Add notify model changed method (#1063)

Co-authored-by: berendjan <kDt2ygc7WsBBZtK>

epoxy-adapter/src/main/java/com/airbnb/epoxy/EpoxyController.java

@@ -690,6 +690,22 @@ public void moveModel(int fromPosition, int toPosition) {
     requestDelayedModelBuild(500);
   }
 
+
+  /**
+   * An way to notify the adapter that a model has changed. This is intended to be used with
+   * {@link androidx.recyclerview.widget.ItemTouchHelper} to allow revert swiping a model.
+   * <p>
+   * This will immediately notify the change to the RecyclerView.
+   *
+   * @param position Position of the item.
+   */
+  public void notifyModelChanged(int position) {
+    assertNotBuildingModels();
+
+    adapter.notifyModelChanged(position);
+  }
+
+
   /**
    * Get the underlying adapter built by this controller. Use this to get the adapter to set on a
    * RecyclerView, or to get information about models currently in use.

epoxy-adapter/src/main/java/com/airbnb/epoxy/EpoxyControllerAdapter.java

@@ -213,6 +213,23 @@ void moveModel(int fromPosition, int toPosition) {
     }
   }
 
+  @UiThread
+  void notifyModelChanged(int position) {
+    ArrayList<EpoxyModel<?>> updatedList = new ArrayList<>(getCurrentModels());
+
+    notifyBlocker.allowChanges();
+    notifyItemChanged(position);
+    notifyBlocker.blockChanges();
+
+    boolean interruptedDiff = differ.forceListOverride(updatedList);
+
+    if (interruptedDiff) {
+      // The move interrupted a model rebuild/diff that was in progress,
+      // so models may be out of date and we should force them to rebuilt
+      epoxyController.requestModelBuild();
+    }
+  }
+
   private static final ItemCallback<EpoxyModel<?>> ITEM_CALLBACK =
       new ItemCallback<EpoxyModel<?>>() {
         @Override