public function process()
    {
        parent::process();

        if ($this->value === null) {
            return;
        }

        if ($this->email_widget === null) {
            throw new SwatException(
                "Property 'email_widget' is null. " .
                    'Expected a reference to a SwatEmailEntry.'
            );
        }

        if ($this->email_widget->value !== null) {
            if ($this->email_widget->value !== $this->value) {
                $message = Swat::_(
                    'Email address and confirmation email ' .
                        'address do not match.'
                );

                $this->addMessage(new SwatMessage($message, 'error'));
            }
        }
    }