StateWrapper.java

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

package com.facebook.react.uimanager;

import com.facebook.react.bridge.ReadableNativeMap;
import com.facebook.react.bridge.WritableMap;
import com.facebook.react.common.mapbuffer.ReadableMapBuffer;
import javax.annotation.Nullable;

/**
 * This is a wrapper that can be used for passing State objects from Fabric C++ core to
 * platform-specific components in Java. State allows you to break out of uni-directional dataflow
 * by calling updateState, which communicates state back to the C++ layer.
 */
public interface StateWrapper {

  /**
   * Get a ReadableMapBuffer object from the C++ layer, which is a K/V map of short keys to values.
   *
   * <p>Unstable API - DO NOT USE.
   */
  @Nullable
  ReadableMapBuffer getStateDataMapBuffer();

  /**
   * Get a ReadableNativeMap object from the C++ layer, which is a K/V map of string keys to values.
   */
  @Nullable
  ReadableNativeMap getStateData();

  /**
   * Pass a map of values back to the C++ layer. The operation is performed synchronously and cannot
   * fail.
   */
  void updateState(WritableMap map);

  /**
   * Mark state as unused and clean up in Java and in native. This should be called as early as
   * possible when you know a StateWrapper will no longer be used. If there's ANY chance of it being
   * used legitimately, don't destroy it! It is expected that all StateWrappers are destroyed
   * immediately upon stopSurface.
   */
  void destroyState();
}