/* 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 "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; }