Method ToRealPositive

cpp/src/arrow/util/decimal.cc:476–492

  /// Here "exact value" means the closest representable value by Real.
  template <typename Real>
  static Real ToRealPositive(const Decimal128& decimal, int32_t scale) {
    if (scale <= 0 || (decimal.high_bits() == 0 &&
                       decimal.low_bits() <= RealTraits<Real>::kMaxPreciseInteger)) {
      // No need to split the decimal if it is already an integer (scale <= 0) or if it
      // can be precisely represented by Real
      return ToRealPositiveNoSplit<Real>(decimal, scale);
    }

    // Split decimal into whole and fractional parts to avoid precision loss
    BasicDecimal128 whole_decimal, fraction_decimal;
    decimal.GetWholeAndFraction(scale, &whole_decimal, &fraction_decimal);

    Real whole = ToRealPositiveNoSplit<Real>(whole_decimal, 0);
    Real fraction = ToRealPositiveNoSplit<Real>(fraction_decimal, scale);

    return whole + fraction;
  }
};

}  // namespace