From 55e4543eea1a2f7a42ed6997c9a692b4fc61550a Mon Sep 17 00:00:00 2001
From: Ramanpreet Nara <ramanpreet@meta.com>
Date: Mon, 25 Dec 2023 19:23:14 -0800
Subject: [PATCH] BridgelessUIManager: Refactor how constants are retrieved and
 cached (#42000)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/42000

I think this makes BridgelessUIManager easier to read: if the getUIManagerConstants method exists, get the cached constants.

Also, this unifies the nomenclature between PaperUIManager and BridgleessUIManager. That way, it's easy to compare/constrast the two files.

Changelog: [Internal]

Reviewed By: dmytrorykun, luluwu2032

Differential Revision: D52002910

fbshipit-source-id: 01bfbd5fedbe3f995b4a1f68309714d84027133b
---
 .../ReactNative/BridgelessUIManager.js        | 39 ++++++++++---------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/packages/react-native/Libraries/ReactNative/BridgelessUIManager.js b/packages/react-native/Libraries/ReactNative/BridgelessUIManager.js
index b7351924327..f001f31c15d 100644
--- a/packages/react-native/Libraries/ReactNative/BridgelessUIManager.js
+++ b/packages/react-native/Libraries/ReactNative/BridgelessUIManager.js
@@ -14,8 +14,7 @@ import type {RootTag} from '../Types/RootTagTypes';
 import type {UIManagerJSInterface} from '../Types/UIManagerJSInterface';
 
 import {unstable_hasComponent} from '../NativeComponent/NativeComponentRegistryUnstable';
-
-let cachedConstants = null;
+import nullthrows from 'nullthrows';
 
 function raiseSoftError(methodName: string, details?: string): void {
   console.error(
@@ -24,21 +23,25 @@ function raiseSoftError(methodName: string, details?: string): void {
   );
 }
 
-function nativeViewConfigsInBridgelessModeEnabled(): boolean {
-  return global.RN$LegacyInterop_UIManager_getConstants !== undefined;
-}
+const getUIManagerConstants: ?() => {[viewManagerName: string]: Object} =
+  global.RN$LegacyInterop_UIManager_getConstants;
 
-function getCachedConstants(): Object {
-  if (!cachedConstants) {
-    cachedConstants = global.RN$LegacyInterop_UIManager_getConstants();
-  }
-  return cachedConstants;
-}
+const getUIManagerConstantsCache = (function () {
+  let wasCalledOnce = false;
+  let result = {};
+  return () => {
+    if (!wasCalledOnce) {
+      result = nullthrows(getUIManagerConstants)();
+      wasCalledOnce = true;
+    }
+    return result;
+  };
+})();
 
 const UIManagerJS: UIManagerJSInterface & {[string]: any} = {
   getViewManagerConfig: (viewManagerName: string): mixed => {
-    if (nativeViewConfigsInBridgelessModeEnabled()) {
-      return getCachedConstants()[viewManagerName];
+    if (getUIManagerConstants) {
+      return getUIManagerConstantsCache()[viewManagerName];
     } else {
       raiseSoftError(
         'getViewManagerConfig',
@@ -51,8 +54,8 @@ const UIManagerJS: UIManagerJSInterface & {[string]: any} = {
     return unstable_hasComponent(viewManagerName);
   },
   getConstants: (): Object => {
-    if (nativeViewConfigsInBridgelessModeEnabled()) {
-      return getCachedConstants();
+    if (getUIManagerConstants) {
+      return getUIManagerConstantsCache();
     } else {
       raiseSoftError('getConstants');
       return null;
@@ -177,9 +180,9 @@ const UIManagerJS: UIManagerJSInterface & {[string]: any} = {
   dismissPopupMenu: (): void => raiseSoftError('dismissPopupMenu'),
 };
 
-if (nativeViewConfigsInBridgelessModeEnabled()) {
-  Object.keys(getCachedConstants()).forEach(viewConfigName => {
-    UIManagerJS[viewConfigName] = getCachedConstants()[viewConfigName];
+if (getUIManagerConstants) {
+  Object.keys(getUIManagerConstantsCache()).forEach(viewConfigName => {
+    UIManagerJS[viewConfigName] = getUIManagerConstantsCache()[viewConfigName];
   });
 }