protected function callReplacer($message, $attribute, $rule, $parameters)
    {
        $callback = $this->replacers[$rule];

        if ($callback instanceof Closure) {
            return call_user_func_array($callback, func_get_args());
        } else if (is_string($callback)) {
            return $this->callClassBasedReplacer($callback, $message, $attribute, $rule, $parameters);
        }
    }