@Override
default <U> Tree<Tuple2<T, U>> zip(Iterable<U> that) {
Objects.requireNonNull(that, "that is null");
if (isEmpty()) {
return Empty.instance();
} else {
return Zip.apply((Node<T>) this, that.iterator());
}
}
@SuppressWarnings("unchecked")
static <T, U> Tree<Tuple2<T, U>> apply(Node<T> node, java.util.Iterator<U> that) {
if (!that.hasNext()) {
return Empty.instance();
} else {
final Tuple2<T, U> value = Tuple.of(node.getValue(), that.next());
final List<Node<Tuple2<T, U>>> children =
(List<Node<Tuple2<T, U>>>)
(Object)
node.getChildren().map(child -> Zip.apply(child, that)).filter(Tree::isDefined);
return new Node<>(value, children);
}
}