From de36e85004dce6ef0f2cee9208bfee9036db7e04 Mon Sep 17 00:00:00 2001
From: Aditya Sharat <adityasharat@fb.com>
Date: Tue, 16 Feb 2021 10:17:36 -0800
Subject: [PATCH] Adds InternalNode#freeze() API

Summary:
Litho needs a new API which is called immediately before yoga begins layout calculations so that the InternalNode gets the opportunity to finalise itself; i.e. perform the last mutations and in effect avoid any more mutations to the hierarchy.

See D26373731 where the mutations from `Layout#collectResults` is moved back into the InternalNode.

Changelog: [Internal]  Adds new API to YogaNodeJNIBase

Reviewed By: SidharthGuglani

Differential Revision: D26373730

fbshipit-source-id: 471346d3444986ada91e86c95f5f9fb98bcd2fa6
---
 java/com/facebook/yoga/YogaNode.java        | 18 ++++++++++++------
 java/com/facebook/yoga/YogaNodeJNIBase.java | 14 +++++++++++++-
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/java/com/facebook/yoga/YogaNode.java b/java/com/facebook/yoga/YogaNode.java
index 9fc8bac9..dfec8ec5 100644
--- a/java/com/facebook/yoga/YogaNode.java
+++ b/java/com/facebook/yoga/YogaNode.java
@@ -10,6 +10,14 @@ package com.facebook.yoga;
 import javax.annotation.Nullable;
 
 public abstract class YogaNode {
+
+  /** The interface the {@link #getData()} object can optionally implement. */
+  public interface Inputs {
+
+    /** Requests the data object to disable mutations of its inputs. */
+    void freeze();
+  }
+
   public abstract void reset();
 
   public abstract int getChildCount();
@@ -25,12 +33,10 @@ public abstract class YogaNode {
   public abstract YogaNode removeChildAt(int i);
 
   /**
-   * @returns the {@link YogaNode} that owns this {@link YogaNode}.
-   * The owner is used to identify the YogaTree that a {@link YogaNode} belongs
-   * to.
-   * This method will return the parent of the {@link YogaNode} when the
-   * {@link YogaNode} only belongs to one YogaTree or null when the
-   * {@link YogaNode} is shared between two or more YogaTrees.
+   * @returns the {@link YogaNode} that owns this {@link YogaNode}. The owner is used to identify
+   *     the YogaTree that a {@link YogaNode} belongs to. This method will return the parent of the
+   *     {@link YogaNode} when the {@link YogaNode} only belongs to one YogaTree or null when the
+   *     {@link YogaNode} is shared between two or more YogaTrees.
    */
   @Nullable
   public abstract YogaNode getOwner();
diff --git a/java/com/facebook/yoga/YogaNodeJNIBase.java b/java/com/facebook/yoga/YogaNodeJNIBase.java
index 6b3dcd26..03354556 100644
--- a/java/com/facebook/yoga/YogaNodeJNIBase.java
+++ b/java/com/facebook/yoga/YogaNodeJNIBase.java
@@ -197,12 +197,17 @@ public abstract class YogaNodeJNIBase extends YogaNode implements Cloneable {
     long[] nativePointers = null;
     YogaNodeJNIBase[] nodes = null;
 
+    freeze();
+
     ArrayList<YogaNodeJNIBase> n = new ArrayList<>();
     n.add(this);
     for (int i = 0; i < n.size(); ++i) {
       List<YogaNodeJNIBase> children = n.get(i).mChildren;
       if (children != null) {
-        n.addAll(children);
+        for (YogaNodeJNIBase child : children) {
+          child.freeze();
+          n.add(child);
+        }
       }
     }
 
@@ -215,6 +220,13 @@ public abstract class YogaNodeJNIBase extends YogaNode implements Cloneable {
     YogaNative.jni_YGNodeCalculateLayoutJNI(mNativePointer, width, height, nativePointers, nodes);
   }
 
+  private void freeze() {
+    Object data = getData();
+    if (data instanceof Inputs) {
+      ((Inputs) data).freeze();
+    }
+  }
+
   public void dirty() {
     YogaNative.jni_YGNodeMarkDirtyJNI(mNativePointer);
   }