Support setting partial state from Android, and filling in data with previous State constructor

Summary:
iOS and other platforms have direct access to C++ StateT structs, whereas Java only has access to a Java map equivalent - state updates from Java can't update complex types, or must incur significant cost to reconstruct large objects from their folly::dynamic representation (not to mention the complexity of implementing the Java-to-C++ struct converters). Thus it's hard for Java to update StateT's with complex types on the C++ side.

This diff makes a minor change to Android's updateState which uses both the folly::dynamic data from Java as well as the previous State, so each StateT can have fields that are read-only from the Java perspective.

Motivation: For AndroidTextInput we need to set params from Java, without being able to send all of the State params from Java.

In this diff, we introduce a new State constructor that takes the previous State value and a folly::dynamic. It is up to each State implementation how the additional parameter will be used.

We migrate every existing component except for AndroidTextInput in this diff.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D18672365

fbshipit-source-id: 4469e0a3c7658c204089c6fed39394979883f124

ReactCommon/fabric/components/modal/ModalHostViewState.h

@@ -29,7 +29,9 @@ class ModalHostViewState final {
   ModalHostViewState(Size screenSize_) : screenSize(screenSize_){};
 
 #ifdef ANDROID
-  ModalHostViewState(folly::dynamic data)
+  ModalHostViewState(
+      ModalHostViewState const &previousState,
+      folly::dynamic data)
       : screenSize(Size{(Float)data["screenWidth"].getDouble(),
                         (Float)data["screenHeight"].getDouble()}){};
 #endif

ReactCommon/fabric/components/scrollview/ScrollViewState.h

@@ -29,7 +29,7 @@ class ScrollViewState final {
 
 #ifdef ANDROID
   ScrollViewState() = default;
-  ScrollViewState(folly::dynamic data){};
+  ScrollViewState(ScrollViewState const &previousState, folly::dynamic data){};
   folly::dynamic getDynamic() const {
     return {};
   };

ReactCommon/fabric/components/text/paragraph/ParagraphState.h

@@ -51,7 +51,9 @@ class ParagraphState final {
         paragraphAttributes(paragraphAttributes),
         layoutManager(layoutManager) {}
   ParagraphState() = default;
-  ParagraphState(folly::dynamic const &data) {
+  ParagraphState(
+      ParagraphState const &previousState,
+      folly::dynamic const &data) {
     assert(false && "Not supported");
   };
   folly::dynamic getDynamic() const;

ReactCommon/fabric/components/textinput/androidtextinput/AndroidTextInputState.h

@@ -51,7 +51,9 @@ class AndroidTextInputState final {
         paragraphAttributes(paragraphAttributes),
         layoutManager(layoutManager) {}
   AndroidTextInputState() = default;
-  AndroidTextInputState(folly::dynamic const &data) {
+  AndroidTextInputState(
+      AndroidTextInputState const &previousState,
+      folly::dynamic const &data) {
     assert(false && "Not supported");
   };
   folly::dynamic getDynamic() const;

ReactCommon/fabric/core/state/ConcreteState.h

@@ -91,7 +91,7 @@ class ConcreteState : public State {
   }
 
   void updateState(folly::dynamic data) const override {
-    updateState(std::move(Data(data)));
+    updateState(std::move(Data(data_, data)));
   }
 #endif
 

ReactCommon/fabric/core/state/StateData.h

@@ -25,7 +25,7 @@ struct StateData final {
 
 #ifdef ANDROID
   StateData() = default;
-  StateData(folly::dynamic data){};
+  StateData(StateData const &previousState, folly::dynamic data){};
   folly::dynamic getDynamic() const;
 #endif
 };