Function type_singleton

cpp/src/arrow/type.cc:3551–3561

}

Result<std::shared_ptr<DataType>> type_singleton(Type::type id) {
  auto visit = [](auto type) -> Result<std::shared_ptr<DataType>> {
    using T = std::decay_t<decltype(*type)>;
    if constexpr (TypeTraits<T>::is_parameter_free) {
      return TypeTraits<T>::type_singleton();
    }
    return Status::TypeError("Type ", internal::ToString(T::type_id),
                             " is not a parameter-free type");
  };
  return VisitTypeId(id, visit);
}

}  // namespace arrow