std::shared_ptr Converter::Make()

in r/src/array_to_vector.cpp [1208:1356]
107 lines of code
38 McCabe index (conditional complexity)

std::shared_ptr<Converter> Converter::Make(
    const std::shared_ptr<ChunkedArray>& chunked_array) {
  const auto& type = chunked_array->type();
  switch (type->id()) {
    // direct support
    case Type::INT32:
      return std::make_shared<arrow::r::Converter_Int<arrow::Int32Type>>(chunked_array);

    case Type::DOUBLE:
      return std::make_shared<arrow::r::Converter_Double<arrow::DoubleType>>(
          chunked_array);

      // need to handle 1-bit case
    case Type::BOOL:
      return std::make_shared<arrow::r::Converter_Boolean>(chunked_array);

    case Type::BINARY:
      return std::make_shared<arrow::r::Converter_Binary<arrow::BinaryArray>>(
          chunked_array);

    case Type::LARGE_BINARY:
      return std::make_shared<arrow::r::Converter_Binary<arrow::LargeBinaryArray>>(
          chunked_array);

    case Type::FIXED_SIZE_BINARY:
      return std::make_shared<arrow::r::Converter_FixedSizeBinary>(
          chunked_array, checked_cast<const FixedSizeBinaryType&>(*type).byte_width());

      // handle memory dense strings
    case Type::STRING:
      return std::make_shared<arrow::r::Converter_String<arrow::StringArray>>(
          chunked_array);

    case Type::LARGE_STRING:
      return std::make_shared<arrow::r::Converter_String<arrow::LargeStringArray>>(
          chunked_array);

    case Type::DICTIONARY:
      return std::make_shared<arrow::r::Converter_Dictionary>(chunked_array);

    case Type::DATE32:
      return std::make_shared<arrow::r::Converter_Date32>(chunked_array);

    case Type::DATE64:
      return std::make_shared<arrow::r::Converter_Date64>(chunked_array);

      // promotions to integer vector
    case Type::INT8:
      return std::make_shared<arrow::r::Converter_Int<arrow::Int8Type>>(chunked_array);

    case Type::UINT8:
      return std::make_shared<arrow::r::Converter_Int<arrow::UInt8Type>>(chunked_array);

    case Type::INT16:
      return std::make_shared<arrow::r::Converter_Int<arrow::Int16Type>>(chunked_array);

    case Type::UINT16:
      return std::make_shared<arrow::r::Converter_Int<arrow::UInt16Type>>(chunked_array);

      // promotions to numeric vector, if they don't fit into int32
    case Type::UINT32:
      if (ArraysCanFitInteger(chunked_array->chunks())) {
        return std::make_shared<arrow::r::Converter_Int<arrow::UInt32Type>>(
            chunked_array);
      } else {
        return std::make_shared<arrow::r::Converter_Double<arrow::UInt32Type>>(
            chunked_array);
      }

    case Type::UINT64:
      if (ArraysCanFitInteger(chunked_array->chunks())) {
        return std::make_shared<arrow::r::Converter_Int<arrow::UInt64Type>>(
            chunked_array);
      } else {
        return std::make_shared<arrow::r::Converter_Double<arrow::UInt64Type>>(
            chunked_array);
      }

    case Type::HALF_FLOAT:
      return std::make_shared<arrow::r::Converter_Double<arrow::HalfFloatType>>(
          chunked_array);

    case Type::FLOAT:
      return std::make_shared<arrow::r::Converter_Double<arrow::FloatType>>(
          chunked_array);

      // time32 and time64
    case Type::TIME32:
      return std::make_shared<arrow::r::Converter_Time<int32_t>>(chunked_array);

    case Type::TIME64:
      return std::make_shared<arrow::r::Converter_Time<int64_t>>(chunked_array);

    case Type::DURATION:
      return std::make_shared<arrow::r::Converter_Duration<int64_t>>(chunked_array);

    case Type::TIMESTAMP:
      return std::make_shared<arrow::r::Converter_Timestamp<int64_t>>(chunked_array);

    case Type::INT64:
      // Prefer integer if it fits, unless option arrow.int64_downcast is `false`
      if (GetBoolOption("arrow.int64_downcast", true) &&
          ArraysCanFitInteger(chunked_array->chunks())) {
        return std::make_shared<arrow::r::Converter_Int<arrow::Int64Type>>(chunked_array);
      } else {
        return std::make_shared<arrow::r::Converter_Int64>(chunked_array);
      }

    case Type::DECIMAL128:
      return std::make_shared<arrow::r::Converter_Decimal<Decimal128Type>>(chunked_array);

    case Type::DECIMAL256:
      return std::make_shared<arrow::r::Converter_Decimal<Decimal256Type>>(chunked_array);

      // nested
    case Type::STRUCT:
      return std::make_shared<arrow::r::Converter_Struct>(chunked_array);

    case Type::LIST:
      return std::make_shared<arrow::r::Converter_List<arrow::ListArray>>(
          chunked_array, checked_cast<const arrow::ListType*>(type.get())->value_type());

    case Type::LARGE_LIST:
      return std::make_shared<arrow::r::Converter_List<arrow::LargeListArray>>(
          chunked_array,
          checked_cast<const arrow::LargeListType*>(type.get())->value_type());

    case Type::FIXED_SIZE_LIST:
      return std::make_shared<arrow::r::Converter_FixedSizeList>(
          chunked_array,
          checked_cast<const arrow::FixedSizeListType&>(*type).value_type(),
          checked_cast<const arrow::FixedSizeListType&>(*type).list_size());

    case Type::MAP:
      return std::make_shared<arrow::r::Converter_List<arrow::MapArray>>(
          chunked_array, checked_cast<const arrow::MapType&>(*type).value_type());

    case Type::NA:
      return std::make_shared<arrow::r::Converter_Null>(chunked_array);

    case Type::EXTENSION:
      return std::make_shared<arrow::r::Converter_Extension>(chunked_array);

    default:
      break;
  }

  cpp11::stop("cannot handle Array of type <%s>", type->name().c_str());
}