Generador de tags

encontre un codigo interesante
function tag_key($texto){

mb_regex_encoding('UTF-8');
$texto = html_entity_decode($texto, ENT_QUOTES, 'UTF-8');
$texto = strip_tags($texto);

$content = str_replace(array("
","\r\n","\n","\n\n",",",".",',', ')', '(', '.', "'", '"','<', '>', ';', '!', '?', '/', '-','_', '[', ']', ':', '+', '=', '#','$', '"', '©', '>', '<',chr(10), chr(13), chr(9)),"",$texto);
$ketxt = preg_replace('/ {2,}/si', " ", $content);
$t = explode(" ", $ketxt);
$total = count($t);
$tg = "";
$i = 0;
foreach($t as $v){ $i++;
$coma = ($i < $total-1) ? ", " : " ";
$tg .= (strlen($v) >= 5 && strlen($v) <=15) ? ($v.$coma) : "";
}
$tag = strtolower($tg);
return ($tag);
}

pruebenlo