third_party/WebKit/Source/platform/LifecycleObserver.h

   1 /*
   2  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  */
  26
  27 #ifndef LifecycleObserver_h
  28 #define LifecycleObserver_h
  29
  30 #include "platform/heap/Handle.h"
  31 #include "wtf/Assertions.h"
  32
  33 namespace blink {
  34
  35 template<typename T, typename Observer, typename Notifier>
  36 class LifecycleObserver : public WillBeGarbageCollectedMixin {
  37 public:
  38     using Context = T;
  39
  40 #if !ENABLE(OILPAN)
  41     virtual ~LifecycleObserver()
  42     {
  43         clearContext();
  44     }
  45 #endif
  46
  47     EAGERLY_FINALIZE_WILL_BE_REMOVED();
  48     DEFINE_INLINE_VIRTUAL_TRACE()
  49     {
  50         visitor->trace(m_lifecycleContext);
  51     }
  52
  53     virtual void contextDestroyed() { }
  54
  55     Context* lifecycleContext() const { return m_lifecycleContext; }
  56     void clearLifecycleContext() { m_lifecycleContext = nullptr; }
  57
  58 protected:
  59     explicit LifecycleObserver(Context* context)
  60         : m_lifecycleContext(nullptr)
  61     {
  62         setContext(context);
  63     }
  64
  65     void setContext(Context*);
  66
  67     void clearContext()
  68     {
  69         setContext(nullptr);
  70     }
  71
  72 private:
  73     RawPtrWillBeWeakMember<Context> m_lifecycleContext;
  74 };
  75
  76 template<typename T, typename Observer, typename Notifier>
  77 inline void LifecycleObserver<T, Observer, Notifier>::setContext(typename LifecycleObserver<T, Observer, Notifier>::Context* context)
  78 {
  79     if (m_lifecycleContext)
  80         static_cast<Notifier*>(m_lifecycleContext.get())->removeObserver(static_cast<Observer*>(this));
  81
  82     m_lifecycleContext = context;
  83
  84     if (m_lifecycleContext)
  85         static_cast<Notifier*>(m_lifecycleContext.get())->addObserver(static_cast<Observer*>(this));
  86 }
  87
  88 } // namespace blink
  89
  90 #endif // LifecycleObserver_h