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)
62 splay_tree_node pending = 0;
63 splay_tree_node active = 0;
68 #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x);
69 #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x);
74 /* We use the "key" field to hold the "next" pointer. */
75 node->key = (splay_tree_key)pending;
76 pending = (splay_tree_node)node;
78 /* Now, keep processing the pending list until there aren't any
79 more. This is a little more complicated than just recursing, but
80 it doesn't toast the stack for large trees. */
90 /* active points to a node which has its key and value
91 deallocated, we just need to process left and right. */
95 KDEL (active->left->key);
96 VDEL (active->left->value);
97 active->left->key = (splay_tree_key)pending;
98 pending = (splay_tree_node)(active->left);
102 KDEL (active->right->key);
103 VDEL (active->right->value);
104 active->right->key = (splay_tree_key)pending;
105 pending = (splay_tree_node)(active->right);
109 active = (splay_tree_node)(temp->key);
110 (*sp->deallocate) ((char*) temp, sp->allocate_data);
117 /* Help splay SP around KEY. PARENT and GRANDPARENT are the parent
118 and grandparent, respectively, of NODE. */
120 static splay_tree_node
121 splay_tree_splay_helper (sp, key, node, parent, grandparent)
124 splay_tree_node *node;
125 splay_tree_node *parent;
126 splay_tree_node *grandparent;
128 splay_tree_node *next;
137 comparison = (*sp->comp) (key, n->key);
140 /* We've found the target. */
142 else if (comparison < 0)
143 /* The target is to the left. */
146 /* The target is to the right. */
151 /* Continue down the tree. */
152 n = splay_tree_splay_helper (sp, key, next, node, parent);
154 /* The recursive call will change the place to which NODE
161 /* NODE is the root. We are done. */
164 /* First, handle the case where there is no grandparent (i.e.,
165 *PARENT is the root of the tree.) */
168 if (n == (*parent)->left)
182 /* Next handle the cases where both N and *PARENT are left children,
183 or where both are right children. */
184 if (n == (*parent)->left && *parent == (*grandparent)->left)
186 splay_tree_node p = *parent;
188 (*grandparent)->left = p->right;
189 p->right = *grandparent;
195 else if (n == (*parent)->right && *parent == (*grandparent)->right)
197 splay_tree_node p = *parent;
199 (*grandparent)->right = p->left;
200 p->left = *grandparent;
207 /* Finally, deal with the case where N is a left child, but *PARENT
208 is a right child, or vice versa. */
209 if (n == (*parent)->left)
211 (*parent)->left = n->right;
213 (*grandparent)->right = n->left;
214 n->left = *grandparent;
220 (*parent)->right = n->left;
222 (*grandparent)->left = n->right;
223 n->right = *grandparent;
229 /* Splay SP around KEY. */
232 splay_tree_splay (sp, key)
239 splay_tree_splay_helper (sp, key, &sp->root,
240 /*grandparent=*/0, /*parent=*/0);
243 /* Call FN, passing it the DATA, for every node below NODE, all of
244 which are from SP, following an in-order traversal. If FN every
245 returns a non-zero value, the iteration ceases immediately, and the
246 value is returned. Otherwise, this function returns 0. */
249 splay_tree_foreach_helper (sp, node, fn, data)
251 splay_tree_node node;
252 splay_tree_foreach_fn fn;
260 val = splay_tree_foreach_helper (sp, node->left, fn, data);
264 val = (*fn)(node, data);
268 return splay_tree_foreach_helper (sp, node->right, fn, data);
272 /* An allocator and deallocator based on xmalloc. */
274 splay_tree_xmalloc_allocate (size, data)
276 void *data ATTRIBUTE_UNUSED;
278 return (void *) xmalloc (size);
282 splay_tree_xmalloc_deallocate (object, data)
284 void *data ATTRIBUTE_UNUSED;
290 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
291 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
292 values. Use xmalloc to allocate the splay tree structure, and any
296 splay_tree_new (compare_fn, delete_key_fn, delete_value_fn)
297 splay_tree_compare_fn compare_fn;
298 splay_tree_delete_key_fn delete_key_fn;
299 splay_tree_delete_value_fn delete_value_fn;
301 return (splay_tree_new_with_allocator
302 (compare_fn, delete_key_fn, delete_value_fn,
303 splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0));
307 /* Allocate a new splay tree, using COMPARE_FN to compare nodes,
308 DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
312 splay_tree_new_with_allocator (compare_fn, delete_key_fn, delete_value_fn,
313 allocate_fn, deallocate_fn, allocate_data)
314 splay_tree_compare_fn compare_fn;
315 splay_tree_delete_key_fn delete_key_fn;
316 splay_tree_delete_value_fn delete_value_fn;
317 splay_tree_allocate_fn allocate_fn;
318 splay_tree_deallocate_fn deallocate_fn;
321 splay_tree sp = (splay_tree) (*allocate_fn) (sizeof (struct splay_tree_s),
324 sp->comp = compare_fn;
325 sp->delete_key = delete_key_fn;
326 sp->delete_value = delete_value_fn;
327 sp->allocate = allocate_fn;
328 sp->deallocate = deallocate_fn;
329 sp->allocate_data = allocate_data;
337 splay_tree_delete (sp)
340 splay_tree_delete_helper (sp, sp->root);
341 (*sp->deallocate) ((char*) sp, sp->allocate_data);
344 /* Insert a new node (associating KEY with DATA) into SP. If a
345 previous node with the indicated KEY exists, its data is replaced
346 with the new value. Returns the new node. */
349 splay_tree_insert (sp, key, value)
352 splay_tree_value value;
356 splay_tree_splay (sp, key);
359 comparison = (*sp->comp)(sp->root->key, key);
361 if (sp->root && comparison == 0)
363 /* If the root of the tree already has the indicated KEY, just
364 replace the value with VALUE. */
365 if (sp->delete_value)
366 (*sp->delete_value)(sp->root->value);
367 sp->root->value = value;
371 /* Create a new node, and insert it at the root. */
372 splay_tree_node node;
374 node = ((splay_tree_node)
375 (*sp->allocate) (sizeof (struct splay_tree_node_s),
381 node->left = node->right = 0;
382 else if (comparison < 0)
384 node->left = sp->root;
385 node->right = node->left->right;
386 node->left->right = 0;
390 node->right = sp->root;
391 node->left = node->right->left;
392 node->right->left = 0;
401 /* Remove KEY from SP. It is not an error if it did not exist. */
404 splay_tree_remove (sp, key)
408 splay_tree_splay (sp, key);
410 if (sp->root && (*sp->comp) (sp->root->key, key) == 0)
412 splay_tree_node left, right;
414 left = sp->root->left;
415 right = sp->root->right;
417 /* Delete the root node itself. */
418 if (sp->delete_value)
419 (*sp->delete_value) (sp->root->value);
420 (*sp->deallocate) (sp->root, sp->allocate_data);
422 /* One of the children is now the root. Doesn't matter much
423 which, so long as we preserve the properties of the tree. */
428 /* If there was a right child as well, hang it off the
429 right-most leaf of the left child. */
442 /* Lookup KEY in SP, returning VALUE if present, and NULL
446 splay_tree_lookup (sp, key)
450 splay_tree_splay (sp, key);
452 if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
458 /* Return the node in SP with the greatest key. */
464 splay_tree_node n = sp->root;
475 /* Return the node in SP with the smallest key. */
481 splay_tree_node n = sp->root;
492 /* Return the immediate predecessor KEY, or NULL if there is no
493 predecessor. KEY need not be present in the tree. */
496 splay_tree_predecessor (sp, key)
501 splay_tree_node node;
503 /* If the tree is empty, there is certainly no predecessor. */
507 /* Splay the tree around KEY. That will leave either the KEY
508 itself, its predecessor, or its successor at the root. */
509 splay_tree_splay (sp, key);
510 comparison = (*sp->comp)(sp->root->key, key);
512 /* If the predecessor is at the root, just return it. */
516 /* Otherwise, find the rightmost element of the left subtree. */
517 node = sp->root->left;
525 /* Return the immediate successor KEY, or NULL if there is no
526 successor. KEY need not be present in the tree. */
529 splay_tree_successor (sp, key)
534 splay_tree_node node;
536 /* If the tree is empty, there is certainly no successor. */
540 /* Splay the tree around KEY. That will leave either the KEY
541 itself, its predecessor, or its successor at the root. */
542 splay_tree_splay (sp, key);
543 comparison = (*sp->comp)(sp->root->key, key);
545 /* If the successor is at the root, just return it. */
549 /* Otherwise, find the leftmost element of the right subtree. */
550 node = sp->root->right;
558 /* Call FN, passing it the DATA, for every node in SP, following an
559 in-order traversal. If FN every returns a non-zero value, the
560 iteration ceases immediately, and the value is returned.
561 Otherwise, this function returns 0. */
564 splay_tree_foreach (sp, fn, data)
566 splay_tree_foreach_fn fn;
569 return splay_tree_foreach_helper (sp, sp->root, fn, data);
572 /* Splay-tree comparison function, treating the keys as ints. */
575 splay_tree_compare_ints (k1, k2)
579 if ((int) k1 < (int) k2)
581 else if ((int) k1 > (int) k2)
587 /* Splay-tree comparison function, treating the keys as pointers. */
590 splay_tree_compare_pointers (k1, k2)
594 if ((char*) k1 < (char*) k2)
596 else if ((char*) k1 > (char*) k2)