void
rbtree_init(struct rbtree *tree, struct rbnode *node)
{
rbtree_node_init(node);
rbtree_black(node);
tree->root = node;
tree->sentinel = node;
}
static void __init_word(struct word *w)
{
string_init(&w->name);
rbtree_node_init(&w->rbtree);
}
void
rbtree_delete(struct rbtree *tree, struct rbnode *node)
{
struct rbnode **root = &tree->root;
struct rbnode *sentinel = tree->sentinel;
struct rbnode *subst, *temp, *w;
uint8_t red;
/* a binary tree delete */
if (node->left == sentinel) {
temp = node->right;
subst = node;
} else if (node->right == sentinel) {
temp = node->left;
subst = node;
} else {
subst = rbtree_node_min(node->right, sentinel);
if (subst->left != sentinel) {
temp = subst->left;
} else {
temp = subst->right;
}
}
if (subst == *root) {
*root = temp;
rbtree_black(temp);
rbtree_node_init(node);
return;
}
red = rbtree_is_red(subst);
if (subst == subst->parent->left) {
subst->parent->left = temp;
} else {
subst->parent->right = temp;
}
if (subst == node) {
temp->parent = subst->parent;
} else {
if (subst->parent == node) {
temp->parent = subst;
} else {
temp->parent = subst->parent;
}
subst->left = node->left;
subst->right = node->right;
subst->parent = node->parent;
rbtree_copy_color(subst, node);
if (node == *root) {
*root = subst;
} else {
if (node == node->parent->left) {
node->parent->left = subst;
} else {
node->parent->right = subst;
}
}
if (subst->left != sentinel) {
subst->left->parent = subst;
}
if (subst->right != sentinel) {
subst->right->parent = subst;
}
}
rbtree_node_init(node);
if (red) {
return;
}
/* a delete fixup */
while (temp != *root && rbtree_is_black(temp)) {
if (temp == temp->parent->left) {
w = temp->parent->right;
if (rbtree_is_red(w)) {
rbtree_black(w);
rbtree_red(temp->parent);
rbtree_left_rotate(root, sentinel, temp->parent);
w = temp->parent->right;
}
if (rbtree_is_black(w->left) && rbtree_is_black(w->right)) {
rbtree_red(w);
temp = temp->parent;
} else {
if (rbtree_is_black(w->right)) {
rbtree_black(w->left);
rbtree_red(w);
rbtree_right_rotate(root, sentinel, w);
w = temp->parent->right;
}
rbtree_copy_color(w, temp->parent);
rbtree_black(temp->parent);
rbtree_black(w->right);
rbtree_left_rotate(root, sentinel, temp->parent);
temp = *root;
}
} else {
w = temp->parent->left;
if (rbtree_is_red(w)) {
rbtree_black(w);
rbtree_red(temp->parent);
rbtree_right_rotate(root, sentinel, temp->parent);
w = temp->parent->left;
}
if (rbtree_is_black(w->left) && rbtree_is_black(w->right)) {
rbtree_red(w);
temp = temp->parent;
} else {
if (rbtree_is_black(w->left)) {
rbtree_black(w->right);
rbtree_red(w);
rbtree_left_rotate(root, sentinel, w);
w = temp->parent->left;
}
rbtree_copy_color(w, temp->parent);
rbtree_black(temp->parent);
rbtree_black(w->left);
rbtree_right_rotate(root, sentinel, temp->parent);
temp = *root;
}
}
}
rbtree_black(temp);
}