WebCore/ActiveDOMObject.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 ActiveDOMObject_h
  28 #define ActiveDOMObject_h
  29
  30 #include <wtf/Assertions.h>
  31
  32 namespace WebCore {
  33
  34     class ScriptExecutionContext;
  35
  36     class ActiveDOMObject {
  37     public:
  38         ActiveDOMObject(ScriptExecutionContext*, void* upcastPointer);
  39
  40         ScriptExecutionContext* scriptExecutionContext() const { return m_scriptExecutionContext; }
  41         virtual bool hasPendingActivity() const;
  42
  43         virtual void contextDestroyed();
  44
  45         // canSuspend() is used by the caller if there is a choice between suspending and stopping.
  46         // For example, a page won't be suspended and placed in the back/forward cache if it has
  47         // the objects that can not be suspended.
  48         // However, 'suspend' can be called even if canSuspend() would return 'false'. That
  49         // happens in step-by-step JS debugging for example - in this case it would be incorrect
  50         // to stop the object. Exact semantics of suspend is up to the object then.
  51         virtual bool canSuspend() const;
  52         virtual void suspend();
  53         virtual void resume();
  54         virtual void stop();
  55
  56     protected:
  57         virtual ~ActiveDOMObject();
  58
  59         template<class T> void setPendingActivity(T* thisObject)
  60         {
  61             ASSERT(thisObject == this);
  62             thisObject->ref();
  63             m_pendingActivityCount++;
  64         }
  65
  66         template<class T> void unsetPendingActivity(T* thisObject)
  67         {
  68             ASSERT(m_pendingActivityCount > 0);
  69             --m_pendingActivityCount;
  70             thisObject->deref();
  71         }
  72
  73     private:
  74         ScriptExecutionContext* m_scriptExecutionContext;
  75         unsigned m_pendingActivityCount;
  76     };
  77
  78 } // namespace WebCore
  79
  80 #endif // ActiveDOMObject_h