1 /* A splay-tree datatype. 2 Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. 3 Contributed by Mark Mitchell (mark@markmitchell.com). 4 5 This file is part of GNU CC. 6 7 GNU CC is free software; you can redistribute it and/or modify it 8 under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 2, or (at your option) 10 any later version. 11 12 GNU CC is distributed in the hope that it will be useful, but 13 WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with GNU CC; see the file COPYING. If not, write to 19 the Free Software Foundation, 51 Franklin Street - Fifth Floor, 20 Boston, MA 02110-1301, USA. */ 21 22 /* For an easily readable description of splay-trees, see: 23 24 Lewis, Harry R. and Denenberg, Larry. Data Structures and Their 25 Algorithms. Harper-Collins, Inc. 1991. */ 26 27 #ifdef HAVE_CONFIG_H 28 #include "config.h" 29 #endif 30 31 #ifdef HAVE_STDLIB_H 32 #include <stdlib.h> 33 #endif 34 35 #include <stdio.h> 36 37 #include "libiberty.h" 38 #include "splay-tree.h" 39 40 static void splay_tree_delete_helper (splay_tree, splay_tree_node); 41 static inline void rotate_left (splay_tree_node *, 42 splay_tree_node, splay_tree_node); 43 static inline void rotate_right (splay_tree_node *, 44 splay_tree_node, splay_tree_node); 45 static void splay_tree_splay (splay_tree, splay_tree_key); 46 static int splay_tree_foreach_helper (splay_tree, splay_tree_node, 47 splay_tree_foreach_fn, void*); 48 49 /* Deallocate NODE (a member of SP), and all its sub-trees. */ 50 51 static void 52 splay_tree_delete_helper (splay_tree sp, splay_tree_node node) 53 { 54 splay_tree_node pending = 0; 55 splay_tree_node active = 0; 56 57 if (!node) 58 return; 59 60 #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x); 61 #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x); 62 63 KDEL (node->key); 64 VDEL (node->value); 65 66 /* We use the "key" field to hold the "next" pointer. */ 67 node->key = (splay_tree_key)pending; 68 pending = (splay_tree_node)node; 69 70 /* Now, keep processing the pending list until there aren't any 71 more. This is a little more complicated than just recursing, but 72 it doesn't toast the stack for large trees. */ 73 74 while (pending) 75 { 76 active = pending; 77 pending = 0; 78 while (active) 79 { 80 splay_tree_node temp; 81 82 /* active points to a node which has its key and value 83 deallocated, we just need to process left and right. */ 84 85 if (active->left) 86 { 87 KDEL (active->left->key); 88 VDEL (active->left->value); 89 active->left->key = (splay_tree_key)pending; 90 pending = (splay_tree_node)(active->left); 91 } 92 if (active->right) 93 { 94 KDEL (active->right->key); 95 VDEL (active->right->value); 96 active->right->key = (splay_tree_key)pending; 97 pending = (splay_tree_node)(active->right); 98 } 99 100 temp = active; 101 active = (splay_tree_node)(temp->key); 102 (*sp->deallocate) ((char*) temp, sp->allocate_data); 103 } 104 } 105 #undef KDEL 106 #undef VDEL 107 } 108 109 /* Rotate the edge joining the left child N with its parent P. PP is the 110 grandparents' pointer to P. */ 111 112 static inline void 113 rotate_left (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) 114 { 115 splay_tree_node tmp; 116 tmp = n->right; 117 n->right = p; 118 p->left = tmp; 119 *pp = n; 120 } 121 122 /* Rotate the edge joining the right child N with its parent P. PP is the 123 grandparents' pointer to P. */ 124 125 static inline void 126 rotate_right (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) 127 { 128 splay_tree_node tmp; 129 tmp = n->left; 130 n->left = p; 131 p->right = tmp; 132 *pp = n; 133 } 134 135 /* Bottom up splay of key. */ 136 137 static void 138 splay_tree_splay (splay_tree sp, splay_tree_key key) 139 { 140 if (sp->root == 0) 141 return; 142 143 do { 144 int cmp1, cmp2; 145 splay_tree_node n, c; 146 147 n = sp->root; 148 cmp1 = (*sp->comp) (key, n->key); 149 150 /* Found. */ 151 if (cmp1 == 0) 152 return; 153 154 /* Left or right? If no child, then we're done. */ 155 if (cmp1 < 0) 156 c = n->left; 157 else 158 c = n->right; 159 if (!c) 160 return; 161 162 /* Next one left or right? If found or no child, we're done 163 after one rotation. */ 164 cmp2 = (*sp->comp) (key, c->key); 165 if (cmp2 == 0 166 || (cmp2 < 0 && !c->left) 167 || (cmp2 > 0 && !c->right)) 168 { 169 if (cmp1 < 0) 170 rotate_left (&sp->root, n, c); 171 else 172 rotate_right (&sp->root, n, c); 173 return; 174 } 175 176 /* Now we have the four cases of double-rotation. */ 177 if (cmp1 < 0 && cmp2 < 0) 178 { 179 rotate_left (&n->left, c, c->left); 180 rotate_left (&sp->root, n, n->left); 181 } 182 else if (cmp1 > 0 && cmp2 > 0) 183 { 184 rotate_right (&n->right, c, c->right); 185 rotate_right (&sp->root, n, n->right); 186 } 187 else if (cmp1 < 0 && cmp2 > 0) 188 { 189 rotate_right (&n->left, c, c->right); 190 rotate_left (&sp->root, n, n->left); 191 } 192 else if (cmp1 > 0 && cmp2 < 0) 193 { 194 rotate_left (&n->right, c, c->left); 195 rotate_right (&sp->root, n, n->right); 196 } 197 } while (1); 198 } 199 200 /* Call FN, passing it the DATA, for every node below NODE, all of 201 which are from SP, following an in-order traversal. If FN every 202 returns a non-zero value, the iteration ceases immediately, and the 203 value is returned. Otherwise, this function returns 0. */ 204 205 static int 206 splay_tree_foreach_helper (splay_tree sp, splay_tree_node node, 207 splay_tree_foreach_fn fn, void *data) 208 { 209 int val; 210 211 if (!node) 212 return 0; 213 214 val = splay_tree_foreach_helper (sp, node->left, fn, data); 215 if (val) 216 return val; 217 218 val = (*fn)(node, data); 219 if (val) 220 return val; 221 222 return splay_tree_foreach_helper (sp, node->right, fn, data); 223 } 224 225 226 /* An allocator and deallocator based on xmalloc. */ 227 static void * 228 splay_tree_xmalloc_allocate (int size, void *data ATTRIBUTE_UNUSED) 229 { 230 return (void *) xmalloc (size); 231 } 232 233 static void 234 splay_tree_xmalloc_deallocate (void *object, void *data ATTRIBUTE_UNUSED) 235 { 236 free (object); 237 } 238 239 240 /* Allocate a new splay tree, using COMPARE_FN to compare nodes, 241 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate 242 values. Use xmalloc to allocate the splay tree structure, and any 243 nodes added. */ 244 245 splay_tree 246 splay_tree_new (splay_tree_compare_fn compare_fn, 247 splay_tree_delete_key_fn delete_key_fn, 248 splay_tree_delete_value_fn delete_value_fn) 249 { 250 return (splay_tree_new_with_allocator 251 (compare_fn, delete_key_fn, delete_value_fn, 252 splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0)); 253 } 254 255 256 /* Allocate a new splay tree, using COMPARE_FN to compare nodes, 257 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate 258 values. */ 259 260 splay_tree 261 splay_tree_new_with_allocator (splay_tree_compare_fn compare_fn, 262 splay_tree_delete_key_fn delete_key_fn, 263 splay_tree_delete_value_fn delete_value_fn, 264 splay_tree_allocate_fn allocate_fn, 265 splay_tree_deallocate_fn deallocate_fn, 266 void *allocate_data) 267 { 268 splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s), 269 allocate_data); 270 sp->root = 0; 271 sp->comp = compare_fn; 272 sp->delete_key = delete_key_fn; 273 sp->delete_value = delete_value_fn; 274 sp->allocate = allocate_fn; 275 sp->deallocate = deallocate_fn; 276 sp->allocate_data = allocate_data; 277 278 return sp; 279 } 280 281 /* Deallocate SP. */ 282 283 void 284 splay_tree_delete (splay_tree sp) 285 { 286 splay_tree_delete_helper (sp, sp->root); 287 (*sp->deallocate) ((char*) sp, sp->allocate_data); 288 } 289 290 /* Insert a new node (associating KEY with DATA) into SP. If a 291 previous node with the indicated KEY exists, its data is replaced 292 with the new value. Returns the new node. */ 293 294 splay_tree_node 295 splay_tree_insert (splay_tree sp, splay_tree_key key, splay_tree_value value) 296 { 297 int comparison = 0; 298 299 splay_tree_splay (sp, key); 300 301 if (sp->root) 302 comparison = (*sp->comp)(sp->root->key, key); 303 304 if (sp->root && comparison == 0) 305 { 306 /* If the root of the tree already has the indicated KEY, just 307 replace the value with VALUE. */ 308 if (sp->delete_value) 309 (*sp->delete_value)(sp->root->value); 310 sp->root->value = value; 311 } 312 else 313 { 314 /* Create a new node, and insert it at the root. */ 315 splay_tree_node node; 316 317 node = ((splay_tree_node) 318 (*sp->allocate) (sizeof (struct splay_tree_node_s), 319 sp->allocate_data)); 320 node->key = key; 321 node->value = value; 322 323 if (!sp->root) 324 node->left = node->right = 0; 325 else if (comparison < 0) 326 { 327 node->left = sp->root; 328 node->right = node->left->right; 329 node->left->right = 0; 330 } 331 else 332 { 333 node->right = sp->root; 334 node->left = node->right->left; 335 node->right->left = 0; 336 } 337 338 sp->root = node; 339 } 340 341 return sp->root; 342 } 343 344 /* Remove KEY from SP. It is not an error if it did not exist. */ 345 346 void 347 splay_tree_remove (splay_tree sp, splay_tree_key key) 348 { 349 splay_tree_splay (sp, key); 350 351 if (sp->root && (*sp->comp) (sp->root->key, key) == 0) 352 { 353 splay_tree_node left, right; 354 355 left = sp->root->left; 356 right = sp->root->right; 357 358 /* Delete the root node itself. */ 359 if (sp->delete_value) 360 (*sp->delete_value) (sp->root->value); 361 (*sp->deallocate) (sp->root, sp->allocate_data); 362 363 /* One of the children is now the root. Doesn't matter much 364 which, so long as we preserve the properties of the tree. */ 365 if (left) 366 { 367 sp->root = left; 368 369 /* If there was a right child as well, hang it off the 370 right-most leaf of the left child. */ 371 if (right) 372 { 373 while (left->right) 374 left = left->right; 375 left->right = right; 376 } 377 } 378 else 379 sp->root = right; 380 } 381 } 382 383 /* Lookup KEY in SP, returning VALUE if present, and NULL 384 otherwise. */ 385 386 splay_tree_node 387 splay_tree_lookup (splay_tree sp, splay_tree_key key) 388 { 389 splay_tree_splay (sp, key); 390 391 if (sp->root && (*sp->comp)(sp->root->key, key) == 0) 392 return sp->root; 393 else 394 return 0; 395 } 396 397 /* Return the node in SP with the greatest key. */ 398 399 splay_tree_node 400 splay_tree_max (splay_tree sp) 401 { 402 splay_tree_node n = sp->root; 403 404 if (!n) 405 return NULL; 406 407 while (n->right) 408 n = n->right; 409 410 return n; 411 } 412 413 /* Return the node in SP with the smallest key. */ 414 415 splay_tree_node 416 splay_tree_min (splay_tree sp) 417 { 418 splay_tree_node n = sp->root; 419 420 if (!n) 421 return NULL; 422 423 while (n->left) 424 n = n->left; 425 426 return n; 427 } 428 429 /* Return the immediate predecessor KEY, or NULL if there is no 430 predecessor. KEY need not be present in the tree. */ 431 432 splay_tree_node 433 splay_tree_predecessor (splay_tree sp, splay_tree_key key) 434 { 435 int comparison; 436 splay_tree_node node; 437 438 /* If the tree is empty, there is certainly no predecessor. */ 439 if (!sp->root) 440 return NULL; 441 442 /* Splay the tree around KEY. That will leave either the KEY 443 itself, its predecessor, or its successor at the root. */ 444 splay_tree_splay (sp, key); 445 comparison = (*sp->comp)(sp->root->key, key); 446 447 /* If the predecessor is at the root, just return it. */ 448 if (comparison < 0) 449 return sp->root; 450 451 /* Otherwise, find the rightmost element of the left subtree. */ 452 node = sp->root->left; 453 if (node) 454 while (node->right) 455 node = node->right; 456 457 return node; 458 } 459 460 /* Return the immediate successor KEY, or NULL if there is no 461 successor. KEY need not be present in the tree. */ 462 463 splay_tree_node 464 splay_tree_successor (splay_tree sp, splay_tree_key key) 465 { 466 int comparison; 467 splay_tree_node node; 468 469 /* If the tree is empty, there is certainly no successor. */ 470 if (!sp->root) 471 return NULL; 472 473 /* Splay the tree around KEY. That will leave either the KEY 474 itself, its predecessor, or its successor at the root. */ 475 splay_tree_splay (sp, key); 476 comparison = (*sp->comp)(sp->root->key, key); 477 478 /* If the successor is at the root, just return it. */ 479 if (comparison > 0) 480 return sp->root; 481 482 /* Otherwise, find the leftmost element of the right subtree. */ 483 node = sp->root->right; 484 if (node) 485 while (node->left) 486 node = node->left; 487 488 return node; 489 } 490 491 /* Call FN, passing it the DATA, for every node in SP, following an 492 in-order traversal. If FN every returns a non-zero value, the 493 iteration ceases immediately, and the value is returned. 494 Otherwise, this function returns 0. */ 495 496 int 497 splay_tree_foreach (splay_tree sp, splay_tree_foreach_fn fn, void *data) 498 { 499 return splay_tree_foreach_helper (sp, sp->root, fn, data); 500 } 501 502 /* Splay-tree comparison function, treating the keys as ints. */ 503 504 int 505 splay_tree_compare_ints (splay_tree_key k1, splay_tree_key k2) 506 { 507 if ((int) k1 < (int) k2) 508 return -1; 509 else if ((int) k1 > (int) k2) 510 return 1; 511 else 512 return 0; 513 } 514 515 /* Splay-tree comparison function, treating the keys as pointers. */ 516 517 int 518 splay_tree_compare_pointers (splay_tree_key k1, splay_tree_key k2) 519 { 520 if ((char*) k1 < (char*) k2) 521 return -1; 522 else if ((char*) k1 > (char*) k2) 523 return 1; 524 else 525 return 0; 526 } 527