Make RCTEventDispatcher TurboModule-compatible

Summary:
This diff ended up being a bit more complicated than I anticipated, since the source files in `ReactInternal` were depending on `RCTEventDispatcher`. I made the following changes:
1. Make `RCTEventDispatcher` a `protocol`, keep it in `ReactInternal`.
2. Rename the `RCTEventDispatcher` NativeModule to `RCTEventDispatcherModule`, make it conform to the `RCTEventEmitter` `protocol`, and move it to `CoreModules`.
3. Where necessary, replace categories of `RCTEventDispatcher` with functions.

Changelog:
[iOS][Added] - Make RCTEventDispatcher TurboModule-comaptible

Reviewed By: fkgozali

Differential Revision: D18439488

fbshipit-source-id: b3da15c29459fddf884519f33b0c3b8c036b5539

Libraries/Image/RCTImageView.mm

@@ -9,7 +9,6 @@
 
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
 #import <React/RCTImageBlurUtils.h>
 #import <React/RCTImageSource.h>
 #import <React/RCTImageUtils.h>

Libraries/LinkingIOS/RCTLinkingManager.mm

@@ -9,7 +9,6 @@
 
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTBridge.h>
-#import <React/RCTEventDispatcher.h>
 #import <React/RCTUtils.h>
 #import <React/RCTLog.h>
 

Libraries/NativeAnimation/Drivers/RCTEventAnimation.h

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 #import "RCTValueAnimatedNode.h"
 

Libraries/NativeAnimation/RCTNativeAnimatedModule.h

@@ -6,7 +6,7 @@
  */
 
 #import <React/RCTBridgeModule.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTEventEmitter.h>
 #import <React/RCTSurfacePresenterStub.h>
 #import <React/RCTUIManager.h>

Libraries/NativeAnimation/RCTNativeAnimatedNodesManager.h

@@ -9,6 +9,7 @@
 #import <React/RCTBridgeModule.h>
 #import <React/RCTUIManager.h>
 #import <React/RCTSurfacePresenterStub.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 @protocol RCTValueAnimatedNodeObserver;
 

Libraries/NativeAnimation/RCTNativeAnimatedTurboModule.h

@@ -6,7 +6,7 @@
  */
 
 #import <React/RCTBridgeModule.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTEventEmitter.h>
 #import <React/RCTSurfacePresenterStub.h>
 #import <React/RCTUIManager.h>

Libraries/Network/RCTNetworking.mm

@@ -11,7 +11,6 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTAssert.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
 #import <React/RCTLog.h>
 #import <React/RCTNetworkTask.h>
 #import <React/RCTNetworking.h>

Libraries/PushNotificationIOS/RCTPushNotificationManager.mm

@@ -12,7 +12,6 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
 #import <React/RCTUtils.h>
 
 #import "RCTPushNotificationPlugins.h"

Libraries/Settings/RCTSettingsManager.mm

@@ -10,7 +10,7 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTUtils.h>
 
 #import "RCTSettingsPlugins.h"

Libraries/Text/TextInput/RCTBaseTextInputView.h

@@ -13,7 +13,6 @@
 #import "RCTBackedTextInputViewProtocol.h"
 
 @class RCTBridge;
-@class RCTEventDispatcher;
 @class RCTTextAttributes;
 @class RCTTextSelection;
 

Libraries/Text/TextInput/RCTBaseTextInputView.m

@@ -9,7 +9,7 @@
 
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTUIManager.h>
 #import <React/RCTUtils.h>
 #import <React/UIView+React.h>
@@ -21,7 +21,7 @@
 
 @implementation RCTBaseTextInputView {
   __weak RCTBridge *_bridge;
-  __weak RCTEventDispatcher *_eventDispatcher;
+  __weak id<RCTEventDispatcherProtocol> _eventDispatcher;
   BOOL _hasInputAccesoryView;
   NSString *_Nullable _predictedText;
   BOOL _didMoveToWindow;

React/Base/RCTBridge.h

@@ -15,7 +15,6 @@
 
 @class JSValue;
 @class RCTBridge;
-@class RCTEventDispatcher;
 @class RCTPerformanceLogger;
 
 /**

React/Base/RCTBridge.m

@@ -11,7 +11,6 @@
 #import <objc/runtime.h>
 
 #import "RCTConvert.h"
-#import "RCTEventDispatcher.h"
 #if RCT_ENABLE_INSPECTOR
 #import "RCTInspectorDevServerHelper.h"
 #endif

React/Base/RCTComponentEvent.h

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 NS_ASSUME_NONNULL_BEGIN
 

React/Base/RCTEventDispatcher.m

@@ -5,14 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#import "RCTEventDispatcher.h"
-
-#import "RCTAssert.h"
-#import "RCTBridge+Private.h"
-#import "RCTBridge.h"
-#import "RCTComponentEvent.h"
-#import "RCTProfile.h"
-#import "RCTUtils.h"
+#import "RCTEventDispatcherProtocol.h"
 
 const NSInteger RCTTextUpdateLagWarningThreshold = 3;
 
@@ -27,217 +20,11 @@ NSString *RCTNormalizeInputEventName(NSString *eventName)
   return eventName;
 }
 
-static NSNumber *RCTGetEventID(NSNumber *viewTag, NSString *eventName, uint16_t coalescingKey)
-{
-  return @(viewTag.intValue | (((uint64_t)eventName.hash & 0xFFFF) << 32) | (((uint64_t)coalescingKey) << 48));
-}
-
-static uint16_t RCTUniqueCoalescingKeyGenerator = 0;
-
-@implementation RCTEventDispatcher {
-  // We need this lock to protect access to _events, _eventQueue and _eventsDispatchScheduled. It's filled in on main
-  // thread and consumed on js thread.
-  NSLock *_eventQueueLock;
-  // We have this id -> event mapping so we coalesce effectively.
-  NSMutableDictionary<NSNumber *, id<RCTEvent>> *_events;
-  // This array contains ids of events in order they come in, so we can emit them to JS in the exact same order.
-  NSMutableArray<NSNumber *> *_eventQueue;
-  BOOL _eventsDispatchScheduled;
-  NSHashTable<id<RCTEventDispatcherObserver>> *_observers;
-  NSLock *_observersLock;
-}
-
-@synthesize bridge = _bridge;
-@synthesize dispatchToJSThread = _dispatchToJSThread;
-@synthesize invokeJS = _invokeJS;
-@synthesize invokeJSWithModuleDotMethod = _invokeJSWithModuleDotMethod;
-
-RCT_EXPORT_MODULE()
-
-- (void)setBridge:(RCTBridge *)bridge
-{
-  _bridge = bridge;
-  _events = [NSMutableDictionary new];
-  _eventQueue = [NSMutableArray new];
-  _eventQueueLock = [NSLock new];
-  _eventsDispatchScheduled = NO;
-  _observers = [NSHashTable weakObjectsHashTable];
-  _observersLock = [NSLock new];
-}
-
-- (void)sendAppEventWithName:(NSString *)name body:(id)body
-{
-  if (_bridge) {
-    [_bridge enqueueJSCall:@"RCTNativeAppEventEmitter"
-                    method:@"emit"
-                      args:body ? @[ name, body ] : @[ name ]
-                completion:NULL];
-  } else {
-    _invokeJS(@"RCTNativeAppEventEmitter", @"emit", body ? @[ name, body ] : @[ name ]);
-  }
-}
-
-- (void)sendDeviceEventWithName:(NSString *)name body:(id)body
-{
-  if (_bridge) {
-    [_bridge enqueueJSCall:@"RCTDeviceEventEmitter"
-                    method:@"emit"
-                      args:body ? @[ name, body ] : @[ name ]
-                completion:NULL];
-  } else {
-    _invokeJS(@"RCTDeviceEventEmitter", @"emit", body ? @[ name, body ] : @[ name ]);
-  }
-}
-
-- (void)sendTextEventWithType:(RCTTextEventType)type
-                     reactTag:(NSNumber *)reactTag
-                         text:(NSString *)text
-                          key:(NSString *)key
-                   eventCount:(NSInteger)eventCount
-{
-  static NSString *events[] = {@"focus", @"blur", @"change", @"submitEditing", @"endEditing", @"keyPress"};
-
-  NSMutableDictionary *body = [[NSMutableDictionary alloc] initWithDictionary:@{
-    @"eventCount" : @(eventCount),
-  }];
-
-  if (text) {
-    body[@"text"] = text;
-  }
-
-  if (key) {
-    if (key.length == 0) {
-      key = @"Backspace"; // backspace
-    } else {
-      switch ([key characterAtIndex:0]) {
-        case '\t':
-          key = @"Tab";
-          break;
-        case '\n':
-          key = @"Enter";
-        default:
-          break;
-      }
-    }
-    body[@"key"] = key;
-  }
-
-  RCTComponentEvent *event = [[RCTComponentEvent alloc] initWithName:events[type] viewTag:reactTag body:body];
-  [self sendEvent:event];
-}
-
-- (void)sendEvent:(id<RCTEvent>)event
-{
-  [_observersLock lock];
-
-  for (id<RCTEventDispatcherObserver> observer in _observers) {
-    [observer eventDispatcherWillDispatchEvent:event];
-  }
-
-  [_observersLock unlock];
-
-  [_eventQueueLock lock];
-
-  NSNumber *eventID;
-  if (event.canCoalesce) {
-    eventID = RCTGetEventID(event.viewTag, event.eventName, event.coalescingKey);
-    id<RCTEvent> previousEvent = _events[eventID];
-    if (previousEvent) {
-      event = [previousEvent coalesceWithEvent:event];
-    } else {
-      [_eventQueue addObject:eventID];
-    }
-  } else {
-    id<RCTEvent> previousEvent = _events[eventID];
-    eventID = RCTGetEventID(event.viewTag, event.eventName, RCTUniqueCoalescingKeyGenerator++);
-    RCTAssert(
-        previousEvent == nil,
-        @"Got event %@ which cannot be coalesced, but has the same eventID %@ as the previous event %@",
-        event,
-        eventID,
-        previousEvent);
-    [_eventQueue addObject:eventID];
-  }
-
-  _events[eventID] = event;
-
-  BOOL scheduleEventsDispatch = NO;
-  if (!_eventsDispatchScheduled) {
-    _eventsDispatchScheduled = YES;
-    scheduleEventsDispatch = YES;
-  }
-
-  // We have to release the lock before dispatching block with events,
-  // since dispatchBlock: can be executed synchronously on the same queue.
-  // (This is happening when chrome debugging is turned on.)
-  [_eventQueueLock unlock];
-
-  if (scheduleEventsDispatch) {
-    if (_bridge) {
-      [_bridge
-          dispatchBlock:^{
-            [self flushEventsQueue];
-          }
-                  queue:RCTJSThread];
-    } else if (_dispatchToJSThread) {
-      _dispatchToJSThread(^{
-        [self flushEventsQueue];
-      });
-    }
-  }
-}
-
-- (void)addDispatchObserver:(id<RCTEventDispatcherObserver>)observer
-{
-  [_observersLock lock];
-  [_observers addObject:observer];
-  [_observersLock unlock];
-}
-
-- (void)removeDispatchObserver:(id<RCTEventDispatcherObserver>)observer
-{
-  [_observersLock lock];
-  [_observers removeObject:observer];
-  [_observersLock unlock];
-}
-
-- (void)dispatchEvent:(id<RCTEvent>)event
-{
-  if (_bridge) {
-    [_bridge enqueueJSCall:[[event class] moduleDotMethod] args:[event arguments]];
-  } else {
-    _invokeJSWithModuleDotMethod([[event class] moduleDotMethod], [event arguments]);
-  }
-}
-
-- (dispatch_queue_t)methodQueue
-{
-  return RCTJSThread;
-}
-
-// js thread only (which surprisingly can be the main thread, depends on used JS executor)
-- (void)flushEventsQueue
-{
-  [_eventQueueLock lock];
-  NSDictionary *events = _events;
-  _events = [NSMutableDictionary new];
-  NSMutableArray *eventQueue = _eventQueue;
-  _eventQueue = [NSMutableArray new];
-  _eventsDispatchScheduled = NO;
-  [_eventQueueLock unlock];
-
-  for (NSNumber *eventId in eventQueue) {
-    [self dispatchEvent:events[eventId]];
-  }
-}
-
-@end
-
 @implementation RCTBridge (RCTEventDispatcher)
 
-- (RCTEventDispatcher *)eventDispatcher
+- (id<RCTEventDispatcherProtocol>)eventDispatcher
 {
-  return [self moduleForClass:[RCTEventDispatcher class]];
+  return [self moduleForName:@"EventDispatcher" lazilyLoadIfNecessary:YES];
 }
 
 @end

React/Base/RCTEventDispatcherProtocol.h

@@ -10,15 +10,6 @@
 #import <React/RCTBridge.h>
 #import <React/RCTJSInvokerModule.h>
 
-typedef NS_ENUM(NSInteger, RCTTextEventType) {
-  RCTTextEventTypeFocus,
-  RCTTextEventTypeBlur,
-  RCTTextEventTypeChange,
-  RCTTextEventTypeSubmit,
-  RCTTextEventTypeEnd,
-  RCTTextEventTypeKeyPress
-};
-
 /**
  * The threshold at which text inputs will start warning that the JS thread
  * has fallen behind (resulting in poor input performance, missed keys, etc.)
@@ -32,6 +23,15 @@ RCT_EXTERN const NSInteger RCTTextUpdateLagWarningThreshold;
  */
 RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
 
+typedef NS_ENUM(NSInteger, RCTTextEventType) {
+  RCTTextEventTypeFocus,
+  RCTTextEventTypeBlur,
+  RCTTextEventTypeChange,
+  RCTTextEventTypeSubmit,
+  RCTTextEventTypeEnd,
+  RCTTextEventTypeKeyPress
+};
+
 @protocol RCTEvent <NSObject>
 @required
 
@@ -80,7 +80,7 @@ RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
  * This class wraps the -[RCTBridge enqueueJSCall:args:] method, and
  * provides some convenience methods for generating event calls.
  */
-@interface RCTEventDispatcher : NSObject <RCTBridgeModule, RCTJSDispatcherModule, RCTJSInvokerModule>
+@protocol RCTEventDispatcherProtocol <RCTBridgeModule, RCTJSDispatcherModule, RCTJSInvokerModule>
 
 /**
  * Deprecated, do not use.
@@ -123,6 +123,6 @@ RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
 
 @interface RCTBridge (RCTEventDispatcher)
 
-- (RCTEventDispatcher *)eventDispatcher;
+- (id<RCTEventDispatcherProtocol>)eventDispatcher;
 
 @end

React/Base/RCTRootView.m

@@ -15,7 +15,6 @@
 #import "RCTBridge+Private.h"
 #import "RCTBridge.h"
 #import "RCTConstants.h"
-#import "RCTEventDispatcher.h"
 #import "RCTKeyCommands.h"
 #import "RCTLog.h"
 #import "RCTPerformanceLogger.h"

React/Base/RCTTouchEvent.h

@@ -7,7 +7,7 @@
 
 #import <Foundation/Foundation.h>
 
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 /**
  * Represents a touch event, which may be composed of several touches (one for every finger).

React/Base/RCTTouchHandler.m

@@ -11,7 +11,7 @@
 
 #import "RCTAssert.h"
 #import "RCTBridge.h"
-#import "RCTEventDispatcher.h"
+#import "RCTEventDispatcherProtocol.h"
 #import "RCTLog.h"
 #import "RCTSurfaceView.h"
 #import "RCTTouchEvent.h"
@@ -25,7 +25,7 @@
 // TODO: this class behaves a lot like a module, and could be implemented as a
 // module if we were to assume that modules and RootViews had a 1:1 relationship
 @implementation RCTTouchHandler {
-  __weak RCTEventDispatcher *_eventDispatcher;
+  __weak id<RCTEventDispatcherProtocol> _eventDispatcher;
 
   /**
    * Arrays managed in parallel tracking native touch object along with the
@@ -47,7 +47,7 @@
   RCTAssertParam(bridge);
 
   if ((self = [super initWithTarget:nil action:NULL])) {
-    _eventDispatcher = [bridge moduleForClass:[RCTEventDispatcher class]];
+    _eventDispatcher = bridge.eventDispatcher;
 
     _nativeTouches = [NSMutableOrderedSet new];
     _reactTouches = [NSMutableArray new];

React/CoreModules/BUCK

@@ -117,6 +117,9 @@ rn_apple_library(
         ) + react_module_plugin_providers(
             name = "DevSplitBundleLoader",
             native_class_func = "RCTDevSplitBundleLoaderCls",
+        ) + react_module_plugin_providers(
+            name = "EventDispatcher",
+            native_class_func = "RCTEventDispatcherCls",
         ),
     plugins_header = "FBCoreModulesPlugins.h",
     preprocessor_flags = OBJC_ARC_PREPROCESSOR_FLAGS + get_preprocessor_flags_for_build_mode() + rn_extra_build_flags() + [

React/CoreModules/CoreModulesPlugins.h

@@ -53,6 +53,7 @@ Class RCTWebSocketExecutorCls(void) __attribute__((used));
 Class RCTWebSocketModuleCls(void) __attribute__((used));
 Class RCTDevLoadingViewCls(void) __attribute__((used));
 Class RCTDevSplitBundleLoaderCls(void) __attribute__((used));
+Class RCTEventDispatcherCls(void) __attribute__((used));
 
 #ifdef __cplusplus
 }

React/CoreModules/CoreModulesPlugins.mm

@@ -42,6 +42,7 @@ Class RCTCoreModulesClassProvider(const char *name) {
     {"WebSocketModule", RCTWebSocketModuleCls},
     {"DevLoadingView", RCTDevLoadingViewCls},
     {"DevSplitBundleLoader", RCTDevSplitBundleLoaderCls},
+    {"EventDispatcher", RCTEventDispatcherCls},
   };
 
   auto p = sCoreModuleClassMap.find(name);

React/CoreModules/RCTAccessibilityManager.mm

@@ -10,7 +10,7 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTBridge.h>
 #import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTLog.h>
 #import <React/RCTUIManager.h>
 

React/CoreModules/RCTAppState.mm

@@ -10,7 +10,7 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTAssert.h>
 #import <React/RCTBridge.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTUtils.h>
 
 #import "CoreModulesPlugins.h"

React/CoreModules/RCTDevSettings.mm

@@ -12,7 +12,7 @@
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
 #import <React/RCTBridge+Private.h>
 #import <React/RCTBridgeModule.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTLog.h>
 #import <React/RCTProfile.h>
 #import <React/RCTReloadCommand.h>

React/CoreModules/RCTDeviceInfo.mm

@@ -11,7 +11,7 @@
 #import <React/RCTAccessibilityManager.h>
 #import <React/RCTAssert.h>
 #import <React/RCTConstants.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTUIUtils.h>
 #import <React/RCTUtils.h>
 

React/CoreModules/RCTEventDispatcher.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) Facebook, Inc. and its 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/RCTBridge.h>
+#import <React/RCTEventDispatcherProtocol.h>
+/**
+ * This class wraps the -[RCTBridge enqueueJSCall:args:] method, and
+ * provides some convenience methods for generating event calls.
+ */
+@interface RCTEventDispatcher : NSObject <RCTEventDispatcherProtocol>
+@end

React/CoreModules/RCTEventDispatcher.mm

@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTEventDispatcher.h"
+
+#import <React/RCTAssert.h>
+#import <React/RCTBridge+Private.h>
+#import <React/RCTBridge.h>
+#import <React/RCTComponentEvent.h>
+#import <React/RCTProfile.h>
+#import <React/RCTUtils.h>
+#import <ReactCommon/RCTTurboModule.h>
+
+#import "CoreModulesPlugins.h"
+
+static NSNumber *RCTGetEventID(NSNumber *viewTag, NSString *eventName, uint16_t coalescingKey)
+{
+  return @(viewTag.intValue | (((uint64_t)eventName.hash & 0xFFFF) << 32) | (((uint64_t)coalescingKey) << 48));
+}
+
+static uint16_t RCTUniqueCoalescingKeyGenerator = 0;
+
+@interface RCTEventDispatcher () <RCTTurboModule>
+@end
+
+@implementation RCTEventDispatcher {
+  // We need this lock to protect access to _events, _eventQueue and _eventsDispatchScheduled. It's filled in on main
+  // thread and consumed on js thread.
+  NSLock *_eventQueueLock;
+  // We have this id -> event mapping so we coalesce effectively.
+  NSMutableDictionary<NSNumber *, id<RCTEvent>> *_events;
+  // This array contains ids of events in order they come in, so we can emit them to JS in the exact same order.
+  NSMutableArray<NSNumber *> *_eventQueue;
+  BOOL _eventsDispatchScheduled;
+  NSHashTable<id<RCTEventDispatcherObserver>> *_observers;
+  NSLock *_observersLock;
+}
+
+@synthesize bridge = _bridge;
+@synthesize dispatchToJSThread = _dispatchToJSThread;
+@synthesize invokeJS = _invokeJS;
+@synthesize invokeJSWithModuleDotMethod = _invokeJSWithModuleDotMethod;
+
+RCT_EXPORT_MODULE()
+
+- (void)setBridge:(RCTBridge *)bridge
+{
+  _bridge = bridge;
+  _events = [NSMutableDictionary new];
+  _eventQueue = [NSMutableArray new];
+  _eventQueueLock = [NSLock new];
+  _eventsDispatchScheduled = NO;
+  _observers = [NSHashTable weakObjectsHashTable];
+  _observersLock = [NSLock new];
+}
+
+- (void)sendAppEventWithName:(NSString *)name body:(id)body
+{
+  if (_bridge) {
+    [_bridge enqueueJSCall:@"RCTNativeAppEventEmitter"
+                    method:@"emit"
+                      args:body ? @[ name, body ] : @[ name ]
+                completion:NULL];
+  } else {
+    _invokeJS(@"RCTNativeAppEventEmitter", @"emit", body ? @[ name, body ] : @[ name ]);
+  }
+}
+
+- (void)sendDeviceEventWithName:(NSString *)name body:(id)body
+{
+  if (_bridge) {
+    [_bridge enqueueJSCall:@"RCTDeviceEventEmitter"
+                    method:@"emit"
+                      args:body ? @[ name, body ] : @[ name ]
+                completion:NULL];
+  } else {
+    _invokeJS(@"RCTDeviceEventEmitter", @"emit", body ? @[ name, body ] : @[ name ]);
+  }
+}
+
+- (void)sendTextEventWithType:(RCTTextEventType)type
+                     reactTag:(NSNumber *)reactTag
+                         text:(NSString *)text
+                          key:(NSString *)key
+                   eventCount:(NSInteger)eventCount
+{
+  static NSString *events[] = {@"focus", @"blur", @"change", @"submitEditing", @"endEditing", @"keyPress"};
+
+  NSMutableDictionary *body = [[NSMutableDictionary alloc] initWithDictionary:@{
+    @"eventCount" : @(eventCount),
+  }];
+
+  if (text) {
+    body[@"text"] = text;
+  }
+
+  if (key) {
+    if (key.length == 0) {
+      key = @"Backspace"; // backspace
+    } else {
+      switch ([key characterAtIndex:0]) {
+        case '\t':
+          key = @"Tab";
+          break;
+        case '\n':
+          key = @"Enter";
+        default:
+          break;
+      }
+    }
+    body[@"key"] = key;
+  }
+
+  RCTComponentEvent *event = [[RCTComponentEvent alloc] initWithName:events[type] viewTag:reactTag body:body];
+  [self sendEvent:event];
+}
+
+- (void)sendEvent:(id<RCTEvent>)event
+{
+  [_observersLock lock];
+
+  for (id<RCTEventDispatcherObserver> observer in _observers) {
+    [observer eventDispatcherWillDispatchEvent:event];
+  }
+
+  [_observersLock unlock];
+
+  [_eventQueueLock lock];
+
+  NSNumber *eventID;
+  if (event.canCoalesce) {
+    eventID = RCTGetEventID(event.viewTag, event.eventName, event.coalescingKey);
+    id<RCTEvent> previousEvent = _events[eventID];
+    if (previousEvent) {
+      event = [previousEvent coalesceWithEvent:event];
+    } else {
+      [_eventQueue addObject:eventID];
+    }
+  } else {
+    id<RCTEvent> previousEvent = _events[eventID];
+    eventID = RCTGetEventID(event.viewTag, event.eventName, RCTUniqueCoalescingKeyGenerator++);
+    RCTAssert(
+        previousEvent == nil,
+        @"Got event %@ which cannot be coalesced, but has the same eventID %@ as the previous event %@",
+        event,
+        eventID,
+        previousEvent);
+    [_eventQueue addObject:eventID];
+  }
+
+  _events[eventID] = event;
+
+  BOOL scheduleEventsDispatch = NO;
+  if (!_eventsDispatchScheduled) {
+    _eventsDispatchScheduled = YES;
+    scheduleEventsDispatch = YES;
+  }
+
+  // We have to release the lock before dispatching block with events,
+  // since dispatchBlock: can be executed synchronously on the same queue.
+  // (This is happening when chrome debugging is turned on.)
+  [_eventQueueLock unlock];
+
+  if (scheduleEventsDispatch) {
+    if (_bridge) {
+      [_bridge
+          dispatchBlock:^{
+            [self flushEventsQueue];
+          }
+                  queue:RCTJSThread];
+    } else if (_dispatchToJSThread) {
+      _dispatchToJSThread(^{
+        [self flushEventsQueue];
+      });
+    }
+  }
+}
+
+- (void)addDispatchObserver:(id<RCTEventDispatcherObserver>)observer
+{
+  [_observersLock lock];
+  [_observers addObject:observer];
+  [_observersLock unlock];
+}
+
+- (void)removeDispatchObserver:(id<RCTEventDispatcherObserver>)observer
+{
+  [_observersLock lock];
+  [_observers removeObject:observer];
+  [_observersLock unlock];
+}
+
+- (void)dispatchEvent:(id<RCTEvent>)event
+{
+  if (_bridge) {
+    [_bridge enqueueJSCall:[[event class] moduleDotMethod] args:[event arguments]];
+  } else {
+    _invokeJSWithModuleDotMethod([[event class] moduleDotMethod], [event arguments]);
+  }
+}
+
+- (dispatch_queue_t)methodQueue
+{
+  return RCTJSThread;
+}
+
+// js thread only (which surprisingly can be the main thread, depends on used JS executor)
+- (void)flushEventsQueue
+{
+  [_eventQueueLock lock];
+  NSDictionary *events = _events;
+  _events = [NSMutableDictionary new];
+  NSMutableArray *eventQueue = _eventQueue;
+  _eventQueue = [NSMutableArray new];
+  _eventsDispatchScheduled = NO;
+  [_eventQueueLock unlock];
+
+  for (NSNumber *eventId in eventQueue) {
+    [self dispatchEvent:events[eventId]];
+  }
+}
+
+@end
+
+Class RCTEventDispatcherCls(void)
+{
+  return RCTEventDispatcher.class;
+}

React/CoreModules/RCTKeyboardObserver.mm

@@ -8,7 +8,7 @@
 #import "RCTKeyboardObserver.h"
 
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 #import "CoreModulesPlugins.h"
 

React/CoreModules/RCTRedBox.mm

@@ -12,7 +12,7 @@
 #import <React/RCTConvert.h>
 #import <React/RCTDefines.h>
 #import <React/RCTErrorInfo.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTJSStackFrame.h>
 #import <React/RCTRedBoxExtraDataViewController.h>
 #import <React/RCTRedBoxSetEnabled.h>

React/CoreModules/RCTStatusBarManager.mm

@@ -8,7 +8,7 @@
 #import "RCTStatusBarManager.h"
 #import "CoreModulesPlugins.h"
 
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTLog.h>
 #import <React/RCTUtils.h>
 

React/Modules/RCTUIManager.m

@@ -17,7 +17,7 @@
 #import "RCTComponentData.h"
 #import "RCTConvert.h"
 #import "RCTDefines.h"
-#import "RCTEventDispatcher.h"
+#import "RCTEventDispatcherProtocol.h"
 #import "RCTLayoutAnimation.h"
 #import "RCTLayoutAnimationGroup.h"
 #import "RCTLog.h"

React/Views/RCTDatePickerManager.m

@@ -10,7 +10,6 @@
 #import <React/RCTUIManager.h>
 #import "RCTBridge.h"
 #import "RCTDatePicker.h"
-#import "RCTEventDispatcher.h"
 #import "UIView+React.h"
 
 @implementation RCTConvert (UIDatePicker)

React/Views/RCTSegmentedControl.m

@@ -8,7 +8,6 @@
 #import "RCTSegmentedControl.h"
 
 #import "RCTConvert.h"
-#import "RCTEventDispatcher.h"
 #import "UIView+React.h"
 
 @implementation RCTSegmentedControl

React/Views/RCTSliderManager.m

@@ -8,7 +8,6 @@
 #import "RCTSliderManager.h"
 
 #import "RCTBridge.h"
-#import "RCTEventDispatcher.h"
 #import "RCTSlider.h"
 #import "UIView+React.h"
 

React/Views/RCTSwitch.m

@@ -7,7 +7,6 @@
 
 #import "RCTSwitch.h"
 
-#import "RCTEventDispatcher.h"
 #import "UIView+React.h"
 
 @implementation RCTSwitch

React/Views/RCTSwitchManager.m

@@ -9,7 +9,6 @@
 
 #import <React/RCTUIManager.h>
 #import "RCTBridge.h"
-#import "RCTEventDispatcher.h"
 #import "RCTSwitch.h"
 #import "UIView+React.h"
 

React/Views/RCTViewManager.h

@@ -10,7 +10,7 @@
 #import <React/RCTBridgeModule.h>
 #import <React/RCTConvert.h>
 #import <React/RCTDefines.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTLog.h>
 #import <React/UIView+React.h>
 

React/Views/RCTViewManager.m

@@ -11,7 +11,6 @@
 #import "RCTBridge.h"
 #import "RCTConvert+Transform.h"
 #import "RCTConvert.h"
-#import "RCTEventDispatcher.h"
 #import "RCTLog.h"
 #import "RCTShadowView.h"
 #import "RCTUIManager.h"

React/Views/RCTWrapperViewController.m

@@ -10,14 +10,12 @@
 #import <UIKit/UIScrollView.h>
 
 #import "RCTAutoInsetsProtocol.h"
-#import "RCTEventDispatcher.h"
 #import "RCTUtils.h"
 #import "UIView+React.h"
 
 @implementation RCTWrapperViewController {
   UIView *_wrapperView;
   UIView *_contentView;
-  RCTEventDispatcher *_eventDispatcher;
   CGFloat _previousTopLayoutLength;
   CGFloat _previousBottomLayoutLength;
 

React/Views/ScrollView/RCTScrollEvent.h

@@ -6,7 +6,7 @@
  */
 
 #import <Foundation/Foundation.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 @interface RCTScrollEvent : NSObject <RCTEvent>
 

React/Views/ScrollView/RCTScrollView.h

@@ -8,7 +8,8 @@
 #import <UIKit/UIScrollView.h>
 
 #import <React/RCTAutoInsetsProtocol.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTDefines.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTScrollableProtocol.h>
 #import <React/RCTView.h>
 
@@ -16,7 +17,7 @@
 
 @interface RCTScrollView : RCTView <UIScrollViewDelegate, RCTScrollableProtocol, RCTAutoInsetsProtocol>
 
-- (instancetype)initWithEventDispatcher:(RCTEventDispatcher *)eventDispatcher NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithEventDispatcher:(id<RCTEventDispatcherProtocol>)eventDispatcher NS_DESIGNATED_INITIALIZER;
 
 /**
  * The `RCTScrollView` may have at most one single subview. This will ensure
@@ -71,11 +72,4 @@
 
 @end
 
-@interface RCTEventDispatcher (RCTScrollView)
-
-/**
- * Send a fake scroll event.
- */
-- (void)sendFakeScrollEvent:(NSNumber *)reactTag;
-
-@end
+RCT_EXTERN void RCTSendFakeScrollEvent(id<RCTEventDispatcherProtocol> eventDispatcher, NSNumber *reactTag);

React/Views/ScrollView/RCTScrollView.m

@@ -261,7 +261,7 @@
 @end
 
 @implementation RCTScrollView {
-  RCTEventDispatcher *_eventDispatcher;
+  id<RCTEventDispatcherProtocol> _eventDispatcher;
   CGRect _prevFirstVisibleFrame;
   __weak UIView *_firstVisibleView;
   RCTCustomScrollView *_scrollView;
@@ -275,7 +275,7 @@
   NSHashTable *_scrollListeners;
 }
 
-- (instancetype)initWithEventDispatcher:(RCTEventDispatcher *)eventDispatcher
+- (instancetype)initWithEventDispatcher:(id<RCTEventDispatcherProtocol>)eventDispatcher
 {
   RCTAssertParam(eventDispatcher);
 
@@ -1022,9 +1022,7 @@ RCT_SET_AND_PRESERVE_OFFSET(setScrollIndicatorInsets, scrollIndicatorInsets, UIE
 
 @end
 
-@implementation RCTEventDispatcher (RCTScrollView)
-
-- (void)sendFakeScrollEvent:(NSNumber *)reactTag
+void RCTSendFakeScrollEvent(id<RCTEventDispatcherProtocol> eventDispatcher, NSNumber *reactTag)
 {
   // Use the selector here in case the onScroll block property is ever renamed
   NSString *eventName = NSStringFromSelector(@selector(onScroll));
@@ -1037,7 +1035,5 @@ RCT_SET_AND_PRESERVE_OFFSET(setScrollIndicatorInsets, scrollIndicatorInsets, UIE
                                                           scrollViewZoomScale:0
                                                                      userData:nil
                                                                 coalescingKey:0];
-  [self sendEvent:fakeScrollEvent];
+  [eventDispatcher sendEvent:fakeScrollEvent];
 }
-
-@end

ReactCommon/react/renderer/components/legacyviewmanagerinterop/RCTLegacyViewManagerInteropCoordinator.mm

@@ -9,6 +9,7 @@
 #include <React/RCTBridge+Private.h>
 #include <React/RCTBridgeMethod.h>
 #include <React/RCTComponentData.h>
+#include <React/RCTEventDispatcherProtocol.h>
 #include <React/RCTFollyConvert.h>
 #include <React/RCTModuleData.h>
 #include <React/RCTUIManager.h>

packages/rn-tester/RCTTest/RCTTestModule.mm

@@ -8,7 +8,7 @@
 #import "RCTTestModule.h"
 
 #import <React/RCTAssert.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTLog.h>
 #import <React/RCTUIManager.h>
 #import <ReactCommon/RCTTurboModule.h>

packages/rn-tester/RNTesterIntegrationTests/RCTRootViewIntegrationTests.m

@@ -9,7 +9,7 @@
 #import <XCTest/XCTest.h>
 
 #import <RCTTest/RCTTestRunner.h>
-#import <React/RCTEventDispatcher.h>
+#import <React/RCTEventDispatcherProtocol.h>
 #import <React/RCTRootView.h>
 #import <React/RCTRootViewDelegate.h>