static bool remove(struct avl *t, void **pp, void **px)
{
if (*pp == NULL) {
*px = NULL;
return false;
}
int cmp = t->cmp(*px, *pp);
struct avl_node *p = node(t, *pp);
bool dir, shrink;
if (cmp == 0) {
*px = *pp;
dir = p->balance > 0;
if (p->child[dir] == NULL) {
*pp = p->child[!dir];
return true;
}
void *swap;
shrink = remove_swap(t, &p->child[dir], !dir, &swap);
*node(t, swap) = *node(t, *pp);
*pp = swap;
} else {
dir = cmp > 0;
shrink = remove(t, &node(t, *pp)->child[dir], px);
}
return remove_fix(t, pp, dir, shrink);
}
static bool remove_swap(struct avl *t, void **pp, bool dir, void **swap)
{
struct avl_node *p = node(t, *pp);
if (p->child[dir] == NULL) {
*swap = *pp;
*pp = p->child[!dir];
return true;
}
bool shrink = remove_swap(t, &p->child[dir], dir, swap);
return remove_fix(t, pp, dir, shrink);
}
bool rbtree_remove(RBTree *tree, const void *key)
{
assert(!tree->nil->red);
RBNode *z = node_get(tree, key);
if (z == tree->nil)
{
return false;
}
RBNode *y = ((z->left == tree->nil) || (z->right == tree->nil)) ? z : node_next(tree, z);
RBNode *x = (y->left == tree->nil) ? y->right : y->left;
x->parent = y->parent;
if (tree->root == x->parent)
{
tree->root->left = x;
}
else
{
if (y == y->parent->left)
{
y->parent->left = x;
}
else
{
y->parent->right = x;
}
}
if (z != y)
{
assert(y != tree->nil);
assert(!tree->nil->red);
if (!y->red)
{
remove_fix(tree, x);
}
y->left = z->left;
y->right = z->right;
y->parent = z->parent;
y->red = z->red;
z->left->parent = y;
z->right->parent = y;
if (z == z->parent->left)
{
z->parent->left = y;
}
else
{
z->parent->right = y;
}
node_destroy(tree, z);
}
else
{
if (!y->red)
{
remove_fix(tree, x);
}
node_destroy(tree, y);
}
assert(!tree->nil->red);
tree->size--;
return true;
}
