include/linux/rbtree_augmented.h

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