JavaScriptEncoder.php

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<?php
namespace TYPO3\CMS\Core\Encoder;

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

class JavaScriptEncoder implements \TYPO3\CMS\Core\SingletonInterface
{
    protected $hexMatrix = [];

    protected $immuneCharacters = [',', '.', '_'];

    protected $charsetConversion = null;

    public function __construct()
    {
        $this->charsetConversion = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Charset\CharsetConverter::class);
        for ($i = 0; $i < 256; $i++) {
            if ($i >= ord('0') && $i <= ord('9') || $i >= ord('A') && $i <= ord('Z') || $i >= ord('a') && $i <= ord('z')) {
                $this->hexMatrix[$i] = null;
            } else {
                $this->hexMatrix[$i] = dechex($i);
            }
        }
    }

    public function encode($input)
    {
        $stringLength = mb_strlen($input, 'utf-8');
        $encodedString = '';
        for ($i = 0; $i < $stringLength; $i++) {
            $c = mb_substr($input, $i, 1, 'utf-8');
            $encodedString .= $this->encodeCharacter($c);
        }
        return $encodedString;
    }

    protected function encodeCharacter($character)
    {
        if ($this->isImmuneCharacter($character)) {
            return $character;
        }
        $ordinalValue = $this->charsetConversion->utf8CharToUnumber($character);
        // Check for alphanumeric characters
        $hex = $this->getHexForNonAlphanumeric($ordinalValue);
        if ($hex === null) {
            return $character;
        }
        // Encode up to 256 with \\xHH
        if ($ordinalValue < 256) {
            $pad = substr('00', strlen($hex));
            return '\\x' . $pad . strtoupper($hex);
        }
        // Otherwise encode with \\uHHHH
        $pad = substr('0000', strlen($hex));
        return '\\u' . $pad . strtoupper($hex);
    }

    protected function isImmuneCharacter($character)
    {
        return in_array($character, $this->immuneCharacters, true);
    }

    protected function getHexForNonAlphanumeric($ordinalValue)
    {
        if ($ordinalValue <= 255) {
            return $this->hexMatrix[$ordinalValue];
        }
        return dechex($ordinalValue);
    }
}