Add the ability to attach data to a java CSSNode

Summary: The C version already has this ability via the same name 'context'. This can be used to attach arbitrary data about your view hierarchy to a CSSNode. Previously this could only be done in java via subclassing CSSNode.

Reviewed By: lucasr

Differential Revision: D3662065

fbshipit-source-id: 560a768092f17381e99b349d08bd4a8b365541be

java/com/facebook/csslayout/CSSNode.java

@@ -63,6 +63,7 @@ public class CSSNode implements CSSNodeAPI<CSSNode> {
   private @Nullable MeasureFunction mMeasureFunction = null;
   private LayoutState mLayoutState = LayoutState.DIRTY;
   private boolean mIsTextNode = false;
+  private Object mData;
 
   @Override
   public void init() {
@@ -621,6 +622,16 @@ public class CSSNode implements CSSNodeAPI<CSSNode> {
     }
   }
 
+  @Override
+  public void setData(Object data) {
+    mData = data;
+  }
+
+  @Override
+  public Object getData() {
+    return mData;
+  }
+
   /**
    * Resets this instance to its default state. This method is meant to be used when
    * recycling {@link CSSNode} instances.

java/com/facebook/csslayout/CSSNodeAPI.java

@@ -88,6 +88,8 @@ public interface CSSNodeAPI<CSSNodeType extends CSSNodeAPI> {
   void setDefaultPadding(int spacingType, float padding);
   CSSOverflow getOverflow();
   void setOverflow(CSSOverflow overflow);
+  void setData(Object data);
+  Object getData();
   void init();
   void reset();
 }

java/com/facebook/csslayout/CSSNodeJNI.java

@@ -33,6 +33,7 @@ public class CSSNodeJNI implements CSSNodeAPI<CSSNodeJNI> {
   private List<CSSNodeJNI> mChildren;
   private MeasureFunction mMeasureFunction;
   private int mNativePointer;
+  private Object mData;
 
   private void assertNativeInstance() {
     if (mNativePointer == 0) {
@@ -718,4 +719,14 @@ public class CSSNodeJNI implements CSSNodeAPI<CSSNodeJNI> {
   public boolean valuesEqual(float f1, float f2) {
     return FloatUtil.floatsEqual(f1, f2);
   }
+
+  @Override
+  public void setData(Object data) {
+    mData = data;
+  }
+
+  @Override
+  public Object getData() {
+    return mData;
+  }
 }