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[binutils.git] / libiberty / splay-tree.c
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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)
10 any later version.
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. */
27 #ifdef HAVE_CONFIG_H
28 #include "config.h"
29 #endif
31 #ifdef HAVE_STDLIB_H
32 #include <stdlib.h>
33 #endif
35 #include <stdio.h>
37 #include "libiberty.h"
38 #include "splay-tree.h"
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*);
49 /* Deallocate NODE (a member of SP), and all its sub-trees. */
51 static void
52 splay_tree_delete_helper (splay_tree sp, splay_tree_node node)
54 splay_tree_node pending = 0;
55 splay_tree_node active = 0;
57 if (!node)
58 return;
60 #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x);
61 #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x);
63 KDEL (node->key);
64 VDEL (node->value);
66 /* We use the "key" field to hold the "next" pointer. */
67 node->key = (splay_tree_key)pending;
68 pending = (splay_tree_node)node;
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. */
74 while (pending)
76 active = pending;
77 pending = 0;
78 while (active)
80 splay_tree_node temp;
82 /* active points to a node which has its key and value
83 deallocated, we just need to process left and right. */
85 if (active->left)
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);
92 if (active->right)
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);
100 temp = active;
101 active = (splay_tree_node)(temp->key);
102 (*sp->deallocate) ((char*) temp, sp->allocate_data);
105 #undef KDEL
106 #undef VDEL
109 /* Rotate the edge joining the left child N with its parent P. PP is the
110 grandparents' pointer to P. */
112 static inline void
113 rotate_left (splay_tree_node *pp, splay_tree_node p, splay_tree_node n)
115 splay_tree_node tmp;
116 tmp = n->right;
117 n->right = p;
118 p->left = tmp;
119 *pp = n;
122 /* Rotate the edge joining the right child N with its parent P. PP is the
123 grandparents' pointer to P. */
125 static inline void
126 rotate_right (splay_tree_node *pp, splay_tree_node p, splay_tree_node n)
128 splay_tree_node tmp;
129 tmp = n->left;
130 n->left = p;
131 p->right = tmp;
132 *pp = n;
135 /* Bottom up splay of key. */
137 static void
138 splay_tree_splay (splay_tree sp, splay_tree_key key)
140 if (sp->root == 0)
141 return;
143 do {
144 int cmp1, cmp2;
145 splay_tree_node n, c;
147 n = sp->root;
148 cmp1 = (*sp->comp) (key, n->key);
150 /* Found. */
151 if (cmp1 == 0)
152 return;
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;
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))
169 if (cmp1 < 0)
170 rotate_left (&sp->root, n, c);
171 else
172 rotate_right (&sp->root, n, c);
173 return;
176 /* Now we have the four cases of double-rotation. */
177 if (cmp1 < 0 && cmp2 < 0)
179 rotate_left (&n->left, c, c->left);
180 rotate_left (&sp->root, n, n->left);
182 else if (cmp1 > 0 && cmp2 > 0)
184 rotate_right (&n->right, c, c->right);
185 rotate_right (&sp->root, n, n->right);
187 else if (cmp1 < 0 && cmp2 > 0)
189 rotate_right (&n->left, c, c->right);
190 rotate_left (&sp->root, n, n->left);
192 else if (cmp1 > 0 && cmp2 < 0)
194 rotate_left (&n->right, c, c->left);
195 rotate_right (&sp->root, n, n->right);
197 } while (1);
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. */
205 static int
206 splay_tree_foreach_helper (splay_tree sp, splay_tree_node node,
207 splay_tree_foreach_fn fn, void *data)
209 int val;
211 if (!node)
212 return 0;
214 val = splay_tree_foreach_helper (sp, node->left, fn, data);
215 if (val)
216 return val;
218 val = (*fn)(node, data);
219 if (val)
220 return val;
222 return splay_tree_foreach_helper (sp, node->right, fn, data);
226 /* An allocator and deallocator based on xmalloc. */
227 static void *
228 splay_tree_xmalloc_allocate (int size, void *data ATTRIBUTE_UNUSED)
230 return (void *) xmalloc (size);
233 static void
234 splay_tree_xmalloc_deallocate (void *object, void *data ATTRIBUTE_UNUSED)
236 free (object);
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. */
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)
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));
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. */
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)
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;
278 return sp;
281 /* Deallocate SP. */
283 void
284 splay_tree_delete (splay_tree sp)
286 splay_tree_delete_helper (sp, sp->root);
287 (*sp->deallocate) ((char*) sp, sp->allocate_data);
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. */
294 splay_tree_node
295 splay_tree_insert (splay_tree sp, splay_tree_key key, splay_tree_value value)
297 int comparison = 0;
299 splay_tree_splay (sp, key);
301 if (sp->root)
302 comparison = (*sp->comp)(sp->root->key, key);
304 if (sp->root && comparison == 0)
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;
312 else
314 /* Create a new node, and insert it at the root. */
315 splay_tree_node node;
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;
323 if (!sp->root)
324 node->left = node->right = 0;
325 else if (comparison < 0)
327 node->left = sp->root;
328 node->right = node->left->right;
329 node->left->right = 0;
331 else
333 node->right = sp->root;
334 node->left = node->right->left;
335 node->right->left = 0;
338 sp->root = node;
341 return sp->root;
344 /* Remove KEY from SP. It is not an error if it did not exist. */
346 void
347 splay_tree_remove (splay_tree sp, splay_tree_key key)
349 splay_tree_splay (sp, key);
351 if (sp->root && (*sp->comp) (sp->root->key, key) == 0)
353 splay_tree_node left, right;
355 left = sp->root->left;
356 right = sp->root->right;
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);
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)
367 sp->root = left;
369 /* If there was a right child as well, hang it off the
370 right-most leaf of the left child. */
371 if (right)
373 while (left->right)
374 left = left->right;
375 left->right = right;
378 else
379 sp->root = right;
383 /* Lookup KEY in SP, returning VALUE if present, and NULL
384 otherwise. */
386 splay_tree_node
387 splay_tree_lookup (splay_tree sp, splay_tree_key key)
389 splay_tree_splay (sp, key);
391 if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
392 return sp->root;
393 else
394 return 0;
397 /* Return the node in SP with the greatest key. */
399 splay_tree_node
400 splay_tree_max (splay_tree sp)
402 splay_tree_node n = sp->root;
404 if (!n)
405 return NULL;
407 while (n->right)
408 n = n->right;
410 return n;
413 /* Return the node in SP with the smallest key. */
415 splay_tree_node
416 splay_tree_min (splay_tree sp)
418 splay_tree_node n = sp->root;
420 if (!n)
421 return NULL;
423 while (n->left)
424 n = n->left;
426 return n;
429 /* Return the immediate predecessor KEY, or NULL if there is no
430 predecessor. KEY need not be present in the tree. */
432 splay_tree_node
433 splay_tree_predecessor (splay_tree sp, splay_tree_key key)
435 int comparison;
436 splay_tree_node node;
438 /* If the tree is empty, there is certainly no predecessor. */
439 if (!sp->root)
440 return NULL;
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);
447 /* If the predecessor is at the root, just return it. */
448 if (comparison < 0)
449 return sp->root;
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;
457 return node;
460 /* Return the immediate successor KEY, or NULL if there is no
461 successor. KEY need not be present in the tree. */
463 splay_tree_node
464 splay_tree_successor (splay_tree sp, splay_tree_key key)
466 int comparison;
467 splay_tree_node node;
469 /* If the tree is empty, there is certainly no successor. */
470 if (!sp->root)
471 return NULL;
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 successor is at the root, just return it. */
479 if (comparison > 0)
480 return sp->root;
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;
488 return node;
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. */
497 splay_tree_foreach (splay_tree sp, splay_tree_foreach_fn fn, void *data)
499 return splay_tree_foreach_helper (sp, sp->root, fn, data);
502 /* Splay-tree comparison function, treating the keys as ints. */
505 splay_tree_compare_ints (splay_tree_key k1, splay_tree_key k2)
507 if ((int) k1 < (int) k2)
508 return -1;
509 else if ((int) k1 > (int) k2)
510 return 1;
511 else
512 return 0;
515 /* Splay-tree comparison function, treating the keys as pointers. */
518 splay_tree_compare_pointers (splay_tree_key k1, splay_tree_key k2)
520 if ((char*) k1 < (char*) k2)
521 return -1;
522 else if ((char*) k1 > (char*) k2)
523 return 1;
524 else
525 return 0;