static velox::TypeKind promote()

in csrc/velox/column.h [121:183]
53 lines of code
5 McCabe index (conditional complexity)

  static velox::TypeKind promote(
      velox::TypeKind a,
      velox::TypeKind b,
      PromoteStrategy promoteStrategy) {
    constexpr auto b1 = velox::TypeKind::BOOLEAN;
    constexpr auto i1 = velox::TypeKind::TINYINT;
    constexpr auto i2 = velox::TypeKind::SMALLINT;
    constexpr auto i4 = velox::TypeKind::INTEGER;
    constexpr auto i8 = velox::TypeKind::BIGINT;
    constexpr auto f4 = velox::TypeKind::REAL;
    constexpr auto f8 = velox::TypeKind::DOUBLE;
    constexpr auto num_numeric_types =
        static_cast<int>(velox::TypeKind::DOUBLE) + 1;

    VELOX_CHECK(
        static_cast<int>(a) < num_numeric_types &&
        static_cast<int>(b) < num_numeric_types);

    if (a == b) {
      return a;
    }

    switch (promoteStrategy) {
      case PromoteStrategy::ColumnColumn: {
        // Sliced from
        // https://github.com/pytorch/pytorch/blob/1c502d1f8ec861c31a08d580ae7b73b7fbebebed/c10/core/ScalarType.h#L402-L421
        static constexpr velox::TypeKind
            promoteTypesLookup[num_numeric_types][num_numeric_types] = {
                /*        b1  i1  i2  i4  i8  f4  f8*/
                /* b1 */ {b1, i1, i2, i4, i8, f4, f8},
                /* i1 */ {i1, i1, i2, i4, i8, f4, f8},
                /* i2 */ {i2, i2, i2, i4, i8, f4, f8},
                /* i4 */ {i4, i4, i4, i4, i8, f4, f8},
                /* i8 */ {i8, i8, i8, i8, i8, f4, f8},
                /* f4 */ {f4, f4, f4, f4, f4, f4, f8},
                /* f8 */ {f8, f8, f8, f8, f8, f8, f8},
            };
        return promoteTypesLookup[static_cast<int>(a)][static_cast<int>(b)];
      } break;
      case PromoteStrategy::ColumnScalar: {
        // TODO: Decide on how we want to handle column-scalar type promotion.
        // Current strategy is to always respect the type of the column for
        // int-int cases.
        static constexpr velox::TypeKind
            promoteTypesLookup[num_numeric_types][num_numeric_types] = {
                /*        b1  i1  i2  i4  i8  f4  f8*/
                /* b1 */ {b1, b1, b1, b1, b1, f4, f8},
                /* i1 */ {i1, i1, i1, i1, i1, f4, f8},
                /* i2 */ {i2, i2, i2, i2, i2, f4, f8},
                /* i4 */ {i4, i4, i4, i4, i4, f4, f8},
                /* i8 */ {i8, i8, i8, i8, i8, f4, f8},
                /* f4 */ {f4, f4, f4, f4, f4, f4, f8},
                /* f8 */ {f8, f8, f8, f8, f8, f8, f8},
            };
        return promoteTypesLookup[static_cast<int>(a)][static_cast<int>(b)];
      } break;
      default: {
        throw std::logic_error(
            "Unsupported promote: " +
            std::to_string(static_cast<int64_t>(promoteStrategy)));
      } break;
    }
  }