Fabric: Introducing ComponentDescriptorProvider

Summary:
ComponentDescriptorProvider represents unified way to create a particular descriptor.
Now all ComponentViews (which support RCTComponentViewProtocol) expose a `ComponentDescriptorProvider` which will allow creating and registering ComponentDescriptor instances for all visual components automatically as a part of ComponentView registration process.
Don't panic, everything is still being as explicit as it always was, no magic involved; we just will have only one registration step instead of two parallel.

That also opens a way to register components on the fly.

Reviewed By: JoshuaGross

Differential Revision: D14963488

fbshipit-source-id: 9e9d9166fabaf7b30b35b8647faa6e3a19cd2435

React/Fabric/Mounting/ComponentViews/ActivityIndicator/RCTActivityIndicatorViewComponentView.mm

@@ -7,9 +7,9 @@
 
 #import "RCTActivityIndicatorViewComponentView.h"
 
+#import <react/components/rncore/ComponentDescriptors.h>
 #import <react/components/rncore/EventEmitters.h>
 #import <react/components/rncore/Props.h>
-#import <react/components/rncore/ShadowNodes.h>
 
 using namespace facebook::react;
 
@@ -29,9 +29,9 @@ @implementation RCTActivityIndicatorViewComponentView {
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return ActivityIndicatorViewShadowNode::Handle();
+  return concreteComponentDescriptorProvider<ActivityIndicatorViewComponentDescriptor>();
 }
 
 - (instancetype)initWithFrame:(CGRect)frame

React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm

@@ -8,10 +8,10 @@
 #import "RCTImageComponentView.h"
 
 #import <React/RCTImageResponseObserverProxy.h>
+#import <react/components/image/ImageComponentDescriptor.h>
 #import <react/components/image/ImageEventEmitter.h>
 #import <react/components/image/ImageLocalData.h>
 #import <react/components/image/ImageProps.h>
-#import <react/components/image/ImageShadowNode.h>
 #import <react/imagemanager/ImageRequest.h>
 #import <react/imagemanager/RCTImagePrimitivesConversions.h>
 
@@ -46,9 +46,9 @@ - (instancetype)initWithFrame:(CGRect)frame
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return ImageShadowNode::Handle();
+  return concreteComponentDescriptorProvider<ImageComponentDescriptor>();
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/ComponentViews/Root/RCTRootComponentView.mm

@@ -7,8 +7,8 @@
 
 #import "RCTRootComponentView.h"
 
+#import <react/components/root/RootComponentDescriptor.h>
 #import <react/components/root/RootProps.h>
-#import <react/components/root/RootShadowNode.h>
 
 using namespace facebook::react;
 
@@ -24,9 +24,11 @@ - (instancetype)initWithFrame:(CGRect)frame
   return self;
 }
 
-+ (ComponentHandle)componentHandle
+#pragma mark - RCTComponentViewProtocol
+
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return RootShadowNode::Handle();
+  return concreteComponentDescriptorProvider<RootComponentDescriptor>();
 }
 
 @end

React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -8,10 +8,10 @@
 #import "RCTScrollViewComponentView.h"
 
 #import <React/RCTAssert.h>
+#import <react/components/scrollview/ScrollViewComponentDescriptor.h>
 #import <react/components/scrollview/ScrollViewEventEmitter.h>
 #import <react/components/scrollview/ScrollViewLocalData.h>
 #import <react/components/scrollview/ScrollViewProps.h>
-#import <react/components/scrollview/ScrollViewShadowNode.h>
 #import <react/graphics/Geometry.h>
 
 #import "RCTConversions.h"
@@ -51,9 +51,9 @@ - (instancetype)initWithFrame:(CGRect)frame
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return ScrollViewShadowNode::Handle();
+  return concreteComponentDescriptorProvider<ScrollViewComponentDescriptor>();
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/ComponentViews/Slider/RCTSliderComponentView.mm

@@ -10,8 +10,8 @@
 #import <React/RCTImageResponseObserverProxy.h>
 #import <react/components/rncore/EventEmitters.h>
 #import <react/components/rncore/Props.h>
+#import <react/components/slider/SliderComponentDescriptor.h>
 #import <react/components/slider/SliderLocalData.h>
-#import <react/components/slider/SliderShadowNode.h>
 
 #import "MainQueueExecutor.h"
 
@@ -104,9 +104,9 @@ - (void)dealloc
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return SliderShadowNode::Handle();
+  return concreteComponentDescriptorProvider<SliderComponentDescriptor>();
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/ComponentViews/Switch/RCTSwitchComponentView.mm

@@ -7,9 +7,9 @@
 
 #import "RCTSwitchComponentView.h"
 
+#import <react/components/rncore/ComponentDescriptors.h>
 #import <react/components/rncore/EventEmitters.h>
 #import <react/components/rncore/Props.h>
-#import <react/components/rncore/ShadowNodes.h>
 
 using namespace facebook::react;
 
@@ -38,9 +38,9 @@ - (instancetype)initWithFrame:(CGRect)frame
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return SwitchShadowNode::Handle();
+  return concreteComponentDescriptorProvider<SwitchComponentDescriptor>();
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/ComponentViews/Text/RCTParagraphComponentView.mm

@@ -7,9 +7,11 @@
 
 #import "RCTParagraphComponentView.h"
 
+#import <react/components/text/ParagraphComponentDescriptor.h>
 #import <react/components/text/ParagraphLocalData.h>
 #import <react/components/text/ParagraphProps.h>
-#import <react/components/text/ParagraphShadowNode.h>
+#import <react/components/text/RawTextComponentDescriptor.h>
+#import <react/components/text/TextComponentDescriptor.h>
 #import <react/core/LocalData.h>
 #import <react/graphics/Geometry.h>
 #import <react/textlayoutmanager/RCTTextLayoutManager.h>
@@ -40,9 +42,15 @@ - (instancetype)initWithFrame:(CGRect)frame
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
-  return ParagraphShadowNode::Handle();
+  return concreteComponentDescriptorProvider<ParagraphComponentDescriptor>();
+}
+
++ (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders
+{
+  return {concreteComponentDescriptorProvider<RawTextComponentDescriptor>(),
+          concreteComponentDescriptorProvider<TextComponentDescriptor>()};
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/ComponentViews/UnimplementedComponent/RCTUnimplementedNativeComponentView.mm

@@ -7,23 +7,16 @@
 
 #import "RCTUnimplementedNativeComponentView.h"
 
+#import <react/components/rncore/ComponentDescriptors.h>
 #import <react/components/rncore/EventEmitters.h>
 #import <react/components/rncore/Props.h>
-#import <react/components/rncore/ShadowNodes.h>
 
 using namespace facebook::react;
 
 @implementation RCTUnimplementedNativeComponentView {
   UILabel *_label;
 }
 
-#pragma mark - RCTComponentViewProtocol
-
-+ (ComponentHandle)componentHandle
-{
-  return UnimplementedNativeViewShadowNode::Handle();
-}
-
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
@@ -45,6 +38,13 @@ - (instancetype)initWithFrame:(CGRect)frame
   return self;
 }
 
+#pragma mark - RCTComponentViewProtocol
+
++ (ComponentDescriptorProvider)componentDescriptorProvider
+{
+  return concreteComponentDescriptorProvider<UnimplementedNativeViewComponentDescriptor>();
+}
+
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
   const auto &oldViewProps = *std::static_pointer_cast<const UnimplementedNativeViewProps>(oldProps ?: _props);

React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -10,9 +10,9 @@
 #import <React/RCTAssert.h>
 #import <React/RCTBorderDrawing.h>
 #import <objc/runtime.h>
+#import <react/components/view/ViewComponentDescriptor.h>
 #import <react/components/view/ViewEventEmitter.h>
 #import <react/components/view/ViewProps.h>
-#import <react/components/view/ViewShadowNode.h>
 
 #import "RCTConversions.h"
 
@@ -85,13 +85,13 @@ - (void)setBackgroundColor:(UIColor *)backgroundColor
 
 #pragma mark - RCTComponentViewProtocol
 
-+ (ComponentHandle)componentHandle
++ (ComponentDescriptorProvider)componentDescriptorProvider
 {
   RCTAssert(
       self == [RCTViewComponentView class],
-      @"`+[RCTComponentViewProtocol componentHandle]` must be implemented for all subclasses (and `%@` particularly).",
+      @"`+[RCTComponentViewProtocol componentDescriptorProvider]` must be implemented for all subclasses (and `%@` particularly).",
       NSStringFromClass([self class]));
-  return ViewShadowNode::Handle();
+  return concreteComponentDescriptorProvider<ViewComponentDescriptor>();
 }
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps

React/Fabric/Mounting/RCTComponentViewFactory.mm

@@ -49,7 +49,7 @@ - (void)registerComponentViewClass:(Class<RCTComponentViewProtocol>)componentVie
 {
   RCTAssertMainQueue();
 
-  ComponentHandle componentHandle = [componentViewClass componentHandle];
+  auto componentHandle = [componentViewClass componentDescriptorProvider].handle;
   _registry[componentHandle] = componentViewClass;
 }
 

React/Fabric/Mounting/RCTComponentViewProtocol.h

@@ -13,6 +13,7 @@
 #import <react/core/LocalData.h>
 #import <react/core/Props.h>
 #import <react/core/State.h>
+#import <react/uimanager/ComponentDescriptorProvider.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -40,10 +41,16 @@ typedef NS_OPTIONS(NSInteger, RNComponentViewUpdateMask) {
 @protocol RCTComponentViewProtocol <NSObject>
 
 /*
- * Returns ComponentHandle of ComponentDescriptor which this ComponentView
+ * Returns a `ComponentDescriptorProvider` of a particular `ComponentDescriptor` which this component view
  * represents.
  */
-+ (facebook::react::ComponentHandle)componentHandle;
++ (facebook::react::ComponentDescriptorProvider)componentDescriptorProvider;
+
+/*
+ * Returns a list of supplemental  `ComponentDescriptorProvider`s (with do not have `ComponentView` counterparts) that
+ * require for this component view.
+ */
++ (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders;
 
 /*
  * Called for mounting (attaching) a child component view inside `self`

React/Fabric/Mounting/RCTComponentViewRegistry.mm

@@ -106,9 +106,9 @@ - (void)preallocateViewComponents
   // This data is based on empirical evidence which should represent the reality pretty well.
   // Regular `<View>` has magnitude equals to `1` by definition.
   std::vector<std::pair<ComponentHandle, float>> componentMagnitudes = {
-      {[RCTViewComponentView componentHandle], 1},
-      {[RCTImageComponentView componentHandle], 0.3},
-      {[RCTParagraphComponentView componentHandle], 0.3},
+      {[RCTViewComponentView componentDescriptorProvider].handle, 1},
+      {[RCTImageComponentView componentDescriptorProvider].handle, 0.3},
+      {[RCTParagraphComponentView componentDescriptorProvider].handle, 0.3},
   };
 
   // `complexity` represents the complexity of a typical surface in a number of `<View>` components (with Flattening

React/Fabric/Mounting/UIView+ComponentViewProtocol.h

@@ -16,6 +16,8 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @interface UIView (ComponentViewProtocol)
 
++ (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders;
+
 - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index;
 
 - (void)unmountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index;

React/Fabric/Mounting/UIView+ComponentViewProtocol.mm

@@ -17,6 +17,11 @@
 
 @implementation UIView (ComponentViewProtocol)
 
++ (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders
+{
+  return {};
+}
+
 - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
 {
   [self insertSubview:childComponentView atIndex:index];

React/Fabric/RCTSurfacePresenter.mm

@@ -175,7 +175,7 @@ - (BOOL)synchronouslyUpdateViewOnUIThread:(NSNumber *)reactTag props:(NSDictiona
   if (componentView == nil) {
     return NO; // This view probably isn't managed by Fabric
   }
-  ComponentHandle handle = [[componentView class] componentHandle];
+  ComponentHandle handle = [[componentView class] componentDescriptorProvider].handle;
   const facebook::react::ComponentDescriptor &componentDescriptor = [self._scheduler getComponentDescriptor:handle];
   [self->_mountingManager synchronouslyUpdateViewOnUIThread:tag
                                                changedProps:props

ReactCommon/fabric/core/componentdescriptor/ComponentDescriptor.h

@@ -30,6 +30,7 @@ using SharedComponentDescriptor = std::shared_ptr<ComponentDescriptor>;
 class ComponentDescriptor {
  public:
   using Shared = std::shared_ptr<ComponentDescriptor const>;
+  using Unique = std::unique_ptr<ComponentDescriptor const>;
 
   ComponentDescriptor(
       EventDispatcher::Shared const &eventDispatcher,

ReactCommon/fabric/uimanager/ComponentDescriptorProvider.h

@@ -0,0 +1,69 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/core/ComponentDescriptor.h>
+#include <react/core/EventDispatcher.h>
+#include <react/utils/ContextContainer.h>
+
+namespace facebook {
+namespace react {
+
+/*
+ * Callable signature that represents the signature of `ComponentDescriptor`
+ * constructor. The callable returns a unique pointer conveniently represents an
+ * abstract type and ownership of the newly created object.
+ */
+using ComponentDescriptorConstructor = ComponentDescriptor::Unique(
+    EventDispatcher::Shared const &eventDispatcher,
+    ContextContainer::Shared const &contextContainer);
+
+/*
+ * Represents a unified way to construct an instance of a particular stored
+ * `ComponentDescriptor` class. C++ does not allow to create pointers to
+ * constructors, so we have to have such data structure to manipulate a
+ * collection of classes.
+ */
+class ComponentDescriptorProvider final {
+ public:
+  ComponentHandle handle;
+  ComponentDescriptorConstructor *constructor;
+};
+
+/*
+ * Creates a `ComponentDescriptorConstructor` for given `ComponentDescriptor`
+ * class.
+ */
+template <typename ComponentDescriptorT>
+ComponentDescriptor::Unique concreteComponentDescriptorConstructor(
+    EventDispatcher::Shared const &eventDispatcher,
+    ContextContainer::Shared const &contextContainer) {
+  static_assert(
+      std::is_base_of<ComponentDescriptor, ComponentDescriptorT>::value,
+      "ComponentDescriptorT must be a descendant of ComponentDescriptor");
+
+  return std::make_unique<ComponentDescriptorT const>(
+      eventDispatcher, contextContainer);
+}
+
+/*
+ * Creates a `ComponentDescriptorProvider` for given `ComponentDescriptor`
+ * class.
+ */
+template <typename ComponentDescriptorT>
+ComponentDescriptorProvider concreteComponentDescriptorProvider() {
+  static_assert(
+      std::is_base_of<ComponentDescriptor, ComponentDescriptorT>::value,
+      "ComponentDescriptorT must be a descendant of ComponentDescriptor");
+
+  return {ComponentDescriptorT::ConcreteShadowNode::Handle(),
+          &concreteComponentDescriptorConstructor<ComponentDescriptorT>};
+}
+
+} // namespace react
+} // namespace facebook