1 /* Produced by texiweb from libavl.w. */
2 /* *INDENT-OFF* */
3
4 /* libavl - library for manipulation of binary trees.
5 Copyright (C) 1998-2002, 2004 Free Software Foundation, Inc.
6
7 This program is free software; you can redistribute it and/or
8 modify it under the terms of the GNU General Public License as
9 published by the Free Software Foundation; either version 2 of the
10 License, or (at your option) any later version.
11
12 This program 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.
15 See the GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA.
21
22 The author may be contacted at <blp@gnu.org> on the Internet, or
23 write to Ben Pfaff, Stanford University, Computer Science Dept., 353
24 Serra Mall, Stanford CA 94305, USA.
25 */
26
27 #include <assert.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include "avl.h"
32
33 /* Creates and returns a new table
34 with comparison function |compare| using parameter |param|
35 and memory allocator |allocator|.
36 Returns |NULL| if memory allocation failed. */
avl_create(avl_comparison_func * compare,void * param,struct libavl_allocator * allocator)37 struct avl_table *avl_create(avl_comparison_func * compare, void *param,
38 struct libavl_allocator *allocator)
39 {
40 struct avl_table *tree;
41
42 assert(compare != NULL);
43
44 if (allocator == NULL)
45 allocator = &avl_allocator_default;
46
47 tree = allocator->libavl_malloc(allocator, sizeof *tree);
48 if (tree == NULL)
49 return NULL;
50
51 tree->avl_root = NULL;
52 tree->avl_compare = compare;
53 tree->avl_param = param;
54 tree->avl_alloc = allocator;
55 tree->avl_count = 0;
56 tree->avl_generation = 0;
57
58 return tree;
59 }
60
61 /* Search |tree| for an item matching |item|, and return it if found.
62 Otherwise return |NULL|. */
avl_find(const struct avl_table * tree,const void * item)63 void *avl_find(const struct avl_table *tree, const void *item)
64 {
65 const struct avl_node *p;
66
67 assert(tree != NULL && item != NULL);
68 for (p = tree->avl_root; p != NULL;) {
69 int cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
70
71 if (cmp < 0)
72 p = p->avl_link[0];
73 else if (cmp > 0)
74 p = p->avl_link[1];
75 else /* |cmp == 0| */
76 return p->avl_data;
77 }
78
79 return NULL;
80 }
81
82 /* Inserts |item| into |tree| and returns a pointer to |item|'s address.
83 If a duplicate item is found in the tree,
84 returns a pointer to the duplicate without inserting |item|.
85 Returns |NULL| in case of memory allocation failure. */
avl_probe(struct avl_table * tree,void * item)86 void **avl_probe(struct avl_table *tree, void *item)
87 {
88 struct avl_node *y, *z; /* Top node to update balance factor, and parent. */
89 struct avl_node *p, *q; /* Iterator, and parent. */
90 struct avl_node *n; /* Newly inserted node. */
91 struct avl_node *w; /* New root of rebalanced subtree. */
92 int dir; /* Direction to descend. */
93
94 unsigned char da[AVL_MAX_HEIGHT]; /* Cached comparison results. */
95 int k = 0; /* Number of cached results. */
96
97 assert(tree != NULL && item != NULL);
98
99 z = (struct avl_node *) &tree->avl_root;
100 y = tree->avl_root;
101 dir = 0;
102 for (q = z, p = y; p != NULL; q = p, p = p->avl_link[dir]) {
103 int cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
104 if (cmp == 0)
105 return &p->avl_data;
106
107 if (p->avl_balance != 0)
108 z = q, y = p, k = 0;
109 dir = cmp > 0;
110 da[k++] = (unsigned char)dir;
111 }
112
113 n = q->avl_link[dir] =
114 tree->avl_alloc->libavl_malloc(tree->avl_alloc, sizeof *n);
115 if (n == NULL)
116 return NULL;
117
118 tree->avl_count++;
119 n->avl_data = item;
120 n->avl_link[0] = n->avl_link[1] = NULL;
121 n->avl_balance = 0;
122 if (y == NULL)
123 return &n->avl_data;
124
125 for (p = y, k = 0; p != n; p = p->avl_link[da[k]], k++)
126 if (da[k] == 0)
127 p->avl_balance--;
128 else
129 p->avl_balance++;
130
131 if (y->avl_balance == -2) {
132 struct avl_node *x = y->avl_link[0];
133 if (x->avl_balance == -1) {
134 w = x;
135 y->avl_link[0] = x->avl_link[1];
136 x->avl_link[1] = y;
137 x->avl_balance = y->avl_balance = 0;
138 } else {
139 assert(x->avl_balance == +1);
140 w = x->avl_link[1];
141 x->avl_link[1] = w->avl_link[0];
142 w->avl_link[0] = x;
143 y->avl_link[0] = w->avl_link[1];
144 w->avl_link[1] = y;
145 if (w->avl_balance == -1)
146 x->avl_balance = 0, y->avl_balance = +1;
147 else if (w->avl_balance == 0)
148 x->avl_balance = y->avl_balance = 0;
149 else /* |w->avl_balance == +1| */
150 x->avl_balance = -1, y->avl_balance = 0;
151 w->avl_balance = 0;
152 }
153 } else if (y->avl_balance == +2) {
154 struct avl_node *x = y->avl_link[1];
155 if (x->avl_balance == +1) {
156 w = x;
157 y->avl_link[1] = x->avl_link[0];
158 x->avl_link[0] = y;
159 x->avl_balance = y->avl_balance = 0;
160 } else {
161 assert(x->avl_balance == -1);
162 w = x->avl_link[0];
163 x->avl_link[0] = w->avl_link[1];
164 w->avl_link[1] = x;
165 y->avl_link[1] = w->avl_link[0];
166 w->avl_link[0] = y;
167 if (w->avl_balance == +1)
168 x->avl_balance = 0, y->avl_balance = -1;
169 else if (w->avl_balance == 0)
170 x->avl_balance = y->avl_balance = 0;
171 else /* |w->avl_balance == -1| */
172 x->avl_balance = +1, y->avl_balance = 0;
173 w->avl_balance = 0;
174 }
175 } else
176 return &n->avl_data;
177 z->avl_link[y != z->avl_link[0]] = w;
178
179 tree->avl_generation++;
180 return &n->avl_data;
181 }
182
183 /* Inserts |item| into |table|.
184 Returns |NULL| if |item| was successfully inserted
185 or if a memory allocation error occurred.
186 Otherwise, returns the duplicate item. */
avl_insert(struct avl_table * table,void * item)187 void *avl_insert(struct avl_table *table, void *item)
188 {
189 void **p = avl_probe(table, item);
190 return p == NULL || *p == item ? NULL : *p;
191 }
192
193 /* Inserts |item| into |table|, replacing any duplicate item.
194 Returns |NULL| if |item| was inserted without replacing a duplicate,
195 or if a memory allocation error occurred.
196 Otherwise, returns the item that was replaced. */
avl_replace(struct avl_table * table,void * item)197 void *avl_replace(struct avl_table *table, void *item)
198 {
199 void **p = avl_probe(table, item);
200 if (p == NULL || *p == item)
201 return NULL;
202 else {
203 void *r = *p;
204 *p = item;
205 return r;
206 }
207 }
208
209 /* Deletes from |tree| and returns an item matching |item|.
210 Returns a null pointer if no matching item found. */
avl_delete(struct avl_table * tree,const void * item)211 void *avl_delete(struct avl_table *tree, const void *item)
212 {
213 /* Stack of nodes. */
214 struct avl_node *pa[AVL_MAX_HEIGHT]; /* Nodes. */
215 unsigned char da[AVL_MAX_HEIGHT]; /* |avl_link[]| indexes. */
216 int k; /* Stack pointer. */
217
218 struct avl_node *p; /* Traverses tree to find node to delete. */
219 int cmp; /* Result of comparison between |item| and |p|. */
220
221 void *res;
222
223 assert(tree != NULL && item != NULL);
224
225 k = 0;
226 p = (struct avl_node *) &tree->avl_root;
227 for (cmp = -1; cmp != 0;
228 cmp = tree->avl_compare(item, p->avl_data, tree->avl_param)) {
229 int dir = cmp > 0;
230
231 pa[k] = p;
232 da[k++] = (unsigned char)dir;
233
234 p = p->avl_link[dir];
235 if (p == NULL)
236 return NULL;
237 }
238 res = p->avl_data;
239
240 if (p->avl_link[1] == NULL)
241 pa[k - 1]->avl_link[da[k - 1]] = p->avl_link[0];
242 else {
243 struct avl_node *r = p->avl_link[1];
244 if (r->avl_link[0] == NULL) {
245 r->avl_link[0] = p->avl_link[0];
246 r->avl_balance = p->avl_balance;
247 pa[k - 1]->avl_link[da[k - 1]] = r;
248 da[k] = 1;
249 pa[k++] = r;
250 } else {
251 struct avl_node *s;
252 int j = k++;
253
254 for (;;) {
255 da[k] = 0;
256 pa[k++] = r;
257 s = r->avl_link[0];
258 if (s->avl_link[0] == NULL)
259 break;
260
261 r = s;
262 }
263
264 s->avl_link[0] = p->avl_link[0];
265 r->avl_link[0] = s->avl_link[1];
266 s->avl_link[1] = p->avl_link[1];
267 s->avl_balance = p->avl_balance;
268
269 pa[j - 1]->avl_link[da[j - 1]] = s;
270 da[j] = 1;
271 pa[j] = s;
272 }
273 }
274
275 tree->avl_alloc->libavl_free(tree->avl_alloc, p);
276
277 assert(k > 0);
278 while (--k > 0) {
279 struct avl_node *y = pa[k];
280
281 if (da[k] == 0) {
282 y->avl_balance++;
283 if (y->avl_balance == +1)
284 break;
285 else if (y->avl_balance == +2) {
286 struct avl_node *x = y->avl_link[1];
287 if (x->avl_balance == -1) {
288 struct avl_node *w;
289 assert(x->avl_balance == -1);
290 w = x->avl_link[0];
291 x->avl_link[0] = w->avl_link[1];
292 w->avl_link[1] = x;
293 y->avl_link[1] = w->avl_link[0];
294 w->avl_link[0] = y;
295 if (w->avl_balance == +1)
296 x->avl_balance = 0, y->avl_balance = -1;
297 else if (w->avl_balance == 0)
298 x->avl_balance = y->avl_balance = 0;
299 else /* |w->avl_balance == -1| */
300 x->avl_balance = +1, y->avl_balance = 0;
301 w->avl_balance = 0;
302 pa[k - 1]->avl_link[da[k - 1]] = w;
303 } else {
304 y->avl_link[1] = x->avl_link[0];
305 x->avl_link[0] = y;
306 pa[k - 1]->avl_link[da[k - 1]] = x;
307 if (x->avl_balance == 0) {
308 x->avl_balance = -1;
309 y->avl_balance = +1;
310 break;
311 } else
312 x->avl_balance = y->avl_balance = 0;
313 }
314 }
315 } else {
316 y->avl_balance--;
317 if (y->avl_balance == -1)
318 break;
319 else if (y->avl_balance == -2) {
320 struct avl_node *x = y->avl_link[0];
321 if (x->avl_balance == +1) {
322 struct avl_node *w;
323 assert(x->avl_balance == +1);
324 w = x->avl_link[1];
325 x->avl_link[1] = w->avl_link[0];
326 w->avl_link[0] = x;
327 y->avl_link[0] = w->avl_link[1];
328 w->avl_link[1] = y;
329 if (w->avl_balance == -1)
330 x->avl_balance = 0, y->avl_balance = +1;
331 else if (w->avl_balance == 0)
332 x->avl_balance = y->avl_balance = 0;
333 else /* |w->avl_balance == +1| */
334 x->avl_balance = -1, y->avl_balance = 0;
335 w->avl_balance = 0;
336 pa[k - 1]->avl_link[da[k - 1]] = w;
337 } else {
338 y->avl_link[0] = x->avl_link[1];
339 x->avl_link[1] = y;
340 pa[k - 1]->avl_link[da[k - 1]] = x;
341 if (x->avl_balance == 0) {
342 x->avl_balance = +1;
343 y->avl_balance = -1;
344 break;
345 } else
346 x->avl_balance = y->avl_balance = 0;
347 }
348 }
349 }
350 }
351
352 tree->avl_count--;
353 tree->avl_generation++;
354 return res;
355 }
356
357 /* Refreshes the stack of parent pointers in |trav|
358 and updates its generation number. */
trav_refresh(struct avl_traverser * trav)359 static void trav_refresh(struct avl_traverser *trav)
360 {
361 assert(trav != NULL);
362
363 trav->avl_generation = trav->avl_table->avl_generation;
364
365 if (trav->avl_node != NULL) {
366 avl_comparison_func *cmp = trav->avl_table->avl_compare;
367 void *param = trav->avl_table->avl_param;
368 struct avl_node *node = trav->avl_node;
369 struct avl_node *i;
370
371 trav->avl_height = 0;
372 for (i = trav->avl_table->avl_root; i != node;) {
373 assert(trav->avl_height < AVL_MAX_HEIGHT);
374 assert(i != NULL);
375
376 trav->avl_stack[trav->avl_height++] = i;
377 i = i->avl_link[cmp(node->avl_data, i->avl_data, param) > 0];
378 }
379 }
380 }
381
382 /* Initializes |trav| for use with |tree|
383 and selects the null node. */
avl_t_init(struct avl_traverser * trav,struct avl_table * tree)384 void avl_t_init(struct avl_traverser *trav, struct avl_table *tree)
385 {
386 trav->avl_table = tree;
387 trav->avl_node = NULL;
388 trav->avl_height = 0;
389 trav->avl_generation = tree->avl_generation;
390 }
391
392 /* Initializes |trav| for |tree|
393 and selects and returns a pointer to its least-valued item.
394 Returns |NULL| if |tree| contains no nodes. */
avl_t_first(struct avl_traverser * trav,struct avl_table * tree)395 void *avl_t_first(struct avl_traverser *trav, struct avl_table *tree)
396 {
397 struct avl_node *x;
398
399 assert(tree != NULL && trav != NULL);
400
401 trav->avl_table = tree;
402 trav->avl_height = 0;
403 trav->avl_generation = tree->avl_generation;
404
405 x = tree->avl_root;
406 if (x != NULL)
407 while (x->avl_link[0] != NULL) {
408 assert(trav->avl_height < AVL_MAX_HEIGHT);
409 trav->avl_stack[trav->avl_height++] = x;
410 x = x->avl_link[0];
411 }
412 trav->avl_node = x;
413
414 return x != NULL ? x->avl_data : NULL;
415 }
416
417 /* Initializes |trav| for |tree|
418 and selects and returns a pointer to its greatest-valued item.
419 Returns |NULL| if |tree| contains no nodes. */
avl_t_last(struct avl_traverser * trav,struct avl_table * tree)420 void *avl_t_last(struct avl_traverser *trav, struct avl_table *tree)
421 {
422 struct avl_node *x;
423
424 assert(tree != NULL && trav != NULL);
425
426 trav->avl_table = tree;
427 trav->avl_height = 0;
428 trav->avl_generation = tree->avl_generation;
429
430 x = tree->avl_root;
431 if (x != NULL)
432 while (x->avl_link[1] != NULL) {
433 assert(trav->avl_height < AVL_MAX_HEIGHT);
434 trav->avl_stack[trav->avl_height++] = x;
435 x = x->avl_link[1];
436 }
437 trav->avl_node = x;
438
439 return x != NULL ? x->avl_data : NULL;
440 }
441
442 /* Searches for |item| in |tree|.
443 If found, initializes |trav| to the item found and returns the item
444 as well.
445 If there is no matching item, initializes |trav| to the null item
446 and returns |NULL|. */
avl_t_find(struct avl_traverser * trav,struct avl_table * tree,void * item)447 void *avl_t_find(struct avl_traverser *trav, struct avl_table *tree, void *item)
448 {
449 struct avl_node *p, *q;
450
451 assert(trav != NULL && tree != NULL && item != NULL);
452 trav->avl_table = tree;
453 trav->avl_height = 0;
454 trav->avl_generation = tree->avl_generation;
455 for (p = tree->avl_root; p != NULL; p = q) {
456 int cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
457
458 if (cmp < 0)
459 q = p->avl_link[0];
460 else if (cmp > 0)
461 q = p->avl_link[1];
462 else { /* |cmp == 0| */
463
464 trav->avl_node = p;
465 return p->avl_data;
466 }
467
468 assert(trav->avl_height < AVL_MAX_HEIGHT);
469 trav->avl_stack[trav->avl_height++] = p;
470 }
471
472 trav->avl_height = 0;
473 trav->avl_node = NULL;
474 return NULL;
475 }
476
477 /* Attempts to insert |item| into |tree|.
478 If |item| is inserted successfully, it is returned and |trav| is
479 initialized to its location.
480 If a duplicate is found, it is returned and |trav| is initialized to
481 its location. No replacement of the item occurs.
482 If a memory allocation failure occurs, |NULL| is returned and |trav|
483 is initialized to the null item. */
avl_t_insert(struct avl_traverser * trav,struct avl_table * tree,void * item)484 void *avl_t_insert(struct avl_traverser *trav, struct avl_table *tree,
485 void *item)
486 {
487 void **p;
488
489 assert(trav != NULL && tree != NULL && item != NULL);
490
491 p = avl_probe(tree, item);
492 if (p != NULL) {
493 trav->avl_table = tree;
494 trav->avl_node = ((struct avl_node *)
495 ((char *) p - offsetof(struct avl_node, avl_data)));
496 trav->avl_generation = tree->avl_generation - 1;
497 return *p;
498 } else {
499 avl_t_init(trav, tree);
500 return NULL;
501 }
502 }
503
504 /* Initializes |trav| to have the same current node as |src|. */
avl_t_copy(struct avl_traverser * trav,const struct avl_traverser * src)505 void *avl_t_copy(struct avl_traverser *trav, const struct avl_traverser *src)
506 {
507 assert(trav != NULL && src != NULL);
508
509 if (trav != src) {
510 trav->avl_table = src->avl_table;
511 trav->avl_node = src->avl_node;
512 trav->avl_generation = src->avl_generation;
513 if (trav->avl_generation == trav->avl_table->avl_generation) {
514 trav->avl_height = src->avl_height;
515 memcpy(trav->avl_stack, (const void *) src->avl_stack,
516 sizeof *trav->avl_stack * trav->avl_height);
517 }
518 }
519
520 return trav->avl_node != NULL ? trav->avl_node->avl_data : NULL;
521 }
522
523 /* Returns the next data item in inorder
524 within the tree being traversed with |trav|,
525 or if there are no more data items returns |NULL|. */
avl_t_next(struct avl_traverser * trav)526 void *avl_t_next(struct avl_traverser *trav)
527 {
528 struct avl_node *x;
529
530 assert(trav != NULL);
531
532 if (trav->avl_generation != trav->avl_table->avl_generation)
533 trav_refresh(trav);
534
535 x = trav->avl_node;
536 if (x == NULL) {
537 return avl_t_first(trav, trav->avl_table);
538 } else if (x->avl_link[1] != NULL) {
539 assert(trav->avl_height < AVL_MAX_HEIGHT);
540 trav->avl_stack[trav->avl_height++] = x;
541 x = x->avl_link[1];
542
543 while (x->avl_link[0] != NULL) {
544 assert(trav->avl_height < AVL_MAX_HEIGHT);
545 trav->avl_stack[trav->avl_height++] = x;
546 x = x->avl_link[0];
547 }
548 } else {
549 struct avl_node *y;
550
551 do {
552 if (trav->avl_height == 0) {
553 trav->avl_node = NULL;
554 return NULL;
555 }
556
557 y = x;
558 x = trav->avl_stack[--trav->avl_height];
559 }
560 while (y == x->avl_link[1]);
561 }
562 trav->avl_node = x;
563
564 return x->avl_data;
565 }
566
567 /* Returns the previous data item in inorder
568 within the tree being traversed with |trav|,
569 or if there are no more data items returns |NULL|. */
avl_t_prev(struct avl_traverser * trav)570 void *avl_t_prev(struct avl_traverser *trav)
571 {
572 struct avl_node *x;
573
574 assert(trav != NULL);
575
576 if (trav->avl_generation != trav->avl_table->avl_generation)
577 trav_refresh(trav);
578
579 x = trav->avl_node;
580 if (x == NULL) {
581 return avl_t_last(trav, trav->avl_table);
582 } else if (x->avl_link[0] != NULL) {
583 assert(trav->avl_height < AVL_MAX_HEIGHT);
584 trav->avl_stack[trav->avl_height++] = x;
585 x = x->avl_link[0];
586
587 while (x->avl_link[1] != NULL) {
588 assert(trav->avl_height < AVL_MAX_HEIGHT);
589 trav->avl_stack[trav->avl_height++] = x;
590 x = x->avl_link[1];
591 }
592 } else {
593 struct avl_node *y;
594
595 do {
596 if (trav->avl_height == 0) {
597 trav->avl_node = NULL;
598 return NULL;
599 }
600
601 y = x;
602 x = trav->avl_stack[--trav->avl_height];
603 }
604 while (y == x->avl_link[0]);
605 }
606 trav->avl_node = x;
607
608 return x->avl_data;
609 }
610
611 /* Returns |trav|'s current item. */
avl_t_cur(struct avl_traverser * trav)612 void *avl_t_cur(struct avl_traverser *trav)
613 {
614 assert(trav != NULL);
615
616 return trav->avl_node != NULL ? trav->avl_node->avl_data : NULL;
617 }
618
619 /* Replaces the current item in |trav| by |new| and returns the item replaced.
620 |trav| must not have the null item selected.
621 The new item must not upset the ordering of the tree. */
avl_t_replace(struct avl_traverser * trav,void * new)622 void *avl_t_replace(struct avl_traverser *trav, void *new)
623 {
624 void *old;
625
626 assert(trav != NULL && trav->avl_node != NULL && new != NULL);
627 old = trav->avl_node->avl_data;
628 trav->avl_node->avl_data = new;
629 return old;
630 }
631
632 /* Destroys |new| with |avl_destroy (new, destroy)|,
633 first setting right links of nodes in |stack| within |new|
634 to null pointers to avoid touching uninitialized data. */
635 static void
copy_error_recovery(struct avl_node ** stack,int height,struct avl_table * new,avl_item_func * destroy)636 copy_error_recovery(struct avl_node **stack, int height,
637 struct avl_table *new, avl_item_func * destroy)
638 {
639 assert(stack != NULL && height >= 0 && new != NULL);
640
641 for (; height > 2; height -= 2)
642 stack[height - 1]->avl_link[1] = NULL;
643 avl_destroy(new, destroy);
644 }
645
646 /* Copies |org| to a newly created tree, which is returned.
647 If |copy != NULL|, each data item in |org| is first passed to |copy|,
648 and the return values are inserted into the tree,
649 with |NULL| return values taken as indications of failure.
650 On failure, destroys the partially created new tree,
651 applying |destroy|, if non-null, to each item in the new tree so far,
652 and returns |NULL|.
653 If |allocator != NULL|, it is used for allocation in the new tree.
654 Otherwise, the same allocator used for |org| is used. */
avl_copy(const struct avl_table * org,avl_copy_func * copy,avl_item_func * destroy,struct libavl_allocator * allocator)655 struct avl_table *avl_copy(const struct avl_table *org, avl_copy_func * copy,
656 avl_item_func * destroy,
657 struct libavl_allocator *allocator)
658 {
659 struct avl_node *stack[2 * (AVL_MAX_HEIGHT + 1)];
660 int height = 0;
661
662 struct avl_table *new;
663 struct avl_node org_head, *x, *y;
664
665 assert(org != NULL);
666 new = avl_create(org->avl_compare, org->avl_param,
667 allocator != NULL ? allocator : org->avl_alloc);
668 if (new == NULL)
669 return NULL;
670 new->avl_count = org->avl_count;
671 if (new->avl_count == 0)
672 return new;
673
674 org_head.avl_link[0] = (struct avl_node *) org->avl_root;
675 x = &org_head;
676 y = (struct avl_node *) &new->avl_root;
677 for (;;) {
678 while (x->avl_link[0] != NULL) {
679 assert(height < 2 * (AVL_MAX_HEIGHT + 1));
680
681 y->avl_link[0] =
682 new->avl_alloc->libavl_malloc(new->avl_alloc,
683 sizeof *y->avl_link[0]);
684 if (y->avl_link[0] == NULL) {
685 if (y != (struct avl_node *) &new->avl_root) {
686 y->avl_data = NULL;
687 y->avl_link[1] = NULL;
688 }
689
690 copy_error_recovery(stack, height, new, destroy);
691 return NULL;
692 }
693
694 stack[height++] = x;
695 stack[height++] = y;
696 x = x->avl_link[0];
697 y = y->avl_link[0];
698 }
699 y->avl_link[0] = NULL;
700
701 for (;;) {
702 y->avl_balance = x->avl_balance;
703 if (copy == NULL)
704 y->avl_data = x->avl_data;
705 else {
706 y->avl_data = copy(x->avl_data, org->avl_param);
707 if (y->avl_data == NULL) {
708 y->avl_link[1] = NULL;
709 copy_error_recovery(stack, height, new, destroy);
710 return NULL;
711 }
712 }
713
714 if (x->avl_link[1] != NULL) {
715 y->avl_link[1] =
716 new->avl_alloc->libavl_malloc(new->avl_alloc,
717 sizeof *y->avl_link[1]);
718 if (y->avl_link[1] == NULL) {
719 copy_error_recovery(stack, height, new, destroy);
720 return NULL;
721 }
722
723 x = x->avl_link[1];
724 y = y->avl_link[1];
725 break;
726 } else
727 y->avl_link[1] = NULL;
728
729 if (height <= 2)
730 return new;
731
732 y = stack[--height];
733 x = stack[--height];
734 }
735 }
736 }
737
738 /* Frees storage allocated for |tree|.
739 If |destroy != NULL|, applies it to each data item in inorder. */
avl_destroy(struct avl_table * tree,avl_item_func * destroy)740 void avl_destroy(struct avl_table *tree, avl_item_func * destroy)
741 {
742 struct avl_node *p, *q;
743
744 assert(tree != NULL);
745
746 for (p = tree->avl_root; p != NULL; p = q)
747 if (p->avl_link[0] == NULL) {
748 q = p->avl_link[1];
749 if (destroy != NULL && p->avl_data != NULL)
750 destroy(p->avl_data, tree->avl_param);
751 tree->avl_alloc->libavl_free(tree->avl_alloc, p);
752 } else {
753 q = p->avl_link[0];
754 p->avl_link[0] = q->avl_link[1];
755 q->avl_link[1] = p;
756 }
757
758 tree->avl_alloc->libavl_free(tree->avl_alloc, tree);
759 }
760
761 /* Allocates |size| bytes of space using |malloc()|.
762 Returns a null pointer if allocation fails. */
avl_malloc(struct libavl_allocator * allocator,size_t size)763 void *avl_malloc(struct libavl_allocator *allocator, size_t size)
764 {
765 assert(allocator != NULL && size > 0);
766 return malloc(size);
767 }
768
769 /* Frees |block|. */
avl_free(struct libavl_allocator * allocator,void * block)770 void avl_free(struct libavl_allocator *allocator, void *block)
771 {
772 assert(allocator != NULL && block != NULL);
773 free(block);
774 }
775
776 /* Default memory allocator that uses |malloc()| and |free()|. */
777 struct libavl_allocator avl_allocator_default = {
778 avl_malloc,
779 avl_free
780 };
781
782 #undef NDEBUG
783 #include <assert.h>
784
785 /* Asserts that |avl_insert()| succeeds at inserting |item| into |table|. */
786 void
787 (avl_assert_insert) (struct avl_table * table, void *item) {
788 void **p = avl_probe(table, item);
789 assert(p != NULL && *p == item);
790 }
791
792 /* Asserts that |avl_delete()| really removes |item| from |table|,
793 and returns the removed item. */
794 void *(avl_assert_delete) (struct avl_table * table, void *item) {
795 void *p = avl_delete(table, item);
796 assert(p != NULL);
797 return p;
798 }
799 /* *INDENT-ON* */
800