44 lines
1.4 KiB
JavaScript
44 lines
1.4 KiB
JavaScript
'use strict';
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var GetIntrinsic = require('get-intrinsic');
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var $Number = GetIntrinsic('%Number%');
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var $SyntaxError = require('es-errors/syntax');
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var $TypeError = require('es-errors/type');
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var IsIntegralNumber = require('./IsIntegralNumber');
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var substring = require('./substring');
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var isNaN = require('../helpers/isNaN');
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// https://262.ecma-international.org/14.0/#sec-parsehexoctet
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module.exports = function ParseHexOctet(string, position) {
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if (typeof string !== 'string') {
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throw new $TypeError('Assertion failed: `string` must be a String');
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}
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if (!IsIntegralNumber(position) || position < 0) {
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throw new $TypeError('Assertion failed: `position` must be a nonnegative integer');
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}
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var len = string.length; // step 1
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if ((position + 2) > len) { // step 2
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var error = new $SyntaxError('requested a position on a string that does not contain 2 characters at that position'); // step 2.a
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return [error]; // step 2.b
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}
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var hexDigits = substring(string, position, position + 2); // step 3
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var n = $Number('0x' + hexDigits);
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if (isNaN(n)) {
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return [new $SyntaxError('Invalid hexadecimal characters')];
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}
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return n;
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/*
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4. Let _parseResult_ be ParseText(StringToCodePoints(_hexDigits_), |HexDigits[~Sep]|).
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5. If _parseResult_ is not a Parse Node, return _parseResult_.
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6. Let _n_ be the unsigned 8-bit value corresponding with the MV of _parseResult_.
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7. Return _n_.
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*/
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};
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