moved PtrJNode map to YGJtypes.h and passing layout context as data in LayoutPassEnd Event

Summary: Move PtrJNodeMap to header file so that it can be accessed in events subscribers outside yoga

Reviewed By: davidaurelio

Differential Revision: D15619629

fbshipit-source-id: 1bf213efd38ec7bcac6a38070f21fa837c5f17da

java/jni/YGJTypes.h

@@ -6,6 +6,11 @@
  */
 #include <fb/fbjni.h>
 #include <yoga/YGValue.h>
+#include <yoga/Yoga.h>
+#include <map>
+
+using namespace facebook::jni;
+using namespace std;
 
 struct JYogaNode : public facebook::jni::JavaClass<JYogaNode> {
   static constexpr auto kJavaDescriptor = "Lcom/facebook/yoga/YogaNodeJNIBase;";
@@ -28,3 +33,31 @@ struct JYogaLogger : public facebook::jni::JavaClass<JYogaLogger> {
       facebook::jni::alias_ref<JYogaLogLevel>,
       jstring);
 };
+
+class PtrJNodeMap {
+  using JNodeArray = JArrayClass<JYogaNode::javaobject>;
+  std::map<YGNodeRef, size_t> ptrsToIdxs_;
+  alias_ref<JNodeArray> javaNodes_;
+
+public:
+  PtrJNodeMap() : ptrsToIdxs_{}, javaNodes_{} {}
+  PtrJNodeMap(
+      alias_ref<JArrayLong> nativePointers,
+      alias_ref<JNodeArray> javaNodes)
+      : javaNodes_{javaNodes} {
+    auto pin = nativePointers->pinCritical();
+    auto ptrs = pin.get();
+    for (size_t i = 0, n = pin.size(); i < n; ++i) {
+      ptrsToIdxs_[(YGNodeRef) ptrs[i]] = i;
+    }
+  }
+
+  local_ref<JYogaNode> ref(YGNodeRef node) {
+    auto idx = ptrsToIdxs_.find(node);
+    if (idx == ptrsToIdxs_.end()) {
+      return local_ref<JYogaNode>{};
+    } else {
+      return javaNodes_->getElement(idx->second);
+    }
+  }
+};