wtf/PassOwnPtr.h

   1 /*
   2  * Copyright (C) 2009 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 WTF_PassOwnPtr_h
  27 #define WTF_PassOwnPtr_h
  28
  29 #include "Assertions.h"
  30 #include "OwnPtrCommon.h"
  31 #include "TypeTraits.h"
  32
  33 namespace WTF {
  34
  35     // Unlike most of our smart pointers, PassOwnPtr can take either the pointer type or the pointed-to type.
  36
  37     template <typename T> class OwnPtr;
  38
  39     template <typename T> class PassOwnPtr {
  40     public:
  41         typedef typename RemovePointer<T>::Type ValueType;
  42         typedef ValueType* PtrType;
  43
  44         PassOwnPtr(PtrType ptr = 0) : m_ptr(ptr) { }
  45         // It somewhat breaks the type system to allow transfer of ownership out of
  46         // a const PassOwnPtr. However, it makes it much easier to work with PassOwnPtr
  47         // temporaries, and we don't really have a need to use real const PassOwnPtrs
  48         // anyway.
  49         PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.release()) { }
  50         template <typename U> PassOwnPtr(const PassOwnPtr<U>& o) : m_ptr(o.release()) { }
  51
  52         ~PassOwnPtr() { deleteOwnedPtr(m_ptr); }
  53
  54         PtrType get() const { return m_ptr; }
  55
  56         void clear() { m_ptr = 0; }
  57         PtrType release() const { PtrType ptr = m_ptr; m_ptr = 0; return ptr; }
  58
  59         ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
  60         PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  61
  62         bool operator!() const { return !m_ptr; }
  63
  64         // This conversion operator allows implicit conversion to bool but not to other integer types.
  65         typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
  66         operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
  67
  68         PassOwnPtr& operator=(T*);
  69         PassOwnPtr& operator=(const PassOwnPtr<T>&);
  70         template <typename U> PassOwnPtr& operator=(const PassOwnPtr<U>&);
  71
  72     private:
  73         mutable PtrType m_ptr;
  74     };
  75
  76     template <typename T> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(T* optr)
  77     {
  78         T* ptr = m_ptr;
  79         m_ptr = optr;
  80         ASSERT(!ptr || m_ptr != ptr);
  81         if (ptr)
  82             deleteOwnedPtr(ptr);
  83         return *this;
  84     }
  85
  86     template <typename T> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(const PassOwnPtr<T>& optr)
  87     {
  88         T* ptr = m_ptr;
  89         m_ptr = optr.release();
  90         ASSERT(!ptr || m_ptr != ptr);
  91         if (ptr)
  92             deleteOwnedPtr(ptr);
  93         return *this;
  94     }
  95
  96     template <typename T> template <typename U> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(const PassOwnPtr<U>& optr)
  97     {
  98         T* ptr = m_ptr;
  99         m_ptr = optr.release();
 100         ASSERT(!ptr || m_ptr != ptr);
 101         if (ptr)
 102             deleteOwnedPtr(ptr);
 103         return *this;
 104     }
 105
 106     template <typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
 107     {
 108         return a.get() == b.get();
 109     }
 110
 111     template <typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
 112     {
 113         return a.get() == b.get();
 114     }
 115
 116     template <typename T, typename U> inline bool operator==(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
 117     {
 118         return a.get() == b.get();
 119     }
 120
 121     template <typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
 122     {
 123         return a.get() == b;
 124     }
 125
 126     template <typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
 127     {
 128         return a == b.get();
 129     }
 130
 131     template <typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
 132     {
 133         return a.get() != b.get();
 134     }
 135
 136     template <typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
 137     {
 138         return a.get() != b.get();
 139     }
 140
 141     template <typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
 142     {
 143         return a.get() != b.get();
 144     }
 145
 146     template <typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
 147     {
 148         return a.get() != b;
 149     }
 150
 151     template <typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
 152     {
 153         return a != b.get();
 154     }
 155
 156     template <typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
 157     {
 158         return PassOwnPtr<T>(static_cast<T*>(p.release()));
 159     }
 160
 161     template <typename T, typename U> inline PassOwnPtr<T> const_pointer_cast(const PassOwnPtr<U>& p)
 162     {
 163         return PassOwnPtr<T>(const_cast<T*>(p.release()));
 164     }
 165
 166     template <typename T> inline T* getPtr(const PassOwnPtr<T>& p)
 167     {
 168         return p.get();
 169     }
 170
 171 } // namespace WTF
 172
 173 using WTF::PassOwnPtr;
 174 using WTF::const_pointer_cast;
 175 using WTF::static_pointer_cast;
 176
 177 #endif // WTF_PassOwnPtr_h