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90 lines
2.5 KiB
90 lines
2.5 KiB
'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 ($isNaN(ny)) { |
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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 ($isNaN(nx)) { |
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return void undefined; |
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} |
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return BigIntLessThan(nx, py); |
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} |
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nx = ToNumeric(px); |
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ny = ToNumeric(py); |
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var nxType = Type(nx); |
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if (nxType === Type(ny)) { |
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return nxType === 'Number' ? NumberLessThan(nx, ny) : BigIntLessThan(nx, ny); |
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} |
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if ($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 nonzero, finite, and not equal |
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};
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