A proxy so a singleton CxxModule can be shared by multiple ModuleRegistry instances.

Reviewed By: mhorowitz

Differential Revision: D4814438

fbshipit-source-id: db6cdd9e948643bb24a443bd45b7b0843a0a86c2

ReactCommon/cxxreact/BUCK

@@ -132,11 +132,11 @@ CXXREACT_PUBLIC_HEADERS = [
     "ExecutorToken.h",
     "ExecutorTokenFactory.h",
     "Instance.h",
+    "JSBigString.h",
+    "JSBundleType.h",
     "JSCExecutor.h",
     "JSCNativeModules.h",
     "JSCWebWorker.h",
-    "JSBigString.h",
-    "JSBundleType.h",
     "JSIndexedRAMBundle.h",
     "JSModulesUnbundle.h",
     "MessageQueueThread.h",
@@ -146,6 +146,7 @@ CXXREACT_PUBLIC_HEADERS = [
     "NativeToJsBridge.h",
     "Platform.h",
     "RecoverableError.h",
+    "SharedProxyCxxModule.h",
     "SystraceSection.h",
 ]
 

ReactCommon/cxxreact/SharedProxyCxxModule.h

@@ -0,0 +1,35 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+#include <memory>
+
+#include <cxxreact/CxxModule.h>
+
+namespace facebook { namespace xplat { namespace module {
+
+// Allows a Cxx-module to be shared or reused across multiple React instances
+// Caveat: the setInstance call is not forwarded, so usages of getInstance inside your
+// module (e.g. dispatching events) will always be nullptr.
+class SharedProxyCxxModule : public CxxModule {
+public:
+  explicit SharedProxyCxxModule(std::shared_ptr<CxxModule> shared)
+    : shared_(shared) {}
+
+  std::string getName() override {
+    return shared_->getName();
+  }
+
+  auto getConstants() -> std::map<std::string, folly::dynamic> override {
+    return shared_->getConstants();
+  }
+
+  auto getMethods() -> std::vector<Method> override {
+    return shared_->getMethods();
+  }
+
+private:
+  std::shared_ptr<CxxModule> shared_;
+};
+
+}
+}
+}