132 lines
3.6 KiB
JavaScript
132 lines
3.6 KiB
JavaScript
'use strict';
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var $ = require('../internals/export');
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var uncurryThis = require('../internals/function-uncurry-this');
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var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
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var thisNumberValue = require('../internals/this-number-value');
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var $repeat = require('../internals/string-repeat');
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var fails = require('../internals/fails');
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var $RangeError = RangeError;
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var $String = String;
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var floor = Math.floor;
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var repeat = uncurryThis($repeat);
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var stringSlice = uncurryThis(''.slice);
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var nativeToFixed = uncurryThis(1.0.toFixed);
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var pow = function (x, n, acc) {
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return n === 0 ? acc : n % 2 === 1 ? pow(x, n - 1, acc * x) : pow(x * x, n / 2, acc);
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};
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var log = function (x) {
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var n = 0;
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var x2 = x;
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while (x2 >= 4096) {
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n += 12;
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x2 /= 4096;
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}
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while (x2 >= 2) {
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n += 1;
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x2 /= 2;
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} return n;
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};
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var multiply = function (data, n, c) {
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var index = -1;
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var c2 = c;
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while (++index < 6) {
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c2 += n * data[index];
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data[index] = c2 % 1e7;
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c2 = floor(c2 / 1e7);
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}
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};
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var divide = function (data, n) {
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var index = 6;
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var c = 0;
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while (--index >= 0) {
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c += data[index];
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data[index] = floor(c / n);
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c = (c % n) * 1e7;
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}
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};
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var dataToString = function (data) {
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var index = 6;
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var s = '';
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while (--index >= 0) {
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if (s !== '' || index === 0 || data[index] !== 0) {
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var t = $String(data[index]);
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s = s === '' ? t : s + repeat('0', 7 - t.length) + t;
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}
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} return s;
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};
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var FORCED = fails(function () {
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return nativeToFixed(0.00008, 3) !== '0.000' ||
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nativeToFixed(0.9, 0) !== '1' ||
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nativeToFixed(1.255, 2) !== '1.25' ||
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nativeToFixed(1000000000000000128.0, 0) !== '1000000000000000128';
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}) || !fails(function () {
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// V8 ~ Android 4.3-
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nativeToFixed({});
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});
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// `Number.prototype.toFixed` method
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// https://tc39.es/ecma262/#sec-number.prototype.tofixed
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$({ target: 'Number', proto: true, forced: FORCED }, {
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toFixed: function toFixed(fractionDigits) {
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var number = thisNumberValue(this);
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var fractDigits = toIntegerOrInfinity(fractionDigits);
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var data = [0, 0, 0, 0, 0, 0];
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var sign = '';
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var result = '0';
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var e, z, j, k;
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// TODO: ES2018 increased the maximum number of fraction digits to 100, need to improve the implementation
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if (fractDigits < 0 || fractDigits > 20) throw new $RangeError('Incorrect fraction digits');
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// eslint-disable-next-line no-self-compare -- NaN check
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if (number !== number) return 'NaN';
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if (number <= -1e21 || number >= 1e21) return $String(number);
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if (number < 0) {
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sign = '-';
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number = -number;
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}
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if (number > 1e-21) {
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e = log(number * pow(2, 69, 1)) - 69;
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z = e < 0 ? number * pow(2, -e, 1) : number / pow(2, e, 1);
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z *= 0x10000000000000;
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e = 52 - e;
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if (e > 0) {
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multiply(data, 0, z);
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j = fractDigits;
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while (j >= 7) {
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multiply(data, 1e7, 0);
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j -= 7;
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}
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multiply(data, pow(10, j, 1), 0);
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j = e - 1;
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while (j >= 23) {
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divide(data, 1 << 23);
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j -= 23;
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}
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divide(data, 1 << j);
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multiply(data, 1, 1);
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divide(data, 2);
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result = dataToString(data);
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} else {
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multiply(data, 0, z);
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multiply(data, 1 << -e, 0);
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result = dataToString(data) + repeat('0', fractDigits);
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}
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}
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if (fractDigits > 0) {
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k = result.length;
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result = sign + (k <= fractDigits
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? '0.' + repeat('0', fractDigits - k) + result
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: stringSlice(result, 0, k - fractDigits) + '.' + stringSlice(result, k - fractDigits));
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} else {
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result = sign + result;
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} return result;
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}
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});
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