MapObjectUpdates<T extends MapObject>.from constructor

MapObjectUpdates<T extends MapObject>.from(Set<T> previous, Set<T> current)

Implementation

MapObjectUpdates.from(this.previous, this.current) {
  final previousObjects = Map<MapObjectId, T>.fromEntries(
    previous.map((T object) => MapEntry(object.mapId, object))
  );
  final currentObjects = Map<MapObjectId, T>.fromEntries(
    current.map((T object) => MapEntry(object.mapId, object))
  );
  final previousObjectIds = previousObjects.keys.toSet();
  final currentObjectIds = currentObjects.keys.toSet();

  _objectsToRemove = previousObjectIds
    .difference(currentObjectIds)
    .map((MapObjectId id) => previousObjects[id]!).
    toSet();

  _objectsToAdd = currentObjectIds
    .difference(previousObjectIds)
    .map((MapObjectId id) => currentObjects[id]!)
    .toSet();

  _objectsToChange = currentObjectIds
    .intersection(previousObjectIds)
    .map((MapObjectId id) => currentObjects[id]!)
    .where((T current) => current != previousObjects[current.mapId])
    .toSet();
}