add NewWeakGlobalRef method to Object

Author: ivovandongen

include/jni/functions.hpp

@@ -162,7 +162,7 @@ namespace jni
        }
 
     template < class T >
-    UniqueWeakGlobalRef<T> NewWeakGlobalRef(JNIEnv& env, T& t)
+    UniqueWeakGlobalRef<T> NewWeakGlobalRef(JNIEnv& env, T* t)
        {
         T* result = Wrap<T*>(env.NewWeakGlobalRef(Unwrap(t)));
         CheckJavaException(env);

include/jni/object.hpp

@@ -26,6 +26,12 @@ namespace jni
     template < class TagType >
     using UniqueObject = std::unique_ptr< const Object<TagType>, ObjectDeleter<TagType> >;
 
+    template < class TagType >
+    class WeakObjectRefDeleter;
+
+    template < class TagType >
+    using UniqueWeakObject = std::unique_ptr< const Object<TagType>, WeakObjectRefDeleter<TagType> >;
+
     template < class TheTag = ObjectTag >
     class Object
        {
@@ -130,6 +136,11 @@ namespace jni
                 return Seize(env, Object(jni::NewGlobalRef(env, obj).release()));
                }
 
+            UniqueWeakObject<TagType> NewWeakGlobalRef(JNIEnv& env) const
+               {
+                return SeizeWeakRef(env, Object(jni::NewWeakGlobalRef(env, obj).release()));
+               }
+
             template < class OtherTag >
             bool IsInstanceOf(JNIEnv& env, const Class<OtherTag>& clazz) const
                {
@@ -165,6 +176,34 @@ namespace jni
         return UniqueObject<TagType>(PointerToValue<Object<TagType>>(std::move(object)), ObjectDeleter<TagType>(env));
        };
 
+    template < class TagType >
+    class WeakObjectRefDeleter
+       {
+        private:
+            JNIEnv* env = nullptr;
+
+        public:
+            using pointer = PointerToValue< Object<TagType> >;
+
+            WeakObjectRefDeleter() = default;
+            WeakObjectRefDeleter(JNIEnv& e) : env(&e) {}
+
+            void operator()(pointer p) const
+               {
+                if (p)
+                   {
+                    assert(env);
+                    env->DeleteWeakGlobalRef(Unwrap(p->Get()));
+                   }
+               }
+       };
+
+    template < class TagType >
+    UniqueWeakObject<TagType> SeizeWeakRef(JNIEnv& env, Object<TagType>&& object)
+       {
+        return UniqueWeakObject<TagType>(PointerToValue<Object<TagType>>(std::move(object)), WeakObjectRefDeleter<TagType>(env));
+       };
+
 
     template < class OutTagType, class InTagType >
     Object<OutTagType> Cast(JNIEnv& env, const Object<InTagType>& object, const Class<OutTagType>& clazz)