Add incomplete support for accessibility state prop

Summary:
Changelog: [internal]

Minimal implementation of `accessibilityState` that supports `disabled` and `selected` props.

Complete implementation will need to support following props
```
export type AccessibilityState = {
  disabled?: boolean,
  selected?: boolean,
  checked?: ?boolean | 'mixed',
  busy?: boolean,
  expanded?: boolean,
  ...
};
```

Reviewed By: mdvacca

Differential Revision: D22016743

fbshipit-source-id: 1748acc4279f60ec8a92c93d5d13b136f57eb8d3

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

@@ -228,11 +228,23 @@ using namespace facebook::react;
     self.accessibilityElement.accessibilityElementsHidden = newViewProps.accessibilityElementsHidden;
   }
 
+  // `accessibilityTraits`
   if (oldViewProps.accessibilityTraits != newViewProps.accessibilityTraits) {
     self.accessibilityElement.accessibilityTraits =
         RCTUIAccessibilityTraitsFromAccessibilityTraits(newViewProps.accessibilityTraits);
   }
 
+  // `accessibilityState`
+  if (oldViewProps.accessibilityState != newViewProps.accessibilityState) {
+    self.accessibilityTraits &= ~(UIAccessibilityTraitNotEnabled | UIAccessibilityTraitSelected);
+    if (newViewProps.accessibilityState.selected) {
+      self.accessibilityTraits |= UIAccessibilityTraitSelected;
+    }
+    if (newViewProps.accessibilityState.disabled) {
+      self.accessibilityTraits |= UIAccessibilityTraitNotEnabled;
+    }
+  }
+
   // `accessibilityIgnoresInvertColors`
   if (oldViewProps.accessibilityIgnoresInvertColors != newViewProps.accessibilityIgnoresInvertColors) {
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */

ReactCommon/fabric/components/view/accessibility/AccessibilityPrimitives.h

@@ -44,5 +44,22 @@ constexpr enum AccessibilityTraits operator&(
   return (enum AccessibilityTraits)((uint32_t)lhs & (uint32_t)rhs);
 }
 
+struct AccessibilityState {
+  bool disabled{false};
+  bool selected{false};
+};
+
+constexpr bool operator==(
+    AccessibilityState const &lhs,
+    AccessibilityState const &rhs) {
+  return lhs.disabled == rhs.disabled && lhs.selected == rhs.selected;
+}
+
+constexpr bool operator!=(
+    AccessibilityState const &lhs,
+    AccessibilityState const &rhs) {
+  return !(rhs == lhs);
+}
+
 } // namespace react
 } // namespace facebook

ReactCommon/fabric/components/view/accessibility/AccessibilityProps.cpp

@@ -28,6 +28,11 @@ AccessibilityProps::AccessibilityProps(
           "accessibilityRole",
           sourceProps.accessibilityTraits,
           AccessibilityTraits::None)),
+      accessibilityState(convertRawProp(
+          rawProps,
+          "accessibilityState",
+          sourceProps.accessibilityState,
+          {})),
       accessibilityLabel(convertRawProp(
           rawProps,
           "accessibilityLabel",

ReactCommon/fabric/components/view/accessibility/AccessibilityProps.h

@@ -26,6 +26,7 @@ class AccessibilityProps {
 
   bool accessible{false};
   AccessibilityTraits accessibilityTraits{AccessibilityTraits::None};
+  AccessibilityState accessibilityState;
   std::string accessibilityLabel{""};
   std::string accessibilityHint{""};
   std::vector<std::string> accessibilityActions{};

ReactCommon/fabric/components/view/accessibility/accessibilityPropsConversions.h

@@ -9,6 +9,7 @@
 
 #include <folly/dynamic.h>
 #include <react/components/view/AccessibilityPrimitives.h>
+#include <react/core/propsConversions.h>
 
 namespace facebook {
 namespace react {
@@ -109,5 +110,17 @@ inline void fromRawValue(const RawValue &value, AccessibilityTraits &result) {
   abort();
 }
 
+inline void fromRawValue(const RawValue &value, AccessibilityState &result) {
+  auto map = (better::map<std::string, RawValue>)value;
+  auto selected = map.find("selected");
+  if (selected != map.end()) {
+    fromRawValue(selected->second, result.selected);
+  }
+  auto disabled = map.find("disabled");
+  if (disabled != map.end()) {
+    fromRawValue(disabled->second, result.disabled);
+  }
+}
+
 } // namespace react
 } // namespace facebook