Fabric: Enhancements in ContextContainer

Summary:
@public
Everything is better with C++ templates.
In this cases templates allow us to remove additional parameters and casts on the callsite.

Reviewed By: mdvacca

Differential Revision: D8754523

fbshipit-source-id: 2340b2cd96ab0a60d54d9aa30dea3c072b951a8a

React/Fabric/RCTScheduler.mm

@@ -49,7 +49,7 @@ private:
     SharedContextContainer contextContainer = std::make_shared<ContextContainer>();
 
     void *imageLoader = (__bridge void *)[[RCTBridge currentBridge] imageLoader];
-    contextContainer->registerInstance(typeid(ImageManager), std::make_shared<ImageManager>(imageLoader));
+    contextContainer->registerInstance(std::make_shared<ImageManager>(imageLoader));
 
     _scheduler = std::make_shared<Scheduler>(contextContainer);
     _scheduler->setDelegate(_delegateProxy.get());

ReactCommon/fabric/components/image/ImageComponentDescriptor.h

@@ -24,7 +24,7 @@ class ImageComponentDescriptor final:
 public:
   ImageComponentDescriptor(SharedEventDispatcher eventDispatcher, const SharedContextContainer &contextContainer):
     ConcreteComponentDescriptor(eventDispatcher),
-    imageManager_(std::static_pointer_cast<ImageManager>(contextContainer->at(typeid(ImageManager)))) {}
+    imageManager_(contextContainer->getInstance<ImageManager>()) {}
 
   void adopt(UnsharedShadowNode shadowNode) const override {
     ConcreteComponentDescriptor::adopt(shadowNode);

ReactCommon/fabric/uimanager/ContextContainer.cpp

@@ -1,22 +0,0 @@
-// Copyright (c) 2004-present, Facebook, Inc.
-
-// This source code is licensed under the MIT license found in the
-// LICENSE file in the root directory of this source tree.
-
-#include "ContextContainer.h"
-
-namespace facebook {
-namespace react {
-
-void ContextContainer::registerInstance(const ClassHandle &handle, SharedInstance instance) {
-  std::lock_guard<std::mutex> lock(mutex_);
-  instances_.insert({handle, instance});
-}
-
-const ContextContainer::SharedInstance &ContextContainer::at(const ClassHandle &handle) const {
-  std::lock_guard<std::mutex> lock(mutex_);
-  return instances_.at(handle);
-}
-
-} // namespace react
-} // namespace facebook

ReactCommon/fabric/uimanager/ContextContainer.h

@@ -24,15 +24,20 @@ using SharedContextContainer = std::shared_ptr<ContextContainer>;
 class ContextContainer final {
 
 public:
-  using ClassHandle = std::type_index;
-  using SharedInstance = std::shared_ptr<void>;
+  template<typename T>
+  void registerInstance(std::shared_ptr<T> instance) {
+    std::lock_guard<std::mutex> lock(mutex_);
+    instances_.insert({std::type_index(typeid(T)), instance});
+  }
 
-  void registerInstance(const ClassHandle &handle, SharedInstance instance);
-
-  const SharedInstance &at(const ClassHandle &handle) const;
+  template<typename T>
+  std::shared_ptr<T> getInstance() const {
+    std::lock_guard<std::mutex> lock(mutex_);
+    return std::static_pointer_cast<T>(instances_.at(std::type_index(typeid(T))));
+  }
 
 private:
-  std::unordered_map<ClassHandle, SharedInstance> instances_;
+  std::unordered_map<std::type_index, std::shared_ptr<void>> instances_;
   mutable std::mutex mutex_;
 };