91 lines
2.5 KiB
JavaScript
91 lines
2.5 KiB
JavaScript
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'use strict';
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var GetIntrinsic = require('get-intrinsic');
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var $Number = GetIntrinsic('%Number%');
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var $TypeError = GetIntrinsic('%TypeError%');
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var $isNaN = require('../helpers/isNaN');
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var IsStringPrefix = require('./IsStringPrefix');
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var StringToBigInt = require('./StringToBigInt');
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var ToNumeric = require('./ToNumeric');
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var ToPrimitive = require('./ToPrimitive');
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var Type = require('./Type');
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var BigIntLessThan = require('./BigInt/lessThan');
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var NumberLessThan = require('./Number/lessThan');
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// https://262.ecma-international.org/13.0/#sec-islessthan
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// eslint-disable-next-line max-statements, max-lines-per-function
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module.exports = function IsLessThan(x, y, LeftFirst) {
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if (Type(LeftFirst) !== 'Boolean') {
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throw new $TypeError('Assertion failed: LeftFirst argument must be a Boolean');
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}
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var px;
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var py;
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if (LeftFirst) {
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px = ToPrimitive(x, $Number);
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py = ToPrimitive(y, $Number);
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} else {
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py = ToPrimitive(y, $Number);
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px = ToPrimitive(x, $Number);
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}
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var pxType = Type(px);
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var pyType = Type(py);
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if (pxType === 'String' && pyType === 'String') {
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if (IsStringPrefix(py, px)) {
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return false;
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}
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if (IsStringPrefix(px, py)) {
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return true;
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}
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/*
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c. Let k be the smallest non-negative integer such that the code unit at index k within px is different from the code unit at index k within py. (There must be such a k, for neither String is a prefix of the other.)
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d. Let m be the integer that is the numeric value of the code unit at index k within px.
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e. Let n be the integer that is the numeric value of the code unit at index k within py.
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f. If m < n, return true. Otherwise, return false.
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*/
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return px < py; // both strings, neither a prefix of the other. shortcut for steps 3 c-f
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}
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var nx;
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var ny;
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if (pxType === 'BigInt' && pyType === 'String') {
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ny = StringToBigInt(py);
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if (typeof ny === 'undefined') {
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return void undefined;
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}
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return BigIntLessThan(px, ny);
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}
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if (pxType === 'String' && pyType === 'BigInt') {
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nx = StringToBigInt(px);
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if (typeof nx === 'undefined') {
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return void undefined;
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}
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return BigIntLessThan(nx, py);
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}
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nx = ToNumeric(px);
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ny = ToNumeric(py);
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var nxType = Type(nx);
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if (nxType === Type(ny)) {
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return nxType === 'Number' ? NumberLessThan(nx, ny) : BigIntLessThan(nx, ny);
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}
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if ($isNaN(nx) || $isNaN(ny)) {
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return void undefined;
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}
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if (nx === -Infinity || ny === Infinity) {
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return true;
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}
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if (nx === Infinity || ny === -Infinity) {
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return false;
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}
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return nx < ny; // by now, these are both finite, and the same type
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};
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