@SuppressWarnings("unchecked")
@Override
default <T1, T2, T3> Tuple3<Tree<T1>, Tree<T2>, Tree<T3>> unzip3(
Function<? super T, Tuple3<? extends T1, ? extends T2, ? extends T3>> unzipper) {
Objects.requireNonNull(unzipper, "unzipper is null");
if (isEmpty()) {
return Tuple.of(Empty.instance(), Empty.instance(), Empty.instance());
} else {
return (Tuple3<Tree<T1>, Tree<T2>, Tree<T3>>) (Object) Unzip.apply3((Node<T>) this, unzipper);
}
}
static <T, T1, T2, T3> Tuple3<Node<T1>, Node<T2>, Node<T3>> apply3(
Node<T> node,
Function<? super T, Tuple3<? extends T1, ? extends T2, ? extends T3>> unzipper) {
final Tuple3<? extends T1, ? extends T2, ? extends T3> value =
unzipper.apply(node.getValue());
final List<Tuple3<Node<T1>, Node<T2>, Node<T3>>> children =
node.getChildren().map(child -> Unzip.apply3(child, unzipper));
final Node<T1> node1 = new Node<>(value._1, children.map(t -> t._1));
final Node<T2> node2 = new Node<>(value._2, children.map(t -> t._2));
final Node<T3> node3 = new Node<>(value._3, children.map(t -> t._3));
return Tuple.of(node1, node2, node3);
}