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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 ResourcePtr_h
     27 #define ResourcePtr_h
     28 
     29 #include "core/fetch/Resource.h"
     30 
     31 namespace WebCore {
     32 
     33 class ResourcePtrBase {
     34 public:
     35     ~ResourcePtrBase();
     36 
     37     Resource* get() const { return m_resource; }
     38     bool operator!() const { return !m_resource; }
     39     void clear() { setResource(0); }
     40 
     41     // This conversion operator allows implicit conversion to bool but not to other integer types.
     42     typedef Resource* ResourcePtrBase::*UnspecifiedBoolType;
     43     operator UnspecifiedBoolType() const { return m_resource ? &ResourcePtrBase::m_resource : 0; }
     44 
     45 protected:
     46     ResourcePtrBase() : m_resource(0) { }
     47     ResourcePtrBase(Resource*);
     48     ResourcePtrBase(const ResourcePtrBase&);
     49 
     50     void setResource(Resource*);
     51 
     52 private:
     53     ResourcePtrBase& operator=(const ResourcePtrBase&) { return *this; }
     54 
     55     friend class Resource;
     56 
     57     Resource* m_resource;
     58 };
     59 
     60 inline ResourcePtrBase::ResourcePtrBase(Resource* res)
     61     : m_resource(res)
     62 {
     63     if (m_resource)
     64         m_resource->registerHandle(this);
     65 }
     66 
     67 inline ResourcePtrBase::~ResourcePtrBase()
     68 {
     69     if (m_resource)
     70         m_resource->unregisterHandle(this);
     71 }
     72 
     73 inline ResourcePtrBase::ResourcePtrBase(const ResourcePtrBase& o)
     74     : m_resource(o.m_resource)
     75 {
     76     if (m_resource)
     77         m_resource->registerHandle(this);
     78 }
     79 
     80 template <class R> class ResourcePtr : public ResourcePtrBase {
     81 public:
     82     ResourcePtr() { }
     83     ResourcePtr(R* res) : ResourcePtrBase(res) { }
     84     ResourcePtr(const ResourcePtr<R>& o) : ResourcePtrBase(o) { }
     85     template<typename U> ResourcePtr(const ResourcePtr<U>& o) : ResourcePtrBase(o.get()) { }
     86 
     87     R* get() const { return reinterpret_cast<R*>(ResourcePtrBase::get()); }
     88     R* operator->() const { return get(); }
     89 
     90     ResourcePtr& operator=(R* res) { setResource(res); return *this; }
     91     ResourcePtr& operator=(const ResourcePtr& o) { setResource(o.get()); return *this; }
     92     template<typename U> ResourcePtr& operator=(const ResourcePtr<U>& o) { setResource(o.get()); return *this; }
     93 
     94     bool operator==(const ResourcePtrBase& o) const { return get() == o.get(); }
     95     bool operator!=(const ResourcePtrBase& o) const { return get() != o.get(); }
     96 };
     97 
     98 template <class R, class RR> bool operator==(const ResourcePtr<R>& h, const RR* res)
     99 {
    100     return h.get() == res;
    101 }
    102 template <class R, class RR> bool operator==(const RR* res, const ResourcePtr<R>& h)
    103 {
    104     return h.get() == res;
    105 }
    106 template <class R, class RR> bool operator!=(const ResourcePtr<R>& h, const RR* res)
    107 {
    108     return h.get() != res;
    109 }
    110 template <class R, class RR> bool operator!=(const RR* res, const ResourcePtr<R>& h)
    111 {
    112     return h.get() != res;
    113 }
    114 }
    115 
    116 #endif
    117