class ActionDispatch::Journey::Route

as requirements.
will have {:controller=>"photos", :action=>"show", :id=>/[A-Z]\d{5}/}

:id => /[A-Z]\d{5}/
get 'photo/:id', :controller => 'photos', :action => 'show',

for a route, for example route
Needed for `rails routes`. Picks up succinctly defined requirements

def requirements
  @defaults.merge(path.requirements).delete_if { |_, v|
    /.+?/ == v
  }
end