1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <andrea (at) suse.de> 4 (C) 2002 David Woodhouse <dwmw2 (at) infradead.org> 5 (C) 2012 Michel Lespinasse <walken (at) 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
