xpcom/base/nsWeakReference.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsWeakReference_h__
   8 #define nsWeakReference_h__
   9
  10 // nsWeakReference.h
  11
  12 // See mfbt/WeakPtr.h for a more typesafe C++ implementation of weak references
  13
  14 #include "nsIWeakReferenceUtils.h"
  15
  16 class nsWeakReference;
  17
  18 class nsSupportsWeakReference : public nsISupportsWeakReference {
  19  public:
  20   nsSupportsWeakReference() : mProxy(0) {}
  21
  22   NS_DECL_NSISUPPORTSWEAKREFERENCE
  23
  24  protected:
  25   inline ~nsSupportsWeakReference();
  26
  27  private:
  28   friend class nsWeakReference;
  29
  30   // Called (only) by an |nsWeakReference| from _its_ dtor.
  31   // The thread safety check is made by the caller.
  32   void NoticeProxyDestruction() { mProxy = nullptr; }
  33
  34   nsWeakReference* MOZ_NON_OWNING_REF mProxy;
  35
  36  protected:
  37   void ClearWeakReferences();
  38   bool HasWeakReferences() const { return !!mProxy; }
  39 };
  40
  41 inline nsSupportsWeakReference::~nsSupportsWeakReference() {
  42   ClearWeakReferences();
  43 }
  44
  45 #define NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE \
  46   tmp->ClearWeakReferences();
  47
  48 #define NS_IMPL_CYCLE_COLLECTION_WEAK(class_, ...) \
  49   NS_IMPL_CYCLE_COLLECTION_CLASS(class_)           \
  50   NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(class_)    \
  51     NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)   \
  52     NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE \
  53   NS_IMPL_CYCLE_COLLECTION_UNLINK_END              \
  54   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(class_)  \
  55     NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__) \
  56   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
  57
  58 #define NS_IMPL_CYCLE_COLLECTION_WEAK_INHERITED(class_, super_, ...) \
  59   NS_IMPL_CYCLE_COLLECTION_CLASS(class_)                             \
  60   NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(class_, super_)    \
  61     NS_IMPL_CYCLE_COLLECTION_UNLINK(__VA_ARGS__)                     \
  62     NS_IMPL_CYCLE_COLLECTION_UNLINK_WEAK_REFERENCE                   \
  63   NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                \
  64   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(class_, super_)  \
  65     NS_IMPL_CYCLE_COLLECTION_TRAVERSE(__VA_ARGS__)                   \
  66   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
  67
  68 #endif