// Use the character preceding the variable as a separator
            $separators = array($match[0][0][0]);

            if ($pos !== $len) {
                // Use the character following the variable as the separator when available
                $separators[] = $pattern[$pos];
            }
            $regexp = sprintf('[^%s]+', preg_quote(implode('', array_unique($separators)), self::REGEX_DELIMITER));