wtf/RetainPtr.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #ifndef RetainPtr_h
  22 #define RetainPtr_h
  23
  24 #include <algorithm>
  25 #include <CoreFoundation/CoreFoundation.h>
  26
  27 #ifdef __OBJC__
  28 #import <Foundation/Foundation.h>
  29 #endif
  30
  31 namespace WTF {
  32
  33     template <typename T> struct RemovePointer {
  34         typedef T type;
  35     };
  36
  37     template <typename T> struct RemovePointer<T*> {
  38         typedef T type;
  39     };
  40
  41     // Unlike most most of our smart pointers, RetainPtr can take either the pointer type or the pointed-to type,
  42     // so both RetainPtr<NSDictionary> and RetainPtr<CFDictionaryRef> will work.
  43
  44     enum AdoptCFTag { AdoptCF };
  45     enum AdoptNSTag { AdoptNS };
  46
  47 #ifdef __OBJC__
  48     inline void adoptNSReference(id ptr)
  49     {
  50         if (ptr) {
  51             CFRetain(ptr);
  52             [ptr release];
  53         }
  54     }
  55 #endif
  56
  57     template <typename T> class RetainPtr {
  58     public:
  59         typedef typename RemovePointer<T>::type ValueType;
  60         typedef ValueType* PtrType;
  61
  62         RetainPtr() : m_ptr(0) {}
  63         RetainPtr(PtrType ptr) : m_ptr(ptr) { if (ptr) CFRetain(ptr); }
  64
  65         RetainPtr(AdoptCFTag, PtrType ptr) : m_ptr(ptr) { }
  66         RetainPtr(AdoptNSTag, PtrType ptr) : m_ptr(ptr) { adoptNSReference(ptr); }
  67
  68         RetainPtr(const RetainPtr& o) : m_ptr(o.m_ptr) { if (PtrType ptr = m_ptr) CFRetain(ptr); }
  69
  70         ~RetainPtr() { if (PtrType ptr = m_ptr) CFRelease(ptr); }
  71
  72         template <typename U> RetainPtr(const RetainPtr<U>& o) : m_ptr(o.get()) { if (PtrType ptr = m_ptr) CFRetain(ptr); }
  73
  74         PtrType get() const { return m_ptr; }
  75
  76         PtrType releaseRef() { PtrType tmp = m_ptr; m_ptr = 0; return tmp; }
  77
  78         PtrType operator->() const { return m_ptr; }
  79
  80         bool operator!() const { return !m_ptr; }
  81
  82         // This conversion operator allows implicit conversion to bool but not to other integer types.
  83         typedef PtrType RetainPtr::*UnspecifiedBoolType;
  84         operator UnspecifiedBoolType() const { return m_ptr ? &RetainPtr::m_ptr : 0; }
  85
  86         RetainPtr& operator=(const RetainPtr&);
  87         template <typename U> RetainPtr& operator=(const RetainPtr<U>&);
  88         RetainPtr& operator=(PtrType);
  89         template <typename U> RetainPtr& operator=(U*);
  90
  91         void adoptCF(PtrType);
  92         void adoptNS(PtrType);
  93
  94         void swap(RetainPtr&);
  95
  96     private:
  97         PtrType m_ptr;
  98     };
  99
 100     template <typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<T>& o)
 101     {
 102         PtrType optr = o.get();
 103         if (optr)
 104             CFRetain(optr);
 105         PtrType ptr = m_ptr;
 106         m_ptr = optr;
 107         if (ptr)
 108             CFRelease(ptr);
 109         return *this;
 110     }
 111
 112     template <typename T> template <typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<U>& o)
 113     {
 114         PtrType optr = o.get();
 115         if (optr)
 116             CFRetain(optr);
 117         PtrType ptr = m_ptr;
 118         m_ptr = optr;
 119         if (ptr)
 120             CFRelease(ptr);
 121         return *this;
 122     }
 123
 124     template <typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(PtrType optr)
 125     {
 126         if (optr)
 127             CFRetain(optr);
 128         PtrType ptr = m_ptr;
 129         m_ptr = optr;
 130         if (ptr)
 131             CFRelease(ptr);
 132         return *this;
 133     }
 134
 135     template <typename T> inline void RetainPtr<T>::adoptCF(PtrType optr)
 136     {
 137         PtrType ptr = m_ptr;
 138         m_ptr = optr;
 139         if (ptr)
 140             CFRelease(ptr);
 141     }
 142
 143     template <typename T> inline void RetainPtr<T>::adoptNS(PtrType optr)
 144     {
 145         adoptNSReference(optr);
 146
 147         PtrType ptr = m_ptr;
 148         m_ptr = optr;
 149         if (ptr)
 150             CFRelease(ptr);
 151     }
 152
 153     template <typename T> template <typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(U* optr)
 154     {
 155         if (optr)
 156             CFRetain(optr);
 157         PtrType ptr = m_ptr;
 158         m_ptr = optr;
 159         if (ptr)
 160             CFRelease(ptr);
 161         return *this;
 162     }
 163
 164     template <class T> inline void RetainPtr<T>::swap(RetainPtr<T>& o)
 165     {
 166         std::swap(m_ptr, o.m_ptr);
 167     }
 168
 169     template <class T> inline void swap(RetainPtr<T>& a, RetainPtr<T>& b)
 170     {
 171         a.swap(b);
 172     }
 173
 174     template <typename T, typename U> inline bool operator==(const RetainPtr<T>& a, const RetainPtr<U>& b)
 175     {
 176         return a.get() == b.get();
 177     }
 178
 179     template <typename T, typename U> inline bool operator==(const RetainPtr<T>& a, U* b)
 180     {
 181         return a.get() == b;
 182     }
 183
 184     template <typename T, typename U> inline bool operator==(T* a, const RetainPtr<U>& b)
 185     {
 186         return a == b.get();
 187     }
 188
 189     template <typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, const RetainPtr<U>& b)
 190     {
 191         return a.get() != b.get();
 192     }
 193
 194     template <typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, U* b)
 195     {
 196         return a.get() != b;
 197     }
 198
 199     template <typename T, typename U> inline bool operator!=(T* a, const RetainPtr<U>& b)
 200     {
 201         return a != b.get();
 202     }
 203
 204 } // namespace WTF
 205
 206 using WTF::AdoptCF;
 207 using WTF::AdoptNS;
 208 using WTF::RetainPtr;
 209
 210 #endif // WTF_RetainPtr_h