[Fabric] Track child set as array instead of native datastructure

Author: javache

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

@@ -47,7 +47,10 @@ const {
   unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
 } = nativeFabricUIManager;
 
-import {useMicrotasksForSchedulingInFabric} from 'shared/ReactFeatureFlags';
+import {
+  useMicrotasksForSchedulingInFabric,
+  passChildrenWhenCloningPersistedNodes,
+} from 'shared/ReactFeatureFlags';
 
 const {get: getViewConfigForType} = ReactNativeViewConfigRegistry;
 
@@ -87,7 +90,7 @@ export type TextInstance = {
 export type HydratableInstance = Instance | TextInstance;
 export type PublicInstance = ReactNativePublicInstance;
 export type Container = number;
-export type ChildSet = Object;
+export type ChildSet = Object | Array<Node>;
 export type HostContext = $ReadOnly<{
   isInAParentText: boolean,
 }>;
@@ -405,15 +408,23 @@ export function cloneHiddenTextInstance(
   throw new Error('Not yet implemented.');
 }
 
-export function createContainerChildSet(container: Container): ChildSet {
-  return createChildNodeSet(container);
+export function createContainerChildSet(): ChildSet {
+  if (passChildrenWhenCloningPersistedNodes) {
+    return [];
+  } else {
+    return createChildNodeSet();
+  }
 }
 
 export function appendChildToContainerChildSet(
   childSet: ChildSet,
   child: Instance | TextInstance,
 ): void {
-  appendChildNodeToSet(childSet, child.node);
+  if (passChildrenWhenCloningPersistedNodes) {
+    childSet.push(child.node);
+  } else {
+    appendChildNodeToSet(childSet, child.node);
+  }
 }
 
 export function finalizeContainerChildren(
@@ -426,7 +437,9 @@ export function finalizeContainerChildren(
 export function replaceContainerChildren(
   container: Container,
   newChildren: ChildSet,
-): void {}
+): void {
+  // Noop - children will be replaced in finalizeContainerChildren
+}
 
 export function getInstanceFromNode(node: any): empty {
   throw new Error('Not yet implemented.');

packages/react-noop-renderer/src/createReactNoop.js

@@ -704,9 +704,7 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
         cloneInstance,
         clearContainer,
 
-        createContainerChildSet(
-          container: Container,
-        ): Array<Instance | TextInstance> {
+        createContainerChildSet(): Array<Instance | TextInstance> {
           return [];
         },
 

packages/react-reconciler/src/ReactFiberCommitWork.js

@@ -1724,7 +1724,7 @@ function emptyPortalContainer(current: Fiber) {
     ...
   } = current.stateNode;
   const {containerInfo} = portal;
-  const emptyChildSet = createContainerChildSet(containerInfo);
+  const emptyChildSet = createContainerChildSet();
   replaceContainerChildren(containerInfo, emptyChildSet);
 }
 

packages/react-reconciler/src/ReactFiberCompleteWork.js

@@ -390,6 +390,7 @@ function appendAllChildrenToContainer(
     }
   }
 }
+
 function updateHostContainer(current: null | Fiber, workInProgress: Fiber) {
   if (supportsPersistence) {
     const portalOrRoot: {
@@ -402,16 +403,22 @@ function updateHostContainer(current: null | Fiber, workInProgress: Fiber) {
       // No changes, just reuse the existing instance.
     } else {
       const container = portalOrRoot.containerInfo;
-      const newChildSet = createContainerChildSet(container);
+      const newChildSet = createContainerChildSet();
       // If children might have changed, we have to add them all to the set.
-      appendAllChildrenToContainer(newChildSet, workInProgress, false, false);
+      appendAllChildrenToContainer(
+        newChildSet,
+        workInProgress,
+        /* needsVisibilityToggle */ false,
+        /* isHidden */ false,
+      );
       portalOrRoot.pendingChildren = newChildSet;
       // Schedule an update on the container to swap out the container.
       markUpdate(workInProgress);
       finalizeContainerChildren(container, newChildSet);
     }
   }
 }
+
 function updateHostComponent(
   current: Fiber,
   workInProgress: Fiber,
@@ -460,6 +467,9 @@ function updateHostComponent(
       return;
     }
 
+    // Certain renderers require commit-time effects for initial mount.
+    // (eg DOM renderer supports auto-focus for certain elements).
+    // Make sure such renderers get scheduled for later work.
     if (
       finalizeInitialChildren(newInstance, type, newProps, currentHostContext)
     ) {
@@ -473,7 +483,12 @@ function updateHostComponent(
       markUpdate(workInProgress);
     } else {
       // If children might have changed, we have to add them all to the set.
-      appendAllChildren(newInstance, workInProgress, false, false);
+      appendAllChildren(
+        newInstance,
+        workInProgress,
+        /* needsVisibilityToggle */ false,
+        /* isHidden */ false,
+      );
     }
   }
 }

scripts/flow/react-native-host-hooks.js

@@ -181,7 +181,7 @@ declare var nativeFabricUIManager: {
   cloneNodeWithNewChildrenAndProps: (node: Object, newProps: ?Object) => Object,
   appendChild: (node: Object, childNode: Object) => void,
 
-  createChildSet: (rootTag: number) => Object,
+  createChildSet: () => Object,
   appendChildToSet: (childSet: Object, childNode: Object) => void,
   completeRoot: (rootTag: number, childSet: Object) => void,
   registerEventHandler: (