Android: Refactor HierarchyOptimizer in preparation of inline view support

Summary:
This PR was split from commits originally in #8619. /cc dmmiller

These refactorings to the HierarchyOptimizer are in preparation for implementing support for inline views in #8619.

**Refactoring 1: Collapse add*LayoutOnlyNodeToLayoutOnlyNode**

addLayoutOnlyNodeToLayoutOnlyNode and addNonLayoutOnlyNodeToLayoutOnlyNode
had nearly identical implementations. They both walk thru the ancestors
looking for a nonlayout-only node and adjusting the passed in index at each
step. This introduces a new function, walkUpUntilNonLayoutOnly, which
takes care of that responsibility. This simplifies addNodeToNode
because it can now consider the type of the parent and the type of
the child independently.

**Refactoring 2: Extract addGrandchildren**

Pull out addLayoutOnlyNode's logic into a helper called
addGrandchildren. We will need to call this method in
another place later.

**Test plan (required)**

This change was tested with UIExplorer and a small test app and it's being used in my team's app.
Closes https://github.com/facebook/react-native/pull/8908

Differential Revision: D3592783

Pulled By: dmmiller

fbshipit-source-id: a513e8d381e71112ce6348bbee7d4a7c62c33619

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

@@ -52,6 +52,16 @@ import com.facebook.react.bridge.ReadableMapKeySetIterator;
  */
 public class NativeViewHierarchyOptimizer {
 
+  private static class NodeIndexPair {
+    public final ReactShadowNode node;
+    public final int index;
+
+    NodeIndexPair(ReactShadowNode node, int index) {
+      this.node = node;
+      this.index = index;
+    }
+  }
+
   private static final boolean ENABLED = true;
 
   private final UIViewOperationQueue mUIViewOperationQueue;
@@ -221,21 +231,39 @@ public class NativeViewHierarchyOptimizer {
     mTagsWithLayoutVisited.clear();
   }
 
+  private NodeIndexPair walkUpUntilNonLayoutOnly(
+      ReactShadowNode node,
+      int indexInNativeChildren) {
+    while (node.isLayoutOnly()) {
+      ReactShadowNode parent = node.getParent();
+      if (parent == null) {
+        return null;
+      }
+
+      indexInNativeChildren = indexInNativeChildren + parent.getNativeOffsetForChild(node);
+      node = parent;
+    }
+
+    return new NodeIndexPair(node, indexInNativeChildren);
+  }
+
   private void addNodeToNode(ReactShadowNode parent, ReactShadowNode child, int index) {
     int indexInNativeChildren = parent.getNativeOffsetForChild(parent.getChildAt(index));
-    boolean parentIsLayoutOnly = parent.isLayoutOnly();
+    if (parent.isLayoutOnly()) {
-    boolean childIsLayoutOnly = child.isLayoutOnly();
+      NodeIndexPair result = walkUpUntilNonLayoutOnly(parent, indexInNativeChildren);
+      if (result == null) {
+        // If the parent hasn't been attached to its native parent yet, don't issue commands to the
+        // native hierarchy. We'll do that when the parent node actually gets attached somewhere.
+        return;
+      }
+      parent = result.node;
+      indexInNativeChildren = result.index;
+    }
 
-    // Switch on the four cases of:
+    if (!child.isLayoutOnly()) {
-    //   add (layout-only|not layout-only) to (layout-only|not layout-only)
+      addNonLayoutNode(parent, child, indexInNativeChildren);
-    if (!parentIsLayoutOnly && !childIsLayoutOnly) {
-      addNonLayoutNodeToNonLayoutNode(parent, child, indexInNativeChildren);
-    } else if (!childIsLayoutOnly) {
-      addNonLayoutOnlyNodeToLayoutOnlyNode(parent, child, indexInNativeChildren);
-    } else if (!parentIsLayoutOnly) {
-      addLayoutOnlyNodeToNonLayoutOnlyNode(parent, child, indexInNativeChildren);
     } else {
-      addLayoutOnlyNodeToLayoutOnlyNode(parent, child, indexInNativeChildren);
+      addLayoutOnlyNode(parent, child, indexInNativeChildren);
     }
   }
 
@@ -262,73 +290,14 @@ public class NativeViewHierarchyOptimizer {
     }
   }
 
-  private void addLayoutOnlyNodeToLayoutOnlyNode(
+  private void addLayoutOnlyNode(
-      ReactShadowNode parent,
-      ReactShadowNode child,
-      int index) {
-    ReactShadowNode parentParent = parent.getParent();
-
-    // If the parent hasn't been attached to its parent yet, don't issue commands to the native
-    // hierarchy. We'll do that when the parent node actually gets attached somewhere.
-    if (parentParent == null) {
-      return;
-    }
-
-    int transformedIndex = index + parentParent.getNativeOffsetForChild(parent);
-    if (parentParent.isLayoutOnly()) {
-      addLayoutOnlyNodeToLayoutOnlyNode(parentParent, child, transformedIndex);
-    } else {
-      addLayoutOnlyNodeToNonLayoutOnlyNode(parentParent, child, transformedIndex);
-    }
-  }
-
-  private void addNonLayoutOnlyNodeToLayoutOnlyNode(
-      ReactShadowNode layoutOnlyNode,
-      ReactShadowNode nonLayoutOnlyNode,
-      int index) {
-    ReactShadowNode parent = layoutOnlyNode.getParent();
-
-    // If the parent hasn't been attached to its parent yet, don't issue commands to the native
-    // hierarchy. We'll do that when the parent node actually gets attached somewhere.
-    if (parent == null) {
-      return;
-    }
-
-    int transformedIndex = index + parent.getNativeOffsetForChild(layoutOnlyNode);
-    if (parent.isLayoutOnly()) {
-      addNonLayoutOnlyNodeToLayoutOnlyNode(parent, nonLayoutOnlyNode, transformedIndex);
-    } else {
-      addNonLayoutNodeToNonLayoutNode(parent, nonLayoutOnlyNode, transformedIndex);
-    }
-  }
-
-  private void addLayoutOnlyNodeToNonLayoutOnlyNode(
       ReactShadowNode nonLayoutOnlyNode,
       ReactShadowNode layoutOnlyNode,
       int index) {
-    // Add all of the layout-only node's children to its parent instead
+    addGrandchildren(nonLayoutOnlyNode, layoutOnlyNode, index);
-    int currentIndex = index;
-    for (int i = 0; i < layoutOnlyNode.getChildCount(); i++) {
-      ReactShadowNode childToAdd = layoutOnlyNode.getChildAt(i);
-      Assertions.assertCondition(childToAdd.getNativeParent() == null);
-
-      if (childToAdd.isLayoutOnly()) {
-        // Adding this layout-only child could result in adding multiple native views
-        int childCountBefore = nonLayoutOnlyNode.getNativeChildCount();
-        addLayoutOnlyNodeToNonLayoutOnlyNode(
-            nonLayoutOnlyNode,
-            childToAdd,
-            currentIndex);
-        int childCountAfter = nonLayoutOnlyNode.getNativeChildCount();
-        currentIndex += childCountAfter - childCountBefore;
-      } else {
-        addNonLayoutNodeToNonLayoutNode(nonLayoutOnlyNode, childToAdd, currentIndex);
-        currentIndex++;
-      }
-    }
   }
 
-  private void addNonLayoutNodeToNonLayoutNode(
+  private void addNonLayoutNode(
       ReactShadowNode parent,
       ReactShadowNode child,
       int index) {
@@ -340,6 +309,31 @@ public class NativeViewHierarchyOptimizer {
         null);
   }
 
+  private void addGrandchildren(
+      ReactShadowNode nativeParent,
+      ReactShadowNode child,
+      int index) {
+    Assertions.assertCondition(!nativeParent.isLayoutOnly());
+
+    // `child` can't hold native children. Add all of `child`'s children to `parent`.
+    int currentIndex = index;
+    for (int i = 0; i < child.getChildCount(); i++) {
+      ReactShadowNode grandchild = child.getChildAt(i);
+      Assertions.assertCondition(grandchild.getNativeParent() == null);
+
+      if (grandchild.isLayoutOnly()) {
+        // Adding this child could result in adding multiple native views
+        int grandchildCountBefore = nativeParent.getNativeChildCount();
+        addLayoutOnlyNode(nativeParent, grandchild, currentIndex);
+        int grandchildCountAfter = nativeParent.getNativeChildCount();
+        currentIndex += grandchildCountAfter - grandchildCountBefore;
+      } else {
+        addNonLayoutNode(nativeParent, grandchild, currentIndex);
+        currentIndex++;
+      }
+    }
+  }
+
   private void applyLayoutBase(ReactShadowNode node) {
     int tag = node.getReactTag();
     if (mTagsWithLayoutVisited.get(tag)) {