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1 /*
2  *  Copyright (C) 2005, 2006, 2007, 2008, 2010 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 "HashTraits.h"
25 #include "NullPtr.h"
26 #include "TypeTraits.h"
27 #include <algorithm>
28 
29 #if USE(CF)
30 #include <CoreFoundation/CoreFoundation.h>
31 #endif
32 
33 #ifdef __OBJC__
34 #import <Foundation/Foundation.h>
35 #endif
36 
37 namespace WTF {
38 
39     // Unlike most most of our smart pointers, RetainPtr can take either the pointer type or the pointed-to type,
40     // so both RetainPtr<NSDictionary> and RetainPtr<CFDictionaryRef> will work.
41 
42     enum AdoptCFTag { AdoptCF };
43     enum AdoptNSTag { AdoptNS };
44 
45 #ifdef __OBJC__
adoptNSReference(id ptr)46     inline void adoptNSReference(id ptr)
47     {
48         if (ptr) {
49             CFRetain(ptr);
50             [ptr release];
51         }
52     }
53 #endif
54 
55     template<typename T> class RetainPtr {
56     public:
57         typedef typename RemovePointer<T>::Type ValueType;
58         typedef ValueType* PtrType;
59 
RetainPtr()60         RetainPtr() : m_ptr(0) {}
RetainPtr(PtrType ptr)61         RetainPtr(PtrType ptr) : m_ptr(ptr) { if (ptr) CFRetain(ptr); }
62 
RetainPtr(AdoptCFTag,PtrType ptr)63         RetainPtr(AdoptCFTag, PtrType ptr) : m_ptr(ptr) { }
RetainPtr(AdoptNSTag,PtrType ptr)64         RetainPtr(AdoptNSTag, PtrType ptr) : m_ptr(ptr) { adoptNSReference(ptr); }
65 
RetainPtr(const RetainPtr & o)66         RetainPtr(const RetainPtr& o) : m_ptr(o.m_ptr) { if (PtrType ptr = m_ptr) CFRetain(ptr); }
67 
68         // Hash table deleted values, which are only constructed and never copied or destroyed.
RetainPtr(HashTableDeletedValueType)69         RetainPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
isHashTableDeletedValue()70         bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
71 
~RetainPtr()72         ~RetainPtr() { if (PtrType ptr = m_ptr) CFRelease(ptr); }
73 
74         template<typename U> RetainPtr(const RetainPtr<U>&);
75 
get()76         PtrType get() const { return m_ptr; }
77 
78         void clear();
79         PtrType leakRef() WARN_UNUSED_RETURN;
80 
81         PtrType operator->() const { return m_ptr; }
82 
83         bool operator!() const { return !m_ptr; }
84 
85         // This conversion operator allows implicit conversion to bool but not to other integer types.
86         typedef PtrType RetainPtr::*UnspecifiedBoolType;
UnspecifiedBoolType()87         operator UnspecifiedBoolType() const { return m_ptr ? &RetainPtr::m_ptr : 0; }
88 
89         RetainPtr& operator=(const RetainPtr&);
90         template<typename U> RetainPtr& operator=(const RetainPtr<U>&);
91         RetainPtr& operator=(PtrType);
92         template<typename U> RetainPtr& operator=(U*);
93 #if !HAVE(NULLPTR)
94         RetainPtr& operator=(std::nullptr_t) { clear(); return *this; }
95 #endif
96 
97         void adoptCF(PtrType);
98         void adoptNS(PtrType);
99 
100         void swap(RetainPtr&);
101 
102         // FIXME: Remove releaseRef once we change all callers to call leakRef instead.
releaseRef()103         PtrType releaseRef() { return leakRef(); }
104 
105     private:
hashTableDeletedValue()106         static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
107 
108         PtrType m_ptr;
109     };
110 
RetainPtr(const RetainPtr<U> & o)111     template<typename T> template<typename U> inline RetainPtr<T>::RetainPtr(const RetainPtr<U>& o)
112         : m_ptr(o.get())
113     {
114         if (PtrType ptr = m_ptr)
115             CFRetain(ptr);
116     }
117 
clear()118     template<typename T> inline void RetainPtr<T>::clear()
119     {
120         if (PtrType ptr = m_ptr) {
121             m_ptr = 0;
122             CFRelease(ptr);
123         }
124     }
125 
leakRef()126     template<typename T> inline typename RetainPtr<T>::PtrType RetainPtr<T>::leakRef()
127     {
128         PtrType ptr = m_ptr;
129         m_ptr = 0;
130         return ptr;
131     }
132 
133     template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<T>& o)
134     {
135         PtrType optr = o.get();
136         if (optr)
137             CFRetain(optr);
138         PtrType ptr = m_ptr;
139         m_ptr = optr;
140         if (ptr)
141             CFRelease(ptr);
142         return *this;
143     }
144 
145     template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<U>& o)
146     {
147         PtrType optr = o.get();
148         if (optr)
149             CFRetain(optr);
150         PtrType ptr = m_ptr;
151         m_ptr = optr;
152         if (ptr)
153             CFRelease(ptr);
154         return *this;
155     }
156 
157     template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(PtrType optr)
158     {
159         if (optr)
160             CFRetain(optr);
161         PtrType ptr = m_ptr;
162         m_ptr = optr;
163         if (ptr)
164             CFRelease(ptr);
165         return *this;
166     }
167 
adoptCF(PtrType optr)168     template<typename T> inline void RetainPtr<T>::adoptCF(PtrType optr)
169     {
170         PtrType ptr = m_ptr;
171         m_ptr = optr;
172         if (ptr)
173             CFRelease(ptr);
174     }
175 
adoptNS(PtrType optr)176     template<typename T> inline void RetainPtr<T>::adoptNS(PtrType optr)
177     {
178         adoptNSReference(optr);
179 
180         PtrType ptr = m_ptr;
181         m_ptr = optr;
182         if (ptr)
183             CFRelease(ptr);
184     }
185 
186     template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(U* optr)
187     {
188         if (optr)
189             CFRetain(optr);
190         PtrType ptr = m_ptr;
191         m_ptr = optr;
192         if (ptr)
193             CFRelease(ptr);
194         return *this;
195     }
196 
swap(RetainPtr<T> & o)197     template<typename T> inline void RetainPtr<T>::swap(RetainPtr<T>& o)
198     {
199         std::swap(m_ptr, o.m_ptr);
200     }
201 
swap(RetainPtr<T> & a,RetainPtr<T> & b)202     template<typename T> inline void swap(RetainPtr<T>& a, RetainPtr<T>& b)
203     {
204         a.swap(b);
205     }
206 
207     template<typename T, typename U> inline bool operator==(const RetainPtr<T>& a, const RetainPtr<U>& b)
208     {
209         return a.get() == b.get();
210     }
211 
212     template<typename T, typename U> inline bool operator==(const RetainPtr<T>& a, U* b)
213     {
214         return a.get() == b;
215     }
216 
217     template<typename T, typename U> inline bool operator==(T* a, const RetainPtr<U>& b)
218     {
219         return a == b.get();
220     }
221 
222     template<typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, const RetainPtr<U>& b)
223     {
224         return a.get() != b.get();
225     }
226 
227     template<typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, U* b)
228     {
229         return a.get() != b;
230     }
231 
232     template<typename T, typename U> inline bool operator!=(T* a, const RetainPtr<U>& b)
233     {
234         return a != b.get();
235     }
236 
237     template<typename P> struct HashTraits<RetainPtr<P> > : SimpleClassHashTraits<RetainPtr<P> > { };
238 
239     template<typename P> struct PtrHash<RetainPtr<P> > : PtrHash<P*> {
240         using PtrHash<P*>::hash;
241         static unsigned hash(const RetainPtr<P>& key) { return hash(key.get()); }
242         using PtrHash<P*>::equal;
243         static bool equal(const RetainPtr<P>& a, const RetainPtr<P>& b) { return a == b; }
244         static bool equal(P* a, const RetainPtr<P>& b) { return a == b; }
245         static bool equal(const RetainPtr<P>& a, P* b) { return a == b; }
246     };
247 
248     template<typename P> struct DefaultHash<RetainPtr<P> > { typedef PtrHash<RetainPtr<P> > Hash; };
249 
250 } // namespace WTF
251 
252 using WTF::AdoptCF;
253 using WTF::AdoptNS;
254 using WTF::RetainPtr;
255 
256 #endif // WTF_RetainPtr_h
257