C++ DigitList::internalSetDouble方法代码示例

/**
 * Currently, getDouble() depends on strtod() to do its conversion.
 *
 * WARNING!!
 * This is an extremely costly function. ~1/2 of the conversion time
 * can be linked to this function.
 */
double
DigitList::getDouble() const
{
    {
        Mutex mutex;
        if (fHave == kDouble) {
            return fUnion.fDouble;
        }
    }

    double tDouble = 0.0;
    if (isZero()) {
        tDouble = 0.0;
        if (decNumberIsNegative(fDecNumber)) {
            tDouble /= -1;
        }
    } else if (isInfinite()) {
        if (std::numeric_limits<double>::has_infinity) {
            tDouble = std::numeric_limits<double>::infinity();
        } else {
            tDouble = std::numeric_limits<double>::max();
        }
        if (!isPositive()) {
            tDouble = -tDouble; //this was incorrectly "-fDouble" originally.
        }
    } else {
        MaybeStackArray<char, MAX_DBL_DIGITS+18> s;
           // Note:  14 is a  magic constant from the decNumber library documentation,
           //        the max number of extra characters beyond the number of digits
           //        needed to represent the number in string form.  Add a few more
           //        for the additional digits we retain.

        // Round down to appx. double precision, if the number is longer than that.
        // Copy the number first, so that we don't modify the original.
        if (getCount() > MAX_DBL_DIGITS + 3) {
            DigitList numToConvert(*this);
            numToConvert.reduce();    // Removes any trailing zeros, so that digit count is good.
            numToConvert.round(MAX_DBL_DIGITS+3);
            uprv_decNumberToString(numToConvert.fDecNumber, s.getAlias());
            // TODO:  how many extra digits should be included for an accurate conversion?
        } else {
            uprv_decNumberToString(this->fDecNumber, s.getAlias());
        }
        U_ASSERT(uprv_strlen(&s[0]) < MAX_DBL_DIGITS+18);

        char *end = NULL;
        tDouble = decimalStrToDouble(s.getAlias(), &end);
    }
    {
        Mutex mutex;
        DigitList *nonConstThis = const_cast<DigitList *>(this);
        nonConstThis->internalSetDouble(tDouble);
    }
    return tDouble;
}

/**
 * Currently, getDouble() depends on strtod() to do its conversion.
 *
 * WARNING!!
 * This is an extremely costly function. ~1/2 of the conversion time
 * can be linked to this function.
 */
double
DigitList::getDouble() const
{
    static char gDecimal = 0;
    char decimalSeparator;
    {
        Mutex mutex;
        if (fHave == kDouble) {
            return fUnion.fDouble;
        } else if(fHave == kInt64) {
            return (double)fUnion.fInt64;
        }
        decimalSeparator = gDecimal;
    }

    if (decimalSeparator == 0) {
        // We need to know the decimal separator character that will be used with strtod().
        // Depends on the C runtime global locale.
        // Most commonly is '.'
        // TODO: caching could fail if the global locale is changed on the fly.
        char rep[MAX_DIGITS];
        sprintf(rep, "%+1.1f", 1.0);
        decimalSeparator = rep[2];
    }

    double tDouble = 0.0;
    if (isZero()) {
        tDouble = 0.0;
        if (decNumberIsNegative(fDecNumber)) {
            tDouble /= -1;
        }
    } else if (isInfinite()) {
        if (std::numeric_limits<double>::has_infinity) {
            tDouble = std::numeric_limits<double>::infinity();
        } else {
            tDouble = std::numeric_limits<double>::max();
        }
        if (!isPositive()) {
            tDouble = -tDouble; //this was incorrectly "-fDouble" originally.
        } 
    } else {
        MaybeStackArray<char, MAX_DBL_DIGITS+18> s;
           // Note:  14 is a  magic constant from the decNumber library documentation,
           //        the max number of extra characters beyond the number of digits 
           //        needed to represent the number in string form.  Add a few more
           //        for the additional digits we retain.

        // Round down to appx. double precision, if the number is longer than that.
        // Copy the number first, so that we don't modify the original.
        if (getCount() > MAX_DBL_DIGITS + 3) {
            DigitList numToConvert(*this);
            numToConvert.reduce();    // Removes any trailing zeros, so that digit count is good.
            numToConvert.round(MAX_DBL_DIGITS+3);
            uprv_decNumberToString(numToConvert.fDecNumber, s);
            // TODO:  how many extra digits should be included for an accurate conversion?
        } else {
            uprv_decNumberToString(this->fDecNumber, s);
        }
        U_ASSERT(uprv_strlen(&s[0]) < MAX_DBL_DIGITS+18);
        
        if (decimalSeparator != '.') {
            char *decimalPt = strchr(s, '.');
            if (decimalPt != NULL) {
                *decimalPt = decimalSeparator;
            }
        }
        char *end = NULL;
        tDouble = uprv_strtod(s, &end);
    }
    {
        Mutex mutex;
        DigitList *nonConstThis = const_cast<DigitList *>(this);
        nonConstThis->internalSetDouble(tDouble);
        gDecimal = decimalSeparator;
    }
    return tDouble;
}