2 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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27 #ifndef ActiveDOMObject_h
28 #define ActiveDOMObject_h
30 #include <wtf/Assertions.h>
34 class ScriptExecutionContext;
36 // FIXME: Move this class to it's own file.
37 class ContextDestructionObserver {
39 explicit ContextDestructionObserver(ScriptExecutionContext*);
40 virtual void contextDestroyed();
42 ScriptExecutionContext* scriptExecutionContext() const { return m_scriptExecutionContext; }
45 virtual ~ContextDestructionObserver();
47 ScriptExecutionContext* m_scriptExecutionContext;
50 class ActiveDOMObject : public ContextDestructionObserver {
52 ActiveDOMObject(ScriptExecutionContext*, void* upcastPointer);
54 virtual bool hasPendingActivity() const;
56 // canSuspend() is used by the caller if there is a choice between suspending and stopping.
57 // For example, a page won't be suspended and placed in the back/forward cache if it has
58 // the objects that can not be suspended.
59 // However, 'suspend' can be called even if canSuspend() would return 'false'. That
60 // happens in step-by-step JS debugging for example - in this case it would be incorrect
61 // to stop the object. Exact semantics of suspend is up to the object then.
62 enum ReasonForSuspension {
63 JavaScriptDebuggerPaused,
65 DocumentWillBecomeInactive
67 virtual bool canSuspend() const;
68 virtual void suspend(ReasonForSuspension);
69 virtual void resume();
72 template<class T> void setPendingActivity(T* thisObject)
74 ASSERT(thisObject == this);
76 m_pendingActivityCount++;
79 template<class T> void unsetPendingActivity(T* thisObject)
81 ASSERT(m_pendingActivityCount > 0);
82 --m_pendingActivityCount;
87 virtual ~ActiveDOMObject();
90 unsigned m_pendingActivityCount;
93 } // namespace WebCore
95 #endif // ActiveDOMObject_h