function unescape($str) {
  $str = rawurldecode($str);
  preg_match_all("/(?:%u.{4})|&#x.{4};|&#\d+;|.+/U",$str,$r);
  $ar = $r[0];
  //print_r($ar);
  foreach($ar as $k=>$v) {
    if(substr($v,0,2) == "%u"){
      $ar[$k] = iconv("UCS-2BE","UTF-8",pack("H4",substr($v,-4)));
 }
    elseif(substr($v,0,3) == "&#x"){
      $ar[$k] = iconv("UCS-2BE","UTF-8",pack("H4",substr($v,3,-1)));
 }
    elseif(substr($v,0,2) == "&#") {
       
      $ar[$k] = iconv("UCS-2BE","UTF-8",pack("n",substr($v,2,-1)));
    }
  }
  return join("",$ar);
}
echo unescape("紫星藍");