1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <[email protected]> 4 (C) 2002 David Woodhouse <[email protected]> 5 (C) 2012 Michel Lespinasse <[email protected]> 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 */ 224