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 "rbtree.h"
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 /*
  34  * Please note - only struct rb_augment_callbacks and the prototypes for
  35  * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
  36  * The rest are implementation details you are not expected to depend on.
  37  *
  38  * See Documentation/rbtree.txt for documentation and samples.
  39  */
  40
  41 struct rb_augment_callbacks {
  42         void (*propagate)(struct rb_node *node, struct rb_node *stop);
  43         void (*copy)(struct rb_node *old, struct rb_node *new);
  44         void (*rotate)(struct rb_node *old, struct rb_node *new);
  45 };
  46
  47 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  48         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
  49 static inline void
  50 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  51                     const struct rb_augment_callbacks *augment)
  52 {
  53         __rb_insert_augmented(node, root, augment->rotate);
  54 }
  55
  56 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
  57                              rbtype, rbaugmented, rbcompute)            \
  58 static inline void                                                      \
  59 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
  60 {                                                                       \
  61         while (rb != stop) {                                            \
  62                 rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
  63                 rbtype augmented = rbcompute(node);                     \
  64                 if (node->rbaugmented == augmented)                     \
  65                         break;                                          \
  66                 node->rbaugmented = augmented;                          \
  67                 rb = rb_parent(&node->rbfield);                         \
  68         }                                                               \
  69 }                                                                       \
  70 static inline void                                                      \
  71 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
  72 {                                                                       \
  73         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  74         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  75         new->rbaugmented = old->rbaugmented;                            \
  76 }                                                                       \
  77 static void                                                             \
  78 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
  79 {                                                                       \
  80         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  81         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  82         new->rbaugmented = old->rbaugmented;                            \
  83         old->rbaugmented = rbcompute(old);                              \
  84 }                                                                       \
  85 rbstatic const struct rb_augment_callbacks rbname = {                   \
  86         rbname ## _propagate, rbname ## _copy, rbname ## _rotate        \
  87 };
  88
  89
  90 #define RB_RED          0
  91 #define RB_BLACK        1
  92
  93 #define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
  94
  95 #define __rb_color(pc)     ((pc) & 1)
  96 #define __rb_is_black(pc)  __rb_color(pc)
  97 #define __rb_is_red(pc)    (!__rb_color(pc))
  98 #define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
  99 #define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
 100 #define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
 101
 102 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 103 {
 104         rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
 105 }
 106
 107 static inline void rb_set_parent_color(struct rb_node *rb,
 108                                        struct rb_node *p, int color)
 109 {
 110         rb->__rb_parent_color = (unsigned long)p | color;
 111 }
 112
 113 static inline void
 114 __rb_change_child(struct rb_node *old, struct rb_node *new,
 115                   struct rb_node *parent, struct rb_root *root)
 116 {
 117         if (parent) {
 118                 if (parent->rb_left == old)
 119                         parent->rb_left = new;
 120                 else
 121                         parent->rb_right = new;
 122         } else
 123                 root->rb_node = new;
 124 }
 125
 126 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
 127         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
 128
 129 static __always_inline struct rb_node *
 130 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 131                      const struct rb_augment_callbacks *augment)
 132 {
 133         struct rb_node *child = node->rb_right, *tmp = node->rb_left;
 134         struct rb_node *parent, *rebalance;
 135         unsigned long pc;
 136
 137         if (!tmp) {
 138                 /*
 139                  * Case 1: node to erase has no more than 1 child (easy!)
 140                  *
 141                  * Note that if there is one child it must be red due to 5)
 142                  * and node must be black due to 4). We adjust colors locally
 143                  * so as to bypass __rb_erase_color() later on.
 144                  */
 145                 pc = node->__rb_parent_color;
 146                 parent = __rb_parent(pc);
 147                 __rb_change_child(node, child, parent, root);
 148                 if (child) {
 149                         child->__rb_parent_color = pc;
 150                         rebalance = NULL;
 151                 } else
 152                         rebalance = __rb_is_black(pc) ? parent : NULL;
 153                 tmp = parent;
 154         } else if (!child) {
 155                 /* Still case 1, but this time the child is node->rb_left */
 156                 tmp->__rb_parent_color = pc = node->__rb_parent_color;
 157                 parent = __rb_parent(pc);
 158                 __rb_change_child(node, tmp, parent, root);
 159                 rebalance = NULL;
 160                 tmp = parent;
 161         } else {
 162                 struct rb_node *successor = child, *child2;
 163                 tmp = child->rb_left;
 164                 if (!tmp) {
 165                         /*
 166                          * Case 2: node's successor is its right child
 167                          *
 168                          *    (n)          (s)
 169                          *    / \          / \
 170                          *  (x) (s)  ->  (x) (c)
 171                          *        \
 172                          *        (c)
 173                          */
 174                         parent = successor;
 175                         child2 = successor->rb_right;
 176                         augment->copy(node, successor);
 177                 } else {
 178                         /*
 179                          * Case 3: node's successor is leftmost under
 180                          * node's right child subtree
 181                          *
 182                          *    (n)          (s)
 183                          *    / \          / \
 184                          *  (x) (y)  ->  (x) (y)
 185                          *      /            /
 186                          *    (p)          (p)
 187                          *    /            /
 188                          *  (s)          (c)
 189                          *    \
 190                          *    (c)
 191                          */
 192                         do {
 193                                 parent = successor;
 194                                 successor = tmp;
 195                                 tmp = tmp->rb_left;
 196                         } while (tmp);
 197                         parent->rb_left = child2 = successor->rb_right;
 198                         successor->rb_right = child;
 199                         rb_set_parent(child, successor);
 200                         augment->copy(node, successor);
 201                         augment->propagate(parent, successor);
 202                 }
 203
 204                 successor->rb_left = tmp = node->rb_left;
 205                 rb_set_parent(tmp, successor);
 206
 207                 pc = node->__rb_parent_color;
 208                 tmp = __rb_parent(pc);
 209                 __rb_change_child(node, successor, tmp, root);
 210                 if (child2) {
 211                         successor->__rb_parent_color = pc;
 212                         rb_set_parent_color(child2, parent, RB_BLACK);
 213                         rebalance = NULL;
 214                 } else {
 215                         unsigned long pc2 = successor->__rb_parent_color;
 216                         successor->__rb_parent_color = pc;
 217                         rebalance = __rb_is_black(pc2) ? parent : NULL;
 218                 }
 219                 tmp = successor;
 220         }
 221
 222         augment->propagate(tmp, NULL);
 223         return rebalance;
 224 }
 225
 226 static __always_inline void
 227 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 228                    const struct rb_augment_callbacks *augment)
 229 {
 230         struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
 231         if (rebalance)
 232                 __rb_erase_color(rebalance, root, augment->rotate);
 233 }
 234
 235 #ifdef __cplusplus
 236 }
 237 #endif
 238
 239 #endif  /* _LINUX_RBTREE_AUGMENTED_H */