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Linux/include/linux/rbtree_augmented.h

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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   (C) 2012  Michel Lespinasse <walken@google.com>
  6 
  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.
 11 
 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.
 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  02111-1307  USA
 20 
 21   linux/include/linux/rbtree_augmented.h
 22 */
 23 
 24 #ifndef _LINUX_RBTREE_AUGMENTED_H
 25 #define _LINUX_RBTREE_AUGMENTED_H
 26 
 27 #include <linux/compiler.h>
 28 #include <linux/rbtree.h>
 29 
 30 /*
 31  * Please note - only struct rb_augment_callbacks and the prototypes for
 32  * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
 33  * The rest are implementation details you are not expected to depend on.
 34  *
 35  * See Documentation/rbtree.txt for documentation and samples.
 36  */
 37 
 38 struct rb_augment_callbacks {
 39         void (*propagate)(struct rb_node *node, struct rb_node *stop);
 40         void (*copy)(struct rb_node *old, struct rb_node *new);
 41         void (*rotate)(struct rb_node *old, struct rb_node *new);
 42 };
 43 
 44 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
 45         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
 46 static inline void
 47 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
 48                     const struct rb_augment_callbacks *augment)
 49 {
 50         __rb_insert_augmented(node, root, augment->rotate);
 51 }
 52 
 53 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
 54                              rbtype, rbaugmented, rbcompute)            \
 55 static inline void                                                      \
 56 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
 57 {                                                                       \
 58         while (rb != stop) {                                            \
 59                 rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
 60                 rbtype augmented = rbcompute(node);                     \
 61                 if (node->rbaugmented == augmented)                     \
 62                         break;                                          \
 63                 node->rbaugmented = augmented;                          \
 64                 rb = rb_parent(&node->rbfield);                         \
 65         }                                                               \
 66 }                                                                       \
 67 static inline void                                                      \
 68 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
 69 {                                                                       \
 70         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
 71         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
 72         new->rbaugmented = old->rbaugmented;                            \
 73 }                                                                       \
 74 static void                                                             \
 75 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
 76 {                                                                       \
 77         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
 78         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
 79         new->rbaugmented = old->rbaugmented;                            \
 80         old->rbaugmented = rbcompute(old);                              \
 81 }                                                                       \
 82 rbstatic const struct rb_augment_callbacks rbname = {                   \
 83         rbname ## _propagate, rbname ## _copy, rbname ## _rotate        \
 84 };
 85 
 86 
 87 #define RB_RED          0
 88 #define RB_BLACK        1
 89 
 90 #define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
 91 
 92 #define __rb_color(pc)     ((pc) & 1)
 93 #define __rb_is_black(pc)  __rb_color(pc)
 94 #define __rb_is_red(pc)    (!__rb_color(pc))
 95 #define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
 96 #define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
 97 #define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
 98 
 99 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
100 {
101         rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
102 }
103 
104 static inline void rb_set_parent_color(struct rb_node *rb,
105                                        struct rb_node *p, int color)
106 {
107         rb->__rb_parent_color = (unsigned long)p | color;
108 }
109 
110 static inline void
111 __rb_change_child(struct rb_node *old, struct rb_node *new,
112                   struct rb_node *parent, struct rb_root *root)
113 {
114         if (parent) {
115                 if (parent->rb_left == old)
116                         parent->rb_left = new;
117                 else
118                         parent->rb_right = new;
119         } else
120                 root->rb_node = new;
121 }
122 
123 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
124         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
125 
126 static __always_inline struct rb_node *
127 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
128                      const struct rb_augment_callbacks *augment)
129 {
130         struct rb_node *child = node->rb_right, *tmp = node->rb_left;
131         struct rb_node *parent, *rebalance;
132         unsigned long pc;
133 
134         if (!tmp) {
135                 /*
136                  * Case 1: node to erase has no more than 1 child (easy!)
137                  *
138                  * Note that if there is one child it must be red due to 5)
139                  * and node must be black due to 4). We adjust colors locally
140                  * so as to bypass __rb_erase_color() later on.
141                  */
142                 pc = node->__rb_parent_color;
143                 parent = __rb_parent(pc);
144                 __rb_change_child(node, child, parent, root);
145                 if (child) {
146                         child->__rb_parent_color = pc;
147                         rebalance = NULL;
148                 } else
149                         rebalance = __rb_is_black(pc) ? parent : NULL;
150                 tmp = parent;
151         } else if (!child) {
152                 /* Still case 1, but this time the child is node->rb_left */
153                 tmp->__rb_parent_color = pc = node->__rb_parent_color;
154                 parent = __rb_parent(pc);
155                 __rb_change_child(node, tmp, parent, root);
156                 rebalance = NULL;
157                 tmp = parent;
158         } else {
159                 struct rb_node *successor = child, *child2;
160                 tmp = child->rb_left;
161                 if (!tmp) {
162                         /*
163                          * Case 2: node's successor is its right child
164                          *
165                          *    (n)          (s)
166                          *    / \          / \
167                          *  (x) (s)  ->  (x) (c)
168                          *        \
169                          *        (c)
170                          */
171                         parent = successor;
172                         child2 = successor->rb_right;
173                         augment->copy(node, successor);
174                 } else {
175                         /*
176                          * Case 3: node's successor is leftmost under
177                          * node's right child subtree
178                          *
179                          *    (n)          (s)
180                          *    / \          / \
181                          *  (x) (y)  ->  (x) (y)
182                          *      /            /
183                          *    (p)          (p)
184                          *    /            /
185                          *  (s)          (c)
186                          *    \
187                          *    (c)
188                          */
189                         do {
190                                 parent = successor;
191                                 successor = tmp;
192                                 tmp = tmp->rb_left;
193                         } while (tmp);
194                         parent->rb_left = child2 = successor->rb_right;
195                         successor->rb_right = child;
196                         rb_set_parent(child, successor);
197                         augment->copy(node, successor);
198                         augment->propagate(parent, successor);
199                 }
200 
201                 successor->rb_left = tmp = node->rb_left;
202                 rb_set_parent(tmp, successor);
203 
204                 pc = node->__rb_parent_color;
205                 tmp = __rb_parent(pc);
206                 __rb_change_child(node, successor, tmp, root);
207                 if (child2) {
208                         successor->__rb_parent_color = pc;
209                         rb_set_parent_color(child2, parent, RB_BLACK);
210                         rebalance = NULL;
211                 } else {
212                         unsigned long pc2 = successor->__rb_parent_color;
213                         successor->__rb_parent_color = pc;
214                         rebalance = __rb_is_black(pc2) ? parent : NULL;
215                 }
216                 tmp = successor;
217         }
218 
219         augment->propagate(tmp, NULL);
220         return rebalance;
221 }
222 
223 static __always_inline void
224 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
225                    const struct rb_augment_callbacks *augment)
226 {
227         struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
228         if (rebalance)
229                 __rb_erase_color(rebalance, root, augment->rotate);
230 }
231 
232 #endif  /* _LINUX_RBTREE_AUGMENTED_H */
233 

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