protected static function _matchLanguage($a, $b)
{
$a = explode('-', $a);
$b = explode('-', $b);
for ($i = 0, $n = min(count($a), count($b)); $i < $n; ++$i) {
if ($a[$i] !== $b[$i]) {
break;
}
}
return $i === 0 ? 0 : (double) $i / count($a);
}