Пример #1
0
double
js::ecmaPow(double x, double y)
{
    /*
     * Use powi if the exponent is an integer-valued double. We don't have to
     * check for NaN since a comparison with NaN is always false.
     */
    int32_t yi;
    if (NumberEqualsInt32(y, &yi))
        return powi(x, yi);

    /*
     * Because C99 and ECMA specify different behavior for pow(),
     * we need to wrap the libm call to make it ECMA compliant.
     */
    if (!IsFinite(y) && (x == 1.0 || x == -1.0))
        return GenericNaN();

    /* pow(x, +-0) is always 1, even for x = NaN (MSVC gets this wrong). */
    if (y == 0)
        return 1;

    /*
     * Special case for square roots. Note that pow(x, 0.5) != sqrt(x)
     * when x = -0.0, so we have to guard for this.
     */
    if (IsFinite(x) && x != 0.0) {
        if (y == 0.5)
            return sqrt(x);
        if (y == -0.5)
            return 1.0 / sqrt(x);
    }
    return pow(x, y);
}
Пример #2
0
bool
HashableValue::setValue(JSContext* cx, HandleValue v)
{
    if (v.isString()) {
        // Atomize so that hash() and operator==() are fast and infallible.
        JSString* str = AtomizeString(cx, v.toString(), DoNotPinAtom);
        if (!str)
            return false;
        value = StringValue(str);
    } else if (v.isDouble()) {
        double d = v.toDouble();
        int32_t i;
        if (NumberEqualsInt32(d, &i)) {
            // Normalize int32_t-valued doubles to int32_t for faster hashing and testing.
            value = Int32Value(i);
        } else if (IsNaN(d)) {
            // NaNs with different bits must hash and test identically.
            value = DoubleNaNValue();
        } else {
            value = v;
        }
    } else {
        value = v;
    }

    MOZ_ASSERT(value.isUndefined() || value.isNull() || value.isBoolean() || value.isNumber() ||
               value.isString() || value.isSymbol() || value.isObject());
    return true;
}