Method visitor

src/tree/binary/tree.rs:38–44

(p: Option<NonNull<Node<K, V>>>)

impl<K, V> Drop for Tree<K, V> {
    fn drop(&mut self) {
        fn visitor<K, V>(p: Option<NonNull<Node<K, V>>>) {
            if let Some(p) = p {
                let p = unsafe { Box::from_raw(p.as_ptr()) };
                visitor(p.left);
                visitor(p.right);
            }
        }
        visitor(self.root);
    }
}