1 files changed, 68 insertions, 0 deletions
diff --git a/xpcom/base/nsWeakReference.h b/xpcom/base/nsWeakReference.h
new file mode 100644
index 0000000000..5303f2d2ea
--- /dev/null
+++ b/xpcom/base/nsWeakReference.h
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWeakReference_h__
+#define nsWeakReference_h__
+
+// nsWeakReference.h
+
+// See mfbt/WeakPtr.h for a more typesafe C++ implementation of weak references
+
+#include "nsIWeakReferenceUtils.h"
+
+class nsWeakReference;
+
+class nsSupportsWeakReference : public nsISupportsWeakReference {
+ public:
+  nsSupportsWeakReference() : mProxy(0) {}
+
+  NS_DECL_NSISUPPORTSWEAKREFERENCE
+
+ protected:
+  inline ~nsSupportsWeakReference();
+
+ private:
+  friend class nsWeakReference;
+
+  // Called (only) by an |nsWeakReference| from _its_ dtor.
+  // The thread safety check is made by the caller.
+  void NoticeProxyDestruction() { mProxy = nullptr; }
+
+  nsWeakReference* MOZ_NON_OWNING_REF mProxy;
+
+ protected:
+  void ClearWeakReferences();
+  bool HasWeakReferences() const { return !!mProxy; }
+};
+
+inline nsSupportsWeakReference::~nsSupportsWeakReference() {
+  ClearWeakReferences();
+}
+
+#define NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE \
+  tmp->ClearWeakReferences();
+
+#define NS_IMPL_CYCLE_COLLECTION_WEAK(class_, ...) \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(class_)           \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(class_)    \
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)   \
+    NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END              \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(class_)  \
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__) \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_IMPL_CYCLE_COLLECTION_WEAK_INHERITED(class_, super_, ...) \
+  NS_IMPL_CYCLE_COLLECTION_CLASS(class_)                             \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(class_, super_)    \
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                     \
+    NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE                   \
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(class_, super_)  \
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                   \
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#endif