std::unique_ptr MakeDecoder()

in cpp-ch/local-engine/Storages/ch_parquet/arrow/encoding.cc [3292:3356]
65 lines of code
22 McCabe index (conditional complexity)

std::unique_ptr<Decoder> MakeDecoder(Type::type type_num, Encoding::type encoding,
                                     const ColumnDescriptor* descr) {
  if (encoding == Encoding::PLAIN) {
    switch (type_num) {
      case Type::BOOLEAN:
        return std::make_unique<PlainBooleanDecoder>(descr);
      case Type::INT32:
        return std::make_unique<PlainDecoder<Int32Type>>(descr);
      case Type::INT64:
        return std::make_unique<PlainDecoder<Int64Type>>(descr);
      case Type::INT96:
        return std::make_unique<PlainDecoder<Int96Type>>(descr);
      case Type::FLOAT:
        return std::make_unique<PlainDecoder<FloatType>>(descr);
      case Type::DOUBLE:
        return std::make_unique<PlainDecoder<DoubleType>>(descr);
      case Type::BYTE_ARRAY:
        return std::make_unique<PlainByteArrayDecoder>(descr);
      case Type::FIXED_LEN_BYTE_ARRAY:
        return std::make_unique<PlainFLBADecoder>(descr);
      default:
        break;
    }
  } else if (encoding == Encoding::BYTE_STREAM_SPLIT) {
    switch (type_num) {
      case Type::FLOAT:
        return std::make_unique<ByteStreamSplitDecoder<FloatType>>(descr);
      case Type::DOUBLE:
        return std::make_unique<ByteStreamSplitDecoder<DoubleType>>(descr);
      default:
        throw ParquetException("BYTE_STREAM_SPLIT only supports FLOAT and DOUBLE");
        break;
    }
  } else if (encoding == Encoding::DELTA_BINARY_PACKED) {
    switch (type_num) {
      case Type::INT32:
        return std::make_unique<DeltaBitPackDecoder<Int32Type>>(descr);
      case Type::INT64:
        return std::make_unique<DeltaBitPackDecoder<Int64Type>>(descr);
      default:
        throw ParquetException(
            "DELTA_BINARY_PACKED decoder only supports INT32 and INT64");
        break;
    }
  } else if (encoding == Encoding::DELTA_BYTE_ARRAY) {
    if (type_num == Type::BYTE_ARRAY) {
      return std::make_unique<DeltaByteArrayDecoder>(descr);
    }
    throw ParquetException("DELTA_BYTE_ARRAY only supports BYTE_ARRAY");
  } else if (encoding == Encoding::DELTA_LENGTH_BYTE_ARRAY) {
    if (type_num == Type::BYTE_ARRAY) {
      return std::make_unique<DeltaLengthByteArrayDecoder>(descr);
    }
    throw ParquetException("DELTA_LENGTH_BYTE_ARRAY only supports BYTE_ARRAY");
  } else if (encoding == Encoding::RLE) {
    if (type_num == Type::BOOLEAN) {
      return std::make_unique<RleBooleanDecoder>(descr);
    }
    throw ParquetException("RLE encoding only supports BOOLEAN");
  } else {
    ParquetException::NYI("Selected encoding is not supported");
  }
  DCHECK(false) << "Should not be able to reach this code";
  return nullptr;
}