Function GetOneOrNoneFlattened

cpp/src/arrow/type.h:2294–2301

  /// retrieved child's null bitmap is ANDed with its ancestors'
  template <typename T>
  Result<GetType<T>> GetOneOrNoneFlattened(const T& root,
                                           MemoryPool* pool = NULLPTR) const {
    ARROW_ASSIGN_OR_RAISE(auto match, FindOneOrNone(root));
    if (match.empty()) {
      return static_cast<GetType<T>>(NULLPTR);
    }
    return match.GetFlattened(root, pool);
  }

 private:
  void Flatten(std::vector<FieldRef> children);