Function FindOne

cpp/src/arrow/type.h:2214–2219

  /// FieldRef. Emit an error if none or multiple match.
  template <typename T>
  Result<FieldPath> FindOne(const T& root) const {
    auto matches = FindAll(root);
    ARROW_RETURN_NOT_OK(CheckNonEmpty(matches, root));
    ARROW_RETURN_NOT_OK(CheckNonMultiple(matches, root));
    return std::move(matches[0]);
  }

  /// \brief Retrieve FieldPath of a single child field which matches this
  /// FieldRef. Emit an error if multiple match. An empty (invalid) FieldPath