setNewRoutePath method Null safety

@override Future<void> setNewRoutePath(Destination configuration)

Called by the Router when the Router.routeInformationProvider reports that a new route has been pushed to the application by the operating system.

Consider using a SynchronousFuture if the result can be computed synchronously, so that the Router does not need to wait for the next microtask to schedule a build.

Implementation

@override
Future<void> setNewRoutePath(Destination configuration) async {
  final DBPage? newPage = await pageBuilders.getPage(configuration);

  // Since this is called mostly for deep linking or web navigation
  // if the path is unknown and can't be handle we just ignore it
  // or we could return the user to a 404 page.
  if (newPage != null) {
    // map the current list of page to it's destination representation.
    final Iterable<Destination> currentHistory = _pages.map(
      (DBPage page) => page.destination,
    );

    // If the new page has a history than we need to check that it's not
    // the same as the current one.
    final List<Destination>? newPageHistory = configuration.metadata.history;

    final Iterable<Destination> newPageFullHistory = <Destination>[
      if (newPageHistory != null) ...newPageHistory,
      configuration, // add the new destination requested.
    ];

    // If the stack are equals then there's no point on updating the pages
    // Because we might loose state of each screen and in a tabbed navigation
    // this might be called when switching tabs.
    if (!areNavigationStackEquals(currentHistory, newPageFullHistory)) {
      // If the new stack is null or empty than we just add the new page.
      if (newPageHistory == null || newPageHistory.isEmpty) {
        _pages.add(newPage);
      } else {
        final List<DBPage> newPages =
            await _pageBuilders.createPages(newPageHistory);

        _pages
          ..addAll(newPages)
          ..add(newPage);
      }
      final Completer<Object> popTracker = Completer<Object>();
      _popResultTracker[configuration.path] = popTracker;
    }
  }
}