Im 4.satıra hata alıyorum

Ayrıştırma hatası: C sözdizimi hatası, beklenmedik T_FUNCTION: hat 21 \ xampp \ htdocs \ iş \ CASC \ admin \ formu-validator.php

herkes yardımcı olabilir?

public function email($message='')
    {
        $message = ( empty ($message) ) ? '%s is an invalid email address.' : $message;
        $this->set_rule(__FUNCTION__, function($email) {
            return ( filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE ) ? FALSE : TRUE;
        }, $message);
        return $this;
    }


private function set_rule($rule, $function, $message='')
    {
         // do not attempt to validate when no post data is present
        if ( $this->haspostdata ) {
            if ( ! array_key_exists($rule, $this->rules) ) {
                $this->rules[$rule] = TRUE;
                if ( ! array_key_exists($rule, $this->functions) && is_callable($function) ) {
                    $this->functions[$rule] = $function;
                }
                if ( !empty ($message) ) {
                    $this->messages[$rule] = $message;
                }
            }
        }
    }