From e4194a20a7a8ba2bfe3f76f9fec38c04687bdf1e Mon Sep 17 00:00:00 2001
From: David Vacca <dvacca@fb.com>
Date: Fri, 31 Jan 2020 17:04:02 -0800
Subject: [PATCH] Return null when requesting constants for nonexistent View
 Managers in RN Android

Summary:
This diff changes the behavior of UIImplementation.resolveViewManager() to return null instead of throwing an exception when trying to find an unexistent viewManager during the computation of constants for view Managers.

The C++/JS code manages exceptions and null results when a view manager doesn't exists, this diff simplifies the way this method operates.

changeLog: [internal]

Reviewed By: rickhanlonii

Differential Revision: D19624423

fbshipit-source-id: df31dcfae9a588bf325b61d529cec6ead59fb19d
---
 .../react/uimanager/UIImplementation.java     |  4 +-
 .../react/uimanager/ViewManagerRegistry.java  | 40 ++++++++++++++++---
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
index 6328a81075..3bdce77ef3 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
@@ -128,8 +128,8 @@ public class UIImplementation {
     return mShadowNodeRegistry.getNode(reactTag);
   }
 
-  protected final ViewManager resolveViewManager(String className) {
-    return mViewManagers.get(className);
+  protected final @Nullable ViewManager resolveViewManager(String className) {
+    return mViewManagers.getViewManagerIfExists(className);
   }
 
   /*package*/ UIViewOperationQueue getUIViewOperationQueue() {
diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java
index debd5ecef2..73c37c10f1 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java
@@ -42,19 +42,49 @@ public final class ViewManagerRegistry {
     mViewManagerResolver = null;
   }
 
+  /**
+   * @param className {@link String} that identifies the {@link ViewManager} inside the {@link
+   *     ViewManagerRegistry}. This methods {@throws IllegalViewOperationException} if there is no
+   *     view manager registered for the className received as a parameter.
+   * @return the {@link ViewManager} registered to the className received as a parameter
+   */
   public ViewManager get(String className) {
     ViewManager viewManager = mViewManagers.get(className);
     if (viewManager != null) {
       return viewManager;
     }
     if (mViewManagerResolver != null) {
-      viewManager = mViewManagerResolver.getViewManager(className);
-      if (viewManager != null) {
-        mViewManagers.put(className, viewManager);
-        return viewManager;
-      }
+      viewManager = getViewManagerFromResolver(className);
+      if (viewManager != null) return viewManager;
       throw new IllegalViewOperationException("ViewManagerResolver returned null for " + className);
     }
     throw new IllegalViewOperationException("No ViewManager found for class " + className);
   }
+
+  private @Nullable ViewManager getViewManagerFromResolver(String className) {
+    @Nullable ViewManager viewManager;
+    viewManager = mViewManagerResolver.getViewManager(className);
+    if (viewManager != null) {
+      mViewManagers.put(className, viewManager);
+    }
+    return viewManager;
+  }
+
+  /**
+   * @param className {@link String} that identifies the {@link ViewManager} inside the {@link
+   *     ViewManagerRegistry}.
+   * @return the {@link ViewManager} registered to the className received as a parameter or null if
+   *     there is no ViewManager associated to the className received as a parameter.
+   */
+  @Nullable
+  ViewManager getViewManagerIfExists(String className) {
+    ViewManager viewManager = mViewManagers.get(className);
+    if (viewManager != null) {
+      return viewManager;
+    }
+    if (mViewManagerResolver != null) {
+      return getViewManagerFromResolver(className);
+    }
+    return null;
+  }
 }