string SummarizeAttrValue(const AttrValue& attr_value) {
  switch (attr_value.value_case()) {
    case AttrValue::kS:
      return SummarizeString(attr_value.s());
    case AttrValue::kI:
      return strings::StrCat(attr_value.i());
    case AttrValue::kF:
      return strings::StrCat(attr_value.f());
    case AttrValue::kB:
      return attr_value.b() ? "true" : "false";
    case AttrValue::kType:
      return EnumName_DataType(attr_value.type());
    case AttrValue::kShape:
      return PartialTensorShape::DebugString(attr_value.shape());
    case AttrValue::kTensor:
      return SummarizeTensor(attr_value.tensor());
    case AttrValue::kList: {
      std::vector<string> pieces;
      if (attr_value.list().s_size() > 0) {
        for (int i = 0; i < attr_value.list().s_size(); ++i) {
          pieces.push_back(SummarizeString(attr_value.list().s(i)));
        }
      } else if (attr_value.list().i_size() > 0) {
        for (int i = 0; i < attr_value.list().i_size(); ++i) {
          pieces.push_back(strings::StrCat(attr_value.list().i(i)));
        }
      } else if (attr_value.list().f_size() > 0) {
        for (int i = 0; i < attr_value.list().f_size(); ++i) {
          pieces.push_back(strings::StrCat(attr_value.list().f(i)));
        }
      } else if (attr_value.list().b_size() > 0) {
        for (int i = 0; i < attr_value.list().b_size(); ++i) {
          pieces.push_back(attr_value.list().b(i) ? "true" : "false");
        }
      } else if (attr_value.list().type_size() > 0) {
        for (int i = 0; i < attr_value.list().type_size(); ++i) {
          pieces.push_back(EnumName_DataType(attr_value.list().type(i)));
        }
      } else if (attr_value.list().shape_size() > 0) {
        for (int i = 0; i < attr_value.list().shape_size(); ++i) {
          pieces.push_back(
              TensorShape::DebugString(attr_value.list().shape(i)));
        }
      } else if (attr_value.list().tensor_size() > 0) {
        for (int i = 0; i < attr_value.list().tensor_size(); ++i) {
          pieces.push_back(SummarizeTensor(attr_value.list().tensor(i)));
        }
      } else if (attr_value.list().func_size() > 0) {
        for (int i = 0; i < attr_value.list().func_size(); ++i) {
          pieces.push_back(SummarizeFunc(attr_value.list().func(i)));
        }
      }
      constexpr int kMaxListSummarySize = 50;
      if (pieces.size() >= kMaxListSummarySize) {
        pieces.erase(pieces.begin() + 5, pieces.begin() + (pieces.size() - 6));
        pieces[5] = "...";
      }
      return strings::StrCat("[", absl::StrJoin(pieces, ", "), "]");
    }
    case AttrValue::kFunc: {
      return SummarizeFunc(attr_value.func());
    }
    case AttrValue::kPlaceholder:
      return strings::StrCat("$", attr_value.placeholder());
    case AttrValue::VALUE_NOT_SET:
      return "<Unknown AttrValue type>";
  }
  return "<Unknown AttrValue type>";  // Prevent missing return warning
}