Method Evaluate

eval/eval/select_step.cc:321–387

        enable_optional_types_(enable_optional_types) {}

  absl::Status Evaluate(ExecutionFrameBase& frame, Value& result,
                        AttributeTrail& attribute) const override {
    CEL_RETURN_IF_ERROR(operand_->Evaluate(frame, result, attribute));

    if (result.IsError() || result.IsUnknown()) {
      // Just forward.
      return absl::OkStatus();
    }

    if (frame.attribute_tracking_enabled()) {
      attribute = attribute.Step(&field_);
      absl::optional<Value> value = CheckForMarkedAttributes(attribute, frame);
      if (value.has_value()) {
        result = std::move(value).value();
        return absl::OkStatus();
      }
    }

    absl::optional<OptionalValue> optional_arg;

    if (enable_optional_types_ && result.IsOptional()) {
      optional_arg = result.GetOptional();
    }

    switch (result.kind()) {
      case ValueKind::kStruct:
      case ValueKind::kMap:
        break;
      default:
        if (optional_arg) {
          break;
        }
        result = cel::ErrorValue(InvalidSelectTargetError());
        return absl::OkStatus();
    }

    if (test_only_) {
      if (optional_arg) {
        if (!optional_arg->HasValue()) {
          result = cel::BoolValue{false};
          return absl::OkStatus();
        }
        Value value;
        optional_arg->Value(&value);
        PerformTestOnlySelect(frame, value, result);
        return absl::OkStatus();
      }
      PerformTestOnlySelect(frame, result, result);
      return absl::OkStatus();
    }

    if (optional_arg) {
      if (!optional_arg->HasValue()) {
        // result is still buffer for the container. just return.
        return absl::OkStatus();
      }
      Value value;
      optional_arg->Value(&value);