public function splitString($string)
    {
        if ($this->digits->hasStringConflict()) {
            throw new \RuntimeException('The number base does not support string presentation');
        }

        $pattern = $this->getDigitPattern();

        if ((string) $string === '') {
            $digits = [];
        } elseif (is_int($pattern)) {
            $digits = str_split($string, $this->digitPattern);
        } else {
            preg_match_all($pattern, $string, $match);
            $digits = $match[0];
        }

        return $this->canonizeDigits($digits);
    }