CodeIgniter Utf8.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package CodeIgniter
 * @author ExpressionEngine Dev Team
 * @copyright Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license http://codeigniter.com/user_guide/license.html
 * @link http://codeigniter.com
 * @since Version 2.0
 * @filesource
 */


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


/**
 * Utf8 Class
 *
 * Provides support for UTF-8 environments
 *
 * @package CodeIgniter
 * @subpackage Libraries
 * @category UTF-8
 * @author ExpressionEngine Dev Team
 * @link http://codeigniter.com/user_guide/libraries/utf8.html
 */
class CI_Utf8 {


/**
* Constructor
*
* Determines if UTF-8 support is to be enabled
*
*/
function __construct()
{
log_message('debug', "Utf8 Class Initialized");
//全局变量
global $CFG;


if (
preg_match('/./u', '茅') === 1// PCRE must support UTF-8
AND function_exists('iconv')// iconv must be installed
AND ini_get('mbstring.func_overload') != 1// Multibyte string function overloading cannot be enabled
AND $CFG->item('charset') == 'UTF-8'// Application charset must be UTF-8
)
{
log_message('debug', "UTF-8 Support Enabled");


define('UTF8_ENABLED', TRUE);


// set internal encoding for multibyte string functions if necessary
// and set a flag so we don't have to repeatedly use extension_loaded()
// or function_exists()
// 检查一个扩展是否已经加载
if (extension_loaded('mbstring'))
{
define('MB_ENABLED', TRUE);
mb_internal_encoding('UTF-8');
}
else
{
define('MB_ENABLED', FALSE);
}
}
else
{
log_message('debug', "UTF-8 Support Disabled");
define('UTF8_ENABLED', FALSE);
}
}


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


/**
* Clean UTF-8 strings
*
* Ensures strings are UTF-8
*
* @access public
* @param string
* @return string
*/
//返回$str是utf-8格式
function clean_string($str)
{
if ($this->_is_ascii($str) === FALSE)
{
$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
*
* @access public
* @param string
* @return string
*/
//移除所有的ASCII控制字符除了水平制表符,换行、回车
function safe_ascii_for_xml($str)
{
return remove_invisible_characters($str, FALSE);
}


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


/**
* Convert to UTF-8
*
* Attempts to convert a string to UTF-8
*
* @access public
* @param string
* @param string - input encoding
* @return string
*/
//把str转成utf8编码格式
function convert_to_utf8($str, $encoding)
{
if (function_exists('iconv'))
{
$str = @iconv($encoding, 'UTF-8', $str);
}
elseif (function_exists('mb_convert_encoding'))
{
$str = @mb_convert_encoding($str, 'UTF-8', $encoding);
}
else
{
return FALSE;
}


return $str;
}


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


/**
* Is ASCII?
*
* Tests if a string is standard 7-bit ASCII or not
*
* @access public
* @param string
* @return bool
*/
//测试$str是否为标准的7位ASCII
function _is_ascii($str)
{
return (preg_match('/[^\x00-\x7F]/S', $str) == 0);
}


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


}
// End Utf8 Class


/* End of file Utf8.php */
/* Location: ./system/core/Utf8.php */