public static ReadableProperty count()

in model/src/main/java/jetbrains/jetpad/model/collections/list/ObservableCollections.java [114:157]

40 lines of code
4 McCabe index (conditional complexity)


  public static <ItemT> ReadableProperty<Integer> count(
      final ObservableCollection<ItemT> collection, final Predicate<? super ItemT> predicate) {
    return new BaseDerivedProperty<Integer>(simpleCount(predicate, collection)) {
      private Registration myCollectionRegistration;
      private int myCount;

      @Override
      protected void doAddListeners() {
        myCollectionRegistration = collection.addListener(new CollectionAdapter<ItemT>() {
          @Override
          public void onItemAdded(CollectionItemEvent<? extends ItemT> event) {
            if (predicate.test(event.getNewItem())) {
              myCount++;
            }
            somethingChanged();
          }

          @Override
          public void onItemRemoved(CollectionItemEvent<? extends ItemT> event) {
            if (predicate.test(event.getOldItem())) {
              myCount--;
            }
            somethingChanged();
          }
        });
        myCount = simpleCount(predicate, collection);
      }

      @Override
      protected void doRemoveListeners() {
        myCollectionRegistration.remove();
        myCollectionRegistration = null;
      }

      @Override
      protected Integer doGet() {
        if (myCollectionRegistration == null) {
          return simpleCount(predicate, collection);
        } else {
          return myCount;
        }
      }
    };
  }