| /* |
| Red Black Trees |
| (C) 1999 Andrea Arcangeli <andrea@suse.de> |
| (C) 2002 David Woodhouse <dwmw2@infradead.org> |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| |
| linux/lib/rbtree.c |
| */ |
| |
| #include <stdlib.h> |
| #include "rbtree.h" |
| |
| static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) |
| { |
| struct rb_node *right = node->rb_right; |
| struct rb_node *parent = rb_parent(node); |
| |
| if ((node->rb_right = right->rb_left)) |
| rb_set_parent(right->rb_left, node); |
| right->rb_left = node; |
| |
| rb_set_parent(right, parent); |
| |
| if (parent) |
| { |
| if (node == parent->rb_left) |
| parent->rb_left = right; |
| else |
| parent->rb_right = right; |
| } |
| else |
| root->rb_node = right; |
| rb_set_parent(node, right); |
| } |
| |
| static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) |
| { |
| struct rb_node *left = node->rb_left; |
| struct rb_node *parent = rb_parent(node); |
| |
| if ((node->rb_left = left->rb_right)) |
| rb_set_parent(left->rb_right, node); |
| left->rb_right = node; |
| |
| rb_set_parent(left, parent); |
| |
| if (parent) |
| { |
| if (node == parent->rb_right) |
| parent->rb_right = left; |
| else |
| parent->rb_left = left; |
| } |
| else |
| root->rb_node = left; |
| rb_set_parent(node, left); |
| } |
| |
| void rb_insert_color(struct rb_node *node, struct rb_root *root) |
| { |
| struct rb_node *parent, *gparent; |
| |
| while ((parent = rb_parent(node)) && rb_is_red(parent)) |
| { |
| gparent = rb_parent(parent); |
| |
| if (parent == gparent->rb_left) |
| { |
| { |
| register struct rb_node *uncle = gparent->rb_right; |
| if (uncle && rb_is_red(uncle)) |
| { |
| rb_set_black(uncle); |
| rb_set_black(parent); |
| rb_set_red(gparent); |
| node = gparent; |
| continue; |
| } |
| } |
| |
| if (parent->rb_right == node) |
| { |
| register struct rb_node *tmp; |
| __rb_rotate_left(parent, root); |
| tmp = parent; |
| parent = node; |
| node = tmp; |
| } |
| |
| rb_set_black(parent); |
| rb_set_red(gparent); |
| __rb_rotate_right(gparent, root); |
| } else { |
| { |
| register struct rb_node *uncle = gparent->rb_left; |
| if (uncle && rb_is_red(uncle)) |
| { |
| rb_set_black(uncle); |
| rb_set_black(parent); |
| rb_set_red(gparent); |
| node = gparent; |
| continue; |
| } |
| } |
| |
| if (parent->rb_left == node) |
| { |
| register struct rb_node *tmp; |
| __rb_rotate_right(parent, root); |
| tmp = parent; |
| parent = node; |
| node = tmp; |
| } |
| |
| rb_set_black(parent); |
| rb_set_red(gparent); |
| __rb_rotate_left(gparent, root); |
| } |
| } |
| |
| rb_set_black(root->rb_node); |
| } |
| |
| static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, |
| struct rb_root *root) |
| { |
| struct rb_node *other; |
| |
| while ((!node || rb_is_black(node)) && node != root->rb_node) |
| { |
| if (parent->rb_left == node) |
| { |
| other = parent->rb_right; |
| if (rb_is_red(other)) |
| { |
| rb_set_black(other); |
| rb_set_red(parent); |
| __rb_rotate_left(parent, root); |
| other = parent->rb_right; |
| } |
| if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| (!other->rb_right || rb_is_black(other->rb_right))) |
| { |
| rb_set_red(other); |
| node = parent; |
| parent = rb_parent(node); |
| } |
| else |
| { |
| if (!other->rb_right || rb_is_black(other->rb_right)) |
| { |
| struct rb_node *o_left; |
| if ((o_left = other->rb_left)) |
| rb_set_black(o_left); |
| rb_set_red(other); |
| __rb_rotate_right(other, root); |
| other = parent->rb_right; |
| } |
| rb_set_color(other, rb_color(parent)); |
| rb_set_black(parent); |
| if (other->rb_right) |
| rb_set_black(other->rb_right); |
| __rb_rotate_left(parent, root); |
| node = root->rb_node; |
| break; |
| } |
| } |
| else |
| { |
| other = parent->rb_left; |
| if (rb_is_red(other)) |
| { |
| rb_set_black(other); |
| rb_set_red(parent); |
| __rb_rotate_right(parent, root); |
| other = parent->rb_left; |
| } |
| if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| (!other->rb_right || rb_is_black(other->rb_right))) |
| { |
| rb_set_red(other); |
| node = parent; |
| parent = rb_parent(node); |
| } |
| else |
| { |
| if (!other->rb_left || rb_is_black(other->rb_left)) |
| { |
| register struct rb_node *o_right; |
| if ((o_right = other->rb_right)) |
| rb_set_black(o_right); |
| rb_set_red(other); |
| __rb_rotate_left(other, root); |
| other = parent->rb_left; |
| } |
| rb_set_color(other, rb_color(parent)); |
| rb_set_black(parent); |
| if (other->rb_left) |
| rb_set_black(other->rb_left); |
| __rb_rotate_right(parent, root); |
| node = root->rb_node; |
| break; |
| } |
| } |
| } |
| if (node) |
| rb_set_black(node); |
| } |
| |
| void rb_erase(struct rb_node *node, struct rb_root *root) |
| { |
| struct rb_node *child, *parent; |
| int color; |
| |
| if (!node->rb_left) |
| child = node->rb_right; |
| else if (!node->rb_right) |
| child = node->rb_left; |
| else |
| { |
| struct rb_node *old = node, *left; |
| |
| node = node->rb_right; |
| while ((left = node->rb_left) != NULL) |
| node = left; |
| child = node->rb_right; |
| parent = rb_parent(node); |
| color = rb_color(node); |
| |
| if (child) |
| rb_set_parent(child, parent); |
| if (parent == old) { |
| parent->rb_right = child; |
| parent = node; |
| } else |
| parent->rb_left = child; |
| |
| node->rb_parent_color = old->rb_parent_color; |
| node->rb_right = old->rb_right; |
| node->rb_left = old->rb_left; |
| |
| if (rb_parent(old)) |
| { |
| if (rb_parent(old)->rb_left == old) |
| rb_parent(old)->rb_left = node; |
| else |
| rb_parent(old)->rb_right = node; |
| } else |
| root->rb_node = node; |
| |
| rb_set_parent(old->rb_left, node); |
| if (old->rb_right) |
| rb_set_parent(old->rb_right, node); |
| goto color; |
| } |
| |
| parent = rb_parent(node); |
| color = rb_color(node); |
| |
| if (child) |
| rb_set_parent(child, parent); |
| if (parent) |
| { |
| if (parent->rb_left == node) |
| parent->rb_left = child; |
| else |
| parent->rb_right = child; |
| } |
| else |
| root->rb_node = child; |
| |
| color: |
| if (color == RB_BLACK) |
| __rb_erase_color(child, parent, root); |
| } |
| |
| /* |
| * This function returns the first node (in sort order) of the tree. |
| */ |
| struct rb_node *rb_first(struct rb_root *root) |
| { |
| struct rb_node *n; |
| |
| n = root->rb_node; |
| if (!n) |
| return NULL; |
| while (n->rb_left) |
| n = n->rb_left; |
| return n; |
| } |
| |
| struct rb_node *rb_last(struct rb_root *root) |
| { |
| struct rb_node *n; |
| |
| n = root->rb_node; |
| if (!n) |
| return NULL; |
| while (n->rb_right) |
| n = n->rb_right; |
| return n; |
| } |
| |
| struct rb_node *rb_next(struct rb_node *node) |
| { |
| struct rb_node *parent; |
| |
| if (rb_parent(node) == node) |
| return NULL; |
| |
| /* If we have a right-hand child, go down and then left as far |
| as we can. */ |
| if (node->rb_right) { |
| node = node->rb_right; |
| while (node->rb_left) |
| node=node->rb_left; |
| return node; |
| } |
| |
| /* No right-hand children. Everything down and left is |
| smaller than us, so any 'next' node must be in the general |
| direction of our parent. Go up the tree; any time the |
| ancestor is a right-hand child of its parent, keep going |
| up. First time it's a left-hand child of its parent, said |
| parent is our 'next' node. */ |
| while ((parent = rb_parent(node)) && node == parent->rb_right) |
| node = parent; |
| |
| return parent; |
| } |
| |
| struct rb_node *rb_prev(struct rb_node *node) |
| { |
| struct rb_node *parent; |
| |
| if (rb_parent(node) == node) |
| return NULL; |
| |
| /* If we have a left-hand child, go down and then right as far |
| as we can. */ |
| if (node->rb_left) { |
| node = node->rb_left; |
| while (node->rb_right) |
| node=node->rb_right; |
| return node; |
| } |
| |
| /* No left-hand children. Go up till we find an ancestor which |
| is a right-hand child of its parent */ |
| while ((parent = rb_parent(node)) && node == parent->rb_left) |
| node = parent; |
| |
| return parent; |
| } |
| |
| void rb_replace_node(struct rb_node *victim, struct rb_node *new, |
| struct rb_root *root) |
| { |
| struct rb_node *parent = rb_parent(victim); |
| |
| /* Set the surrounding nodes to point to the replacement */ |
| if (parent) { |
| if (victim == parent->rb_left) |
| parent->rb_left = new; |
| else |
| parent->rb_right = new; |
| } else { |
| root->rb_node = new; |
| } |
| if (victim->rb_left) |
| rb_set_parent(victim->rb_left, new); |
| if (victim->rb_right) |
| rb_set_parent(victim->rb_right, new); |
| |
| /* Copy the pointers/colour from the victim to the replacement */ |
| *new = *victim; |
| } |