1 /* A splay-tree datatype.
2 Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
3 Contributed by Mark Mitchell (mark@markmitchell.com).
5 This file is part of GNU CC.
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)
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.
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, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* For an easily readable description of splay-trees, see:
24 Lewis, Harry R. and Denenberg, Larry. Data Structures and Their
25 Algorithms. Harper-Collins, Inc. 1991. */
37 #include "libiberty.h"
38 #include "splay-tree.h"
40 static void splay_tree_delete_helper PARAMS((splay_tree,
42 static void splay_tree_splay PARAMS((splay_tree,
44 static splay_tree_node splay_tree_splay_helper
50 static int splay_tree_foreach_helper PARAMS((splay_tree,
52 splay_tree_foreach_fn,
55 /* Deallocate NODE (a member of SP), and all its sub-trees. */
58 splay_tree_delete_helper (sp, node)
65 splay_tree_delete_helper (sp, node->left);
66 splay_tree_delete_helper (sp, node->right);
69 (*sp->delete_key)(node->key);
71 (*sp->delete_value)(node->value);
73 (*sp->deallocate) ((char*) node, sp->allocate_data);
76 /* Help splay SP around KEY. PARENT and GRANDPARENT are the parent
77 and grandparent, respectively, of NODE. */
79 static splay_tree_node
80 splay_tree_splay_helper (sp, key, node, parent, grandparent)
83 splay_tree_node *node;
84 splay_tree_node *parent;
85 splay_tree_node *grandparent;
87 splay_tree_node *next;
96 comparison = (*sp->comp) (key, n->key);
99 /* We've found the target. */
101 else if (comparison < 0)
102 /* The target is to the left. */
105 /* The target is to the right. */
110 /* Continue down the tree. */
111 n = splay_tree_splay_helper (sp, key, next, node, parent);
113 /* The recursive call will change the place to which NODE
120 /* NODE is the root. We are done. */
123 /* First, handle the case where there is no grandparent (i.e.,
124 *PARENT is the root of the tree.) */
127 if (n == (*parent)->left)
141 /* Next handle the cases where both N and *PARENT are left children,
142 or where both are right children. */
143 if (n == (*parent)->left && *parent == (*grandparent)->left)
145 splay_tree_node p = *parent;
147 (*grandparent)->left = p->right;
148 p->right = *grandparent;
154 else if (n == (*parent)->right && *parent == (*grandparent)->right)
156 splay_tree_node p = *parent;
158 (*grandparent)->right = p->left;
159 p->left = *grandparent;
166 /* Finally, deal with the case where N is a left child, but *PARENT
167 is a right child, or vice versa. */
168 if (n == (*parent)->left)
170 (*parent)->left = n->right;
172 (*grandparent)->right = n->left;
173 n->left = *grandparent;
179 (*parent)->right = n->left;
181 (*grandparent)->left = n->right;
182 n->right = *grandparent;
188 /* Splay SP around KEY. */
191 splay_tree_splay (sp, key)
198 splay_tree_splay_helper (sp, key, &sp->root,
199 /*grandparent=*/0, /*parent=*/0);
202 /* Call FN, passing it the DATA, for every node below NODE, all of
203 which are from SP, following an in-order traversal. If FN every
204 returns a non-zero value, the iteration ceases immediately, and the
205 value is returned. Otherwise, this function returns 0. */
208 splay_tree_foreach_helper (sp, node, fn, data)
210 splay_tree_node node;
211 splay_tree_foreach_fn fn;
219 val = splay_tree_foreach_helper (sp, node->left, fn, data);
223 val = (*fn)(node, data);
227 return splay_tree_foreach_helper (sp, node->right, fn, data);
231 /* An allocator and deallocator based on xmalloc. */
233 splay_tree_xmalloc_allocate (int size, void *data)
235 return xmalloc (size);
239 splay_tree_xmalloc_deallocate (void *object, void *data)
245 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
246 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
247 values. Use xmalloc to allocate the splay tree structure, and any
251 splay_tree_new (compare_fn, delete_key_fn, delete_value_fn)
252 splay_tree_compare_fn compare_fn;
253 splay_tree_delete_key_fn delete_key_fn;
254 splay_tree_delete_value_fn delete_value_fn;
256 return (splay_tree_new_with_allocator
257 (compare_fn, delete_key_fn, delete_value_fn,
258 splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0));
262 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
263 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
267 splay_tree_new_with_allocator (compare_fn, delete_key_fn, delete_value_fn,
268 allocate_fn, deallocate_fn, allocate_data)
269 splay_tree_compare_fn compare_fn;
270 splay_tree_delete_key_fn delete_key_fn;
271 splay_tree_delete_value_fn delete_value_fn;
272 splay_tree_allocate_fn allocate_fn;
273 splay_tree_deallocate_fn deallocate_fn;
276 splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s),
279 sp->comp = compare_fn;
280 sp->delete_key = delete_key_fn;
281 sp->delete_value = delete_value_fn;
282 sp->allocate = allocate_fn;
283 sp->deallocate = deallocate_fn;
284 sp->allocate_data = allocate_data;
292 splay_tree_delete (sp)
295 splay_tree_delete_helper (sp, sp->root);
296 (*sp->deallocate) ((char*) sp, sp->allocate_data);
299 /* Insert a new node (associating KEY with DATA) into SP. If a
300 previous node with the indicated KEY exists, its data is replaced
301 with the new value. Returns the new node. */
304 splay_tree_insert (sp, key, value)
307 splay_tree_value value;
311 splay_tree_splay (sp, key);
314 comparison = (*sp->comp)(sp->root->key, key);
316 if (sp->root && comparison == 0)
318 /* If the root of the tree already has the indicated KEY, just
319 replace the value with VALUE. */
320 if (sp->delete_value)
321 (*sp->delete_value)(sp->root->value);
322 sp->root->value = value;
326 /* Create a new node, and insert it at the root. */
327 splay_tree_node node;
329 node = ((splay_tree_node)
330 (*sp->allocate) (sizeof (struct splay_tree_node_s),
336 node->left = node->right = 0;
337 else if (comparison < 0)
339 node->left = sp->root;
340 node->right = node->left->right;
341 node->left->right = 0;
345 node->right = sp->root;
346 node->left = node->right->left;
347 node->right->left = 0;
356 /* Remove KEY from SP. It is not an error if it did not exist. */
359 splay_tree_remove (sp, key)
363 splay_tree_splay (sp, key);
365 if (sp->root && (*sp->comp) (sp->root->key, key) == 0)
367 splay_tree_node left, right;
369 left = sp->root->left;
370 right = sp->root->right;
372 /* Delete the root node itself. */
373 if (sp->delete_value)
374 (*sp->delete_value) (sp->root->value);
375 (*sp->deallocate) (sp->root, sp->allocate_data);
377 /* One of the children is now the root. Doesn't matter much
378 which, so long as we preserve the properties of the tree. */
383 /* If there was a right child as well, hang it off the
384 right-most leaf of the left child. */
397 /* Lookup KEY in SP, returning VALUE if present, and NULL
401 splay_tree_lookup (sp, key)
405 splay_tree_splay (sp, key);
407 if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
413 /* Return the node in SP with the greatest key. */
419 splay_tree_node n = sp->root;
430 /* Return the node in SP with the smallest key. */
436 splay_tree_node n = sp->root;
447 /* Return the immediate predecessor KEY, or NULL if there is no
448 predecessor. KEY need not be present in the tree. */
451 splay_tree_predecessor (sp, key)
456 splay_tree_node node;
458 /* If the tree is empty, there is certainly no predecessor. */
462 /* Splay the tree around KEY. That will leave either the KEY
463 itself, its predecessor, or its successor at the root. */
464 splay_tree_splay (sp, key);
465 comparison = (*sp->comp)(sp->root->key, key);
467 /* If the predecessor is at the root, just return it. */
471 /* Otherwise, find the leftmost element of the right subtree. */
472 node = sp->root->left;
480 /* Return the immediate successor KEY, or NULL if there is no
481 predecessor. KEY need not be present in the tree. */
484 splay_tree_successor (sp, key)
489 splay_tree_node node;
491 /* If the tree is empty, there is certainly no predecessor. */
495 /* Splay the tree around KEY. That will leave either the KEY
496 itself, its predecessor, or its successor at the root. */
497 splay_tree_splay (sp, key);
498 comparison = (*sp->comp)(sp->root->key, key);
500 /* If the successor is at the root, just return it. */
504 /* Otherwise, find the rightmost element of the left subtree. */
505 node = sp->root->right;
513 /* Call FN, passing it the DATA, for every node in SP, following an
514 in-order traversal. If FN every returns a non-zero value, the
515 iteration ceases immediately, and the value is returned.
516 Otherwise, this function returns 0. */
519 splay_tree_foreach (sp, fn, data)
521 splay_tree_foreach_fn fn;
524 return splay_tree_foreach_helper (sp, sp->root, fn, data);
527 /* Splay-tree comparison function, treating the keys as ints. */
530 splay_tree_compare_ints (k1, k2)
534 if ((int) k1 < (int) k2)
536 else if ((int) k1 > (int) k2)
542 /* Splay-tree comparison function, treating the keys as pointers. */
545 splay_tree_compare_pointers (k1, k2)
549 if ((char*) k1 < (char*) k2)
551 else if ((char*) k1 > (char*) k2)