module Devise::Controllers::UrlHelpers

def self.generate_helpers!(routes=nil)
  routes ||= begin
    mappings = Devise.mappings.values.map(&:used_helpers).flatten.uniq
    Devise::URL_HELPERS.slice(*mappings)
  end
  routes.each do |module_name, actions|
    [:path, :url].each do |path_or_url|
      actions.each do |action|
        action = action ? "#{action}_" : ""
        method = "#{action}#{module_name}_#{path_or_url}"
        class_eval <<-URL_HELPERS, __FILE__, __LINE__ + 1
          def #{method}(resource_or_scope, *args)
            scope = Devise::Mapping.find_scope!(resource_or_scope)
            send("#{action}\#{scope}_#{module_name}_#{path_or_url}", *args)
          end
        URL_HELPERS
      end
    end
  end
end