How to add locale scope to i18n_routing

action_dispatch_extensions.rb

class ActionDispatch::Routing::Mapper
  def localize_and_scope_for(locales, options = {}, &block)
    scoped_locales = locales - Array(options[:skip_scope])

    localized(locales) do
      locale_regexp = Regexp.new(scoped_locales.join('|'))
      scope("/:i18n_locale", :constraints => {:i18n_locale => locale_regexp}) do
        yield
      end
      yield if options[:skip_scope]
    end
  end
end

routes.rb

MyApp::Application.routes.draw do
  localize_and_scope_for(I18n.available_locales, :skip_scope => I18n.default_locale) do
    # Your routes here. 

    # Example:
    #
    # resources :pages
    #
    # You will have no scope for the default locale, i.e. '/pages/new'
    # but all other locales will create a scope, i.e. '/es/paginas/nueva'
  end
end