| 1 | /* |
| 2 | Red Black Trees |
| 3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> |
| 4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 19 | |
| 20 | linux/lib/rbtree.c |
| 21 | */ |
| 22 | |
| 23 | #include "rbtree.h" |
| 24 | |
| 25 | static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) |
| 26 | { |
| 27 | struct rb_node *right = node->rb_right; |
| 28 | struct rb_node *parent = rb_parent(node); |
| 29 | |
| 30 | if ((node->rb_right = right->rb_left)) |
| 31 | rb_set_parent(right->rb_left, node); |
| 32 | right->rb_left = node; |
| 33 | |
| 34 | rb_set_parent(right, parent); |
| 35 | |
| 36 | if (parent) |
| 37 | { |
| 38 | if (node == parent->rb_left) |
| 39 | parent->rb_left = right; |
| 40 | else |
| 41 | parent->rb_right = right; |
| 42 | } |
| 43 | else |
| 44 | root->rb_node = right; |
| 45 | rb_set_parent(node, right); |
| 46 | } |
| 47 | |
| 48 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) |
| 49 | { |
| 50 | struct rb_node *left = node->rb_left; |
| 51 | struct rb_node *parent = rb_parent(node); |
| 52 | |
| 53 | if ((node->rb_left = left->rb_right)) |
| 54 | rb_set_parent(left->rb_right, node); |
| 55 | left->rb_right = node; |
| 56 | |
| 57 | rb_set_parent(left, parent); |
| 58 | |
| 59 | if (parent) |
| 60 | { |
| 61 | if (node == parent->rb_right) |
| 62 | parent->rb_right = left; |
| 63 | else |
| 64 | parent->rb_left = left; |
| 65 | } |
| 66 | else |
| 67 | root->rb_node = left; |
| 68 | rb_set_parent(node, left); |
| 69 | } |
| 70 | |
| 71 | void rb_insert_color(struct rb_node *node, struct rb_root *root) |
| 72 | { |
| 73 | struct rb_node *parent, *gparent; |
| 74 | |
| 75 | while ((parent = rb_parent(node)) && rb_is_red(parent)) |
| 76 | { |
| 77 | gparent = rb_parent(parent); |
| 78 | |
| 79 | if (parent == gparent->rb_left) |
| 80 | { |
| 81 | { |
| 82 | register struct rb_node *uncle = gparent->rb_right; |
| 83 | if (uncle && rb_is_red(uncle)) |
| 84 | { |
| 85 | rb_set_black(uncle); |
| 86 | rb_set_black(parent); |
| 87 | rb_set_red(gparent); |
| 88 | node = gparent; |
| 89 | continue; |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | if (parent->rb_right == node) |
| 94 | { |
| 95 | register struct rb_node *tmp; |
| 96 | __rb_rotate_left(parent, root); |
| 97 | tmp = parent; |
| 98 | parent = node; |
| 99 | node = tmp; |
| 100 | } |
| 101 | |
| 102 | rb_set_black(parent); |
| 103 | rb_set_red(gparent); |
| 104 | __rb_rotate_right(gparent, root); |
| 105 | } else { |
| 106 | { |
| 107 | register struct rb_node *uncle = gparent->rb_left; |
| 108 | if (uncle && rb_is_red(uncle)) |
| 109 | { |
| 110 | rb_set_black(uncle); |
| 111 | rb_set_black(parent); |
| 112 | rb_set_red(gparent); |
| 113 | node = gparent; |
| 114 | continue; |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | if (parent->rb_left == node) |
| 119 | { |
| 120 | register struct rb_node *tmp; |
| 121 | __rb_rotate_right(parent, root); |
| 122 | tmp = parent; |
| 123 | parent = node; |
| 124 | node = tmp; |
| 125 | } |
| 126 | |
| 127 | rb_set_black(parent); |
| 128 | rb_set_red(gparent); |
| 129 | __rb_rotate_left(gparent, root); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | rb_set_black(root->rb_node); |
| 134 | } |
| 135 | |
| 136 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, |
| 137 | struct rb_root *root) |
| 138 | { |
| 139 | struct rb_node *other; |
| 140 | |
| 141 | while ((!node || rb_is_black(node)) && node != root->rb_node) |
| 142 | { |
| 143 | if (parent->rb_left == node) |
| 144 | { |
| 145 | other = parent->rb_right; |
| 146 | if (rb_is_red(other)) |
| 147 | { |
| 148 | rb_set_black(other); |
| 149 | rb_set_red(parent); |
| 150 | __rb_rotate_left(parent, root); |
| 151 | other = parent->rb_right; |
| 152 | } |
| 153 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| 154 | (!other->rb_right || rb_is_black(other->rb_right))) |
| 155 | { |
| 156 | rb_set_red(other); |
| 157 | node = parent; |
| 158 | parent = rb_parent(node); |
| 159 | } |
| 160 | else |
| 161 | { |
| 162 | if (!other->rb_right || rb_is_black(other->rb_right)) |
| 163 | { |
| 164 | struct rb_node *o_left; |
| 165 | if ((o_left = other->rb_left)) |
| 166 | rb_set_black(o_left); |
| 167 | rb_set_red(other); |
| 168 | __rb_rotate_right(other, root); |
| 169 | other = parent->rb_right; |
| 170 | } |
| 171 | rb_set_color(other, rb_color(parent)); |
| 172 | rb_set_black(parent); |
| 173 | if (other->rb_right) |
| 174 | rb_set_black(other->rb_right); |
| 175 | __rb_rotate_left(parent, root); |
| 176 | node = root->rb_node; |
| 177 | break; |
| 178 | } |
| 179 | } |
| 180 | else |
| 181 | { |
| 182 | other = parent->rb_left; |
| 183 | if (rb_is_red(other)) |
| 184 | { |
| 185 | rb_set_black(other); |
| 186 | rb_set_red(parent); |
| 187 | __rb_rotate_right(parent, root); |
| 188 | other = parent->rb_left; |
| 189 | } |
| 190 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| 191 | (!other->rb_right || rb_is_black(other->rb_right))) |
| 192 | { |
| 193 | rb_set_red(other); |
| 194 | node = parent; |
| 195 | parent = rb_parent(node); |
| 196 | } |
| 197 | else |
| 198 | { |
| 199 | if (!other->rb_left || rb_is_black(other->rb_left)) |
| 200 | { |
| 201 | register struct rb_node *o_right; |
| 202 | if ((o_right = other->rb_right)) |
| 203 | rb_set_black(o_right); |
| 204 | rb_set_red(other); |
| 205 | __rb_rotate_left(other, root); |
| 206 | other = parent->rb_left; |
| 207 | } |
| 208 | rb_set_color(other, rb_color(parent)); |
| 209 | rb_set_black(parent); |
| 210 | if (other->rb_left) |
| 211 | rb_set_black(other->rb_left); |
| 212 | __rb_rotate_right(parent, root); |
| 213 | node = root->rb_node; |
| 214 | break; |
| 215 | } |
| 216 | } |
| 217 | } |
| 218 | if (node) |
| 219 | rb_set_black(node); |
| 220 | } |
| 221 | |
| 222 | void rb_erase(struct rb_node *node, struct rb_root *root) |
| 223 | { |
| 224 | struct rb_node *child, *parent; |
| 225 | int color; |
| 226 | |
| 227 | if (!node->rb_left) |
| 228 | child = node->rb_right; |
| 229 | else if (!node->rb_right) |
| 230 | child = node->rb_left; |
| 231 | else |
| 232 | { |
| 233 | struct rb_node *old = node, *left; |
| 234 | |
| 235 | node = node->rb_right; |
| 236 | while ((left = node->rb_left) != NULL) |
| 237 | node = left; |
| 238 | child = node->rb_right; |
| 239 | parent = rb_parent(node); |
| 240 | color = rb_color(node); |
| 241 | |
| 242 | if (child) |
| 243 | rb_set_parent(child, parent); |
| 244 | if (parent == old) { |
| 245 | parent->rb_right = child; |
| 246 | parent = node; |
| 247 | } else |
| 248 | parent->rb_left = child; |
| 249 | |
| 250 | node->rb_parent_color = old->rb_parent_color; |
| 251 | node->rb_right = old->rb_right; |
| 252 | node->rb_left = old->rb_left; |
| 253 | |
| 254 | if (rb_parent(old)) |
| 255 | { |
| 256 | if (rb_parent(old)->rb_left == old) |
| 257 | rb_parent(old)->rb_left = node; |
| 258 | else |
| 259 | rb_parent(old)->rb_right = node; |
| 260 | } else |
| 261 | root->rb_node = node; |
| 262 | |
| 263 | rb_set_parent(old->rb_left, node); |
| 264 | if (old->rb_right) |
| 265 | rb_set_parent(old->rb_right, node); |
| 266 | goto color; |
| 267 | } |
| 268 | |
| 269 | parent = rb_parent(node); |
| 270 | color = rb_color(node); |
| 271 | |
| 272 | if (child) |
| 273 | rb_set_parent(child, parent); |
| 274 | if (parent) |
| 275 | { |
| 276 | if (parent->rb_left == node) |
| 277 | parent->rb_left = child; |
| 278 | else |
| 279 | parent->rb_right = child; |
| 280 | } |
| 281 | else |
| 282 | root->rb_node = child; |
| 283 | |
| 284 | color: |
| 285 | if (color == RB_BLACK) |
| 286 | __rb_erase_color(child, parent, root); |
| 287 | } |
| 288 | |
| 289 | /* |
| 290 | * This function returns the first node (in sort order) of the tree. |
| 291 | */ |
| 292 | struct rb_node *rb_first(struct rb_root *root) |
| 293 | { |
| 294 | struct rb_node *n; |
| 295 | |
| 296 | n = root->rb_node; |
| 297 | if (!n) |
| 298 | return NULL; |
| 299 | while (n->rb_left) |
| 300 | n = n->rb_left; |
| 301 | return n; |
| 302 | } |