php中国語・英語変換クラスの詳しい説明

class language 
{ 
static $lanObject; 
public $type; // unit , dashboard , menu ,other 
public $lan; // language 
private $special; // The common in the file 
private function construct() 
{ 
if( isset($_GET['hl']) || isset($_POST['hl']) ) 
{ 
switch( isset($_GET['hl'])?$_GET['hl']:$_POST['hl'] ) 
{ 
case 'en': 
$this->lan = 'en'; 
case 'zh': 
$this->lan = 'zh'; 
case 'all': 
$this->lan = 'all'; 
default: 
$this->error(); 
} 
} 
else 
$this->lan = isset($_COOKIE['hl']) ? $_COOKIE['hl']:'zh'; 
} 
public static function getObject() 
{ 
if( !(self::$lanObject instanceof self) ) 
self::$lanObject = new language(); 
return self::$lanObject; 
} 
public function lto($key) //$key is English 
{ 
if( $this->lan !== 'zh' ) 
return $key; 
if( empty($this->special) ) // if the $special is null 
{ 
if( isset($this->type) ) 
$this->special = file_get_contents($this->type.'.txt'); 
else 
return $key; 
} 
echo $this->search($key); 
} 
private function search($searchTozh) // PHP String 
{ 
$key_start = strpos($this->special,$searchTozh); 
$key_end = strpos($this->special,' ',$key_start); 
$len_str = strlen($searchTozh); 
$for_sub = $key_start + $len_str + 1; 
return substr($this->special, $for_sub, $key_end - $for_sub); 
} 
}

$la = language::getObject(); 
$la->type = 'unit'; 
$la->lto('min'); 
echo &#39;<br/>&#39;; 
$la->lto(&#39;hello&#39;);