Only sets unsets tag if actually set

Summary: Only sets unsets tag if actually set

Reviewed By: pentiumao, kingsleyadio

Differential Revision: D44170172

fbshipit-source-id: d211b5354254f6ec6f7304771b683201ee47f702

Author: adityasharat

litho-core/src/main/java/com/facebook/litho/LithoViewAttributesExtension.java

@@ -214,7 +214,9 @@ static void setViewAttributes(Object content, ViewAttributes attributes, RenderU
     }
 
     setViewId(view, attributes.getViewId());
-    setViewTag(view, attributes.getViewTag());
+    if (attributes.isTagSet()) {
+      setViewTag(view, attributes.getViewTag());
+    }
     setViewTags(view, attributes.getViewTags());
 
     setShadowElevation(view, attributes.getShadowElevation());
@@ -297,7 +299,9 @@ static void unsetViewAttributes(
       unsetInterceptTouchEventHandler(view);
     }
 
-    unsetViewTag(view);
+    if (attributes.isTagSet()) {
+      unsetViewTag(view);
+    }
     unsetViewTags(view, attributes.getViewTags());
 
     unsetShadowElevation(view, attributes.getShadowElevation());
@@ -550,9 +554,7 @@ private static void setViewId(View view, @IdRes int id) {
   }
 
   private static void setViewTag(View view, @Nullable Object viewTag) {
-    if (viewTag != null) {
-      view.setTag(viewTag);
-    }
+    view.setTag(viewTag);
   }
 
   private static void setViewTags(View view, @Nullable SparseArray<Object> viewTags) {

litho-core/src/main/java/com/facebook/litho/ViewAttributes.kt

@@ -43,6 +43,11 @@ class ViewAttributes {
   var contentDescription: CharSequence? = null
   var viewId: Int = View.NO_ID
   var viewTag: Any? = null
+    set(value) {
+      field = value
+      flags = flags or FLAG_VIEW_TAG
+    }
+
   var transitionName: String? = null
   var viewTags: SparseArray<Any>? = null
   var outlineProvider: ViewOutlineProvider? = null
@@ -174,6 +179,8 @@ class ViewAttributes {
     get() = flags and FLAG_ROTATION_X != 0
   val isRotationYSet: Boolean
     get() = flags and FLAG_ROTATION_Y != 0
+  val isTagSet: Boolean
+    get() = flags and FLAG_VIEW_TAG != 0
 
   fun hasPadding(): Boolean = padding != null
 
@@ -335,5 +342,7 @@ class ViewAttributes {
     private const val FLAG_SHADOW_ELEVATION = 1 shl 12
     private const val FLAG_AMBIENT_SHADOW_COLOR = 1 shl 13
     private const val FLAG_SPOT_SHADOW_COLOR = 1 shl 14
+
+    private const val FLAG_VIEW_TAG = 1 shl 15
   }
 }