WebCore/CachedResourceHandle.h

   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         typedef CachedResource* CachedResourceHandleBase::*UnspecifiedBoolType;
  42         operator UnspecifiedBoolType() const { return m_resource ? &CachedResourceHandleBase::m_resource : 0; }
  43
  44     protected:
  45         CachedResourceHandleBase() : m_resource(0) {}
  46         CachedResourceHandleBase(CachedResource* res) { m_resource = res; if (m_resource) m_resource->registerHandle(this); }
  47         CachedResourceHandleBase(const CachedResourceHandleBase& o) : m_resource(o.m_resource) { if (m_resource) m_resource->registerHandle(this); }
  48
  49         void setResource(CachedResource*);
  50
  51     private:
  52         CachedResourceHandleBase& operator=(const CachedResourceHandleBase&) { return *this; }
  53
  54         friend class CachedResource;
  55
  56         CachedResource* m_resource;
  57     };
  58
  59     template <class R> class CachedResourceHandle : public CachedResourceHandleBase {
  60     public:
  61         CachedResourceHandle() { }
  62         CachedResourceHandle(R* res) : CachedResourceHandleBase(res) { }
  63         CachedResourceHandle(const CachedResourceHandle<R>& o) : CachedResourceHandleBase(o) { }
  64
  65         R* get() const { return reinterpret_cast<R*>(CachedResourceHandleBase::get()); }
  66         R* operator->() const { return get(); }
  67
  68         CachedResourceHandle& operator=(R* res) { setResource(res); return *this; }
  69         CachedResourceHandle& operator=(const CachedResourceHandle& o) { setResource(o.get()); return *this; }
  70         bool operator==(const CachedResourceHandleBase& o) const { return get() == o.get(); }
  71         bool operator!=(const CachedResourceHandleBase& o) const { return get() != o.get(); }
  72     };
  73
  74     template <class R, class RR> bool operator==(const CachedResourceHandle<R>& h, const RR* res)
  75     {
  76         return h.get() == res;
  77     }
  78     template <class R, class RR> bool operator==(const RR* res, const CachedResourceHandle<R>& h)
  79     {
  80         return h.get() == res;
  81     }
  82     template <class R, class RR> bool operator!=(const CachedResourceHandle<R>& h, const RR* res)
  83     {
  84         return h.get() != res;
  85     }
  86     template <class R, class RR> bool operator!=(const RR* res, const CachedResourceHandle<R>& h)
  87     {
  88         return h.get() != res;
  89     }
  90 }
  91
  92 #endif