Function MakeMaybeMapIterator

cpp/src/arrow/util/iterator.h:467–469

template <typename Fn, typename From = internal::call_traits::argument_type<0, Fn>,
          typename To = typename internal::call_traits::return_type<Fn>::ValueType>
Iterator<To> MakeMaybeMapIterator(Fn map, Iterator<From> it) {
  return Iterator<To>(MapIterator<Fn, From, To>(std::move(map), std::move(it)));
}

struct FilterIterator {
  enum Action { ACCEPT, REJECT };