Event name normalization (#42586)

Summary:
Pull Request resolved: #42586

Every event name must be normalized.

The normalization strategy is:
1. If it starts with `top` -> do nothing.
2. If it starts with `on` -> replace `on` with `top`.
3. Else -> capitalize the first character and prepend `top`.

We have it for the old renderer on iOS [here](https://github.com/facebook/react-native/blob/a7586947d719a9cd2344ad346d271e7ca900de87/packages/react-native/React/Base/RCTEventDispatcher.m#L12-L21). This one is also used by the interop layer.
Static ViewConfigs being a part of the new renderer [replicate](https://github.com/facebook/react-native/blob/a7586947d719a9cd2344ad346d271e7ca900de87/packages/react-native-codegen/src/generators/components/GenerateViewConfigJs.js#L164-L172) this behavior to match the old rendered.

The Android that we have is incomplete, it is missing the [*2. If it starts with `on` -> replace `on` with `top`*]. This means that some events names that worked with the old renderer would not be compatible with the new renderer + Static ViewConfigs. Specifically every event names that start with `on`.

This diff implements event name normalization on Android.

Changelog: [Internal] - Update event normalization algorithm to match SVCs.

Reviewed By: cortinico

Differential Revision: D50604571

fbshipit-source-id: cef34d8baa2cf31f641be423a16bca7ea9fa20c4

packages/react-native-codegen/e2e/__tests__/components/__snapshots__/GenerateViewConfigJs-test.js.snap

@@ -294,7 +294,7 @@ export const __INTERNAL_VIEW_CONFIG = {
   uiViewClassName: 'EventPropsNativeComponentView',
 
   bubblingEventTypes: {
-    paperDirectName: {
+    topPaperDirectName: {
       phasedRegistrationNames: {
         captured: 'onChangeCapture',
         bubbled: 'onChange',
@@ -308,7 +308,7 @@ export const __INTERNAL_VIEW_CONFIG = {
       },
     },
 
-    paperBubblingName: {
+    topPaperBubblingName: {
       phasedRegistrationNames: {
         captured: 'onEventBubblingWithPaperNameCapture',
         bubbled: 'onEventBubblingWithPaperName',
@@ -321,11 +321,11 @@ export const __INTERNAL_VIEW_CONFIG = {
       registrationName: 'onEventDirect',
     },
 
-    paperDirectName: {
+    topPaperDirectName: {
       registrationName: 'onEventDirectWithPaperName',
     },
 
-    paperBubblingName: {
+    topPaperBubblingName: {
       registrationName: 'onOrientationChange',
     },
   },

packages/react-native-codegen/src/generators/components/GenerateViewConfigJs.js

@@ -197,7 +197,7 @@ function generateBubblingEventInfo(
 ) {
   return j.property(
     'init',
-    j.identifier(nameOveride || normalizeInputEventName(event.name)),
+    j.identifier(normalizeInputEventName(nameOveride || event.name)),
     j.objectExpression([
       j.property(
         'init',
@@ -221,7 +221,7 @@ function generateDirectEventInfo(
 ) {
   return j.property(
     'init',
-    j.identifier(nameOveride || normalizeInputEventName(event.name)),
+    j.identifier(normalizeInputEventName(nameOveride || event.name)),
     j.objectExpression([
       j.property(
         'init',

packages/react-native-codegen/src/generators/components/__tests__/__snapshots__/GenerateViewConfigJs-test.js.snap

@@ -468,7 +468,7 @@ export const __INTERNAL_VIEW_CONFIG = {
   uiViewClassName: 'RCTInterfaceOnlyComponent',
 
   bubblingEventTypes: {
-    paperChange: {
+    topPaperChange: {
       phasedRegistrationNames: {
         captured: 'onChangeCapture',
         bubbled: 'onChange',
@@ -477,7 +477,7 @@ export const __INTERNAL_VIEW_CONFIG = {
   },
 
   directEventTypes: {
-    paperDirectChange: {
+    topPaperDirectChange: {
       registrationName: 'onDirectChange',
     },
   },

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModuleConstantsHelper.java

@@ -206,7 +206,15 @@ private static void validateDirectEventNames(
     }
     for (String oldKey : keysToNormalize) {
       Object value = events.get(oldKey);
-      String newKey = "top" + oldKey.substring(0, 1).toUpperCase() + oldKey.substring(1);
+      String baseKey = "";
+      if (oldKey.startsWith("on")) {
+        // Drop "on" prefix.
+        baseKey = oldKey.substring(2);
+      } else {
+        // Capitalize first letter.
+        baseKey = oldKey.substring(0, 1).toUpperCase() + oldKey.substring(1);
+      }
+      String newKey = "top" + baseKey;
       events.put(newKey, value);
     }
   }

packages/react-native/ReactAndroid/src/test/java/com/facebook/react/uimanager/UIManagerModuleConstantsHelperTest.kt

@@ -32,7 +32,7 @@ class UIManagerModuleConstantsHelperTest {
     val onClickMap: Map<String, String> =
         MapBuilder.builder<String, String>().put("onClick", "¯\\_(ツ)_/¯").build()
     UIManagerModuleConstantsHelper.normalizeEventTypes(onClickMap)
-    assertTrue(onClickMap.containsKey("topOnClick"))
+    assertTrue(onClickMap.containsKey("topClick"))
     assertTrue(onClickMap.containsKey("onClick"))
   }
 
@@ -58,16 +58,16 @@ class UIManagerModuleConstantsHelperTest {
                         "bubbled", "onColorChanged", "captured", "onColorChangedCapture")))
             .build()
     UIManagerModuleConstantsHelper.normalizeEventTypes(nestedObjects)
-    assertTrue(nestedObjects.containsKey("topOnColorChanged"))
-    var innerMap = nestedObjects["topOnColorChanged"] as? Map<String, Any?>
+    assertTrue(nestedObjects.containsKey("topColorChanged"))
+    var innerMap = nestedObjects["topColorChanged"] as? Map<String, Any?>
     assertNotNull(innerMap)
     assertTrue(innerMap!!.containsKey("phasedRegistrationNames"))
     var innerInnerMap = innerMap.get("phasedRegistrationNames") as? Map<String, Any?>
     assertNotNull(innerInnerMap)
     assertEquals("onColorChanged", innerInnerMap!!.get("bubbled"))
     assertEquals("onColorChangedCapture", innerInnerMap.get("captured"))
     assertTrue(nestedObjects.containsKey("onColorChanged"))
-    innerMap = nestedObjects.get("topOnColorChanged") as? Map<String, Any?>
+    innerMap = nestedObjects.get("topColorChanged") as? Map<String, Any?>
     assertNotNull(innerMap)
     assertTrue(innerMap!!.containsKey("phasedRegistrationNames"))
     innerInnerMap = innerMap.get("phasedRegistrationNames") as? Map<String, Any?>

packages/react-native/ReactCommon/react/renderer/core/EventEmitter.cpp

@@ -16,18 +16,26 @@
 
 namespace facebook::react {
 
+static bool hasPrefix(const std::string& str, const std::string& prefix) {
+  return str.compare(0, prefix.length(), prefix) == 0;
+}
+
 // TODO(T29874519): Get rid of "top" prefix once and for all.
 /*
- * Capitalizes the first letter of the event type and adds "top" prefix if
- * necessary (e.g. "layout" becames "topLayout").
+ * Replaces "on" with "top" if present. Or capitalizes the first letter and adds
+ * "top" prefix. E.g. "eventName" becomes "topEventName", "onEventName" also
+ * becomes "topEventName".
  */
 static std::string normalizeEventType(std::string type) {
   auto prefixedType = std::move(type);
-  if (prefixedType.find("top", 0) != 0) {
-    prefixedType.insert(0, "top");
-    prefixedType[3] = static_cast<char>(toupper(prefixedType[3]));
+  if (facebook::react::hasPrefix(prefixedType, "top")) {
+    return prefixedType;
+  }
+  if (facebook::react::hasPrefix(prefixedType, "on")) {
+    return "top" + prefixedType.substr(2);
   }
-  return prefixedType;
+  prefixedType[0] = static_cast<char>(toupper(prefixedType[0]));
+  return "top" + prefixedType;
 }
 
 std::mutex& EventEmitter::DispatchMutex() {