Back Dispatch

BackDispatcher coordinates one navigator plus nested descendants as an acyclic graph; the widget BackButtonDispatcher is the retained boundary variant (NavigationBackButtonDispatcher alias).

use incular::prelude::*;

fn main() {
    let dispatcher = BackDispatcher::new(Navigator::new());
    let report = dispatcher.dispatch_back();
    println!(
        "handled: {}, depth: {}, blocked: {}",
        report.handled, report.depth, report.blocked
    );
}

BackButtonListener::new(child) with on_back_button_pressed, dispatcher, and register binds retained widget boundaries; dropping the BackRegistration unregisters.

BackDispatchReport (nav): { handled, depth, blocked }. Widget report adds pop: Option<PopAttempt>; PopAttempt: popped(result) / rejected() / blocked() / unhandled(). BackHandlerResult: handled() / unhandled() / from_pop(pop). BackRegistration owns retained registrations. App-shell RootBackButtonDispatcher: add_callback(f) → BackCallbackSubscription, dispatch_back() -> bool.

Related: Navigator, PopScope.