1 files changed, 85 insertions, 0 deletions
diff --git a/xpcom/base/nsCycleCollectionNoteChild.h b/xpcom/base/nsCycleCollectionNoteChild.h
new file mode 100644
index 0000000000..3e1d345aa3
--- /dev/null
+++ b/xpcom/base/nsCycleCollectionNoteChild.h
@@ -0,0 +1,85 @@
+/* -*- 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/. */
+
+// This header will be included by headers that define refpointer and array
+// classes in order to specialize CC helpers such as ImplCycleCollectionTraverse
+// for them.
+
+#ifndef nsCycleCollectionNoteChild_h__
+#define nsCycleCollectionNoteChild_h__
+
+#include "nsCycleCollectionTraversalCallback.h"
+#include "mozilla/Likely.h"
+
+enum { CycleCollectionEdgeNameArrayFlag = 1 };
+
+// Just a helper for appending "[i]". Didn't want to pull in string headers
+// here.
+void CycleCollectionNoteEdgeNameImpl(
+    nsCycleCollectionTraversalCallback& aCallback, const char* aName,
+    uint32_t aFlags = 0);
+
+// Should be inlined so that in the no-debug-info case this is just a simple
+// if().
+MOZ_ALWAYS_INLINE void CycleCollectionNoteEdgeName(
+    nsCycleCollectionTraversalCallback& aCallback, const char* aName,
+    uint32_t aFlags = 0) {
+  if (MOZ_UNLIKELY(aCallback.WantDebugInfo())) {
+    CycleCollectionNoteEdgeNameImpl(aCallback, aName, aFlags);
+  }
+}
+
+#define NS_CYCLE_COLLECTION_INNERCLASS cycleCollection
+
+#define NS_CYCLE_COLLECTION_INNERNAME _cycleCollectorGlobal
+
+#define NS_CYCLE_COLLECTION_PARTICIPANT(_class) \
+  _class::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant()
+
+template <typename T>
+nsISupports* ToSupports(
+    T* aPtr, typename T::NS_CYCLE_COLLECTION_INNERCLASS* aDummy = 0) {
+  return T::NS_CYCLE_COLLECTION_INNERCLASS::Upcast(aPtr);
+}
+
+// The default implementation of this class template is empty, because it
+// should never be used: see the partial specializations below.
+template <typename T, bool IsXPCOM = std::is_base_of<nsISupports, T>::value>
+struct CycleCollectionNoteChildImpl {};
+
+template <typename T>
+struct CycleCollectionNoteChildImpl<T, true> {
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild) {
+    aCallback.NoteXPCOMChild(ToSupports(aChild));
+  }
+};
+
+template <typename T>
+struct CycleCollectionNoteChildImpl<T, false> {
+  static void Run(nsCycleCollectionTraversalCallback& aCallback, T* aChild) {
+    aCallback.NoteNativeChild(aChild, NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+};
+
+// We declare CycleCollectionNoteChild in 3-argument and 4-argument variants,
+// rather than using default arguments, so that forward declarations work
+// regardless of header inclusion order.
+template <typename T>
+inline void CycleCollectionNoteChild(
+    nsCycleCollectionTraversalCallback& aCallback, T* aChild, const char* aName,
+    uint32_t aFlags) {
+  CycleCollectionNoteEdgeName(aCallback, aName, aFlags);
+  CycleCollectionNoteChildImpl<T>::Run(aCallback, aChild);
+}
+
+template <typename T>
+inline void CycleCollectionNoteChild(
+    nsCycleCollectionTraversalCallback& aCallback, T* aChild,
+    const char* aName) {
+  CycleCollectionNoteChild(aCallback, aChild, aName, 0);
+}
+
+#endif  // nsCycleCollectionNoteChild_h__