Fabric: Unification of props management in RCTViewComponentView and subclasses

Summary:
* Now all `RCTViewComponentView` subclasses are required to set `_props` instance variable in the constructor with a default value;
* `RCTViewComponentView`'s `_props` instance variable now has `ShadredViewProps` type (that enforced by `static_assert` in `ConcreteViewShadowNode` template);
* New we use `static_pointer_cast` instead of `dynamic_pointer_cast` for casting props.

Reviewed By: mdvacca

Differential Revision: D9734199

fbshipit-source-id: b0a0939c936f8b5b540fa5fa1e4a2f1037346fc5

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

@@ -27,19 +27,20 @@ static UIActivityIndicatorViewStyle convertActivityIndicatorViewStyle(const Acti
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const ActivityIndicatorViewProps>();
+    _props = defaultProps;
+
     _activityIndicatorView = [[UIActivityIndicatorView alloc] initWithFrame:self.bounds];
     _activityIndicatorView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
 
-    const auto &defaultProps = ActivityIndicatorViewProps();
-
-    if (defaultProps.animating) {
+    if (defaultProps->animating) {
       [_activityIndicatorView startAnimating];
     } else {
       [_activityIndicatorView stopAnimating];
     }
-    _activityIndicatorView.color = [UIColor colorWithCGColor:defaultProps.color.get()];
-    _activityIndicatorView.hidesWhenStopped = defaultProps.hidesWhenStopped;
-    _activityIndicatorView.activityIndicatorViewStyle = convertActivityIndicatorViewStyle(defaultProps.size);
+    _activityIndicatorView.color = [UIColor colorWithCGColor:defaultProps->color.get()];
+    _activityIndicatorView.hidesWhenStopped = defaultProps->hidesWhenStopped;
+    _activityIndicatorView.activityIndicatorViewStyle = convertActivityIndicatorViewStyle(defaultProps->size);
 
     [self addSubview:_activityIndicatorView];
   }
@@ -49,16 +50,11 @@ static UIActivityIndicatorViewStyle convertActivityIndicatorViewStyle(const Acti
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
-  if (!oldProps) {
-    oldProps = _props ?: std::make_shared<ActivityIndicatorViewProps>();
-  }
-  _props = props;
+  const auto &oldViewProps = *std::static_pointer_cast<const ActivityIndicatorViewProps>(oldProps ?: _props);
+  const auto &newViewProps = *std::static_pointer_cast<const ActivityIndicatorViewProps>(props);
 
   [super updateProps:props oldProps:oldProps];
 
-  auto oldViewProps = *std::dynamic_pointer_cast<const ActivityIndicatorViewProps>(oldProps);
-  auto newViewProps = *std::dynamic_pointer_cast<const ActivityIndicatorViewProps>(props);
-
   if (oldViewProps.animating != newViewProps.animating) {
     if (newViewProps.animating) {
       [_activityIndicatorView startAnimating];

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

@@ -27,11 +27,13 @@ using namespace facebook::react;
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const ImageProps>();
+    _props = defaultProps;
+
     _imageView = [[UIImageView alloc] initWithFrame:self.bounds];
     _imageView.clipsToBounds = YES;
 
-    auto defaultProps = ImageProps();
-    _imageView.contentMode = (UIViewContentMode)RCTResizeModeFromImageResizeMode(defaultProps.resizeMode);
+    _imageView.contentMode = (UIViewContentMode)RCTResizeModeFromImageResizeMode(defaultProps->resizeMode);
 
     self.contentView = _imageView;
   }
@@ -43,16 +45,11 @@ using namespace facebook::react;
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
-  if (!oldProps) {
-    oldProps = _props ?: std::make_shared<const ImageProps>();
-  }
-  _props = props;
+  const auto &oldImageProps = *std::static_pointer_cast<const ImageProps>(oldProps ?: _props);
+  const auto &newImageProps = *std::static_pointer_cast<const ImageProps>(props);
 
   [super updateProps:props oldProps:oldProps];
 
-  const auto &oldImageProps = *std::dynamic_pointer_cast<const ImageProps>(oldProps);
-  const auto &newImageProps = *std::dynamic_pointer_cast<const ImageProps>(props);
-
   // `resizeMode`
   if (oldImageProps.resizeMode != newImageProps.resizeMode) {
     if (newImageProps.resizeMode == ImageResizeMode::Repeat) {

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

@@ -7,6 +7,20 @@
 
 #import "RCTRootComponentView.h"
 
+#import <fabric/components/root/RootProps.h>
+
+using namespace facebook::react;
+
 @implementation RCTRootComponentView
 
+- (instancetype)initWithFrame:(CGRect)frame
+{
+  if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const RootProps>();
+    _props = defaultProps;
+  }
+
+  return self;
+}
+
 @end

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

@@ -33,6 +33,9 @@ using namespace facebook::react;
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const ScrollViewProps>();
+    _props = defaultProps;
+
     _scrollView = [[RCTEnhancedScrollView alloc] initWithFrame:self.bounds];
     _scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
     _scrollView.delegate = self;
@@ -49,16 +52,11 @@ using namespace facebook::react;
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
+  const auto &oldScrollViewProps = *std::static_pointer_cast<const ScrollViewProps>(oldProps ?: _props);
+  const auto &newScrollViewProps = *std::static_pointer_cast<const ScrollViewProps>(props);
+
   [super updateProps:props oldProps:oldProps];
 
-  if (!oldProps) {
-    oldProps = _props ?: std::make_shared<ScrollViewProps>();
-  }
-  _props = props;
-
-  auto oldScrollViewProps = *std::dynamic_pointer_cast<const ScrollViewProps>(oldProps);
-  auto newScrollViewProps = *std::dynamic_pointer_cast<const ScrollViewProps>(props);
-
 #define REMAP_PROP(reactName, localName, target) \
   if (oldScrollViewProps.reactName != newScrollViewProps.reactName) { \
     target.localName = newScrollViewProps.reactName; \

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

@@ -20,15 +20,16 @@ using namespace facebook::react;
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const SwitchProps>();
+    _props = defaultProps;
+
     _switchView = [[UISwitch alloc] initWithFrame:self.bounds];
 
     [_switchView addTarget:self
-                 action:@selector(onChange:)
-       forControlEvents:UIControlEventValueChanged];
+                    action:@selector(onChange:)
+          forControlEvents:UIControlEventValueChanged];
 
-    const auto &defaultProps = SwitchProps();
-
-    _switchView.on = defaultProps.value;
+    _switchView.on = defaultProps->value;
 
     self.contentView = _switchView;
   }
@@ -38,16 +39,11 @@ using namespace facebook::react;
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
-  if (!oldProps) {
-    oldProps = _props ?: std::make_shared<SwitchProps>();
-  }
-  _props = props;
+  const auto &oldSwitchProps = *std::static_pointer_cast<const SwitchProps>(oldProps ?: _props);
+  const auto &newSwitchProps = *std::static_pointer_cast<const SwitchProps>(props);
 
   [super updateProps:props oldProps:oldProps];
 
-  auto oldSwitchProps = *std::dynamic_pointer_cast<const SwitchProps>(oldProps);
-  auto newSwitchProps = *std::dynamic_pointer_cast<const SwitchProps>(props);
-
   // `value`
   if (oldSwitchProps.value != newSwitchProps.value) {
     _switchView.on = newSwitchProps.value;

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

@@ -25,6 +25,9 @@ using namespace facebook::react;
 - (instancetype)initWithFrame:(CGRect)frame
 {
   if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const ParagraphProps>();
+    _props = defaultProps;
+
     self.isAccessibilityElement = YES;
     self.accessibilityTraits |= UIAccessibilityTraitStaticText;
     self.opaque = NO;
@@ -36,8 +39,10 @@ using namespace facebook::react;
 
 - (void)updateProps:(SharedProps)props oldProps:(SharedProps)oldProps
 {
+  const auto &paragraphProps = std::static_pointer_cast<const ParagraphProps>(props);
+
   [super updateProps:props oldProps:oldProps];
-  auto paragraphProps = std::static_pointer_cast<const ParagraphProps>(props);
+
   assert(paragraphProps);
   _paragraphAttributes = paragraphProps->paragraphAttributes;
 }

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

@@ -12,6 +12,7 @@
 #import <fabric/core/LayoutMetrics.h>
 #import <fabric/core/Props.h>
 #import <fabric/components/view/ViewEventEmitter.h>
+#import <fabric/components/view/ViewProps.h>
 #import <fabric/events/EventEmitter.h>
 #import <React/RCTTouchableComponentViewProtocol.h>
 
@@ -23,7 +24,7 @@ NS_ASSUME_NONNULL_BEGIN
 @interface RCTViewComponentView : UIView <RCTComponentViewProtocol, RCTTouchableComponentViewProtocol> {
 @protected
   facebook::react::LayoutMetrics _layoutMetrics;
-  facebook::react::SharedProps _props;
+  facebook::react::SharedViewProps _props;
   facebook::react::SharedViewEventEmitter _eventEmitter;
 }
 

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

@@ -10,6 +10,7 @@
 #import <fabric/components/view/ViewProps.h>
 #import <fabric/components/view/ViewEventEmitter.h>
 #import <objc/runtime.h>
+#import <React/RCTAssert.h>
 #import <React/RCTBorderDrawing.h>
 
 #import "RCTConversions.h"
@@ -21,6 +22,16 @@ using namespace facebook::react;
   UIColor *_backgroundColor;
 }
 
+- (instancetype)initWithFrame:(CGRect)frame
+{
+  if (self = [super initWithFrame:frame]) {
+    static const auto defaultProps = std::make_shared<const ViewProps>();
+    _props = defaultProps;
+  }
+
+  return self;
+}
+
 - (void)setContentView:(UIView *)contentView
 {
   if (_contentView) {
@@ -65,13 +76,23 @@ using namespace facebook::react;
 - (void)updateProps:(SharedProps)props
            oldProps:(SharedProps)oldProps
 {
-  if (!oldProps) {
-    oldProps = _props ?: std::make_shared<ViewProps>();
-  }
-  _props = props;
+#ifndef NS_BLOCK_ASSERTIONS
+  auto propsRawPtr = _props.get();
+  RCTAssert(
+    propsRawPtr &&
+    (
+      [self class] == [RCTViewComponentView class] ||
+      typeid(*propsRawPtr).hash_code() != typeid(const ViewProps).hash_code()
+    ),
+    @"`RCTViewComponentView` subclasses (and `%@` particularly) must setup `_props`"
+      " instance variable with a default value in the constructor.", NSStringFromClass([self class])
+  );
+#endif
 
-  auto oldViewProps = *std::dynamic_pointer_cast<const ViewProps>(oldProps);
-  auto newViewProps = *std::dynamic_pointer_cast<const ViewProps>(props);
+  const auto &oldViewProps = *std::static_pointer_cast<const ViewProps>(oldProps ?: _props);
+  const auto &newViewProps = *std::static_pointer_cast<const ViewProps>(props);
+
+  _props = std::static_pointer_cast<const ViewProps>(props);
 
   BOOL needsInvalidateLayer = NO;
 
@@ -232,8 +253,7 @@ using namespace facebook::react;
 
 - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
 {
-  auto viewProps = *std::static_pointer_cast<const ViewProps>(_props);
-  switch (viewProps.pointerEvents) {
+  switch (_props->pointerEvents) {
     case PointerEventsMode::Auto:
       return [self betterHitTest:point withEvent:event];
     case PointerEventsMode::None:
@@ -286,10 +306,8 @@ static RCTBorderStyle RCTBorderStyleFromBorderStyle(BorderStyle borderStyle) {
 
 - (void)invalidateLayer
 {
-  const auto &props = *std::dynamic_pointer_cast<const ViewProps>(_props);
-
   const auto borderMetrics =
-    props.resolveBorderMetrics(_layoutMetrics.layoutDirection == LayoutDirection::RightToLeft);
+    _props->resolveBorderMetrics(_layoutMetrics.layoutDirection == LayoutDirection::RightToLeft);
 
   CALayer *layer = self.layer;
 
@@ -415,14 +433,14 @@ static RCTBorderStyle RCTBorderStyleFromBorderStyle(BorderStyle borderStyle) {
 
 - (NSArray<UIAccessibilityCustomAction *> *)accessibilityCustomActions
 {
-  const auto &accessibilityProps = *std::dynamic_pointer_cast<const AccessibilityProps>(_props);
+  const auto &accessibilityActions = _props->accessibilityActions;
 
-  if (accessibilityProps.accessibilityActions.size() == 0) {
+  if (accessibilityActions.size() == 0) {
     return nil;
   }
 
   NSMutableArray<UIAccessibilityCustomAction *> *customActions = [NSMutableArray array];
-  for (const auto &accessibilityAction : accessibilityProps.accessibilityActions) {
+  for (const auto &accessibilityAction : accessibilityActions) {
     [customActions addObject:[[UIAccessibilityCustomAction alloc] initWithName:RCTNSStringFromString(accessibilityAction)
                                                                         target:self
                                                                       selector:@selector(didActivateAccessibilityCustomAction:)]];