Function field_path

cpp/src/arrow/type.h:2167–2169

  }

  const FieldPath* field_path() const {
    return IsFieldPath() ? &std::get<FieldPath>(impl_) : NULLPTR;
  }
  const std::string* name() const {
    return IsName() ? &std::get<std::string>(impl_) : NULLPTR;
  }