number.js

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/**
@fileOverview
Implementation of ECMAScript 5 Number methods and prototype.

@author
Maxime Chevalier-Boisvert
*/

/**
15.7.1 The Number function/constructor
new Number([ value ])
Number([ value ])
*/
function Number(value)
{
    // If this is a constructor call (new Number)
    if ($rt_isGlobalObj(this) === false)
    {
        // Convert the value to a number
        var numVal = $rt_toNumber(value);

        // If the value is not a number, return it directly
        if (isNaN(numVal))
            return numVal;

        // Store the value in the new object
        this.value = numVal;
    }
    else
    {
        // Convert the value to a number
        return $rt_toNumber(value);
    }
}

//-----------------------------------------------------------------------------

// TODO min and max representable values
// use int64 and bit patterns casted to float64?
// 15.7.3.2 Number.MAX_VALUE
// 15.7.3.3 Number.MIN_VALUE

// 15.7.3.4 Not a Number value
Number.NaN = NaN;

// 15.7.3.5 Number.NEGATIVE_INFINITY
Number.NEGATIVE_INFINITY = -Infinity;

// 15.7.3.6 Number.POSITIVE_INFINITY
Number.POSITIVE_INFINITY = Infinity;

/**
Internal function to get the number value of a number or number object
*/
function getNumVal(num)
{
    if (num instanceof Number)
        return num.value;

    return num;
}

/**
15.7.4.2 Number.prototype.toString ([ radix ])
*/
Number.prototype.toString = function (radix)
{
    var num = getNumVal(this);

    // Convert radix from string to integer
    if ($ir_is_string(radix))
    {
        radix = parseInt(radix, 10);
    }

    return $rt_numToStr(num, radix);
};

/**
15.7.4.4 Number.prototype.valueOf ( )
*/
Number.prototype.valueOf = function ()
{
    return getNumVal(this);
};

/**
15.7.4.5 Number.prototype.toFixed (fractionDigits)
*/
Number.prototype.toFixed = function (fractionDigits)
{
    var m;
    var padding;
    var intl;
    var i;

    // 1. Let f be ToInteger(fractionDigits).
    // (If fractionDigits is undefined, this step produces the value 0)
    var f = $rt_toNumber(fractionDigits);
    if (isNaN(f))
        f = 0;
    else if ($ir_is_float64(f))
        f = (f > 0 ? 1 : - 1) * $ir_floor_f64((f > 0 ? f : -f));

    // 2. If f < 0 or f > 20, throw a RangeError exception.
    if (f < 0 || f > 20)
        throw new RangeError("toFixed argument out of range.");

    // 3. Let x be this Number value.
    var x = getNumVal(this);

    // 4. If x is NaN, return the String "NaN".
    if (isNaN(x))
        return "NaN";

    // 5. Let s be the empty String.
    var s = "";

    // 6. If x < 0, then
    if (x < 0)
    {
        // 6.a Let s be "-".
        s = "-";
        // 6.b Let x = –x.
        x = -x;
    }

    // 7. If x ≥ Math.pow(10, 21), then
    if (x >= 1e+21)
    {
        m = $rt_toString(x);
    }
    else if ($ir_is_int32(x) || ($ir_is_float64(x) && $ir_floor_f64(x) === x))
    {
        // In this case we just need to add padding 0s after decimal point and can skip the rest
        if ($ir_is_int32(x))
        {
            m = $rt_toString(x);
        }
        else
        {
            m = $ir_f64_to_str_lng(x);
            intl = $rt_str_get_len(m) - 16;
            m = m.substr(0, intl);
        }

        if (f !== 0)
        {
            padding = $rt_str_alloc(f + 1);
            $rt_str_set_data(padding, 0, 46);
            for (i = 1; i <= f; i++)
                $rt_str_set_data(padding, i, 48);

            m = $rt_strcat(m, $ir_get_str(padding));
        }
    }
    else
    {
        // 8. Else, x < Math.pow(10, 21)

        // 8.a Let n be an integer for which the exact mathematical value of n ÷ 10f – x
        // is as close to zero as possible. If there are two such n, pick the larger n.
        var tenf = 1;
        for(i = 0; i < f; i++)
            tenf *= 10;

        var n = x * tenf;
        if ($ir_is_float64(n))
            n = $ir_floor_f64(n);

        var delta = 0 - (n / tenf - x);
        delta = (delta > 0) ? delta : -delta;
        var delta2;
        while (true)
        {
            delta2 = 0 - ((n + 1) / tenf - x);
            delta2 = (delta2 > 0) ? delta2 : -delta2;
            if (delta2 > delta)
                break;
            n += 1;
            delta = delta2;
            if (delta === 0)
                break;
        }

        // 8.b If n = 0, let m be the String "0". Otherwise, let m be the String
        // consisting of the digits of the decimal representation of n
        // (in order, with no leading zeroes).
        if (n === 0)
        {
            m = "0";
        }
        else
        {
            if ($ir_is_int32(n))
            {
                m = $rt_toString(n);
            }
            else
            {
                // ir_f64_to_str_lng will return a string with . and 15 decimal places;
                // remove them
                m = $ir_f64_to_str_lng(n);
                intl = $rt_str_get_len(m) - 16;
                m = m.substr(0, intl);
            }
        }

        // 8.c if f ≠ 0, then
        if (f !== 0)
        {
            // 8.c.i Let k be the number of characters in m.
            var k = $rt_str_get_len(m);

            // 8.c.ii If k ≤ f, then
            if (k <= f)
            {
                // 8.c.ii.1 Let z be the String consisting of f+1–k occurrences of the
                // character ‘0’
                var end = f + 1 - k;
                padding = $rt_str_alloc(end);
                for (i = 0; i < end; i++)
                    $rt_str_set_data(padding, i, 48);

                // 8.c.ii.2 Let m be the concatenation of Strings z and m.
                m = $rt_strcat($ir_get_str(padding), m);
                // 8.c.ii.3 Let k = f + 1
                k = f + 1;
            }

            // 8.c.iii Let a be the first k–f characters of m,
            // and let b be the remaining f characters of m.
            var a = m.substring(0, k - f);
            var b = m.substring(k - f);

            // 8.c.iv Let m be the concatenation of the three Strings a, ".", and b.
            m = $rt_strcat(a, $rt_strcat('.', b));
        }
    }

    // 9. Return the concatenation of the Strings s and m
    return $rt_strcat(s, m);
};

// Make the Number.prototype properties non-enumerable
for (p in Number.prototype)
{
    Object.defineProperty(
        Number.prototype,
        p,
        {enumerable:false, writable:true, configurable:true }
    );
}