public static function getMetaTagAttributes(&$html_source)
  {                
    preg_match_all("#<\s*meta\s+".
                   "name\s*=\s*(?|\"([^\"]+)\"|'([^']+)'|([^\s><'\"]+))\s+".
                   "content\s*=\s*(?|\"([^\"]+)\"|'([^']+)'|([^\s><'\"]+))".
                   ".*># Uis", $html_source, $matches);
    
    $tags = array();            
    for ($x=0; $x<count($matches[0]); $x++)
    {
      $meta_name = strtolower(trim($matches[1][$x]));
      $meta_value = strtolower(trim($matches[2][$x]));
      
      $tags[$meta_name] = $meta_value;
    }
    
    return $tags;
  }