) {
 458                 splay_insert_before(tree, after->next, node);
 459                 return;
 460         }
 461
 462         node->prev = after;
 463         node->parent = after;
 464         node->next = after->next;
 465
 466         if(after->next)
 467                 after->next->prev = node;
 468         else
 469                 tree->tail = node;
 470
 471         after->next = node;
 472         after->right = node;
 473
 474         splay_bottom_up(tree, node);
 475 }
 476
 477 splay_node_t *splay_unlink(splay_tree_t *tree, void *data) {
 478         splay_node_t *node;
 479         int result;
 480
 481         node = splay_search_closest_node_nosplay(tree, data, &result);
 482
 483         if(node && !result)
 484                 splay_unlink_node(tree, node);
 485
 486         return node;
 487 }
 488
 489 void splay_unlink_node(splay_tree_t *tree, splay_node_t *node) {
 490         if(node->prev)
 491                 node->prev->next = node->next;
 492         else
 493                 tree->head = node->next;
 494
 495         if(node->next)
 496                 node->next->prev = node->prev;
 497         else
 498                 tree->tail = node->prev;
 499
 500         if(node->left) {
 501                 node->left->parent = NULL;
 502                 tree->root = node->left;
 503
 504                 if(node->right) {
 505                         splay_bottom_up(tree, node->prev);
 506                         node->prev->right = node->right;
 507                         node->right->parent = node->prev;
 508                 }
 509         } else {
 510                 node->right->parent = NULL;
 511                 tree->root = node->right;
 512         }
 513 }
 514
 515 void splay_delete_node(splay_tree_t *tree, splay_node_t *node) {
 516         splay_unlink_node(tree, node);
 517         splay_free_node(tree, node);
 518 }
 519
 520 void splay_delete(splay_tree_t *tree, void *data) {
 521         splay_node_t *node;
 522
 523         node = splay_search_node(tree, data);
 524
 525         if(node)
 526                 splay_delete_node(tree, node);
 527 }
 528
 529 /* Fast tree cleanup */
 530
 531 void splay_delete_tree(splay_tree_t *tree) {
 532         splay_node_t *node, *next;
 533
 534         for(node = tree->root; node; node = next) {
 535                 next = node->next;
 536                 splay_free_node(tree, node);
 537         }
 538
 539         splay_free_tree(tree);
 540 }
 541
 542 /* Tree walking */
 543
 544 void splay_foreach(const splay_tree_t *tree, splay_action_t action) {
 545         splay_node_t *node, *next;
 546
 547         for(node = tree->head; node; node = next) {
 548                 next = node->next;
 549                 action(node->data);
 550         }
 551 }
 552
 553 void splay_foreach_node(const splay_tree_t *tree, splay_action_t action) {
 554         splay_node_t *node, *next;
 555
 556         for(node = tree->head; node; node = next) {
 557                 next = node->next;
 558                 action(node);
 559         }
 560 }