Router

protocol Routable: class {
    associatedtype I: Interactable

    func configure(interactor: I, viewController: UIViewController?)
    func attach(router: Router<I>)
    func detach(router: Router<I>)
}

class Router<I: Interactable>: Routable {
    var interactor: Interactable!
    var viewController: UIViewController?
    private var childRouters = Set<Router>()

    func configure(interactor: I, viewController: UIViewController? = nil) {
        self.interactor = interactor
        self.viewController = viewController
    }

    func attach(router: Router) {
        childRouters.insert(router)
        router.interactor.interactorDidAttach()
    }

    func detach(router: Router) {
        router.interactor.interactorWillDetach()
        childRouters.remove(router)
    }
}

extension Router: Hashable, Equatable {
    var hashValue: Int {
        return ObjectIdentifier(self).hashValue
    }

    final class func == (lhs: Router, rhs: Router) -> Bool {
        return lhs.hashValue == rhs.hashValue
    }
}