private function _do_never_allowed(string $str): string
    {
        static $NEVER_ALLOWED_CACHE = [];

        $NEVER_ALLOWED_CACHE['keys'] = null;
        $NEVER_ALLOWED_CACHE['regex'] = null;

        if ($NEVER_ALLOWED_CACHE['keys'] === null) {
            $NEVER_ALLOWED_CACHE['keys'] = \array_keys($this->_never_allowed_str);
        }

        $str = \str_ireplace(
            $NEVER_ALLOWED_CACHE['keys'],
            $this->_never_allowed_str,
            $str
        );

        // ---

        foreach (self::$_never_allowed_call as $call) {
            if (\stripos($str, $call) !== false) {
                $str = (string) \preg_replace(
                    '#([^\p{L}]|^)' . $call . '\s*:#ius',
                    '$1' . $this->_replacement,
                    $str
                );
            }
        }

        // ---

        if ($NEVER_ALLOWED_CACHE['regex'] === null) {
            $NEVER_ALLOWED_CACHE['regex'] = \implode('|', self::$_never_allowed_regex);
        }

        $str = (string) \preg_replace(
            '#' . $NEVER_ALLOWED_CACHE['regex'] . '#ius',
            $this->_replacement,
            $str
        );

        return $str;
    }