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Commit | Line | Data |
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1 | /* | |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> | |
4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | ||
20 | linux/lib/rbtree.c | |
21 | */ | |
22 | ||
23 | #include <linux/rbtree.h> | |
24 | #include <linux/module.h> | |
25 | ||
26 | static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) | |
27 | { | |
28 | struct rb_node *right = node->rb_right; | |
29 | struct rb_node *parent = rb_parent(node); | |
30 | ||
31 | if ((node->rb_right = right->rb_left)) | |
32 | rb_set_parent(right->rb_left, node); | |
33 | right->rb_left = node; | |
34 | ||
35 | rb_set_parent(right, parent); | |
36 | ||
37 | if (parent) | |
38 | { | |
39 | if (node == parent->rb_left) | |
40 | parent->rb_left = right; | |
41 | else | |
42 | parent->rb_right = right; | |
43 | } | |
44 | else | |
45 | root->rb_node = right; | |
46 | rb_set_parent(node, right); | |
47 | } | |
48 | ||
49 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) | |
50 | { | |
51 | struct rb_node *left = node->rb_left; | |
52 | struct rb_node *parent = rb_parent(node); | |
53 | ||
54 | if ((node->rb_left = left->rb_right)) | |
55 | rb_set_parent(left->rb_right, node); | |
56 | left->rb_right = node; | |
57 | ||
58 | rb_set_parent(left, parent); | |
59 | ||
60 | if (parent) | |
61 | { | |
62 | if (node == parent->rb_right) | |
63 | parent->rb_right = left; | |
64 | else | |
65 | parent->rb_left = left; | |
66 | } | |
67 | else | |
68 | root->rb_node = left; | |
69 | rb_set_parent(node, left); | |
70 | } | |
71 | ||
72 | void rb_insert_color(struct rb_node *node, struct rb_root *root) | |
73 | { | |
74 | struct rb_node *parent, *gparent; | |
75 | ||
76 | while ((parent = rb_parent(node)) && rb_is_red(parent)) | |
77 | { | |
78 | gparent = rb_parent(parent); | |
79 | ||
80 | if (parent == gparent->rb_left) | |
81 | { | |
82 | { | |
83 | register struct rb_node *uncle = gparent->rb_right; | |
84 | if (uncle && rb_is_red(uncle)) | |
85 | { | |
86 | rb_set_black(uncle); | |
87 | rb_set_black(parent); | |
88 | rb_set_red(gparent); | |
89 | node = gparent; | |
90 | continue; | |
91 | } | |
92 | } | |
93 | ||
94 | if (parent->rb_right == node) | |
95 | { | |
96 | register struct rb_node *tmp; | |
97 | __rb_rotate_left(parent, root); | |
98 | tmp = parent; | |
99 | parent = node; | |
100 | node = tmp; | |
101 | } | |
102 | ||
103 | rb_set_black(parent); | |
104 | rb_set_red(gparent); | |
105 | __rb_rotate_right(gparent, root); | |
106 | } else { | |
107 | { | |
108 | register struct rb_node *uncle = gparent->rb_left; | |
109 | if (uncle && rb_is_red(uncle)) | |
110 | { | |
111 | rb_set_black(uncle); | |
112 | rb_set_black(parent); | |
113 | rb_set_red(gparent); | |
114 | node = gparent; | |
115 | continue; | |
116 | } | |
117 | } | |
118 | ||
119 | if (parent->rb_left == node) | |
120 | { | |
121 | register struct rb_node *tmp; | |
122 | __rb_rotate_right(parent, root); | |
123 | tmp = parent; | |
124 | parent = node; | |
125 | node = tmp; | |
126 | } | |
127 | ||
128 | rb_set_black(parent); | |
129 | rb_set_red(gparent); | |
130 | __rb_rotate_left(gparent, root); | |
131 | } | |
132 | } | |
133 | ||
134 | rb_set_black(root->rb_node); | |
135 | } | |
136 | EXPORT_SYMBOL(rb_insert_color); | |
137 | ||
138 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
139 | struct rb_root *root) | |
140 | { | |
141 | struct rb_node *other; | |
142 | ||
143 | while ((!node || rb_is_black(node)) && node != root->rb_node) | |
144 | { | |
145 | if (parent->rb_left == node) | |
146 | { | |
147 | other = parent->rb_right; | |
148 | if (rb_is_red(other)) | |
149 | { | |
150 | rb_set_black(other); | |
151 | rb_set_red(parent); | |
152 | __rb_rotate_left(parent, root); | |
153 | other = parent->rb_right; | |
154 | } | |
155 | if ((!other->rb_left || rb_is_black(other->rb_left)) && | |
156 | (!other->rb_right || rb_is_black(other->rb_right))) | |
157 | { | |
158 | rb_set_red(other); | |
159 | node = parent; | |
160 | parent = rb_parent(node); | |
161 | } | |
162 | else | |
163 | { | |
164 | if (!other->rb_right || rb_is_black(other->rb_right)) | |
165 | { | |
166 | rb_set_black(other->rb_left); | |
167 | rb_set_red(other); | |
168 | __rb_rotate_right(other, root); | |
169 | other = parent->rb_right; | |
170 | } | |
171 | rb_set_color(other, rb_color(parent)); | |
172 | rb_set_black(parent); | |
173 | rb_set_black(other->rb_right); | |
174 | __rb_rotate_left(parent, root); | |
175 | node = root->rb_node; | |
176 | break; | |
177 | } | |
178 | } | |
179 | else | |
180 | { | |
181 | other = parent->rb_left; | |
182 | if (rb_is_red(other)) | |
183 | { | |
184 | rb_set_black(other); | |
185 | rb_set_red(parent); | |
186 | __rb_rotate_right(parent, root); | |
187 | other = parent->rb_left; | |
188 | } | |
189 | if ((!other->rb_left || rb_is_black(other->rb_left)) && | |
190 | (!other->rb_right || rb_is_black(other->rb_right))) | |
191 | { | |
192 | rb_set_red(other); | |
193 | node = parent; | |
194 | parent = rb_parent(node); | |
195 | } | |
196 | else | |
197 | { | |
198 | if (!other->rb_left || rb_is_black(other->rb_left)) | |
199 | { | |
200 | rb_set_black(other->rb_right); | |
201 | rb_set_red(other); | |
202 | __rb_rotate_left(other, root); | |
203 | other = parent->rb_left; | |
204 | } | |
205 | rb_set_color(other, rb_color(parent)); | |
206 | rb_set_black(parent); | |
207 | rb_set_black(other->rb_left); | |
208 | __rb_rotate_right(parent, root); | |
209 | node = root->rb_node; | |
210 | break; | |
211 | } | |
212 | } | |
213 | } | |
214 | if (node) | |
215 | rb_set_black(node); | |
216 | } | |
217 | ||
218 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
219 | { | |
220 | struct rb_node *child, *parent; | |
221 | int color; | |
222 | ||
223 | if (!node->rb_left) | |
224 | child = node->rb_right; | |
225 | else if (!node->rb_right) | |
226 | child = node->rb_left; | |
227 | else | |
228 | { | |
229 | struct rb_node *old = node, *left; | |
230 | ||
231 | node = node->rb_right; | |
232 | while ((left = node->rb_left) != NULL) | |
233 | node = left; | |
234 | ||
235 | if (rb_parent(old)) { | |
236 | if (rb_parent(old)->rb_left == old) | |
237 | rb_parent(old)->rb_left = node; | |
238 | else | |
239 | rb_parent(old)->rb_right = node; | |
240 | } else | |
241 | root->rb_node = node; | |
242 | ||
243 | child = node->rb_right; | |
244 | parent = rb_parent(node); | |
245 | color = rb_color(node); | |
246 | ||
247 | if (parent == old) { | |
248 | parent = node; | |
249 | } else { | |
250 | if (child) | |
251 | rb_set_parent(child, parent); | |
252 | parent->rb_left = child; | |
253 | ||
254 | node->rb_right = old->rb_right; | |
255 | rb_set_parent(old->rb_right, node); | |
256 | } | |
257 | ||
258 | node->rb_parent_color = old->rb_parent_color; | |
259 | node->rb_left = old->rb_left; | |
260 | rb_set_parent(old->rb_left, node); | |
261 | ||
262 | goto color; | |
263 | } | |
264 | ||
265 | parent = rb_parent(node); | |
266 | color = rb_color(node); | |
267 | ||
268 | if (child) | |
269 | rb_set_parent(child, parent); | |
270 | if (parent) | |
271 | { | |
272 | if (parent->rb_left == node) | |
273 | parent->rb_left = child; | |
274 | else | |
275 | parent->rb_right = child; | |
276 | } | |
277 | else | |
278 | root->rb_node = child; | |
279 | ||
280 | color: | |
281 | if (color == RB_BLACK) | |
282 | __rb_erase_color(child, parent, root); | |
283 | } | |
284 | EXPORT_SYMBOL(rb_erase); | |
285 | ||
286 | static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data) | |
287 | { | |
288 | struct rb_node *parent; | |
289 | ||
290 | up: | |
291 | func(node, data); | |
292 | parent = rb_parent(node); | |
293 | if (!parent) | |
294 | return; | |
295 | ||
296 | if (node == parent->rb_left && parent->rb_right) | |
297 | func(parent->rb_right, data); | |
298 | else if (parent->rb_left) | |
299 | func(parent->rb_left, data); | |
300 | ||
301 | node = parent; | |
302 | goto up; | |
303 | } | |
304 | ||
305 | /* | |
306 | * after inserting @node into the tree, update the tree to account for | |
307 | * both the new entry and any damage done by rebalance | |
308 | */ | |
309 | void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data) | |
310 | { | |
311 | if (node->rb_left) | |
312 | node = node->rb_left; | |
313 | else if (node->rb_right) | |
314 | node = node->rb_right; | |
315 | ||
316 | rb_augment_path(node, func, data); | |
317 | } | |
318 | EXPORT_SYMBOL(rb_augment_insert); | |
319 | ||
320 | /* | |
321 | * before removing the node, find the deepest node on the rebalance path | |
322 | * that will still be there after @node gets removed | |
323 | */ | |
324 | struct rb_node *rb_augment_erase_begin(struct rb_node *node) | |
325 | { | |
326 | struct rb_node *deepest; | |
327 | ||
328 | if (!node->rb_right && !node->rb_left) | |
329 | deepest = rb_parent(node); | |
330 | else if (!node->rb_right) | |
331 | deepest = node->rb_left; | |
332 | else if (!node->rb_left) | |
333 | deepest = node->rb_right; | |
334 | else { | |
335 | deepest = rb_next(node); | |
336 | if (deepest->rb_right) | |
337 | deepest = deepest->rb_right; | |
338 | else if (rb_parent(deepest) != node) | |
339 | deepest = rb_parent(deepest); | |
340 | } | |
341 | ||
342 | return deepest; | |
343 | } | |
344 | EXPORT_SYMBOL(rb_augment_erase_begin); | |
345 | ||
346 | /* | |
347 | * after removal, update the tree to account for the removed entry | |
348 | * and any rebalance damage. | |
349 | */ | |
350 | void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data) | |
351 | { | |
352 | if (node) | |
353 | rb_augment_path(node, func, data); | |
354 | } | |
355 | EXPORT_SYMBOL(rb_augment_erase_end); | |
356 | ||
357 | /* | |
358 | * This function returns the first node (in sort order) of the tree. | |
359 | */ | |
360 | struct rb_node *rb_first(const struct rb_root *root) | |
361 | { | |
362 | struct rb_node *n; | |
363 | ||
364 | n = root->rb_node; | |
365 | if (!n) | |
366 | return NULL; | |
367 | while (n->rb_left) | |
368 | n = n->rb_left; | |
369 | return n; | |
370 | } | |
371 | EXPORT_SYMBOL(rb_first); | |
372 | ||
373 | struct rb_node *rb_last(const struct rb_root *root) | |
374 | { | |
375 | struct rb_node *n; | |
376 | ||
377 | n = root->rb_node; | |
378 | if (!n) | |
379 | return NULL; | |
380 | while (n->rb_right) | |
381 | n = n->rb_right; | |
382 | return n; | |
383 | } | |
384 | EXPORT_SYMBOL(rb_last); | |
385 | ||
386 | struct rb_node *rb_next(const struct rb_node *node) | |
387 | { | |
388 | struct rb_node *parent; | |
389 | ||
390 | if (rb_parent(node) == node) | |
391 | return NULL; | |
392 | ||
393 | /* If we have a right-hand child, go down and then left as far | |
394 | as we can. */ | |
395 | if (node->rb_right) { | |
396 | node = node->rb_right; | |
397 | while (node->rb_left) | |
398 | node=node->rb_left; | |
399 | return (struct rb_node *)node; | |
400 | } | |
401 | ||
402 | /* No right-hand children. Everything down and left is | |
403 | smaller than us, so any 'next' node must be in the general | |
404 | direction of our parent. Go up the tree; any time the | |
405 | ancestor is a right-hand child of its parent, keep going | |
406 | up. First time it's a left-hand child of its parent, said | |
407 | parent is our 'next' node. */ | |
408 | while ((parent = rb_parent(node)) && node == parent->rb_right) | |
409 | node = parent; | |
410 | ||
411 | return parent; | |
412 | } | |
413 | EXPORT_SYMBOL(rb_next); | |
414 | ||
415 | struct rb_node *rb_prev(const struct rb_node *node) | |
416 | { | |
417 | struct rb_node *parent; | |
418 | ||
419 | if (rb_parent(node) == node) | |
420 | return NULL; | |
421 | ||
422 | /* If we have a left-hand child, go down and then right as far | |
423 | as we can. */ | |
424 | if (node->rb_left) { | |
425 | node = node->rb_left; | |
426 | while (node->rb_right) | |
427 | node=node->rb_right; | |
428 | return (struct rb_node *)node; | |
429 | } | |
430 | ||
431 | /* No left-hand children. Go up till we find an ancestor which | |
432 | is a right-hand child of its parent */ | |
433 | while ((parent = rb_parent(node)) && node == parent->rb_left) | |
434 | node = parent; | |
435 | ||
436 | return parent; | |
437 | } | |
438 | EXPORT_SYMBOL(rb_prev); | |
439 | ||
440 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
441 | struct rb_root *root) | |
442 | { | |
443 | struct rb_node *parent = rb_parent(victim); | |
444 | ||
445 | /* Set the surrounding nodes to point to the replacement */ | |
446 | if (parent) { | |
447 | if (victim == parent->rb_left) | |
448 | parent->rb_left = new; | |
449 | else | |
450 | parent->rb_right = new; | |
451 | } else { | |
452 | root->rb_node = new; | |
453 | } | |
454 | if (victim->rb_left) | |
455 | rb_set_parent(victim->rb_left, new); | |
456 | if (victim->rb_right) | |
457 | rb_set_parent(victim->rb_right, new); | |
458 | ||
459 | /* Copy the pointers/colour from the victim to the replacement */ | |
460 | *new = *victim; | |
461 | } | |
462 | EXPORT_SYMBOL(rb_replace_node); |