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Commit | Line | Data |
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1da177e4 LT |
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; | |
55a98102 | 29 | struct rb_node *parent = rb_parent(node); |
1da177e4 LT |
30 | |
31 | if ((node->rb_right = right->rb_left)) | |
55a98102 | 32 | rb_set_parent(right->rb_left, node); |
1da177e4 LT |
33 | right->rb_left = node; |
34 | ||
55a98102 DW |
35 | rb_set_parent(right, parent); |
36 | ||
37 | if (parent) | |
1da177e4 | 38 | { |
55a98102 DW |
39 | if (node == parent->rb_left) |
40 | parent->rb_left = right; | |
1da177e4 | 41 | else |
55a98102 | 42 | parent->rb_right = right; |
1da177e4 LT |
43 | } |
44 | else | |
45 | root->rb_node = right; | |
55a98102 | 46 | rb_set_parent(node, right); |
17d9ddc7 PV |
47 | |
48 | if (root->augment_cb) { | |
49 | root->augment_cb(node); | |
50 | root->augment_cb(right); | |
51 | } | |
1da177e4 LT |
52 | } |
53 | ||
54 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) | |
55 | { | |
56 | struct rb_node *left = node->rb_left; | |
55a98102 | 57 | struct rb_node *parent = rb_parent(node); |
1da177e4 LT |
58 | |
59 | if ((node->rb_left = left->rb_right)) | |
55a98102 | 60 | rb_set_parent(left->rb_right, node); |
1da177e4 LT |
61 | left->rb_right = node; |
62 | ||
55a98102 DW |
63 | rb_set_parent(left, parent); |
64 | ||
65 | if (parent) | |
1da177e4 | 66 | { |
55a98102 DW |
67 | if (node == parent->rb_right) |
68 | parent->rb_right = left; | |
1da177e4 | 69 | else |
55a98102 | 70 | parent->rb_left = left; |
1da177e4 LT |
71 | } |
72 | else | |
73 | root->rb_node = left; | |
55a98102 | 74 | rb_set_parent(node, left); |
17d9ddc7 PV |
75 | |
76 | if (root->augment_cb) { | |
77 | root->augment_cb(node); | |
78 | root->augment_cb(left); | |
79 | } | |
1da177e4 LT |
80 | } |
81 | ||
82 | void rb_insert_color(struct rb_node *node, struct rb_root *root) | |
83 | { | |
84 | struct rb_node *parent, *gparent; | |
85 | ||
17d9ddc7 PV |
86 | if (root->augment_cb) |
87 | root->augment_cb(node); | |
88 | ||
55a98102 | 89 | while ((parent = rb_parent(node)) && rb_is_red(parent)) |
1da177e4 | 90 | { |
55a98102 | 91 | gparent = rb_parent(parent); |
1da177e4 LT |
92 | |
93 | if (parent == gparent->rb_left) | |
94 | { | |
95 | { | |
96 | register struct rb_node *uncle = gparent->rb_right; | |
55a98102 | 97 | if (uncle && rb_is_red(uncle)) |
1da177e4 | 98 | { |
55a98102 DW |
99 | rb_set_black(uncle); |
100 | rb_set_black(parent); | |
101 | rb_set_red(gparent); | |
1da177e4 LT |
102 | node = gparent; |
103 | continue; | |
104 | } | |
105 | } | |
106 | ||
107 | if (parent->rb_right == node) | |
108 | { | |
109 | register struct rb_node *tmp; | |
110 | __rb_rotate_left(parent, root); | |
111 | tmp = parent; | |
112 | parent = node; | |
113 | node = tmp; | |
114 | } | |
115 | ||
55a98102 DW |
116 | rb_set_black(parent); |
117 | rb_set_red(gparent); | |
1da177e4 LT |
118 | __rb_rotate_right(gparent, root); |
119 | } else { | |
120 | { | |
121 | register struct rb_node *uncle = gparent->rb_left; | |
55a98102 | 122 | if (uncle && rb_is_red(uncle)) |
1da177e4 | 123 | { |
55a98102 DW |
124 | rb_set_black(uncle); |
125 | rb_set_black(parent); | |
126 | rb_set_red(gparent); | |
1da177e4 LT |
127 | node = gparent; |
128 | continue; | |
129 | } | |
130 | } | |
131 | ||
132 | if (parent->rb_left == node) | |
133 | { | |
134 | register struct rb_node *tmp; | |
135 | __rb_rotate_right(parent, root); | |
136 | tmp = parent; | |
137 | parent = node; | |
138 | node = tmp; | |
139 | } | |
140 | ||
55a98102 DW |
141 | rb_set_black(parent); |
142 | rb_set_red(gparent); | |
1da177e4 LT |
143 | __rb_rotate_left(gparent, root); |
144 | } | |
145 | } | |
146 | ||
55a98102 | 147 | rb_set_black(root->rb_node); |
1da177e4 LT |
148 | } |
149 | EXPORT_SYMBOL(rb_insert_color); | |
150 | ||
151 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
152 | struct rb_root *root) | |
153 | { | |
154 | struct rb_node *other; | |
155 | ||
55a98102 | 156 | while ((!node || rb_is_black(node)) && node != root->rb_node) |
1da177e4 LT |
157 | { |
158 | if (parent->rb_left == node) | |
159 | { | |
160 | other = parent->rb_right; | |
55a98102 | 161 | if (rb_is_red(other)) |
1da177e4 | 162 | { |
55a98102 DW |
163 | rb_set_black(other); |
164 | rb_set_red(parent); | |
1da177e4 LT |
165 | __rb_rotate_left(parent, root); |
166 | other = parent->rb_right; | |
167 | } | |
55a98102 DW |
168 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
169 | (!other->rb_right || rb_is_black(other->rb_right))) | |
1da177e4 | 170 | { |
55a98102 | 171 | rb_set_red(other); |
1da177e4 | 172 | node = parent; |
55a98102 | 173 | parent = rb_parent(node); |
1da177e4 LT |
174 | } |
175 | else | |
176 | { | |
55a98102 | 177 | if (!other->rb_right || rb_is_black(other->rb_right)) |
1da177e4 | 178 | { |
55a63998 | 179 | rb_set_black(other->rb_left); |
55a98102 | 180 | rb_set_red(other); |
1da177e4 LT |
181 | __rb_rotate_right(other, root); |
182 | other = parent->rb_right; | |
183 | } | |
2f3243ae | 184 | rb_set_color(other, rb_color(parent)); |
55a98102 | 185 | rb_set_black(parent); |
55a63998 | 186 | rb_set_black(other->rb_right); |
1da177e4 LT |
187 | __rb_rotate_left(parent, root); |
188 | node = root->rb_node; | |
189 | break; | |
190 | } | |
191 | } | |
192 | else | |
193 | { | |
194 | other = parent->rb_left; | |
55a98102 | 195 | if (rb_is_red(other)) |
1da177e4 | 196 | { |
55a98102 DW |
197 | rb_set_black(other); |
198 | rb_set_red(parent); | |
1da177e4 LT |
199 | __rb_rotate_right(parent, root); |
200 | other = parent->rb_left; | |
201 | } | |
55a98102 DW |
202 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
203 | (!other->rb_right || rb_is_black(other->rb_right))) | |
1da177e4 | 204 | { |
55a98102 | 205 | rb_set_red(other); |
1da177e4 | 206 | node = parent; |
55a98102 | 207 | parent = rb_parent(node); |
1da177e4 LT |
208 | } |
209 | else | |
210 | { | |
55a98102 | 211 | if (!other->rb_left || rb_is_black(other->rb_left)) |
1da177e4 | 212 | { |
55a63998 | 213 | rb_set_black(other->rb_right); |
55a98102 | 214 | rb_set_red(other); |
1da177e4 LT |
215 | __rb_rotate_left(other, root); |
216 | other = parent->rb_left; | |
217 | } | |
2f3243ae | 218 | rb_set_color(other, rb_color(parent)); |
55a98102 | 219 | rb_set_black(parent); |
55a63998 | 220 | rb_set_black(other->rb_left); |
1da177e4 LT |
221 | __rb_rotate_right(parent, root); |
222 | node = root->rb_node; | |
223 | break; | |
224 | } | |
225 | } | |
226 | } | |
227 | if (node) | |
55a98102 | 228 | rb_set_black(node); |
1da177e4 LT |
229 | } |
230 | ||
231 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
232 | { | |
233 | struct rb_node *child, *parent; | |
234 | int color; | |
235 | ||
236 | if (!node->rb_left) | |
237 | child = node->rb_right; | |
238 | else if (!node->rb_right) | |
239 | child = node->rb_left; | |
240 | else | |
241 | { | |
242 | struct rb_node *old = node, *left; | |
17d9ddc7 PV |
243 | int old_parent_cb = 0; |
244 | int successor_parent_cb = 0; | |
1da177e4 LT |
245 | |
246 | node = node->rb_right; | |
247 | while ((left = node->rb_left) != NULL) | |
248 | node = left; | |
16c047ad WS |
249 | |
250 | if (rb_parent(old)) { | |
17d9ddc7 | 251 | old_parent_cb = 1; |
16c047ad WS |
252 | if (rb_parent(old)->rb_left == old) |
253 | rb_parent(old)->rb_left = node; | |
254 | else | |
255 | rb_parent(old)->rb_right = node; | |
256 | } else | |
257 | root->rb_node = node; | |
258 | ||
1da177e4 | 259 | child = node->rb_right; |
55a98102 | 260 | parent = rb_parent(node); |
2f3243ae | 261 | color = rb_color(node); |
1da177e4 | 262 | |
55a98102 | 263 | if (parent == old) { |
1da177e4 | 264 | parent = node; |
4c601178 | 265 | } else { |
17d9ddc7 | 266 | successor_parent_cb = 1; |
4c601178 WS |
267 | if (child) |
268 | rb_set_parent(child, parent); | |
17d9ddc7 | 269 | |
1975e593 | 270 | parent->rb_left = child; |
4b324126 WS |
271 | |
272 | node->rb_right = old->rb_right; | |
273 | rb_set_parent(old->rb_right, node); | |
4c601178 | 274 | } |
1975e593 | 275 | |
2f3243ae | 276 | node->rb_parent_color = old->rb_parent_color; |
1da177e4 | 277 | node->rb_left = old->rb_left; |
55a98102 | 278 | rb_set_parent(old->rb_left, node); |
4b324126 | 279 | |
17d9ddc7 PV |
280 | if (root->augment_cb) { |
281 | /* | |
282 | * Here, three different nodes can have new children. | |
283 | * The parent of the successor node that was selected | |
284 | * to replace the node to be erased. | |
285 | * The node that is getting erased and is now replaced | |
286 | * by its successor. | |
287 | * The parent of the node getting erased-replaced. | |
288 | */ | |
289 | if (successor_parent_cb) | |
290 | root->augment_cb(parent); | |
291 | ||
292 | root->augment_cb(node); | |
293 | ||
294 | if (old_parent_cb) | |
295 | root->augment_cb(rb_parent(old)); | |
296 | } | |
297 | ||
1da177e4 LT |
298 | goto color; |
299 | } | |
300 | ||
55a98102 | 301 | parent = rb_parent(node); |
2f3243ae | 302 | color = rb_color(node); |
1da177e4 LT |
303 | |
304 | if (child) | |
55a98102 | 305 | rb_set_parent(child, parent); |
17d9ddc7 PV |
306 | |
307 | if (parent) { | |
1da177e4 LT |
308 | if (parent->rb_left == node) |
309 | parent->rb_left = child; | |
310 | else | |
311 | parent->rb_right = child; | |
17d9ddc7 PV |
312 | |
313 | if (root->augment_cb) | |
314 | root->augment_cb(parent); | |
315 | ||
316 | } else { | |
1da177e4 | 317 | root->rb_node = child; |
17d9ddc7 | 318 | } |
1da177e4 LT |
319 | |
320 | color: | |
321 | if (color == RB_BLACK) | |
322 | __rb_erase_color(child, parent, root); | |
323 | } | |
324 | EXPORT_SYMBOL(rb_erase); | |
325 | ||
326 | /* | |
327 | * This function returns the first node (in sort order) of the tree. | |
328 | */ | |
f4b477c4 | 329 | struct rb_node *rb_first(const struct rb_root *root) |
1da177e4 LT |
330 | { |
331 | struct rb_node *n; | |
332 | ||
333 | n = root->rb_node; | |
334 | if (!n) | |
335 | return NULL; | |
336 | while (n->rb_left) | |
337 | n = n->rb_left; | |
338 | return n; | |
339 | } | |
340 | EXPORT_SYMBOL(rb_first); | |
341 | ||
f4b477c4 | 342 | struct rb_node *rb_last(const struct rb_root *root) |
1da177e4 LT |
343 | { |
344 | struct rb_node *n; | |
345 | ||
346 | n = root->rb_node; | |
347 | if (!n) | |
348 | return NULL; | |
349 | while (n->rb_right) | |
350 | n = n->rb_right; | |
351 | return n; | |
352 | } | |
353 | EXPORT_SYMBOL(rb_last); | |
354 | ||
f4b477c4 | 355 | struct rb_node *rb_next(const struct rb_node *node) |
1da177e4 | 356 | { |
55a98102 DW |
357 | struct rb_node *parent; |
358 | ||
10fd48f2 JA |
359 | if (rb_parent(node) == node) |
360 | return NULL; | |
361 | ||
1da177e4 LT |
362 | /* If we have a right-hand child, go down and then left as far |
363 | as we can. */ | |
364 | if (node->rb_right) { | |
365 | node = node->rb_right; | |
366 | while (node->rb_left) | |
367 | node=node->rb_left; | |
f4b477c4 | 368 | return (struct rb_node *)node; |
1da177e4 LT |
369 | } |
370 | ||
371 | /* No right-hand children. Everything down and left is | |
372 | smaller than us, so any 'next' node must be in the general | |
373 | direction of our parent. Go up the tree; any time the | |
374 | ancestor is a right-hand child of its parent, keep going | |
375 | up. First time it's a left-hand child of its parent, said | |
376 | parent is our 'next' node. */ | |
55a98102 DW |
377 | while ((parent = rb_parent(node)) && node == parent->rb_right) |
378 | node = parent; | |
1da177e4 | 379 | |
55a98102 | 380 | return parent; |
1da177e4 LT |
381 | } |
382 | EXPORT_SYMBOL(rb_next); | |
383 | ||
f4b477c4 | 384 | struct rb_node *rb_prev(const struct rb_node *node) |
1da177e4 | 385 | { |
55a98102 DW |
386 | struct rb_node *parent; |
387 | ||
10fd48f2 JA |
388 | if (rb_parent(node) == node) |
389 | return NULL; | |
390 | ||
1da177e4 LT |
391 | /* If we have a left-hand child, go down and then right as far |
392 | as we can. */ | |
393 | if (node->rb_left) { | |
394 | node = node->rb_left; | |
395 | while (node->rb_right) | |
396 | node=node->rb_right; | |
f4b477c4 | 397 | return (struct rb_node *)node; |
1da177e4 LT |
398 | } |
399 | ||
400 | /* No left-hand children. Go up till we find an ancestor which | |
401 | is a right-hand child of its parent */ | |
55a98102 DW |
402 | while ((parent = rb_parent(node)) && node == parent->rb_left) |
403 | node = parent; | |
1da177e4 | 404 | |
55a98102 | 405 | return parent; |
1da177e4 LT |
406 | } |
407 | EXPORT_SYMBOL(rb_prev); | |
408 | ||
409 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
410 | struct rb_root *root) | |
411 | { | |
55a98102 | 412 | struct rb_node *parent = rb_parent(victim); |
1da177e4 LT |
413 | |
414 | /* Set the surrounding nodes to point to the replacement */ | |
415 | if (parent) { | |
416 | if (victim == parent->rb_left) | |
417 | parent->rb_left = new; | |
418 | else | |
419 | parent->rb_right = new; | |
420 | } else { | |
421 | root->rb_node = new; | |
422 | } | |
423 | if (victim->rb_left) | |
55a98102 | 424 | rb_set_parent(victim->rb_left, new); |
1da177e4 | 425 | if (victim->rb_right) |
55a98102 | 426 | rb_set_parent(victim->rb_right, new); |
1da177e4 LT |
427 | |
428 | /* Copy the pointers/colour from the victim to the replacement */ | |
429 | *new = *victim; | |
430 | } | |
431 | EXPORT_SYMBOL(rb_replace_node); |