private function getTransliterator(string $rule, string $locale): \Transliterator
	{
		$key = $rule.'|'.$locale;

		if (!isset($this->transliterators[$key])) {
			$this->transliterators[$key] = $this->findMatchingTransliterator($rule, $locale);
		}

		return $this->transliterators[$key];
	}