Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 1 | 'use strict'; |
| 2 | |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 3 | var isInteger = require('../helpers/isInteger'); |
Tim van der Lippe | 2c89197 | 2021-07-29 15:22:50 | [diff] [blame] | 4 | var isLeadingSurrogate = require('../helpers/isLeadingSurrogate'); |
| 5 | var isTrailingSurrogate = require('../helpers/isTrailingSurrogate'); |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 6 | var MAX_SAFE_INTEGER = require('../helpers/maxSafeInteger'); |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 7 | |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 8 | var $TypeError = require('es-errors/type'); |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 9 | |
Tim van der Lippe | 2c89197 | 2021-07-29 15:22:50 | [diff] [blame] | 10 | var $charCodeAt = require('call-bind/callBound')('String.prototype.charCodeAt'); |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 11 | |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 12 | // https://262.ecma-international.org/6.0/#sec-advancestringindex |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 13 | |
| 14 | module.exports = function AdvanceStringIndex(S, index, unicode) { |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 15 | if (typeof S !== 'string') { |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 16 | throw new $TypeError('Assertion failed: `S` must be a String'); |
| 17 | } |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 18 | if (!isInteger(index) || index < 0 || index > MAX_SAFE_INTEGER) { |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 19 | throw new $TypeError('Assertion failed: `length` must be an integer >= 0 and <= 2**53'); |
| 20 | } |
Nikolay Vitkov | d76576c | 2024-12-02 14:10:15 | [diff] [blame] | 21 | if (typeof unicode !== 'boolean') { |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 22 | throw new $TypeError('Assertion failed: `unicode` must be a Boolean'); |
| 23 | } |
| 24 | if (!unicode) { |
| 25 | return index + 1; |
| 26 | } |
| 27 | var length = S.length; |
| 28 | if ((index + 1) >= length) { |
| 29 | return index + 1; |
| 30 | } |
| 31 | |
| 32 | var first = $charCodeAt(S, index); |
Tim van der Lippe | 2c89197 | 2021-07-29 15:22:50 | [diff] [blame] | 33 | if (!isLeadingSurrogate(first)) { |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 34 | return index + 1; |
| 35 | } |
| 36 | |
| 37 | var second = $charCodeAt(S, index + 1); |
Tim van der Lippe | 2c89197 | 2021-07-29 15:22:50 | [diff] [blame] | 38 | if (!isTrailingSurrogate(second)) { |
Tim van der Lippe | fdbd42e | 2020-04-07 14:14:36 | [diff] [blame] | 39 | return index + 1; |
| 40 | } |
| 41 | |
| 42 | return index + 2; |
| 43 | }; |