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      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:
     35         ~CachedResourceHandleBase() { if (m_resource) m_resource->unregisterHandle(this); }
     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);
     43         operator UnspecifiedBoolType() const { return m_resource ? &CachedResourceHandleBase::m_resource : 0; }
     44 
     45     protected:
     46         CachedResourceHandleBase() : m_resource(0) {}
     47         CachedResourceHandleBase(CachedResource* res) { m_resource = res; if (m_resource) m_resource->registerHandle(this); }
     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:
     62         CachedResourceHandle() { }
     63         CachedResourceHandle(R* res);
     64         CachedResourceHandle(const CachedResourceHandle<R>& o) : CachedResourceHandleBase(o) { }
     65 
     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
     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