wtf/OwnPtr.h

   1 // -*- mode: c++; c-basic-offset: 4 -*-
   2 /*
   3  *  Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
   4  *
   5  *  This library is free software; you can redistribute it and/or
   6  *  modify it under the terms of the GNU Library General Public
   7  *  License as published by the Free Software Foundation; either
   8  *  version 2 of the License, or (at your option) any later version.
   9  *
  10  *  This library is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  Library General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU Library General Public License
  16  *  along with this library; see the file COPYING.LIB.  If not, write to
  17  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  18  *  Boston, MA 02110-1301, USA.
  19  *
  20  */
  21
  22 #ifndef WTF_OwnPtr_h
  23 #define WTF_OwnPtr_h
  24
  25 #include <algorithm>
  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() { deleteOwnedPtr(m_ptr); }
  71
  72         PtrType get() const { return m_ptr; }
  73         PtrType release() { PtrType ptr = m_ptr; m_ptr = 0; return ptr; }
  74
  75         void set(PtrType ptr) { ASSERT(!ptr || m_ptr != ptr); deleteOwnedPtr(m_ptr); m_ptr = ptr; }
  76         void clear() { deleteOwnedPtr(m_ptr); m_ptr = 0; }
  77
  78         ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
  79         PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  80
  81         bool operator!() const { return !m_ptr; }
  82
  83         // This conversion operator allows implicit conversion to bool but not to other integer types.
  84         typedef PtrType OwnPtr::*UnspecifiedBoolType;
  85         operator UnspecifiedBoolType() const { return m_ptr ? &OwnPtr::m_ptr : 0; }
  86
  87         void swap(OwnPtr& o) { std::swap(m_ptr, o.m_ptr); }
  88
  89     private:
  90         PtrType m_ptr;
  91     };
  92
  93     template <typename T> inline void swap(OwnPtr<T>& a, OwnPtr<T>& b) { a.swap(b); }
  94
  95     template <typename T, typename U> inline bool operator==(const OwnPtr<T>& a, U* b)
  96     {
  97         return a.get() == b;
  98     }
  99
 100     template <typename T, typename U> inline bool operator==(T* a, const OwnPtr<U>& b)
 101     {
 102         return a == b.get();
 103     }
 104
 105     template <typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, U* b)
 106     {
 107         return a.get() != b;
 108     }
 109
 110     template <typename T, typename U> inline bool operator!=(T* a, const OwnPtr<U>& b)
 111     {
 112         return a != b.get();
 113     }
 114
 115     template <typename T> inline typename OwnPtr<T>::PtrType getPtr(const OwnPtr<T>& p)
 116     {
 117         return p.get();
 118     }
 119
 120 } // namespace WTF
 121
 122 using WTF::OwnPtr;
 123
 124 #endif // WTF_OwnPtr_h