protected static function _matchLanguage($a, $b) {
		$a = explode('-', strtolower($a));
		$b = explode('-', strtolower($b));

		for ($i = 0, $n = min(count($a), count($b)); $i < $n; $i++) {
			if ($a[$i] !== $b[$i]) {
				break;
			}
		}
		return $i === 0 ? 0 : (float)$i / count($a);
	}