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27 lines
760 B
27 lines
760 B
'use strict'; |
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var callBound = require('call-bound'); |
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var $TypeError = require('es-errors/type'); |
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var isInteger = require('math-intrinsics/isInteger'); |
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var StringToCodePoints = require('./StringToCodePoints'); |
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var $indexOf = callBound('String.prototype.indexOf'); |
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// https://262.ecma-international.org/13.0/#sec-getstringindex |
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module.exports = function GetStringIndex(S, e) { |
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if (typeof S !== 'string') { |
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throw new $TypeError('Assertion failed: `S` must be a String'); |
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} |
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if (!isInteger(e) || e < 0) { |
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throw new $TypeError('Assertion failed: `e` must be a non-negative integer'); |
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} |
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if (S === '') { |
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return 0; |
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} |
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var codepoints = StringToCodePoints(S); |
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var eUTF = e >= codepoints.length ? S.length : $indexOf(S, codepoints[e]); |
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return eUTF; |
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};
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