Remember ShadowNode of RawText's parent in attribute string

Summary:
When a user clicks on some text, `RCTSurfaceTouchHandler` will call into a method on `RCTParagraphComponentView`. That method (i.e: `touchEventEmitter`) would be responsible for identifying the closest ancestral `<Text/>` component to which we should dispatch the `onPress` event, given the point where the user clicked. To answer this query, we'll use a data structure called `UIAttributedString`.

This data structure represents a string, and a corresponding mapping from sequences of its characters to some arbitrary data. In this attributed string, we'll map sequences of characters to their closest ancestral `ParagraphShadowNode` or `TextShadowNode`. That way, when we get a click event on `RCTParagraphComponentView`, we can just look at the character that was clicked, and use that information to do a lookup in the attributed string to find the shadow node who's EventEmitter is responsible for processing the click event.

Reviewed By: shergin

Differential Revision: D9696904

fbshipit-source-id: a199649981ad271afa85414ce4c3f056851348be

ReactCommon/fabric/attributedstring/AttributedString.h

@@ -39,6 +39,7 @@ public:
     std::string string;
     TextAttributes textAttributes;
     SharedShadowNode shadowNode;
+    SharedShadowNode parentShadowNode;
   };
 
   using Fragments = std::vector<Fragment>;

ReactCommon/fabric/components/text/basetext/BaseTextShadowNode.cpp

@@ -29,6 +29,7 @@ AttributedString BaseTextShadowNode::getAttributedString(
       AttributedString::Fragment fragment;
       fragment.string = rawTextShadowNode->getProps()->text;
       fragment.textAttributes = textAttributes;
+      fragment.parentShadowNode = parentNode;
       attributedString.appendFragment(fragment);
       continue;
     }

ReactCommon/fabric/textlayoutmanager/platform/ios/RCTAttributedTextUtils.h

@@ -13,11 +13,15 @@
 NS_ASSUME_NONNULL_BEGIN
 
 NSString *const RCTAttributedStringIsHighlightedAttributeName = @"IsHighlighted";
-NSString *const RCTAttributedStringReactTagAttributeName = @"ReactTag";
+NSString *const RCTAttributedStringParentShadowNode = @"ParentShadowNode";
 
 /**
  * Constructs ready-to-render `NSAttributedString` by given `AttributedString`.
  */
 NSAttributedString *RCTNSAttributedStringFromAttributedString(const facebook::react::AttributedString &attributedString);
 
+@interface RCTSharedShadowNodeWrapper : NSObject
+@property (nonatomic, assign) facebook::react::SharedShadowNode node;
+@end
+
 NS_ASSUME_NONNULL_END

ReactCommon/fabric/textlayoutmanager/platform/ios/RCTAttributedTextUtils.mm

@@ -12,6 +12,9 @@
 #include <fabric/textlayoutmanager/RCTFontUtils.h>
 #include <fabric/textlayoutmanager/RCTTextPrimitivesConversions.h>
 
+@implementation RCTSharedShadowNodeWrapper
+@end
+
 inline static UIFont *RCTEffectiveFontFromTextAttributes(const TextAttributes &textAttributes) {
   NSString *fontFamily = [NSString stringWithCString:textAttributes.fontFamily.c_str()
                                             encoding:NSUTF8StringEncoding];
@@ -209,12 +212,15 @@ NSAttributedString *RCTNSAttributedStringFromAttributedString(const AttributedSt
     NSMutableAttributedString *nsMutableAttributedStringFragment =
       [[NSMutableAttributedString alloc] initWithAttributedString:nsAttributedStringFragment];
 
-    if (fragment.shadowNode) {
+    if (fragment.parentShadowNode) {
+      RCTSharedShadowNodeWrapper *parentShadowNode = [RCTSharedShadowNodeWrapper new];
+      parentShadowNode.node = fragment.parentShadowNode;
+      
       NSDictionary<NSAttributedStringKey, id> *additionalTextAttributes = @{
-        RCTAttributedStringReactTagAttributeName: @(fragment.shadowNode->getTag())
+        RCTAttributedStringParentShadowNode: parentShadowNode
       };
 
-      [nsMutableAttributedStringFragment setAttributes:additionalTextAttributes
+      [nsMutableAttributedStringFragment addAttributes:additionalTextAttributes
                                                  range:NSMakeRange(0, nsMutableAttributedStringFragment.length)];
     }