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 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 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#ifndef CachedResourceHandle_h
27#define CachedResourceHandle_h
28
29#include <wtf/Forward.h>
30
31namespace WebCore {
32
33class CachedResource;
34
35class CachedResourceHandleBase {
36public:
37    ~CachedResourceHandleBase();
38
39    CachedResource* get() const { return m_resource; }
40
41    bool operator!() const { return !m_resource; }
42
43    // This conversion operator allows implicit conversion to bool but not to other integer types.
44    typedef CachedResource* CachedResourceHandleBase::*UnspecifiedBoolType;
45    operator UnspecifiedBoolType() const { return m_resource ? &CachedResourceHandleBase::m_resource : 0; }
46
47protected:
48    CachedResourceHandleBase();
49    CachedResourceHandleBase(CachedResource*);
50    CachedResourceHandleBase(const CachedResourceHandleBase&);
51
52    void setResource(CachedResource*);
53
54private:
55    CachedResourceHandleBase& operator=(const CachedResourceHandleBase&) { return *this; }
56
57    friend class CachedResource;
58
59    CachedResource* m_resource;
60};
61
62template <class R> class CachedResourceHandle : public CachedResourceHandleBase {
63public:
64    CachedResourceHandle() { }
65    CachedResourceHandle(R* res) : CachedResourceHandleBase(res) { }
66    CachedResourceHandle(const CachedResourceHandle<R>& o) : CachedResourceHandleBase(o) { }
67    template<typename U> CachedResourceHandle(const CachedResourceHandle<U>& o) : CachedResourceHandleBase(o.get()) { }
68
69    R* get() const { return reinterpret_cast<R*>(CachedResourceHandleBase::get()); }
70    R* operator->() const { return get(); }
71
72    CachedResourceHandle& operator=(R* res) { setResource(res); return *this; }
73    CachedResourceHandle& operator=(const CachedResourceHandle& o) { setResource(o.get()); return *this; }
74    template<typename U> CachedResourceHandle& operator=(const CachedResourceHandle<U>& o) { setResource(o.get()); return *this; }
75
76    bool operator==(const CachedResourceHandleBase& o) const { return get() == o.get(); }
77    bool operator!=(const CachedResourceHandleBase& o) const { return get() != o.get(); }
78};
79
80template <class R, class RR> bool operator==(const CachedResourceHandle<R>& h, const RR* res)
81{
82    return h.get() == res;
83}
84template <class R, class RR> bool operator==(const RR* res, const CachedResourceHandle<R>& h)
85{
86    return h.get() == res;
87}
88template <class R, class RR> bool operator!=(const CachedResourceHandle<R>& h, const RR* res)
89{
90    return h.get() != res;
91}
92template <class R, class RR> bool operator!=(const RR* res, const CachedResourceHandle<R>& h)
93{
94    return h.get() != res;
95}
96
97} // namespace WebCore
98
99#endif // CachedResourceHandle
100