3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
5 (C) 2007 Andre Noll <maan@systemlinux.org>
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
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 02111-1307 USA
24 /** \file rbtree.c Red-black tree implementation. */
29 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
31 struct rb_node *right = node->rb_right;
32 struct rb_node *parent = rb_parent(node);
34 if ((node->rb_right = right->rb_left))
35 rb_set_parent(right->rb_left, node);
36 right->rb_left = node;
38 rb_set_parent(right, parent);
42 if (node == parent->rb_left)
43 parent->rb_left = right;
45 parent->rb_right = right;
48 root->rb_node = right;
49 rb_set_parent(node, right);
50 right->size = node->size;
53 node->size += node->rb_right->size;
55 node->size += node->rb_left->size;
58 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
60 struct rb_node *left = node->rb_left;
61 struct rb_node *parent = rb_parent(node);
63 if ((node->rb_left = left->rb_right))
64 rb_set_parent(left->rb_right, node);
65 left->rb_right = node;
67 rb_set_parent(left, parent);
71 if (node == parent->rb_right)
72 parent->rb_right = left;
74 parent->rb_left = left;
78 rb_set_parent(node, left);
79 left->size = node->size;
82 node->size += node->rb_right->size;
84 node->size += node->rb_left->size;
87 void rb_insert_color(struct rb_node *node, struct rb_root *root)
89 struct rb_node *parent, *gparent;
91 while ((parent = rb_parent(node)) && rb_is_red(parent))
93 gparent = rb_parent(parent);
95 if (parent == gparent->rb_left)
98 register struct rb_node *uncle = gparent->rb_right;
99 if (uncle && rb_is_red(uncle))
102 rb_set_black(parent);
109 if (parent->rb_right == node)
111 register struct rb_node *tmp;
112 __rb_rotate_left(parent, root);
118 rb_set_black(parent);
120 __rb_rotate_right(gparent, root);
123 register struct rb_node *uncle = gparent->rb_left;
124 if (uncle && rb_is_red(uncle))
127 rb_set_black(parent);
134 if (parent->rb_left == node)
136 register struct rb_node *tmp;
137 __rb_rotate_right(parent, root);
143 rb_set_black(parent);
145 __rb_rotate_left(gparent, root);
149 rb_set_black(root->rb_node);
152 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
153 struct rb_root *root)
155 struct rb_node *other;
157 while ((!node || rb_is_black(node)) && node != root->rb_node)
159 if (parent->rb_left == node)
161 other = parent->rb_right;
162 if (rb_is_red(other))
166 __rb_rotate_left(parent, root);
167 other = parent->rb_right;
169 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
170 (!other->rb_right || rb_is_black(other->rb_right)))
174 parent = rb_parent(node);
178 if (!other->rb_right || rb_is_black(other->rb_right))
180 struct rb_node *o_left;
181 if ((o_left = other->rb_left))
182 rb_set_black(o_left);
184 __rb_rotate_right(other, root);
185 other = parent->rb_right;
187 rb_set_color(other, rb_color(parent));
188 rb_set_black(parent);
190 rb_set_black(other->rb_right);
191 __rb_rotate_left(parent, root);
192 node = root->rb_node;
198 other = parent->rb_left;
199 if (rb_is_red(other))
203 __rb_rotate_right(parent, root);
204 other = parent->rb_left;
206 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
207 (!other->rb_right || rb_is_black(other->rb_right)))
211 parent = rb_parent(node);
215 if (!other->rb_left || rb_is_black(other->rb_left))
217 register struct rb_node *o_right;
218 if ((o_right = other->rb_right))
219 rb_set_black(o_right);
221 __rb_rotate_left(other, root);
222 other = parent->rb_left;
224 rb_set_color(other, rb_color(parent));
225 rb_set_black(parent);
227 rb_set_black(other->rb_left);
228 __rb_rotate_right(parent, root);
229 node = root->rb_node;
238 void rb_erase(struct rb_node *node, struct rb_root *root)
240 struct rb_node *child, *parent;
244 child = node->rb_right;
245 else if (!node->rb_right)
246 child = node->rb_left;
249 struct rb_node *old = node, *left;
251 node = node->rb_right;
252 while ((left = node->rb_left) != NULL)
254 child = node->rb_right;
255 parent = rb_parent(node);
256 color = rb_color(node);
259 rb_set_parent(child, parent);
261 parent->rb_right = child;
264 parent->rb_left = child;
266 node->rb_parent_color = old->rb_parent_color;
267 node->rb_right = old->rb_right;
268 node->rb_left = old->rb_left;
269 node->size = old->size;
273 if (rb_parent(old)->rb_left == old)
274 rb_parent(old)->rb_left = node;
276 rb_parent(old)->rb_right = node;
278 root->rb_node = node;
280 rb_set_parent(old->rb_left, node);
282 rb_set_parent(old->rb_right, node);
286 parent = rb_parent(node);
287 color = rb_color(node);
290 rb_set_parent(child, parent);
293 if (parent->rb_left == node)
294 parent->rb_left = child;
296 parent->rb_right = child;
299 root->rb_node = child;
302 if (color == RB_BLACK)
303 __rb_erase_color(child, parent, root);
307 * This function returns the first node (in sort order) of the tree.
309 struct rb_node *rb_first(struct rb_root *root)
321 struct rb_node *rb_last(struct rb_root *root)
333 struct rb_node *rb_next(struct rb_node *node)
335 struct rb_node *parent;
337 if (rb_parent(node) == node)
340 /* If we have a right-hand child, go down and then left as far
342 if (node->rb_right) {
343 node = node->rb_right;
344 while (node->rb_left)
349 /* No right-hand children. Everything down and left is
350 smaller than us, so any 'next' node must be in the general
351 direction of our parent. Go up the tree; any time the
352 ancestor is a right-hand child of its parent, keep going
353 up. First time it's a left-hand child of its parent, said
354 parent is our 'next' node. */
355 while ((parent = rb_parent(node)) && node == parent->rb_right)
361 struct rb_node *rb_prev(struct rb_node *node)
363 struct rb_node *parent;
365 if (rb_parent(node) == node)
368 /* If we have a left-hand child, go down and then right as far
371 node = node->rb_left;
372 while (node->rb_right)
377 /* No left-hand children. Go up till we find an ancestor which
378 is a right-hand child of its parent */
379 while ((parent = rb_parent(node)) && node == parent->rb_left)
385 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
386 struct rb_root *root)
388 struct rb_node *parent = rb_parent(victim);
390 /* Set the surrounding nodes to point to the replacement */
392 if (victim == parent->rb_left)
393 parent->rb_left = new;
395 parent->rb_right = new;
400 rb_set_parent(victim->rb_left, new);
401 if (victim->rb_right)
402 rb_set_parent(victim->rb_right, new);
404 /* Copy the pointers/colour from the victim to the replacement */
409 * Get the n-th node (in sort order) of the tree.
411 * \param node The root of the subtree to consider.
412 * \param n The order statistic to compute.
414 * \return Pointer to the \a n th greatest node on success, \p NULL on errors.
416 struct rb_node *rb_nth(struct rb_node *node, unsigned n)
423 size += node->rb_left->size;
427 return rb_nth(node->rb_left, n);
428 return rb_nth(node->rb_right, n - size);
432 * Get the rank of a node in O(log n) time.
434 * \param node The node to get the rank of.
435 * \param rank Result pointer.
437 * \return Positive on success, -1 on errors.
439 int rb_rank(struct rb_node *node, unsigned *rank)
442 struct rb_node *parent;
447 *rank += node->rb_left->size;
448 while ((parent = rb_parent(node))) {
449 if (node == parent->rb_right) {
452 *rank += parent->rb_left->size;