private function locale2handle (string $locale): string
	{
		if (
			!preg_match('/^' . HandleValidator::$handlePattern . '$/', $locale) ||
			in_array(strtolower($locale), HandleValidator::$baseReservedWords, true)
		) {
			$localeParts = array_filter(preg_split('/[^a-zA-Z0-9]/', $locale));

			return $localeParts ? '_' . implode('_', $localeParts) : '';
		}

		return $locale;
	}