feat: js runtime switching C API for Swift (#49489)

Summary:
This PR implements a C API to switch JS Engines that can be used from Swift.

Here is an example:

```swift
import React
import React_RCTAppDelegate
import ReactAppDependencyProvider
import UIKit
import RCTRuntime

class ReactNativeDelegate: RCTDefaultReactNativeFactoryDelegate {
  override func sourceURL(for bridge: RCTBridge) -> URL? {
    self.bundleURL()
  }

  override func bundleURL() -> URL? {
    #if DEBUG
    RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: "index")
    #else
    Bundle.main.url(forResource: "main", withExtension: "jsbundle")
    #endif
  }

  override func createJSRuntimeFactory() -> JSRuntimeFactory {
    jsrt_create_jsc_factory() // Easily switch engines here
  }
}
```

## Changelog:

[IOS] [ADDED] -  js runtime C API for Swift

Pull Request resolved: #49489

Test Plan: CI Green

Reviewed By: huntie

Differential Revision: D69976988

Pulled By: cipolleschi

fbshipit-source-id: 9333ec62ca99a28c3121f558bbff1ce0457779e3

Author: okwasniewski

packages/react-native/Libraries/AppDelegate/RCTAppDelegate.mm

@@ -23,11 +23,6 @@
 #endif
 #import <React/RCTComponentViewFactory.h>
 #import <React/RCTComponentViewProtocol.h>
-#if USE_HERMES
-#import <ReactCommon/RCTHermesInstance.h>
-#elif USE_THIRD_PARTY_JSC != 1
-#import <ReactCommon/RCTJscInstance.h>
-#endif // USE_HERMES
 #import <react/nativemodule/defaults/DefaultTurboModules.h>
 
 using namespace facebook::react;

packages/react-native/Libraries/AppDelegate/RCTDefaultReactNativeFactoryDelegate.mm

@@ -9,6 +9,11 @@
 #import <ReactCommon/RCTHost.h>
 #import "RCTAppSetupUtils.h"
 #import "RCTDependencyProvider.h"
+#if USE_HERMES
+#import <React/RCTHermesInstanceFactory.h>
+#elif USE_THIRD_PARTY_JSC != 1
+#import <React/RCTJscInstanceFactory.h>
+#endif
 
 #import <react/nativemodule/defaults/DefaultTurboModules.h>
 
@@ -38,6 +43,15 @@ - (void)setRootView:(UIView *)rootView toRootViewController:(UIViewController *)
   rootViewController.view = rootView;
 }
 
+- (JSRuntimeFactoryRef)createJSRuntimeFactory
+{
+#if USE_HERMES
+  return jsrt_create_hermes_factory();
+#elif USE_THIRD_PARTY_JSC != 1
+  return jsrt_create_jsc_factory();
+#endif
+}
+
 - (void)customizeRootView:(RCTRootView *)rootView
 {
   // Override point for customization after application launch.

packages/react-native/Libraries/AppDelegate/RCTJSRuntimeConfiguratorProtocol.h

@@ -0,0 +1,21 @@
+/*
+ * 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.
+ */
+
+#import <UIKit/UIKit.h>
+#import <react/runtime/JSRuntimeFactoryCAPI.h>
+
+#pragma once
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol RCTJSRuntimeConfiguratorProtocol
+
+- (JSRuntimeFactoryRef)createJSRuntimeFactory;
+
+@end
+
+NS_ASSUME_NONNULL_END

packages/react-native/Libraries/AppDelegate/RCTReactNativeFactory.h

@@ -10,6 +10,7 @@
 #import <UIKit/UIKit.h>
 #import "RCTArchConfiguratorProtocol.h"
 #import "RCTDependencyProvider.h"
+#import "RCTJSRuntimeConfiguratorProtocol.h"
 #import "RCTRootViewFactory.h"
 #import "RCTUIConfiguratorProtocol.h"
 
@@ -34,6 +35,7 @@ NS_ASSUME_NONNULL_BEGIN
     RCTTurboModuleManagerDelegate,
     RCTComponentViewFactoryComponentProvider,
 #endif
+    RCTJSRuntimeConfiguratorProtocol,
     RCTArchConfiguratorProtocol>
 
 /// Return the bundle URL for the main bundle.

packages/react-native/Libraries/AppDelegate/RCTReactNativeFactory.mm

@@ -25,11 +25,6 @@
 #endif
 #import <React/RCTComponentViewFactory.h>
 #import <React/RCTComponentViewProtocol.h>
-#if USE_HERMES
-#import <ReactCommon/RCTHermesInstance.h>
-#elif USE_THIRD_PARTY_JSC != 1
-#import <ReactCommon/RCTJscInstance.h>
-#endif // USE_HERMES
 #import <react/nativemodule/defaults/DefaultTurboModules.h>
 
 #import "RCTDependencyProvider.h"
@@ -39,6 +34,7 @@
 @interface RCTReactNativeFactory () <
     RCTComponentViewFactoryComponentProvider,
     RCTHostDelegate,
+    RCTJSRuntimeConfiguratorProtocol,
     RCTTurboModuleManagerDelegate>
 @end
 
@@ -114,6 +110,13 @@ - (NSURL *_Nullable)bundleURL
   return _delegate.bundleURL;
 }
 
+#pragma mark - RCTJSRuntimeConfiguratorProtocol
+
+- (JSRuntimeFactoryRef)createJSRuntimeFactory
+{
+  return [_delegate createJSRuntimeFactory];
+}
+
 #pragma mark - RCTArchConfiguratorProtocol
 
 - (BOOL)newArchEnabled
@@ -269,6 +272,8 @@ - (RCTRootViewFactory *)createRCTRootViewFactory
     };
   }
 
+  configuration.jsRuntimeConfiguratorDelegate = self;
+
   return [[RCTRootViewFactory alloc] initWithTurboModuleDelegate:self hostDelegate:self configuration:configuration];
 }
 

packages/react-native/Libraries/AppDelegate/RCTRootViewFactory.h

@@ -8,6 +8,7 @@
 #import <React/RCTBridge.h>
 #import <React/RCTRootView.h>
 #import <React/RCTUtils.h>
+#import "RCTJSRuntimeConfiguratorProtocol.h"
 
 @protocol RCTCxxBridgeDelegate;
 @protocol RCTComponentViewFactoryComponentProvider;
@@ -110,6 +111,8 @@ typedef void (^RCTLoadSourceForBridgeBlock)(RCTBridge *bridge, RCTSourceLoadBloc
  */
 @property (nonatomic, nullable) RCTCustomizeRootViewBlock customizeRootView;
 
+@property (nonatomic, weak, nullable) id<RCTJSRuntimeConfiguratorProtocol> jsRuntimeConfiguratorDelegate;
+
 #pragma mark - RCTBridgeDelegate blocks
 
 /**

packages/react-native/Libraries/AppDelegate/RCTRootViewFactory.mm

@@ -26,12 +26,6 @@
 #import <React/RCTFabricSurface.h>
 #import <React/RCTSurfaceHostingProxyRootView.h>
 #import <React/RCTSurfacePresenter.h>
-#if USE_HERMES
-#import <ReactCommon/RCTHermesInstance.h>
-#elif USE_THIRD_PARTY_JSC != 1
-#import <ReactCommon/RCTJscInstance.h>
-#else
-#endif // USE_HERMES
 #import <ReactCommon/RCTHost+Internal.h>
 #import <ReactCommon/RCTHost.h>
 #import <ReactCommon/RCTTurboModuleManager.h>
@@ -264,13 +258,16 @@ - (RCTHost *)createReactHost:(NSDictionary *)launchOptions
 
 - (std::shared_ptr<facebook::react::JSRuntimeFactory>)createJSRuntimeFactory
 {
-#if USE_HERMES
-  return std::make_shared<facebook::react::RCTHermesInstance>(nullptr, /* allocInOldGenBeforeTTI */ false);
-#elif USE_THIRD_PARTY_JSC != 1
-  return std::make_shared<facebook::react::RCTJscInstance>();
-#else
-  throw std::runtime_error("No JSRuntimeFactory specified.");
-#endif
+  if (_configuration.jsRuntimeConfiguratorDelegate == nil) {
+    [NSException raise:@"RCTReactNativeFactoryDelegate::createJSRuntimeFactory not implemented"
+                format:@"Delegate must implement a valid createJSRuntimeFactory method"];
+    return nullptr;
+  }
+
+  auto jsRuntimeFactory = [_configuration.jsRuntimeConfiguratorDelegate createJSRuntimeFactory];
+
+  return std::shared_ptr<facebook::react::JSRuntimeFactory>(
+      reinterpret_cast<facebook::react::JSRuntimeFactory *>(jsRuntimeFactory), &js_runtime_factory_destroy);
 }
 
 - (NSArray<id<RCTBridgeModule>> *)extraModulesForBridge:(RCTBridge *)bridge

packages/react-native/Libraries/AppDelegate/React-RCTAppDelegate.podspec

@@ -90,6 +90,7 @@ Pod::Spec.new do |s|
   add_dependency(s, "React-rendererdebug")
   add_dependency(s, "React-featureflags")
   add_dependency(s, "React-jsitooling", :framework_name => "JSITooling")
+  add_dependency(s, "React-RCTRuntime", :framework_name => "RCTRuntime")
 
   depend_on_js_engine(s)
 end

packages/react-native/React-Core.podspec

@@ -93,12 +93,16 @@ Pod::Spec.new do |s|
       "React/FBReactNativeSpec/**/*",
       "React/Tests/**/*",
       "React/Inspector/**/*",
+      "React/Runtime/**/*",
     ]
     # If we are using Hermes (the default is use hermes, so USE_HERMES can be nil), we don't have jsc installed
     # So we have to exclude the JSCExecutorFactory
-    if use_hermes || ENV['USE_THIRD_PARTY_JSC'] == '1'
+    if use_hermes 
+      exclude_files = exclude_files.append("React/CxxBridge/JSCExecutorFactory.{h,mm}")
+    elsif ENV['USE_THIRD_PARTY_JSC'] == '1'
       exclude_files = exclude_files.append("React/CxxBridge/JSCExecutorFactory.{h,mm}")
     end
+
     ss.exclude_files = exclude_files
     ss.private_header_files   = "React/Cxx*/*.h"
   end
@@ -141,6 +145,7 @@ Pod::Spec.new do |s|
   s.resource_bundles = {'React-Core_privacy' => 'React/Resources/PrivacyInfo.xcprivacy'}
 
   add_dependency(s, "React-jsinspector", :framework_name => 'jsinspector_modern')
+  add_dependency(s, "React-jsitooling", :framework_name => "JSITooling")
   add_dependency(s, "RCTDeprecation")
 
   depend_on_js_engine(s)

packages/react-native/React/Runtime/RCTHermesInstanceFactory.h

@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+#import <react/runtime/JSRuntimeFactoryCAPI.h>
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+JSRuntimeFactoryRef jsrt_create_hermes_factory(void);
+
+#ifdef __cplusplus
+}
+#endif

packages/react-native/React/Runtime/RCTHermesInstanceFactory.mm

@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+#import "RCTHermesInstanceFactory.h"
+#import <ReactCommon/RCTHermesInstance.h>
+
+using namespace facebook::react;
+
+extern "C" {
+
+JSRuntimeFactoryRef jsrt_create_hermes_factory(void)
+{
+  return reinterpret_cast<JSRuntimeFactoryRef>(new RCTHermesInstance(nullptr, /* allocInOldGenBeforeTTI */ false));
+}
+
+} // extern "C"

packages/react-native/React/Runtime/RCTJscInstanceFactory.h

@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+#import <react/runtime/JSRuntimeFactoryCAPI.h>
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+JSRuntimeFactoryRef jsrt_create_jsc_factory(void);
+
+#ifdef __cplusplus
+}
+#endif

packages/react-native/React/Runtime/RCTJscInstanceFactory.mm

@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+#import "RCTJscInstanceFactory.h"
+#import <ReactCommon/RCTJscInstance.h>
+
+using namespace facebook::react;
+
+extern "C" {
+
+JSRuntimeFactoryRef jsrt_create_jsc_factory(void)
+{
+  return reinterpret_cast<JSRuntimeFactoryRef>(new RCTJscInstance());
+}
+
+} // extern "C"

packages/react-native/React/Runtime/React-RCTRuntime.podspec

@@ -0,0 +1,84 @@
+# 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.
+
+require "json"
+
+package = JSON.parse(File.read(File.join(__dir__, "..", "..", "package.json")))
+version = package['version']
+
+source = { :git => 'https://github.com/facebook/react-native.git' }
+if version == '1000.0.0'
+  # This is an unpublished version, use the latest commit hash of the react-native repo, which we’re presumably in.
+  source[:commit] = `git rev-parse HEAD`.strip if system("git rev-parse --git-dir > /dev/null 2>&1")
+else
+  source[:tag] = "v#{version}"
+end
+
+folly_config = get_folly_config()
+folly_compiler_flags = folly_config[:compiler_flags]
+folly_version = folly_config[:version]
+boost_config = get_boost_config()
+boost_compiler_flags = boost_config[:compiler_flags]
+new_arch_flags = ENV['RCT_NEW_ARCH_ENABLED'] == '1' ? ' -DRCT_NEW_ARCH_ENABLED=1' : ''
+
+header_search_paths = [
+  "\"$(PODS_ROOT)/boost\"",
+  "\"$(PODS_ROOT)/RCT-Folly\"",
+  "\"$(PODS_ROOT)/DoubleConversion\"",
+  "\"$(PODS_ROOT)/fast_float/include\"",
+  "\"$(PODS_ROOT)/fmt/include\""
+]
+
+module_name = "RCTRuntime"
+header_dir = "React"
+
+Pod::Spec.new do |s|
+  s.name                   = "React-RCTRuntime"
+  s.version                = version
+  s.summary                = "RCTRuntime for React Native."
+  s.homepage               = "https://reactnative.dev/"
+  s.license                = package["license"]
+  s.author                 = "Meta Platforms, Inc. and its affiliates"
+  s.platforms              = min_supported_versions
+  s.source                 = source
+  s.source_files           = "*.{h,mm}"
+  s.compiler_flags         = folly_compiler_flags + ' ' + boost_compiler_flags + new_arch_flags
+  s.header_dir             = header_dir
+  s.module_name          = module_name
+
+  if ENV['USE_FRAMEWORKS']
+    s.header_mappings_dir = "./"
+  end
+
+  s.pod_target_xcconfig    = {
+    "HEADER_SEARCH_PATHS" => header_search_paths,
+    "OTHER_CFLAGS" => "$(inherited) " + folly_compiler_flags + new_arch_flags,
+    "DEFINES_MODULE" => "YES",
+    "CLANG_CXX_LANGUAGE_STANDARD" => rct_cxx_language_standard()
+  }.merge!(ENV['USE_FRAMEWORKS'] != nil ? {
+    "PUBLIC_HEADERS_FOLDER_PATH" => "#{module_name}.framework/Headers/#{header_dir}"
+  }: {})
+
+  s.dependency "React-Core"
+  s.dependency "RCT-Folly/Fabric", folly_version
+  s.dependency "glog"
+  s.dependency "React-jsi"
+  add_dependency(s, "React-jsitooling", :framework_name => "JSITooling")
+  add_dependency(s, "React-jsinspector", :framework_name => 'jsinspector_modern')
+
+  add_dependency(s, "React-RuntimeCore")
+  add_dependency(s, "React-RuntimeApple")
+
+  if ENV["USE_HERMES"] == nil || ENV["USE_HERMES"] == "1"
+    s.dependency "hermes-engine"
+    add_dependency(s, "React-RuntimeHermes")
+    s.exclude_files = "RCTJscInstanceFactory.{h,mm}"
+  elsif ENV['USE_THIRD_PARTY_JSC'] == '1'
+    s.exclude_files = ["RCTHermesInstanceFactory.{mm,h}", "RCTJscInstanceFactory.{mm,h}"]
+  else 
+    s.exclude_files = ["RCTHermesInstanceFactory.{mm,h}"]
+  end
+  depend_on_js_engine(s)
+end

packages/react-native/ReactCommon/jsitooling/react/runtime/JSRuntimeFactoryCAPI.cpp

@@ -0,0 +1,15 @@
+/*
+ * 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.
+ */
+
+#include "JSRuntimeFactoryCAPI.h"
+#include "JSRuntimeFactory.h"
+
+void js_runtime_factory_destroy(JSRuntimeFactoryRef factory) {
+  if (factory) {
+    delete static_cast<facebook::react::JSRuntimeFactory*>(factory);
+  }
+}