1/*
2 * Copyright (C) 2013 Google 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef ResourceOwner_h
32#define ResourceOwner_h
33
34#include "core/fetch/ResourcePtr.h"
35
36namespace blink {
37
38
39template<class R, class C = typename R::ClientType>
40class ResourceOwner : public C {
41public:
42    typedef R ResourceType;
43
44    virtual ~ResourceOwner();
45    ResourceType* resource() const { return m_resource.get(); }
46
47protected:
48    ResourceOwner();
49    ResourceOwner(const ResourceOwner& other) { setResource(other.resource()); }
50    explicit ResourceOwner(const ResourcePtr<ResourceType>&);
51
52    void setResource(const ResourcePtr<ResourceType>&);
53    void clearResource();
54
55    ResourceOwner& operator=(const ResourceOwner& other);
56
57private:
58    ResourcePtr<ResourceType> m_resource;
59};
60
61template<class R, class C>
62inline ResourceOwner<R, C>::ResourceOwner()
63{
64}
65
66template<class R, class C>
67inline ResourceOwner<R, C>::~ResourceOwner()
68{
69    clearResource();
70}
71
72template<class R, class C>
73inline ResourceOwner<R, C>::ResourceOwner(const ResourcePtr<R>& resource)
74    : m_resource(resource)
75{
76    if (m_resource)
77        m_resource->addClient(this);
78}
79
80template<class R, class C>
81inline void ResourceOwner<R, C>::setResource(const ResourcePtr<R>& newResource)
82{
83    if (newResource == m_resource)
84        return;
85
86    // Some ResourceClient implementations reenter this so
87    // we need to prevent double removal.
88    if (ResourcePtr<ResourceType> oldResource = m_resource) {
89        m_resource.clear();
90        oldResource->removeClient(this);
91    }
92
93    if (newResource) {
94        m_resource = newResource;
95        m_resource->addClient(this);
96    }
97}
98
99template<class R, class C>
100inline void ResourceOwner<R, C>::clearResource()
101{
102    setResource(0);
103}
104
105template<class R, class C>
106inline ResourceOwner<R, C>& ResourceOwner<R, C>::operator=(const ResourceOwner<R, C>& other)
107{
108    if (this == &other)
109        return *this;
110    setResource(other.resource());
111    return *this;
112}
113
114} // namespace blink
115
116#endif
117