wtf/OwnPtr.h

   1 /*
   2  *  Copyright (C) 2006, 2007 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 WTF_OwnPtr_h
  22 #define WTF_OwnPtr_h
  23
  24 #include <algorithm>
  25 #include <memory>
  26 #include <wtf/Assertions.h>
  27 #include <wtf/Noncopyable.h>
  28
  29 #if PLATFORM(WIN)
  30
  31 typedef struct HBITMAP__* HBITMAP;
  32 typedef struct HBRUSH__* HBRUSH;
  33 typedef struct HFONT__* HFONT;
  34 typedef struct HPALETTE__* HPALETTE;
  35 typedef struct HPEN__* HPEN;
  36 typedef struct HRGN__* HRGN;
  37
  38 #endif
  39
  40 namespace WTF {
  41
  42     // Unlike most of our smart pointers, OwnPtr can take either the pointer type or the pointed-to type.
  43
  44     // FIXME: Share a single RemovePointer class template with RetainPtr.
  45     template <typename T> struct OwnPtrRemovePointer { typedef T type; };
  46     template <typename T> struct OwnPtrRemovePointer<T*> { typedef T type; };
  47
  48     template <typename T> inline void deleteOwnedPtr(T* ptr)
  49     {
  50         typedef char known[sizeof(T) ? 1 : -1];
  51         if (sizeof(known))
  52             delete ptr;
  53     }
  54
  55 #if PLATFORM(WIN)
  56     void deleteOwnedPtr(HBITMAP);
  57     void deleteOwnedPtr(HBRUSH);
  58     void deleteOwnedPtr(HFONT);
  59     void deleteOwnedPtr(HPALETTE);
  60     void deleteOwnedPtr(HPEN);
  61     void deleteOwnedPtr(HRGN);
  62 #endif
  63
  64     template <typename T> class OwnPtr : Noncopyable {
  65     public:
  66         typedef typename OwnPtrRemovePointer<T>::type ValueType;
  67         typedef ValueType* PtrType;
  68
  69         explicit OwnPtr(PtrType ptr = 0) : m_ptr(ptr) { }
  70         OwnPtr(std::auto_ptr<ValueType> autoPtr) : m_ptr(autoPtr.release()) { }
  71         ~OwnPtr() { deleteOwnedPtr(m_ptr); }
  72
  73         PtrType get() const { return m_ptr; }
  74         PtrType release() { PtrType ptr = m_ptr; m_ptr = 0; return ptr; }
  75
  76         // FIXME: This should be renamed to adopt.
  77         void set(PtrType ptr) { ASSERT(!ptr || m_ptr != ptr); deleteOwnedPtr(m_ptr); m_ptr = ptr; }
  78
  79         void adopt(std::auto_ptr<ValueType> autoPtr) { ASSERT(!autoPtr.get() || m_ptr != autoPtr.get()); deleteOwnedPtr(m_ptr); m_ptr = autoPtr.release(); }
  80
  81         void clear() { deleteOwnedPtr(m_ptr); m_ptr = 0; }
  82
  83         ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
  84         PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  85
  86         bool operator!() const { return !m_ptr; }
  87
  88         // This conversion operator allows implicit conversion to bool but not to other integer types.
  89         typedef PtrType OwnPtr::*UnspecifiedBoolType;
  90         operator UnspecifiedBoolType() const { return m_ptr ? &OwnPtr::m_ptr : 0; }
  91
  92         void swap(OwnPtr& o) { std::swap(m_ptr, o.m_ptr); }
  93
  94     private:
  95         PtrType m_ptr;
  96     };
  97
  98     template <typename T> inline void swap(OwnPtr<T>& a, OwnPtr<T>& b) { a.swap(b); }
  99
 100     template <typename T, typename U> inline bool operator==(const OwnPtr<T>& a, U* b)
 101     {
 102         return a.get() == b;
 103     }
 104
 105     template <typename T, typename U> inline bool operator==(T* a, const OwnPtr<U>& b)
 106     {
 107         return a == b.get();
 108     }
 109
 110     template <typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, U* b)
 111     {
 112         return a.get() != b;
 113     }
 114
 115     template <typename T, typename U> inline bool operator!=(T* a, const OwnPtr<U>& b)
 116     {
 117         return a != b.get();
 118     }
 119
 120     template <typename T> inline typename OwnPtr<T>::PtrType getPtr(const OwnPtr<T>& p)
 121     {
 122         return p.get();
 123     }
 124
 125 } // namespace WTF
 126
 127 using WTF::OwnPtr;
 128
 129 #endif // WTF_OwnPtr_h