ActiveDOMObject.h revision cad810f21b803229eb11403f9209855525a25d57 
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
32namespace 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        enum ReasonForSuspension {
52            JavaScriptDebuggerPaused,
53            WillShowDialog,
54            DocumentWillBecomeInactive
55        };
56        virtual bool canSuspend() const;
57        virtual void suspend(ReasonForSuspension);
58        virtual void resume();
59        virtual void stop();
60
61        template<class T> void setPendingActivity(T* thisObject)
62        {
63            ASSERT(thisObject == this);
64            thisObject->ref();
65            m_pendingActivityCount++;
66        }
67
68        template<class T> void unsetPendingActivity(T* thisObject)
69        {
70            ASSERT(m_pendingActivityCount > 0);
71            --m_pendingActivityCount;
72            thisObject->deref();
73        }
74
75    protected:
76        virtual ~ActiveDOMObject();
77
78    private:
79        ScriptExecutionContext* m_scriptExecutionContext;
80        unsigned m_pendingActivityCount;
81    };
82
83} // namespace WebCore
84
85#endif // ActiveDOMObject_h
86