update method

Implementation

@override
S update(Updater<S> updater) => delegate.update((state) {
  // Only remember the current state if it is not filtered.
  if (filter == null || !filter!(state)) {
    _past.addLast(state);
    // Limit the number of history items to remember.
    if (limit != null) {
      while (limit! < _past.length) {
        _past.removeFirst();
      }
    }
  }
  // Erase all future states.
  _future.clear();
  return updater(state);
});