Implement lazy discovery for ViewManagers.

Reviewed By: kathryngray

Differential Revision: D5865095

fbshipit-source-id: c94970e4cd7aafb20cf844c48feea053ac8b6b0f

ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java

@@ -9,35 +9,53 @@
 
 package com.facebook.react.uimanager;
 
-import java.util.HashMap;
+import com.facebook.react.common.MapBuilder;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.Nullable;
 
 /**
  * Class that stores the mapping between native view name used in JS and the corresponding instance
  * of {@link ViewManager}.
  */
-public class ViewManagerRegistry {
+public final class ViewManagerRegistry {
 
   private final Map<String, ViewManager> mViewManagers;
+  private final @Nullable UIManagerModule.ViewManagerResolver mViewManagerResolver;
+
+  public ViewManagerRegistry(UIManagerModule.ViewManagerResolver viewManagerResolver) {
+    mViewManagers = MapBuilder.newHashMap();
+    mViewManagerResolver = viewManagerResolver;
+  }
 
   public ViewManagerRegistry(List<ViewManager> viewManagerList) {
-    mViewManagers = new HashMap<>();
+    Map<String, ViewManager> viewManagerMap = MapBuilder.newHashMap();
     for (ViewManager viewManager : viewManagerList) {
-      mViewManagers.put(viewManager.getName(), viewManager);
+      viewManagerMap.put(viewManager.getName(), viewManager);
     }
+
+    mViewManagers = viewManagerMap;
+    mViewManagerResolver = null;
   }
 
   public ViewManagerRegistry(Map<String, ViewManager> viewManagerMap) {
-    mViewManagers = viewManagerMap;
+    mViewManagers =
+        viewManagerMap != null ? viewManagerMap : MapBuilder.<String, ViewManager>newHashMap();
+    mViewManagerResolver = null;
   }
 
   public ViewManager get(String className) {
     ViewManager viewManager = mViewManagers.get(className);
     if (viewManager != null) {
       return viewManager;
-    } else {
-      throw new IllegalViewOperationException("No ViewManager defined for class " + className);
     }
+    if (mViewManagerResolver != null) {
+      viewManager = mViewManagerResolver.getViewManager(className);
+      if (viewManager != null) {
+        mViewManagers.put(className, viewManager);
+        return viewManager;
+      }
+    }
+    throw new IllegalViewOperationException("No ViewManager defined for class " + className);
   }
 }