Refactor reload command in React Native

Summary: Introduces an API to register a weakly-held listener for the reload (Cmd+R) command. This allows external infrastructure to hook into the reload command before the `RCTBridge` object is even created.

Reviewed By: javache

Differential Revision: D4286980

fbshipit-source-id: 51012fb8cbeb433dc880d9d98d847b07fdbb4c4f

React/Base/RCTBridge.m

@@ -14,11 +14,11 @@
 
 #import "RCTConvert.h"
 #import "RCTEventDispatcher.h"
-#import "RCTKeyCommands.h"
 #import "RCTLog.h"
 #import "RCTModuleData.h"
 #import "RCTPerformanceLogger.h"
 #import "RCTProfile.h"
+#import "RCTReloadCommand.h"
 #import "RCTUtils.h"
 
 NSString *const RCTJavaScriptWillStartLoadingNotification = @"RCTJavaScriptWillStartLoadingNotification";
@@ -119,6 +119,9 @@ void RCTVerifyAllModulesExported(NSArray *extraModules)
 }
 #endif
 
+@interface RCTBridge () <RCTReloadListener>
+@end
+
 @implementation RCTBridge
 {
   NSURL *_delegateBundleURL;
@@ -207,18 +210,15 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   RCTAssertMainQueue();
 
 #if TARGET_IPHONE_SIMULATOR
-  RCTKeyCommands *commands = [RCTKeyCommands sharedInstance];
-
-  // reload in current mode
-  __weak typeof(self) weakSelf = self;
-  [commands registerKeyCommandWithInput:@"r"
-                          modifierFlags:UIKeyModifierCommand
-                                 action:^(__unused UIKeyCommand *command) {
-    [weakSelf reload];
-  }];
+  RCTRegisterReloadCommandListener(self);
 #endif
 }
 
+- (void)didReceiveReloadCommand
+{
+  [self reload];
+}
+
 - (NSArray<Class> *)moduleClasses
 {
   return self.batchedBridge.moduleClasses;

React/Base/RCTReloadCommand.h

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import <React/RCTDefines.h>
+
+@protocol RCTReloadListener
+- (void)didReceiveReloadCommand;
+@end
+
+/** Registers a weakly-held observer of the Command+R reload key command. */
+RCT_EXTERN void RCTRegisterReloadCommandListener(id<RCTReloadListener> listener);

React/Base/RCTReloadCommand.m

@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "RCTReloadCommand.h"
+
+#import "RCTKeyCommands.h"
+
+void RCTRegisterReloadCommandListener(id<RCTReloadListener> listener)
+{
+  static NSHashTable<id<RCTReloadListener>> *listeners;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    listeners = [NSHashTable weakObjectsHashTable];
+    [[RCTKeyCommands sharedInstance] registerKeyCommandWithInput:@"r"
+                                                   modifierFlags:UIKeyModifierCommand
+                                                          action:
+     ^(__unused UIKeyCommand *command) {
+       NSArray<id<RCTReloadListener>> *copiedListeners;
+       @synchronized (listeners) { // avoid mutation-while-enumerating
+         copiedListeners = [listeners allObjects];
+       }
+       for (id<RCTReloadListener> l in copiedListeners) {
+         [l didReceiveReloadCommand];
+       }
+     }];
+  });
+
+  @synchronized (listeners) {
+    [listeners addObject:listener];
+  }
+}

React/React.xcodeproj/project.pbxproj

@@ -710,6 +710,9 @@
 		83CBBA691A601EF300E9B192 /* RCTEventDispatcher.m in Sources */ = {isa = PBXBuildFile; fileRef = 83CBBA661A601EF300E9B192 /* RCTEventDispatcher.m */; };
 		83CBBA981A6020BB00E9B192 /* RCTTouchHandler.m in Sources */ = {isa = PBXBuildFile; fileRef = 83CBBA971A6020BB00E9B192 /* RCTTouchHandler.m */; };
 		83CBBACC1A6023D300E9B192 /* RCTConvert.m in Sources */ = {isa = PBXBuildFile; fileRef = 83CBBACB1A6023D300E9B192 /* RCTConvert.m */; };
+		A2440AA21DF8D854006E7BFC /* RCTReloadCommand.h in Headers */ = {isa = PBXBuildFile; fileRef = A2440AA01DF8D854006E7BFC /* RCTReloadCommand.h */; settings = {ATTRIBUTES = (Private, ); }; };
+		A2440AA31DF8D854006E7BFC /* RCTReloadCommand.m in Sources */ = {isa = PBXBuildFile; fileRef = A2440AA11DF8D854006E7BFC /* RCTReloadCommand.m */; };
+		A2440AA41DF8D865006E7BFC /* RCTReloadCommand.h in Headers */ = {isa = PBXBuildFile; fileRef = A2440AA01DF8D854006E7BFC /* RCTReloadCommand.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		AC70D2E91DE489E4002E6351 /* RCTJavaScriptLoader.mm in Sources */ = {isa = PBXBuildFile; fileRef = AC70D2E81DE489E4002E6351 /* RCTJavaScriptLoader.mm */; };
 		B233E6EA1D2D845D00BC68BA /* RCTI18nManager.m in Sources */ = {isa = PBXBuildFile; fileRef = B233E6E91D2D845D00BC68BA /* RCTI18nManager.m */; };
 		B95154321D1B34B200FE7B80 /* RCTActivityIndicatorView.m in Sources */ = {isa = PBXBuildFile; fileRef = B95154311D1B34B200FE7B80 /* RCTActivityIndicatorView.m */; };
@@ -1335,6 +1338,8 @@
 		83CBBACA1A6023D300E9B192 /* RCTConvert.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; lineEnding = 0; path = RCTConvert.h; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
 		83CBBACB1A6023D300E9B192 /* RCTConvert.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTConvert.m; sourceTree = "<group>"; };
 		83F15A171B7CC46900F10295 /* UIView+Private.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "UIView+Private.h"; sourceTree = "<group>"; };
+		A2440AA01DF8D854006E7BFC /* RCTReloadCommand.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTReloadCommand.h; sourceTree = "<group>"; };
+		A2440AA11DF8D854006E7BFC /* RCTReloadCommand.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTReloadCommand.m; sourceTree = "<group>"; };
 		AC70D2E81DE489E4002E6351 /* RCTJavaScriptLoader.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = RCTJavaScriptLoader.mm; sourceTree = "<group>"; };
 		AC70D2EB1DE48A22002E6351 /* JSBundleType.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSBundleType.cpp; sourceTree = "<group>"; };
 		AC70D2EE1DE48AC5002E6351 /* oss-compat-util.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "oss-compat-util.h"; sourceTree = "<group>"; };
@@ -1725,6 +1730,8 @@
 				142014171B32094000CC17BA /* RCTPerformanceLogger.m */,
 				3D7749421DC1065C007EC8D8 /* RCTPlatform.h */,
 				3D7749431DC1065C007EC8D8 /* RCTPlatform.m */,
+				A2440AA01DF8D854006E7BFC /* RCTReloadCommand.h */,
+				A2440AA11DF8D854006E7BFC /* RCTReloadCommand.m */,
 				830A229C1A66C68A008503DA /* RCTRootView.h */,
 				830A229D1A66C68A008503DA /* RCTRootView.m */,
 				13AFBCA21C07287B00BBAEAA /* RCTRootViewDelegate.h */,
@@ -1856,6 +1863,7 @@
 				3D302F851DF828F800D6DDAE /* RCTProgressViewManager.h in Headers */,
 				3D302F861DF828F800D6DDAE /* RCTRefreshControl.h in Headers */,
 				3D302F871DF828F800D6DDAE /* RCTRefreshControlManager.h in Headers */,
+				A2440AA41DF8D865006E7BFC /* RCTReloadCommand.h in Headers */,
 				3D302F881DF828F800D6DDAE /* RCTRootShadowView.h in Headers */,
 				3D302F891DF828F800D6DDAE /* RCTScrollableProtocol.h in Headers */,
 				3D302F8A1DF828F800D6DDAE /* RCTScrollView.h in Headers */,
@@ -2042,6 +2050,7 @@
 				3D80DA791DF820620028D040 /* RCTPointerEvents.h in Headers */,
 				3D80DA7A1DF820620028D040 /* RCTProgressViewManager.h in Headers */,
 				3D80DA7B1DF820620028D040 /* RCTRefreshControl.h in Headers */,
+				A2440AA21DF8D854006E7BFC /* RCTReloadCommand.h in Headers */,
 				3D80DA7C1DF820620028D040 /* RCTRefreshControlManager.h in Headers */,
 				3D80DA7D1DF820620028D040 /* RCTRootShadowView.h in Headers */,
 				3D80DA7E1DF820620028D040 /* RCTScrollableProtocol.h in Headers */,
@@ -2519,6 +2528,7 @@
 				369123E11DDC75850095B341 /* JSCSamplingProfiler.m in Sources */,
 				13B080261A694A8400A75B9A /* RCTWrapperViewController.m in Sources */,
 				13B080051A6947C200A75B9A /* RCTScrollView.m in Sources */,
+				A2440AA31DF8D854006E7BFC /* RCTReloadCommand.m in Sources */,
 				E9B20B7B1B500126007A2DA7 /* RCTAccessibilityManager.m in Sources */,
 				3D7A27E21DE325B7002E3F95 /* RCTJSCErrorHandling.mm in Sources */,
 				13A0C2891B74F71200B29F6F /* RCTDevLoadingView.m in Sources */,