TM iOS: rollout strategy 1 - added RCTEnableJSINativeModule(BOOL)

Summary:
To be able to test out new approach for NativeModules, introduce a simple runtime flag to enable the new system (doesn't exist yet). In addition, each module should declare a static `+ (BOOL)allowJSIBinding` in the objc class to be considered for the new approach. Doing so skips the processing of the module during bridge startup.

Note: this doesn't do anything special for `- (NSArray *)extraModulesForBridge:(RCTBridge *)bridge` impl yet.

Differential Revision: D9554296

fbshipit-source-id: 3508db6589e9f72367f62aa7ca15fce3d3adda72

React/Base/RCTBridge.h

@@ -93,6 +93,13 @@ typedef NSArray<id<RCTBridgeModule>> *(^RCTBridgeModuleListProvider)(void);
  */
 RCT_EXTERN NSString *RCTBridgeModuleNameForClass(Class bridgeModuleClass);
 
+/**
+ * Experimental.
+ * Check/set if JSI-bound NativeModule is enabled. By default it's off.
+ */
+RCT_EXTERN BOOL RCTJSINativeModuleEnabled(void);
+RCT_EXTERN void RCTEnableJSINativeModule(BOOL enabled);
+
 /**
  * Async batched bridge used to communicate with the JavaScript application.
  */

React/Base/RCTBridge.m

@@ -93,6 +93,16 @@ NSString *RCTBridgeModuleNameForClass(Class cls)
   return name;
 }
 
+static BOOL jsiNativeModuleEnabled = NO;
+BOOL RCTJSINativeModuleEnabled(void)
+{
+  return jsiNativeModuleEnabled;
+}
+
+void RCTEnableJSINativeModule(BOOL enabled) {
+  jsiNativeModuleEnabled = enabled;
+}
+
 #if RCT_DEBUG
 void RCTVerifyAllModulesExported(NSArray *extraModules)
 {

React/Base/RCTBridgeModule.h

@@ -289,6 +289,12 @@ RCT_EXTERN void RCTRegisterModule(Class); \
  */
 + (BOOL)requiresMainQueueSetup;
 
+/**
+ * Experimental.
+ * If YES, this module will be set up via JSI binding instead.
+ */
++ (BOOL)allowJSIBinding;
+
 /**
  * Injects methods into JS.  Entries in this array are used in addition to any
  * methods defined using the macros above.  This method is called only once,

React/CxxBridge/RCTCxxBridge.mm

@@ -549,6 +549,9 @@ struct RCTInstanceCallback : public InstanceCallback {
   NSArray *moduleClassesCopy = [moduleClasses copy];
   NSMutableArray<RCTModuleData *> *moduleDataByID = [NSMutableArray arrayWithCapacity:moduleClassesCopy.count];
   for (Class moduleClass in moduleClassesCopy) {
+    if (RCTJSINativeModuleEnabled() && [moduleClass respondsToSelector:@selector(allowJSIBinding)] && [moduleClass allowJSIBinding]) {
+      continue;
+    }
     NSString *moduleName = RCTBridgeModuleNameForClass(moduleClass);
 
     // Check for module name collisions