src/vsmartptr.h

   1 ///
   2 /// \file       vsmartptr.h
   3 ///             Smart pointer that accepts custom 'free' functions.
   4 ///
   5
   6 /*
   7     Copyright (C) 2006-2013, Net Direct Inc. (http://www.netdirect.ca/)
   8
   9     This program is free software; you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License as published by
  11     the Free Software Foundation; either version 2 of the License, or
  12     (at your option) any later version.
  13
  14     This program is distributed in the hope that it will be useful,
  15     but WITHOUT ANY WARRANTY; without even the implied warranty of
  16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  17
  18     See the GNU General Public License in the COPYING file at the
  19     root directory of this project for more details.
  20 */
  21
  22 #ifndef __BARRY_VSMARTPTR_H__
  23 #define __BARRY_VSMARTPTR_H__
  24
  25 namespace Barry {
  26
  27 //
  28 // vSmartPtr
  29 //
  30 /// A special smart pointer for variables that have their own
  31 /// special 'free' functions.  Behaves like std::auto_ptr<>
  32 /// in that only one object at a time owns the pointer,
  33 /// and destruction frees it by calling the given FreeFunc.
  34 ///
  35 template <class T, class FT, void (*FreeFunc)(FT *pt)>
  36 class vSmartPtr
  37 {
  38         mutable T *m_pt;
  39
  40 public:
  41         vSmartPtr() : m_pt(0) {}
  42         vSmartPtr(T *pt) : m_pt(pt) {}
  43         vSmartPtr(const vSmartPtr &sp) : m_pt(sp.m_pt)
  44         {
  45                 sp.m_pt = 0;
  46         }
  47         ~vSmartPtr()
  48         {
  49                 reset();
  50         }
  51
  52         vSmartPtr& operator=(T *pt)
  53         {
  54                 reset(pt);
  55                 return *this;
  56         }
  57
  58         vSmartPtr& operator=(const vSmartPtr &sp)
  59         {
  60                 reset(sp.release());
  61                 return *this;
  62         }
  63
  64         // Some non-standard APIs used by Barry
  65         T* Extract()
  66         {
  67                 return this->release();
  68         }
  69
  70         T* Get()
  71         {
  72                 return this->get();
  73         }
  74
  75         // std::auto_ptr<> style API
  76         T* get()
  77         {
  78                 return m_pt;
  79         }
  80
  81         T* release()
  82         {
  83                 T *rp = m_pt;
  84                 m_pt = 0;
  85                 return rp;
  86         }
  87
  88         void reset(T *new_obj = 0)
  89         {
  90                 if( m_pt )
  91                         FreeFunc(m_pt);
  92                 m_pt = new_obj;
  93         }
  94 };
  95
  96 //
  97 // vLateSmartPtr
  98 //
  99 /// Variation of the above smart pointer that allows the user to
 100 /// assign a free function after construction, in the case of
 101 /// dlopen()'d frees.
 102 ///
 103 template <class T, class FreeFuncPtrT>
 104 class vLateSmartPtr
 105 {
 106         mutable T *m_pt;
 107         FreeFuncPtrT m_FreeFuncPtr;
 108
 109 public:
 110         explicit vLateSmartPtr(FreeFuncPtrT freefunc = 0)
 111                 : m_pt(0)
 112                 , m_FreeFuncPtr(freefunc)
 113         {
 114         }
 115
 116         vLateSmartPtr(T *pt, FreeFuncPtrT freefunc = 0)
 117                 : m_pt(pt)
 118                 , m_FreeFuncPtr(freefunc)
 119         {
 120         }
 121
 122         vLateSmartPtr(const vLateSmartPtr &sp)
 123                 : m_pt(sp.m_pt)
 124                 , m_FreeFuncPtr(sp.m_FreeFuncPtr)
 125         {
 126                 sp.m_pt = 0;
 127         }
 128
 129         ~vLateSmartPtr()
 130         {
 131                 reset();
 132         }
 133
 134         void SetFreeFunc(FreeFuncPtrT freefunc)
 135         {
 136                 m_FreeFuncPtr = freefunc;
 137         }
 138
 139         vLateSmartPtr& operator=(T *pt)
 140         {
 141                 reset(pt);
 142                 return *this;
 143         }
 144
 145         vLateSmartPtr& operator=(const vLateSmartPtr &sp)
 146         {
 147                 reset(sp.release());
 148                 m_FreeFuncPtr = sp.m_FreeFuncPtr;
 149                 return *this;
 150         }
 151
 152         // Some non-standard APIs used by Barry
 153         T* Extract()
 154         {
 155                 return this->release();
 156         }
 157
 158         T* Get()
 159         {
 160                 return this->get();
 161         }
 162
 163         // std::auto_ptr<> style API
 164         T* get()
 165         {
 166                 return m_pt;
 167         }
 168
 169         T* release()
 170         {
 171                 T *rp = m_pt;
 172                 m_pt = 0;
 173                 return rp;
 174         }
 175
 176         void reset(T *new_obj = 0)
 177         {
 178                 // don't check for null m_FreeFuncPtr, since
 179                 // that should be an obvious crash and requires fixing
 180                 if( m_pt )
 181                         (*m_FreeFuncPtr)(m_pt);
 182                 m_pt = new_obj;
 183         }
 184 };
 185
 186 /*
 187
 188 Example usage:
 189
 190 typedef vSmartPtr<b_VFormatAttribute, b_VFormatAttribute, &b_vformat_attribute_free> vAttrPtr;
 191 typedef vSmartPtr<b_VFormatParam, b_VFormatParam, &b_vformat_attribute_param_free> vParamPtr;
 192 typedef vSmartPtr<char, void, &g_free> gStringPtr;
 193
 194 */
 195
 196 } // namespace Barry
 197
 198 #endif
 199