google_forms/system/core/Utf8.php

<?php

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2019 - 2022, CodeIgniter Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package CodeIgniter
 * @author  EllisLab Dev Team
 * @copyright   Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright   Copyright (c) 2014 - 2019, British Columbia Institute of Technology (https://bcit.ca/)
 * @copyright   Copyright (c) 2019 - 2022, CodeIgniter Foundation (https://codeigniter.com/)
 * @license https://opensource.org/licenses/MIT MIT License
 * @link    https://codeigniter.com
 * @since   Version 2.0.0
 * @filesource
 */

defined('BASEPATH') or exit('No direct script access allowed');

/**
 * Utf8 Class
 *
 * Provides support for UTF-8 environments
 *
 * @package     CodeIgniter
 * @subpackage  Libraries
 * @category    UTF-8
 * @author      EllisLab Dev Team
 * @link        https://codeigniter.com/userguide3/libraries/utf8.html
 */
class CI_Utf8
{
    /**
     * Class constructor
     *
     * Determines if UTF-8 support is to be enabled.
     *
     * @return  void
     */
    public function __construct()
    {
        if (
            defined('PREG_BAD_UTF8_ERROR')              // PCRE must support UTF-8
            && (ICONV_ENABLED === true or MB_ENABLED === true)  // iconv or mbstring must be installed
            && strtoupper(config_item('charset')) === 'UTF-8'   // Application charset must be UTF-8
        ) {
            define('UTF8_ENABLED', true);
            log_message('debug', 'UTF-8 Support Enabled');
        } else {
            define('UTF8_ENABLED', false);
            log_message('debug', 'UTF-8 Support Disabled');
        }

        log_message('info', 'Utf8 Class Initialized');
    }

    // --------------------------------------------------------------------

    /**
     * Clean UTF-8 strings
     *
     * Ensures strings contain only valid UTF-8 characters.
     *
     * @param   string  $str    String to clean
     * @return  string
     */
    public function clean_string($str)
    {
        if ($this->is_ascii($str) === false) {
            if (MB_ENABLED) {
                $str = mb_convert_encoding($str, 'UTF-8', 'UTF-8');
            } elseif (ICONV_ENABLED) {
                $str = @iconv('UTF-8', 'UTF-8//IGNORE', $str);
            }
        }

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * Remove ASCII control characters
     *
     * Removes all ASCII control characters except horizontal tabs,
     * line feeds, and carriage returns, as all others can cause
     * problems in XML.
     *
     * @param   string  $str    String to clean
     * @return  string
     */
    public function safe_ascii_for_xml($str)
    {
        return remove_invisible_characters($str, false);
    }

    // --------------------------------------------------------------------

    /**
     * Convert to UTF-8
     *
     * Attempts to convert a string to UTF-8.
     *
     * @param   string  $str        Input string
     * @param   string  $encoding   Input encoding
     * @return  string  $str encoded in UTF-8 or FALSE on failure
     */
    public function convert_to_utf8($str, $encoding)
    {
        if (MB_ENABLED) {
            return mb_convert_encoding($str, 'UTF-8', $encoding);
        } elseif (ICONV_ENABLED) {
            return @iconv($encoding, 'UTF-8', $str);
        }

        return false;
    }

    // --------------------------------------------------------------------

    /**
     * Is ASCII?
     *
     * Tests if a string is standard 7-bit ASCII or not.
     *
     * @param   string  $str    String to check
     * @return  bool
     */
    public function is_ascii($str)
    {
        return (preg_match('/[^\x00-\x7F]/S', $str) === 0);
    }
}