Подсветка кода с нумерацией строк

private function _line_numbers($code)
    {
    $code = strtr($code,array('<br />'=>"\r\n",'[br]'=>"\r\n",'<br/>'=>"\r\n"));
    $code = trim($code);
        $codeline = explode(PHP_EOL, $code);
              foreach ($codeline as $line => $string){
                    if($string!=''){
         $ret.='<div style="display:inline-block; width:28px; color:'.$this->_colors['css']['linenumber'].'">'.($line+1).'</div>'.$string.PHP_EOL;
                    }
              }
        return '<pre>'.$ret.'</pre>';
        }