closeUntil method Null safety

@override void closeUntil({required String location, Map<String, Object?>? resultMap})

Close the current top most location and every location after it until location is visible.

resultMap of String location path to Object as result for screen.

Implementation

@override
void closeUntil({required String location, Map<String, Object?>? resultMap}) {
  if (_pages.isEmpty) {
    throw const DBRouterDelegateCantClosePageException(
      "there's no page in the stack to close",
    );
  }

  if (_pages.length < 2) {
    throw const DBRouterDelegateCantClosePageException(
      "You can't remove the only page in the stack",
    );
  }

  final int locationIndex = _pages.indexWhere((DBPage page) {
    return page.destination.path == location;
  });

  if (locationIndex < 0) {
    throw DBRouterDelegateCantClosePageException(
      '$location not found in the list of available\nPages: '
      '${_pages.reversed.map((DBPage page) => page.destination.path)}',
    );
  }

  assert(
    (locationIndex + 1) < _pages.length,
    "$location is the top most, so it's make no sense to use closeUntil, "
    'use close method to close a single location',
  );

  final List<DBPage> pagesToClose = _pages.sublist(locationIndex + 1);
  _pages.removeRange(locationIndex + 1, _pages.length);

  // Run throughout the list of pages, from the top most page first and on.
  for (final DBPage page in pagesToClose.reversed) {
    final Completer<Object?>? tracker = _popResultTracker.remove(
      page.destination.path,
    );

    final Object? result = resultMap?[page.destination.path];

    if (tracker != null && !tracker.isCompleted) {
      tracker.complete(result);
    }
  }

  notifyListeners();
}