class ActionDispatch::Routing::RouteSet

def add_route(app, conditions = {}, requirements = {}, defaults = {}, name = nil, anchor = true)
  raise ArgumentError, "Invalid route name: '#{name}'" unless name.blank? || name.to_s.match(/^[_a-z]\w*$/i)
  if name && named_routes[name]
    raise ArgumentError, "Invalid route name, already in use: '#{name}' \n" \
      "You may have defined two routes with the same name using the `:as` option, or " \
      "you may be overriding a route already defined by a resource with the same naming. " \
      "For the latter, you can restrict the routes created with `resources` as explained here: \n" \
      "http://guides.rubyonrails.org/routing.html#restricting-the-routes-created"
  end
  path = build_path(conditions.delete(:path_info), requirements, SEPARATORS, anchor)
  conditions = build_conditions(conditions, path.names.map { |x| x.to_sym })
  route = @set.add_route(app, path, conditions, defaults, name)
  named_routes[name] = route if name
  route
end