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 "wtf/Assertions.h"
31
32 namespace WebCore {
33
34 template<typename T>
35 class LifecycleObserver {
36 public:
37 typedef T Context;
38
39 enum Type {
40 ActiveDOMObjectType,
41 DocumentLifecycleObserverType,
42 GenericType,
43 PageLifecycleObserverType,
44 DOMWindowLifecycleObserverType
45 };
46
47 explicit LifecycleObserver(Context* context, Type type = GenericType)
m_lifecycleContext(context)48 : m_lifecycleContext(context)
49 , m_observerType(type)
50 {
51 observeContext(context);
52 }
53
~LifecycleObserver()54 virtual ~LifecycleObserver()
55 {
56 observeContext(0);
57 }
58
contextDestroyed()59 virtual void contextDestroyed() { m_lifecycleContext = 0; }
60
61
lifecycleContext()62 Context* lifecycleContext() const { return m_lifecycleContext; }
observerType()63 Type observerType() const { return m_observerType; }
64
65 protected:
66 void observeContext(Context*);
67
68 Context* m_lifecycleContext;
69 Type m_observerType;
70 };
71
72 //
73 // These functions should be specialized for each LifecycleObserver instances.
74 //
observerContext(T *,LifecycleObserver<T> *)75 template<typename T> void observerContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
unobserverContext(T *,LifecycleObserver<T> *)76 template<typename T> void unobserverContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
77
78
79 template<typename T>
observeContext(typename LifecycleObserver<T>::Context * context)80 inline void LifecycleObserver<T>::observeContext(typename LifecycleObserver<T>::Context* context)
81 {
82 if (m_lifecycleContext)
83 unobserverContext(m_lifecycleContext, this);
84
85 m_lifecycleContext = context;
86
87 if (m_lifecycleContext)
88 observerContext(m_lifecycleContext, this);
89 }
90
91 } // namespace WebCore
92
93 #endif // LifecycleObserver_h
94