urlがcontrollerにmappingされるまで
rails middleware
ActionDispatch::Routing::RouteSet#call
ActionDispatch::Journey::Router#serve
ActionDispatch::Journey::Router#find_routes
ActionDispatch::Journey::Route#app
ActionDispatch::Routing::RouteSet::Dispatcher#serve
ActionController::Base#dispatch
config/routesから追加まで
ActionDispatch::Routing::RouteSet#draw
ActionDispatch::Routing::Mapper::HttpHelpers#get
ActionDispatch::Routing::Mapper::Resources#match
ActionDispatch::Routing::RouteSet#add_route
ActionDispatch::Journey::Routes#add_route
custom_routes << route
判定
custom_routes.select { |r| r.path.match(arg) }