mirror of https://github.com/jkjoy/sunpeiwen.git
115 lines
2.7 KiB
JavaScript
115 lines
2.7 KiB
JavaScript
'use strict';
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var $export = require('./_export');
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var toInteger = require('./_to-integer');
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var aNumberValue = require('./_a-number-value');
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var repeat = require('./_string-repeat');
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var $toFixed = 1.0.toFixed;
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var floor = Math.floor;
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var data = [0, 0, 0, 0, 0, 0];
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var ERROR = 'Number.toFixed: incorrect invocation!';
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var ZERO = '0';
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var multiply = function (n, c) {
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var i = -1;
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var c2 = c;
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while (++i < 6) {
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c2 += n * data[i];
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data[i] = 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 (n) {
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var i = 6;
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var c = 0;
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while (--i >= 0) {
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c += data[i];
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data[i] = floor(c / n);
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c = (c % n) * 1e7;
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}
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};
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var numToString = function () {
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var i = 6;
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var s = '';
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while (--i >= 0) {
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if (s !== '' || i === 0 || data[i] !== 0) {
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var t = String(data[i]);
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s = s === '' ? t : s + repeat.call(ZERO, 7 - t.length) + t;
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}
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} return s;
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};
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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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$export($export.P + $export.F * (!!$toFixed && (
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0.00008.toFixed(3) !== '0.000' ||
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0.9.toFixed(0) !== '1' ||
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1.255.toFixed(2) !== '1.25' ||
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1000000000000000128.0.toFixed(0) !== '1000000000000000128'
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) || !require('./_fails')(function () {
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// V8 ~ Android 4.3-
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$toFixed.call({});
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})), 'Number', {
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toFixed: function toFixed(fractionDigits) {
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var x = aNumberValue(this, ERROR);
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var f = toInteger(fractionDigits);
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var s = '';
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var m = ZERO;
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var e, z, j, k;
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if (f < 0 || f > 20) throw RangeError(ERROR);
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// eslint-disable-next-line no-self-compare
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if (x != x) return 'NaN';
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if (x <= -1e21 || x >= 1e21) return String(x);
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if (x < 0) {
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s = '-';
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x = -x;
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}
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if (x > 1e-21) {
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e = log(x * pow(2, 69, 1)) - 69;
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z = e < 0 ? x * pow(2, -e, 1) : x / 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(0, z);
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j = f;
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while (j >= 7) {
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multiply(1e7, 0);
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j -= 7;
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}
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multiply(pow(10, j, 1), 0);
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j = e - 1;
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while (j >= 23) {
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divide(1 << 23);
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j -= 23;
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}
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divide(1 << j);
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multiply(1, 1);
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divide(2);
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m = numToString();
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} else {
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multiply(0, z);
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multiply(1 << -e, 0);
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m = numToString() + repeat.call(ZERO, f);
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}
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}
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if (f > 0) {
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k = m.length;
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m = s + (k <= f ? '0.' + repeat.call(ZERO, f - k) + m : m.slice(0, k - f) + '.' + m.slice(k - f));
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} else {
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m = s + m;
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} return m;
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}
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});
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