Provide function to access public instance from internal instance handle in Fabric

Author: rubennorte

packages/react-native-renderer/src/ReactFabric.js

@@ -40,6 +40,7 @@ import {
   sendAccessibilityEvent,
   getNodeFromInternalInstanceHandle,
 } from './ReactNativePublicCompat';
+import {getPublicInstanceFromInternalInstanceHandle} from './ReactFabricHostConfig';
 
 // $FlowFixMe[missing-local-annot]
 function onRecoverableError(error) {
@@ -124,6 +125,10 @@ export {
   // This method allows it to acess the most recent shadow node for
   // the instance (it's only accessible through it).
   getNodeFromInternalInstanceHandle,
+  // Fabric native methods to traverse the host tree return the same internal
+  // instance handles we use to dispatch events. This provides a way to access
+  // the public instances we created from them (potentially created lazily).
+  getPublicInstanceFromInternalInstanceHandle,
 };
 
 injectIntoDevTools({

packages/react-native-renderer/src/ReactFabricHostConfig.js

@@ -241,6 +241,13 @@ export function getPublicInstance(instance: Instance): null | PublicInstance {
   return null;
 }
 
+export function getPublicInstanceFromInternalInstanceHandle(
+  internalInstanceHandle: Object,
+): null | PublicInstance {
+  const instance: Instance = internalInstanceHandle.stateNode;
+  return getPublicInstance(instance);
+}
+
 export function prepareForCommit(containerInfo: Container): null | Object {
   // Noop
   return null;

packages/react-native-renderer/src/ReactNativeTypes.js

@@ -213,6 +213,8 @@ export type ReactNativeType = {
 };
 
 export opaque type Node = mixed;
+type InternalInstanceHandle = mixed;
+type PublicInstance = mixed;
 
 export type ReactFabricType = {
   findHostInstance_DEPRECATED<TElementType: ElementType>(
@@ -237,7 +239,12 @@ export type ReactFabricType = {
     concurrentRoot: ?boolean,
   ): ?ElementRef<ElementType>,
   unmountComponentAtNode(containerTag: number): void,
-  getNodeFromInternalInstanceHandle(internalInstanceHandle: mixed): ?Node,
+  getNodeFromInternalInstanceHandle(
+    internalInstanceHandle: InternalInstanceHandle,
+  ): ?Node,
+  getPublicInstanceFromInternalInstanceHandle(
+    internalInstanceHandle: InternalInstanceHandle,
+  ): PublicInstance,
   ...
 };