third_party/WebKit/Source/wtf/PassOwnPtr.h

   1 /*
   2  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
   3  * Copyright (C) 2013 Intel Corporation. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  21  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  22  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #ifndef WTF_PassOwnPtr_h
  28 #define WTF_PassOwnPtr_h
  29
  30 #include "wtf/NullPtr.h"
  31 #include "wtf/OwnPtrCommon.h"
  32
  33 namespace WTF {
  34
  35     template<typename T> class OwnPtr;
  36     template<typename T> class PassOwnPtr;
  37     template<typename T> PassOwnPtr<T> adoptPtr(T*);
  38     template<typename T> PassOwnPtr<T[]> adoptArrayPtr(T*);
  39
  40     template<typename T> class PassOwnPtr {
  41     public:
  42         typedef typename RemoveExtent<T>::Type ValueType;
  43         typedef ValueType* PtrType;
  44
  45         PassOwnPtr() : m_ptr(0) { }
  46         PassOwnPtr(std::nullptr_t) : m_ptr(0) { }
  47
  48         // It somewhat breaks the type system to allow transfer of ownership out of
  49         // a const PassOwnPtr. However, it makes it much easier to work with PassOwnPtr
  50         // temporaries, and we don't have a need to use real const PassOwnPtrs anyway.
  51         PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) { }
  52         template<typename U> PassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
  53
  54         ~PassOwnPtr() { OwnedPtrDeleter<T>::deletePtr(m_ptr); }
  55
  56         PtrType get() const { return m_ptr; }
  57
  58         PtrType leakPtr() const WARN_UNUSED_RETURN;
  59
  60         ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
  61         PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  62
  63         bool operator!() const { return !m_ptr; }
  64
  65         // This conversion operator allows implicit conversion to bool but not to other integer types.
  66         typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
  67         operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
  68
  69         template<typename U> friend PassOwnPtr<U> adoptPtr(U*);
  70         template<typename U> friend PassOwnPtr<U[]> adoptArrayPtr(U*);
  71         template<typename U> friend class OwnPtr;
  72
  73     private:
  74         explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) { }
  75
  76         PassOwnPtr& operator=(const PassOwnPtr&) { static_assert(!sizeof(T*), "PassOwnPtr should never be assigned to"); return *this; }
  77
  78         // We should never have two OwnPtrs for the same underlying object (otherwise we'll get
  79         // double-destruction), so these equality operators should never be needed.
  80         template<typename U> bool operator==(const PassOwnPtr<U>&) const { static_assert(!sizeof(U*), "OwnPtrs should never be equal"); return false; }
  81         template<typename U> bool operator!=(const PassOwnPtr<U>&) const { static_assert(!sizeof(U*), "OwnPtrs should never be equal"); return false; }
  82         template<typename U> bool operator==(const OwnPtr<U>&) const { static_assert(!sizeof(U*), "OwnPtrs should never be equal"); return false; }
  83         template<typename U> bool operator!=(const OwnPtr<U>&) const { static_assert(!sizeof(U*), "OwnPtrs should never be equal"); return false; }
  84
  85         mutable PtrType m_ptr;
  86     };
  87
  88     template<typename T> template<typename U> inline PassOwnPtr<T>::PassOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
  89         : m_ptr(o.leakPtr())
  90     {
  91         static_assert(!IsArray<T>::value, "pointers to array must never be converted");
  92     }
  93
  94     template<typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
  95     {
  96         PtrType ptr = m_ptr;
  97         m_ptr = 0;
  98         return ptr;
  99     }
 100
 101     template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
 102     {
 103         return a.get() == b;
 104     }
 105
 106     template<typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
 107     {
 108         return a == b.get();
 109     }
 110
 111     template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
 112     {
 113         return a.get() != b;
 114     }
 115
 116     template<typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
 117     {
 118         return a != b.get();
 119     }
 120
 121     template<typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
 122     {
 123         return PassOwnPtr<T>(ptr);
 124     }
 125
 126     template<typename T> inline PassOwnPtr<T[]> adoptArrayPtr(T* ptr)
 127     {
 128         return PassOwnPtr<T[]>(ptr);
 129     }
 130
 131     template<typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
 132     {
 133         static_assert(!IsArray<T>::value, "pointers to array must never be converted");
 134         return adoptPtr(static_cast<T*>(p.leakPtr()));
 135     }
 136
 137     template<typename T> inline T* getPtr(const PassOwnPtr<T>& p)
 138     {
 139         return p.get();
 140     }
 141
 142 } // namespace WTF
 143
 144 using WTF::PassOwnPtr;
 145 using WTF::adoptPtr;
 146 using WTF::adoptArrayPtr;
 147 using WTF::static_pointer_cast;
 148
 149 #endif // WTF_PassOwnPtr_h