Class AttributeQualifier

base/attribute.h:37–125

AttributeQualifier represents a segment in attribute resolutuion path. A segment can be qualified by values of following types: string/int64_t/uint64_t/bool.

// attribute resolutuion path. A segment can be qualified by values of
// following types: string/int64_t/uint64_t/bool.
class AttributeQualifier final {
 private:
  struct ComparatorVisitor;

  using Variant = absl::variant<Kind, int64_t, uint64_t, std::string, bool>;

 public:
  static AttributeQualifier OfInt(int64_t value) {
    return AttributeQualifier(absl::in_place_type<int64_t>, std::move(value));
  }

  static AttributeQualifier OfUint(uint64_t value) {
    return AttributeQualifier(absl::in_place_type<uint64_t>, std::move(value));
  }

  static AttributeQualifier OfString(std::string value) {
    return AttributeQualifier(absl::in_place_type<std::string>,
                              std::move(value));
  }

  static AttributeQualifier OfBool(bool value) {
    return AttributeQualifier(absl::in_place_type<bool>, std::move(value));
  }

  AttributeQualifier() = default;

  AttributeQualifier(const AttributeQualifier&) = default;
  AttributeQualifier(AttributeQualifier&&) = default;

  AttributeQualifier& operator=(const AttributeQualifier&) = default;
  AttributeQualifier& operator=(AttributeQualifier&&) = default;

  Kind kind() const;

  // Family of Get... methods. Return values if requested type matches the
  // stored one.
  absl::optional<int64_t> GetInt64Key() const {
    return absl::holds_alternative<int64_t>(value_)
               ? absl::optional<int64_t>(absl::get<1>(value_))
               : absl::nullopt;
  }

  absl::optional<uint64_t> GetUint64Key() const {
    return absl::holds_alternative<uint64_t>(value_)
               ? absl::optional<uint64_t>(absl::get<2>(value_))
               : absl::nullopt;
  }

  absl::optional<absl::string_view> GetStringKey() const {
    return absl::holds_alternative<std::string>(value_)
               ? absl::optional<absl::string_view>(absl::get<3>(value_))
               : absl::nullopt;
  }

  absl::optional<bool> GetBoolKey() const {
    return absl::holds_alternative<bool>(value_)
               ? absl::optional<bool>(absl::get<4>(value_))
               : absl::nullopt;