Combine commitWork into single switch statement

commitWork is forked into a separate implementation for mutation mode
(DOM) and persistent mode (React Native). But unlike when it was first
introduced, there's more overlap than differences between the forks,
mainly because we've added new types of fibers. So this joins the two
forks and adds more local branches where the behavior actually
diverges: host nodes, host containers, and portals.

Author: acdlite

packages/react-reconciler/src/ReactFiberCommitWork.new.js

@@ -1481,36 +1481,6 @@ function emptyPortalContainer(current: Fiber) {
   replaceContainerChildren(containerInfo, emptyChildSet);
 }
 
-function commitContainer(finishedWork: Fiber) {
-  if (!supportsPersistence) {
-    return;
-  }
-
-  switch (finishedWork.tag) {
-    case ClassComponent:
-    case HostComponent:
-    case HostText: {
-      return;
-    }
-    case HostRoot:
-    case HostPortal: {
-      const portalOrRoot: {
-        containerInfo: Container,
-        pendingChildren: ChildSet,
-        ...
-      } = finishedWork.stateNode;
-      const {containerInfo, pendingChildren} = portalOrRoot;
-      replaceContainerChildren(containerInfo, pendingChildren);
-      return;
-    }
-  }
-
-  throw new Error(
-    'This unit of work tag should not have side-effects. This error is ' +
-      'likely caused by a bug in React. Please file an issue.',
-  );
-}
-
 function getHostParentFiber(fiber: Fiber): Fiber {
   let parent = fiber.return;
   while (parent !== null) {
@@ -1830,87 +1800,6 @@ function commitDeletion(
 }
 
 function commitWork(current: Fiber | null, finishedWork: Fiber): void {
-  if (!supportsMutation) {
-    switch (finishedWork.tag) {
-      case FunctionComponent:
-      case ForwardRef:
-      case MemoComponent:
-      case SimpleMemoComponent: {
-        commitHookEffectListUnmount(
-          HookInsertion | HookHasEffect,
-          finishedWork,
-          finishedWork.return,
-        );
-        commitHookEffectListMount(HookInsertion | HookHasEffect, finishedWork);
-
-        // Layout effects are destroyed during the mutation phase so that all
-        // destroy functions for all fibers are called before any create functions.
-        // This prevents sibling component effects from interfering with each other,
-        // e.g. a destroy function in one component should never override a ref set
-        // by a create function in another component during the same commit.
-        // TODO: Check if we're inside an Offscreen subtree that disappeared
-        // during this commit. If so, we would have already unmounted its
-        // layout hooks. (However, since we null out the `destroy` function
-        // right before calling it, the behavior is already correct, so this
-        // would mostly be for modeling purposes.)
-        if (
-          enableProfilerTimer &&
-          enableProfilerCommitHooks &&
-          finishedWork.mode & ProfileMode
-        ) {
-          try {
-            startLayoutEffectTimer();
-            commitHookEffectListUnmount(
-              HookLayout | HookHasEffect,
-              finishedWork,
-              finishedWork.return,
-            );
-          } finally {
-            recordLayoutEffectDuration(finishedWork);
-          }
-        } else {
-          commitHookEffectListUnmount(
-            HookLayout | HookHasEffect,
-            finishedWork,
-            finishedWork.return,
-          );
-        }
-        return;
-      }
-      case Profiler: {
-        return;
-      }
-      case SuspenseComponent: {
-        commitSuspenseCallback(finishedWork);
-        attachSuspenseRetryListeners(finishedWork);
-        return;
-      }
-      case SuspenseListComponent: {
-        attachSuspenseRetryListeners(finishedWork);
-        return;
-      }
-      case HostRoot: {
-        if (supportsHydration) {
-          if (current !== null) {
-            const prevRootState: RootState = current.memoizedState;
-            if (prevRootState.isDehydrated) {
-              const root: FiberRoot = finishedWork.stateNode;
-              commitHydratedContainer(root.containerInfo);
-            }
-          }
-        }
-        break;
-      }
-      case OffscreenComponent:
-      case LegacyHiddenComponent: {
-        return;
-      }
-    }
-
-    commitContainer(finishedWork);
-    return;
-  }
-
   switch (finishedWork.tag) {
     case FunctionComponent:
     case ForwardRef:
@@ -1955,51 +1844,55 @@ function commitWork(current: Fiber | null, finishedWork: Fiber): void {
       return;
     }
     case HostComponent: {
-      const instance: Instance = finishedWork.stateNode;
-      if (instance != null) {
-        // Commit the work prepared earlier.
-        const newProps = finishedWork.memoizedProps;
-        // For hydration we reuse the update path but we treat the oldProps
-        // as the newProps. The updatePayload will contain the real change in
-        // this case.
-        const oldProps = current !== null ? current.memoizedProps : newProps;
-        const type = finishedWork.type;
-        // TODO: Type the updateQueue to be specific to host components.
-        const updatePayload: null | UpdatePayload = (finishedWork.updateQueue: any);
-        finishedWork.updateQueue = null;
-        if (updatePayload !== null) {
-          commitUpdate(
-            instance,
-            updatePayload,
-            type,
-            oldProps,
-            newProps,
-            finishedWork,
-          );
+      if (supportsMutation) {
+        const instance: Instance = finishedWork.stateNode;
+        if (instance != null) {
+          // Commit the work prepared earlier.
+          const newProps = finishedWork.memoizedProps;
+          // For hydration we reuse the update path but we treat the oldProps
+          // as the newProps. The updatePayload will contain the real change in
+          // this case.
+          const oldProps = current !== null ? current.memoizedProps : newProps;
+          const type = finishedWork.type;
+          // TODO: Type the updateQueue to be specific to host components.
+          const updatePayload: null | UpdatePayload = (finishedWork.updateQueue: any);
+          finishedWork.updateQueue = null;
+          if (updatePayload !== null) {
+            commitUpdate(
+              instance,
+              updatePayload,
+              type,
+              oldProps,
+              newProps,
+              finishedWork,
+            );
+          }
         }
       }
       return;
     }
     case HostText: {
-      if (finishedWork.stateNode === null) {
-        throw new Error(
-          'This should have a text node initialized. This error is likely ' +
-            'caused by a bug in React. Please file an issue.',
-        );
-      }
+      if (supportsMutation) {
+        if (finishedWork.stateNode === null) {
+          throw new Error(
+            'This should have a text node initialized. This error is likely ' +
+              'caused by a bug in React. Please file an issue.',
+          );
+        }
 
-      const textInstance: TextInstance = finishedWork.stateNode;
-      const newText: string = finishedWork.memoizedProps;
-      // For hydration we reuse the update path but we treat the oldProps
-      // as the newProps. The updatePayload will contain the real change in
-      // this case.
-      const oldText: string =
-        current !== null ? current.memoizedProps : newText;
-      commitTextUpdate(textInstance, oldText, newText);
+        const textInstance: TextInstance = finishedWork.stateNode;
+        const newText: string = finishedWork.memoizedProps;
+        // For hydration we reuse the update path but we treat the oldProps
+        // as the newProps. The updatePayload will contain the real change in
+        // this case.
+        const oldText: string =
+          current !== null ? current.memoizedProps : newText;
+        commitTextUpdate(textInstance, oldText, newText);
+      }
       return;
     }
     case HostRoot: {
-      if (supportsHydration) {
+      if (supportsMutation && supportsHydration) {
         if (current !== null) {
           const prevRootState: RootState = current.memoizedState;
           if (prevRootState.isDehydrated) {
@@ -2008,6 +1901,21 @@ function commitWork(current: Fiber | null, finishedWork: Fiber): void {
           }
         }
       }
+      if (supportsPersistence) {
+        const fiberRoot: FiberRoot = finishedWork.stateNode;
+        const containerInfo = fiberRoot.containerInfo;
+        const pendingChildren = fiberRoot.pendingChildren;
+        replaceContainerChildren(containerInfo, pendingChildren);
+      }
+      return;
+    }
+    case HostPortal: {
+      if (supportsPersistence) {
+        const portal = finishedWork.stateNode;
+        const containerInfo = portal.containerInfo;
+        const pendingChildren = portal.pendingChildren;
+        replaceContainerChildren(containerInfo, pendingChildren);
+      }
       return;
     }
     case Profiler: {