Lazy create children list when first child is added

astreet · Facebook Github Bot · commit 01a388142669 · 2016-11-07T05:52:41.000-08:00
Summary: @public We don't need to allocate a list for every node since leaf nodes don't have children. Reviewed By: emilsjolander Differential Revision: D4130818 fbshipit-source-id: 80d3e98fce9d2daa0676fd1cbed0e81edcf7adb3
diff --git a/java/com/facebook/csslayout/CSSNode.java b/java/com/facebook/csslayout/CSSNode.java
@@ -62,8 +62,6 @@ public CSSNode() {
     if (mNativePointer == 0) {
       throw new IllegalStateException("Failed to allocate native memory");
     }
-
-    mChildren = new ArrayList<>(4);
   }
 
   private native void jni_CSSNodeFree(long nativePointer);
@@ -98,7 +96,7 @@ public void reset() {
 
   @Override
   public int getChildCount() {
-    return mChildren.size();
+    return mChildren == null ? 0 : mChildren.size();
   }
 
   @Override
@@ -113,6 +111,9 @@ public void addChildAt(CSSNode child, int i) {
       throw new IllegalStateException("Child already has a parent, it must be removed first.");
     }
 
+    if (mChildren == null) {
+      mChildren = new ArrayList<>(4);
+    }
     mChildren.add(i, child);
     child.mParent = this;
     jni_CSSNodeInsertChild(mNativePointer, child.mNativePointer, i);
@@ -136,7 +137,7 @@ CSSNode getParent() {
 
   @Override
   public int indexOf(CSSNode child) {
-    return mChildren.indexOf(child);
+    return mChildren == null ? -1 : mChildren.indexOf(child);
   }
 
   private native void jni_CSSNodeSetIsTextNode(long nativePointer, boolean isTextNode);

Original file line number	Diff line number	Diff line change
`@@ -62,8 +62,6 @@ public CSSNode() {`
`62`	`62`	`if (mNativePointer == 0) {`
`63`	`63`	`throw new IllegalStateException("Failed to allocate native memory");`
`64`	`64`	`}`
`65`		`-`
`66`		`- mChildren = new ArrayList<>(4);`
`67`	`65`	`}`
`68`	`66`
`69`	`67`	`private native void jni_CSSNodeFree(long nativePointer);`
`@@ -98,7 +96,7 @@ public void reset() {`
`98`	`96`
`99`	`97`	`@Override`
`100`	`98`	`public int getChildCount() {`
`101`		`- return mChildren.size();`
	`99`	`+ return mChildren == null ? 0 : mChildren.size();`
`102`	`100`	`}`
`103`	`101`
`104`	`102`	`@Override`
`@@ -113,6 +111,9 @@ public void addChildAt(CSSNode child, int i) {`
`113`	`111`	`throw new IllegalStateException("Child already has a parent, it must be removed first.");`
`114`	`112`	`}`
`115`	`113`
	`114`	`+ if (mChildren == null) {`
	`115`	`+ mChildren = new ArrayList<>(4);`
	`116`	`+ }`
`116`	`117`	`mChildren.add(i, child);`
`117`	`118`	`child.mParent = this;`
`118`	`119`	`jni_CSSNodeInsertChild(mNativePointer, child.mNativePointer, i);`
`@@ -136,7 +137,7 @@ CSSNode getParent() {`
`136`	`137`
`137`	`138`	`@Override`
`138`	`139`	`public int indexOf(CSSNode child) {`
`139`		`- return mChildren.indexOf(child);`
	`140`	`+ return mChildren == null ? -1 : mChildren.indexOf(child);`
`140`	`141`	`}`
`141`	`142`
`142`	`143`	`private native void jni_CSSNodeSetIsTextNode(long nativePointer, boolean isTextNode);`