class ActionDispatch::Routing::PolymorphicRoutes::HelperMethodBuilder

def handle_list(list)
  record_list = list.dup
  record      = record_list.pop
  args = []
  route  = record_list.map { |parent|
    case parent
    when Symbol, String
      parent.to_s
    when Class
      args << parent
      parent.model_name.singular_route_key
    else
      args << parent.to_model
      parent.to_model.model_name.singular_route_key
    end
  }
  route <<
  case record
  when Symbol, String
    record.to_s
  when Class
    @key_strategy.call record.model_name
  else
    model = record.to_model
    if model.persisted?
      args << model
      model.model_name.singular_route_key
    else
      @key_strategy.call model.model_name
    end
  end
  route << suffix
  named_route = prefix + route.join("_")
  [named_route, args]
end