How can i access the user Role in Form Builder class in Symfony2

I have the form as UserType with field like this

->add('description')
  ->add('createdAt')

Now i want that if the Logged in user has Role (ROLE_SUPERADMIN) then he can see extra fields like this

 ->add('description')
if($user.hasRole(ROLE_SUPERADMIN))
->add('createdAt')

Actually i have to do that for many fields . is there any way i can make some custom type so that if that type is there then only admin can see those like

->add('createdAt',"MyCustomType")