Fabric: []-family of methods was removed from ComponentDescriptorRegistry

Summary:
Motivation:
 * We don't use them much, and we already have `at`-methods, which are better.
* We don't want to expose `ComponentDescriptor`s as shared pointers (because it's not clear, not so performant, and because we don't want to store them as shared pointer in the future);
* In idiomatic C++ `[]` operator has mutating semantic, that's not what we want to communicate via the interface of the class.

Reviewed By: sahrens

Differential Revision: D14963487

fbshipit-source-id: dbfddee2ba90d70c3bb8dcf1959d553571c47bab

ReactCommon/fabric/uimanager/ComponentDescriptorRegistry.cpp

@@ -20,23 +20,7 @@ void ComponentDescriptorRegistry::registerComponentDescriptor(
   _registryByName[componentName] = componentDescriptor;
 }
 
-const SharedComponentDescriptor ComponentDescriptorRegistry::operator[](
-    const SharedShadowNode &shadowNode) const {
-  ComponentHandle componentHandle = shadowNode->getComponentHandle();
-  return _registryByHandle.at(componentHandle);
-}
-
-const SharedComponentDescriptor ComponentDescriptorRegistry::operator[](
-    const ComponentName &componentName) const {
-  auto it = _registryByName.find(componentName);
-  if (it == _registryByName.end()) {
-    throw std::invalid_argument(
-        ("Unable to find componentDescriptor for " + componentName).c_str());
-  }
-  return it->second;
-}
-
-static const std::string componentNameByReactViewName(std::string viewName) {
+static ComponentName componentNameByReactViewName(ComponentName viewName) {
   // We need this function only for the transition period;
   // eventually, all names will be unified.
 
@@ -86,8 +70,8 @@ static const std::string componentNameByReactViewName(std::string viewName) {
   return viewName;
 }
 
-const ComponentDescriptor &ComponentDescriptorRegistry::at(
-    ComponentName componentName) const {
+ComponentDescriptor const &ComponentDescriptorRegistry::at(
+    ComponentName const &componentName) const {
   auto unifiedComponentName = componentNameByReactViewName(componentName);
 
   auto it = _registryByName.find(unifiedComponentName);
@@ -102,28 +86,26 @@ const ComponentDescriptor &ComponentDescriptorRegistry::at(
   return *it->second;
 }
 
-const ComponentDescriptor &ComponentDescriptorRegistry::at(
+ComponentDescriptor const &ComponentDescriptorRegistry::at(
     ComponentHandle componentHandle) const {
   return *_registryByHandle.at(componentHandle);
 }
 
 SharedShadowNode ComponentDescriptorRegistry::createNode(
     Tag tag,
-    const std::string &viewName,
+    ComponentName const &viewName,
     Tag rootTag,
-    const folly::dynamic &props,
-    const SharedEventTarget &eventTarget) const {
-  ComponentName componentName = componentNameByReactViewName(viewName);
-  const SharedComponentDescriptor &componentDescriptor = (*this)[componentName];
-
-  SharedShadowNode shadowNode = componentDescriptor->createShadowNode({
+    folly::dynamic const &props,
+    SharedEventTarget const &eventTarget) const {
+  auto unifiedComponentName = componentNameByReactViewName(viewName);
+  auto const &componentDescriptor = this->at(unifiedComponentName);
+  return componentDescriptor.createShadowNode({
       /* .tag = */ tag,
       /* .rootTag = */ rootTag,
-      /* .props = */ componentDescriptor->cloneProps(nullptr, RawProps(props)),
+      /* .props = */ componentDescriptor.cloneProps(nullptr, RawProps(props)),
       /* .eventEmitter = */
-      componentDescriptor->createEventEmitter(std::move(eventTarget), tag),
+      componentDescriptor.createEventEmitter(std::move(eventTarget), tag),
   });
-  return shadowNode;
 }
 
 void ComponentDescriptorRegistry::setFallbackComponentDescriptor(
@@ -132,7 +114,7 @@ void ComponentDescriptorRegistry::setFallbackComponentDescriptor(
   registerComponentDescriptor(descriptor);
 }
 
-const SharedComponentDescriptor
+ComponentDescriptor::Shared
 ComponentDescriptorRegistry::getFallbackComponentDescriptor() const {
   return _fallbackComponentDescriptor;
 }

ReactCommon/fabric/uimanager/ComponentDescriptorRegistry.h

@@ -23,29 +23,28 @@ using SharedComponentDescriptorRegistry =
  */
 class ComponentDescriptorRegistry {
  public:
+  using Shared = std::shared_ptr<const ComponentDescriptorRegistry>;
+
   void registerComponentDescriptor(
       SharedComponentDescriptor componentDescriptor);
 
-  const ComponentDescriptor &at(ComponentName componentName) const;
-  const ComponentDescriptor &at(ComponentHandle componentHandle) const;
+  ComponentDescriptor const &at(ComponentName const &componentName) const;
+  ComponentDescriptor const &at(ComponentHandle componentHandle) const;
 
-  const SharedComponentDescriptor operator[](
-      const SharedShadowNode &shadowNode) const;
-  const SharedComponentDescriptor operator[](
-      const ComponentName &componentName) const;
   SharedShadowNode createNode(
       Tag tag,
-      const std::string &viewName,
+      ComponentName const &viewName,
       Tag rootTag,
-      const folly::dynamic &props,
-      const SharedEventTarget &eventTarget) const;
+      folly::dynamic const &props,
+      SharedEventTarget const &eventTarget) const;
+
   void setFallbackComponentDescriptor(SharedComponentDescriptor descriptor);
-  const SharedComponentDescriptor getFallbackComponentDescriptor() const;
+  ComponentDescriptor::Shared getFallbackComponentDescriptor() const;
 
  private:
   better::map<ComponentHandle, SharedComponentDescriptor> _registryByHandle;
   better::map<ComponentName, SharedComponentDescriptor> _registryByName;
-  SharedComponentDescriptor _fallbackComponentDescriptor;
+  ComponentDescriptor::Shared _fallbackComponentDescriptor;
 };
 
 } // namespace react

ReactCommon/fabric/uimanager/UITemplateProcessor.cpp

@@ -52,9 +52,9 @@ SharedShadowNode UITemplateProcessor::runCommand(
         tag + tagOffset, type, rootTag, props, nullptr);
     if (parentTag > -1) { // parentTag == -1 indicates root node
       auto parentShadowNode = nodes[parentTag];
-      const SharedComponentDescriptor &componentDescriptor =
-          componentDescriptorRegistry[parentShadowNode];
-      componentDescriptor->appendChild(parentShadowNode, nodes[tag]);
+      auto const &componentDescriptor = componentDescriptorRegistry.at(
+          parentShadowNode->getComponentHandle());
+      componentDescriptor.appendChild(parentShadowNode, nodes[tag]);
     }
   } else if (opcode == "returnRoot") {
     if (DEBUG_FLY) {