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, 51 Franklin Street - Fifth Floor,
20 Boston, MA 02110-1301, 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 (splay_tree, splay_tree_node);
41 static void splay_tree_splay (splay_tree, splay_tree_key);
42 static splay_tree_node splay_tree_splay_helper (splay_tree,
47 static int splay_tree_foreach_helper (splay_tree, splay_tree_node,
48 splay_tree_foreach_fn, void*);
50 /* Deallocate NODE (a member of SP), and all its sub-trees. */
53 splay_tree_delete_helper (splay_tree sp, splay_tree_node node)
55 splay_tree_node pending = 0;
56 splay_tree_node active = 0;
61 #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x);
62 #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x);
67 /* We use the "key" field to hold the "next" pointer. */
68 node->key = (splay_tree_key)pending;
69 pending = (splay_tree_node)node;
71 /* Now, keep processing the pending list until there aren't any
72 more. This is a little more complicated than just recursing, but
73 it doesn't toast the stack for large trees. */
83 /* active points to a node which has its key and value
84 deallocated, we just need to process left and right. */
88 KDEL (active->left->key);
89 VDEL (active->left->value);
90 active->left->key = (splay_tree_key)pending;
91 pending = (splay_tree_node)(active->left);
95 KDEL (active->right->key);
96 VDEL (active->right->value);
97 active->right->key = (splay_tree_key)pending;
98 pending = (splay_tree_node)(active->right);
102 active = (splay_tree_node)(temp->key);
103 (*sp->deallocate) ((char*) temp, sp->allocate_data);
110 /* Help splay SP around KEY. PARENT and GRANDPARENT are the parent
111 and grandparent, respectively, of NODE. */
113 static splay_tree_node
114 splay_tree_splay_helper (splay_tree sp, splay_tree_key key,
115 splay_tree_node *node, splay_tree_node *parent,
116 splay_tree_node *grandparent)
118 splay_tree_node *next;
127 comparison = (*sp->comp) (key, n->key);
130 /* We've found the target. */
132 else if (comparison < 0)
133 /* The target is to the left. */
136 /* The target is to the right. */
141 /* Continue down the tree. */
142 n = splay_tree_splay_helper (sp, key, next, node, parent);
144 /* The recursive call will change the place to which NODE
151 /* NODE is the root. We are done. */
154 /* First, handle the case where there is no grandparent (i.e.,
155 *PARENT is the root of the tree.) */
158 if (n == (*parent)->left)
172 /* Next handle the cases where both N and *PARENT are left children,
173 or where both are right children. */
174 if (n == (*parent)->left && *parent == (*grandparent)->left)
176 splay_tree_node p = *parent;
178 (*grandparent)->left = p->right;
179 p->right = *grandparent;
185 else if (n == (*parent)->right && *parent == (*grandparent)->right)
187 splay_tree_node p = *parent;
189 (*grandparent)->right = p->left;
190 p->left = *grandparent;
197 /* Finally, deal with the case where N is a left child, but *PARENT
198 is a right child, or vice versa. */
199 if (n == (*parent)->left)
201 (*parent)->left = n->right;
203 (*grandparent)->right = n->left;
204 n->left = *grandparent;
210 (*parent)->right = n->left;
212 (*grandparent)->left = n->right;
213 n->right = *grandparent;
219 /* Splay SP around KEY. */
222 splay_tree_splay (splay_tree sp, splay_tree_key key)
227 splay_tree_splay_helper (sp, key, &sp->root,
228 /*grandparent=*/0, /*parent=*/0);
231 /* Call FN, passing it the DATA, for every node below NODE, all of
232 which are from SP, following an in-order traversal. If FN every
233 returns a non-zero value, the iteration ceases immediately, and the
234 value is returned. Otherwise, this function returns 0. */
237 splay_tree_foreach_helper (splay_tree sp, splay_tree_node node,
238 splay_tree_foreach_fn fn, void *data)
245 val = splay_tree_foreach_helper (sp, node->left, fn, data);
249 val = (*fn)(node, data);
253 return splay_tree_foreach_helper (sp, node->right, fn, data);
257 /* An allocator and deallocator based on xmalloc. */
259 splay_tree_xmalloc_allocate (int size, void *data ATTRIBUTE_UNUSED)
261 return (void *) xmalloc (size);
265 splay_tree_xmalloc_deallocate (void *object, void *data ATTRIBUTE_UNUSED)
271 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
272 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
273 values. Use xmalloc to allocate the splay tree structure, and any
277 splay_tree_new (splay_tree_compare_fn compare_fn,
278 splay_tree_delete_key_fn delete_key_fn,
279 splay_tree_delete_value_fn delete_value_fn)
281 return (splay_tree_new_with_allocator
282 (compare_fn, delete_key_fn, delete_value_fn,
283 splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0));
287 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
288 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
292 splay_tree_new_with_allocator (splay_tree_compare_fn compare_fn,
293 splay_tree_delete_key_fn delete_key_fn,
294 splay_tree_delete_value_fn delete_value_fn,
295 splay_tree_allocate_fn allocate_fn,
296 splay_tree_deallocate_fn deallocate_fn,
299 splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s),
302 sp->comp = compare_fn;
303 sp->delete_key = delete_key_fn;
304 sp->delete_value = delete_value_fn;
305 sp->allocate = allocate_fn;
306 sp->deallocate = deallocate_fn;
307 sp->allocate_data = allocate_data;
315 splay_tree_delete (splay_tree sp)
317 splay_tree_delete_helper (sp, sp->root);
318 (*sp->deallocate) ((char*) sp, sp->allocate_data);
321 /* Insert a new node (associating KEY with DATA) into SP. If a
322 previous node with the indicated KEY exists, its data is replaced
323 with the new value. Returns the new node. */
326 splay_tree_insert (splay_tree sp, splay_tree_key key, splay_tree_value value)
330 splay_tree_splay (sp, key);
333 comparison = (*sp->comp)(sp->root->key, key);
335 if (sp->root && comparison == 0)
337 /* If the root of the tree already has the indicated KEY, just
338 replace the value with VALUE. */
339 if (sp->delete_value)
340 (*sp->delete_value)(sp->root->value);
341 sp->root->value = value;
345 /* Create a new node, and insert it at the root. */
346 splay_tree_node node;
348 node = ((splay_tree_node)
349 (*sp->allocate) (sizeof (struct splay_tree_node_s),
355 node->left = node->right = 0;
356 else if (comparison < 0)
358 node->left = sp->root;
359 node->right = node->left->right;
360 node->left->right = 0;
364 node->right = sp->root;
365 node->left = node->right->left;
366 node->right->left = 0;
375 /* Remove KEY from SP. It is not an error if it did not exist. */
378 splay_tree_remove (splay_tree sp, splay_tree_key key)
380 splay_tree_splay (sp, key);
382 if (sp->root && (*sp->comp) (sp->root->key, key) == 0)
384 splay_tree_node left, right;
386 left = sp->root->left;
387 right = sp->root->right;
389 /* Delete the root node itself. */
390 if (sp->delete_value)
391 (*sp->delete_value) (sp->root->value);
392 (*sp->deallocate) (sp->root, sp->allocate_data);
394 /* One of the children is now the root. Doesn't matter much
395 which, so long as we preserve the properties of the tree. */
400 /* If there was a right child as well, hang it off the
401 right-most leaf of the left child. */
414 /* Lookup KEY in SP, returning VALUE if present, and NULL
418 splay_tree_lookup (splay_tree sp, splay_tree_key key)
420 splay_tree_splay (sp, key);
422 if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
428 /* Return the node in SP with the greatest key. */
431 splay_tree_max (splay_tree sp)
433 splay_tree_node n = sp->root;
444 /* Return the node in SP with the smallest key. */
447 splay_tree_min (splay_tree sp)
449 splay_tree_node n = sp->root;
460 /* Return the immediate predecessor KEY, or NULL if there is no
461 predecessor. KEY need not be present in the tree. */
464 splay_tree_predecessor (splay_tree sp, splay_tree_key key)
467 splay_tree_node node;
469 /* If the tree is empty, there is certainly no predecessor. */
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);
478 /* If the predecessor is at the root, just return it. */
482 /* Otherwise, find the rightmost element of the left subtree. */
483 node = sp->root->left;
491 /* Return the immediate successor KEY, or NULL if there is no
492 successor. KEY need not be present in the tree. */
495 splay_tree_successor (splay_tree sp, splay_tree_key key)
498 splay_tree_node node;
500 /* If the tree is empty, there is certainly no successor. */
504 /* Splay the tree around KEY. That will leave either the KEY
505 itself, its predecessor, or its successor at the root. */
506 splay_tree_splay (sp, key);
507 comparison = (*sp->comp)(sp->root->key, key);
509 /* If the successor is at the root, just return it. */
513 /* Otherwise, find the leftmost element of the right subtree. */
514 node = sp->root->right;
522 /* Call FN, passing it the DATA, for every node in SP, following an
523 in-order traversal. If FN every returns a non-zero value, the
524 iteration ceases immediately, and the value is returned.
525 Otherwise, this function returns 0. */
528 splay_tree_foreach (splay_tree sp, splay_tree_foreach_fn fn, void *data)
530 return splay_tree_foreach_helper (sp, sp->root, fn, data);
533 /* Splay-tree comparison function, treating the keys as ints. */
536 splay_tree_compare_ints (splay_tree_key k1, splay_tree_key k2)
538 if ((int) k1 < (int) k2)
540 else if ((int) k1 > (int) k2)
546 /* Splay-tree comparison function, treating the keys as pointers. */
549 splay_tree_compare_pointers (splay_tree_key k1, splay_tree_key k2)
551 if ((char*) k1 < (char*) k2)
553 else if ((char*) k1 > (char*) k2)