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 "CachedResource.h"
30 
31 namespace WebCore {
32 
33     class CachedResourceHandleBase {
34     public:
~CachedResourceHandleBase()35         ~CachedResourceHandleBase() { if (m_resource) m_resource->unregisterHandle(this); }
get()36         CachedResource* get() const { return m_resource; }
37 
38         bool operator!() const { return !m_resource; }
39 
40         // This conversion operator allows implicit conversion to bool but not to other integer types.
41         // Parenthesis is needed for winscw compiler to resolve class qualifier in this case.
42         typedef CachedResource* (CachedResourceHandleBase::*UnspecifiedBoolType);
UnspecifiedBoolType()43         operator UnspecifiedBoolType() const { return m_resource ? &CachedResourceHandleBase::m_resource : 0; }
44 
45     protected:
CachedResourceHandleBase()46         CachedResourceHandleBase() : m_resource(0) {}
CachedResourceHandleBase(CachedResource * res)47         CachedResourceHandleBase(CachedResource* res) { m_resource = res; if (m_resource) m_resource->registerHandle(this); }
CachedResourceHandleBase(const CachedResourceHandleBase & o)48         CachedResourceHandleBase(const CachedResourceHandleBase& o) : m_resource(o.m_resource) { if (m_resource) m_resource->registerHandle(this); }
49 
50         void setResource(CachedResource*);
51 
52     private:
53         CachedResourceHandleBase& operator=(const CachedResourceHandleBase&) { return *this; }
54 
55         friend class CachedResource;
56 
57         CachedResource* m_resource;
58     };
59 
60     template <class R> class CachedResourceHandle : public CachedResourceHandleBase {
61     public:
CachedResourceHandle()62         CachedResourceHandle() { }
63         CachedResourceHandle(R* res);
CachedResourceHandle(const CachedResourceHandle<R> & o)64         CachedResourceHandle(const CachedResourceHandle<R>& o) : CachedResourceHandleBase(o) { }
65 
get()66         R* get() const { return reinterpret_cast<R*>(CachedResourceHandleBase::get()); }
67         R* operator->() const { return get(); }
68 
69         CachedResourceHandle& operator=(R* res) { setResource(res); return *this; }
70         CachedResourceHandle& operator=(const CachedResourceHandle& o) { setResource(o.get()); return *this; }
71         bool operator==(const CachedResourceHandleBase& o) const { return get() == o.get(); }
72         bool operator!=(const CachedResourceHandleBase& o) const { return get() != o.get(); }
73     };
74 
75     // Don't inline for winscw compiler to prevent the compiler aggressively resolving
76     // the base class of R* when CachedResourceHandler<T>(R*) is inlined.  The bug is
77     // reported at: https://xdabug001.ext.nokia.com/bugzilla/show_bug.cgi?id=9812.
78     template <class R>
79 #if !COMPILER(WINSCW)
80     inline
81 #endif
CachedResourceHandle(R * res)82     CachedResourceHandle<R>::CachedResourceHandle(R* res) : CachedResourceHandleBase(res)
83     {
84     }
85 
86     template <class R, class RR> bool operator==(const CachedResourceHandle<R>& h, const RR* res)
87     {
88         return h.get() == res;
89     }
90     template <class R, class RR> bool operator==(const RR* res, const CachedResourceHandle<R>& h)
91     {
92         return h.get() == res;
93     }
94     template <class R, class RR> bool operator!=(const CachedResourceHandle<R>& h, const RR* res)
95     {
96         return h.get() != res;
97     }
98     template <class R, class RR> bool operator!=(const RR* res, const CachedResourceHandle<R>& h)
99     {
100         return h.get() != res;
101     }
102 }
103 
104 #endif
105