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132 lines
3.7 KiB
132 lines
3.7 KiB
'use strict'; |
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var $ = require('../internals/export'); |
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var global = require('../internals/global'); |
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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 $repeat = require('../internals/string-repeat'); |
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var fails = require('../internals/fails'); |
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var RangeError = global.RangeError; |
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var String = global.String; |
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var floor = Math.floor; |
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var repeat = uncurryThis($repeat); |
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var stringSlice = uncurryThis(''.slice); |
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var un$ToFixed = 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 un$ToFixed(0.00008, 3) !== '0.000' || |
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un$ToFixed(0.9, 0) !== '1' || |
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un$ToFixed(1.255, 2) !== '1.25' || |
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un$ToFixed(1000000000000000128.0, 0) !== '1000000000000000128'; |
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}) || !fails(function () { |
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// V8 ~ Android 4.3- |
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un$ToFixed({}); |
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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 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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