summaryrefslogtreecommitdiff
path: root/libstdc++-v3/include/backward/auto_ptr.h
blob: e86876510340c34bf0398644555d408d89fee05c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
// auto_ptr implementation -*- C++ -*-

// Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file backward/auto_ptr.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{memory}
 */

#ifndef _BACKWARD_AUTO_PTR_H
#define _BACKWARD_AUTO_PTR_H 1

#include <bits/c++config.h>
#include <debug/debug.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   *  A wrapper class to provide auto_ptr with reference semantics.
   *  For example, an auto_ptr can be assigned (or constructed from)
   *  the result of a function which returns an auto_ptr by value.
   *
   *  All the auto_ptr_ref stuff should happen behind the scenes.
   */
  template<typename _Tp1>
    struct auto_ptr_ref
    {
      _Tp1* _M_ptr;
      
      explicit
      auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { }
    } _GLIBCXX_DEPRECATED;


  /**
   *  @brief  A simple smart pointer providing strict ownership semantics.
   *
   *  The Standard says:
   *  <pre>
   *  An @c auto_ptr owns the object it holds a pointer to.  Copying
   *  an @c auto_ptr copies the pointer and transfers ownership to the
   *  destination.  If more than one @c auto_ptr owns the same object
   *  at the same time the behavior of the program is undefined.
   *
   *  The uses of @c auto_ptr include providing temporary
   *  exception-safety for dynamically allocated memory, passing
   *  ownership of dynamically allocated memory to a function, and
   *  returning dynamically allocated memory from a function.  @c
   *  auto_ptr does not meet the CopyConstructible and Assignable
   *  requirements for Standard Library <a
   *  href="tables.html#65">container</a> elements and thus
   *  instantiating a Standard Library container with an @c auto_ptr
   *  results in undefined behavior.
   *  </pre>
   *  Quoted from [20.4.5]/3.
   *
   *  Good examples of what can and cannot be done with auto_ptr can
   *  be found in the libstdc++ testsuite.
   *
   *  _GLIBCXX_RESOLVE_LIB_DEFECTS
   *  127.  auto_ptr<> conversion issues
   *  These resolutions have all been incorporated.
   */
  template<typename _Tp>
    class auto_ptr
    {
    private:
      _Tp* _M_ptr;
      
    public:
      /// The pointed-to type.
      typedef _Tp element_type;
      
      /**
       *  @brief  An %auto_ptr is usually constructed from a raw pointer.
       *  @param  p  A pointer (defaults to NULL).
       *
       *  This object now @e owns the object pointed to by @a p.
       */
      explicit
      auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { }

      /**
       *  @brief  An %auto_ptr can be constructed from another %auto_ptr.
       *  @param  a  Another %auto_ptr of the same type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownership.
       */
      auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { }

      /**
       *  @brief  An %auto_ptr can be constructed from another %auto_ptr.
       *  @param  a  Another %auto_ptr of a different but related type.
       *
       *  A pointer-to-Tp1 must be convertible to a
       *  pointer-to-Tp/element_type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownership.
       */
      template<typename _Tp1>
        auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { }

      /**
       *  @brief  %auto_ptr assignment operator.
       *  @param  a  Another %auto_ptr of the same type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownership.  The object that this one @e
       *  used to own and track has been deleted.
       */
      auto_ptr&
      operator=(auto_ptr& __a) throw()
      {
	reset(__a.release());
	return *this;
      }

      /**
       *  @brief  %auto_ptr assignment operator.
       *  @param  a  Another %auto_ptr of a different but related type.
       *
       *  A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownership.  The object that this one @e
       *  used to own and track has been deleted.
       */
      template<typename _Tp1>
        auto_ptr&
        operator=(auto_ptr<_Tp1>& __a) throw()
        {
	  reset(__a.release());
	  return *this;
	}

      /**
       *  When the %auto_ptr goes out of scope, the object it owns is
       *  deleted.  If it no longer owns anything (i.e., @c get() is
       *  @c NULL), then this has no effect.
       *
       *  The C++ standard says there is supposed to be an empty throw
       *  specification here, but omitting it is standard conforming.  Its
       *  presence can be detected only if _Tp::~_Tp() throws, but this is
       *  prohibited.  [17.4.3.6]/2
       */
      ~auto_ptr() { delete _M_ptr; }
      
      /**
       *  @brief  Smart pointer dereferencing.
       *
       *  If this %auto_ptr no longer owns anything, then this
       *  operation will crash.  (For a smart pointer, <em>no longer owns
       *  anything</em> is the same as being a null pointer, and you know
       *  what happens when you dereference one of those...)
       */
      element_type&
      operator*() const throw() 
      {
	_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
	return *_M_ptr; 
      }
      
      /**
       *  @brief  Smart pointer dereferencing.
       *
       *  This returns the pointer itself, which the language then will
       *  automatically cause to be dereferenced.
       */
      element_type*
      operator->() const throw() 
      {
	_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
	return _M_ptr; 
      }
      
      /**
       *  @brief  Bypassing the smart pointer.
       *  @return  The raw pointer being managed.
       *
       *  You can get a copy of the pointer that this object owns, for
       *  situations such as passing to a function which only accepts
       *  a raw pointer.
       *
       *  @note  This %auto_ptr still owns the memory.
       */
      element_type*
      get() const throw() { return _M_ptr; }
      
      /**
       *  @brief  Bypassing the smart pointer.
       *  @return  The raw pointer being managed.
       *
       *  You can get a copy of the pointer that this object owns, for
       *  situations such as passing to a function which only accepts
       *  a raw pointer.
       *
       *  @note  This %auto_ptr no longer owns the memory.  When this object
       *  goes out of scope, nothing will happen.
       */
      element_type*
      release() throw()
      {
	element_type* __tmp = _M_ptr;
	_M_ptr = 0;
	return __tmp;
      }
      
      /**
       *  @brief  Forcibly deletes the managed object.
       *  @param  p  A pointer (defaults to NULL).
       *
       *  This object now @e owns the object pointed to by @a p.  The
       *  previous object has been deleted.
       */
      void
      reset(element_type* __p = 0) throw()
      {
	if (__p != _M_ptr)
	  {
	    delete _M_ptr;
	    _M_ptr = __p;
	  }
      }
      
      /** 
       *  @brief  Automatic conversions
       *
       *  These operations convert an %auto_ptr into and from an auto_ptr_ref
       *  automatically as needed.  This allows constructs such as
       *  @code
       *    auto_ptr<Derived>  func_returning_auto_ptr(.....);
       *    ...
       *    auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
       *  @endcode
       */
      auto_ptr(auto_ptr_ref<element_type> __ref) throw()
      : _M_ptr(__ref._M_ptr) { }
      
      auto_ptr&
      operator=(auto_ptr_ref<element_type> __ref) throw()
      {
	if (__ref._M_ptr != this->get())
	  {
	    delete _M_ptr;
	    _M_ptr = __ref._M_ptr;
	  }
	return *this;
      }
      
      template<typename _Tp1>
        operator auto_ptr_ref<_Tp1>() throw()
        { return auto_ptr_ref<_Tp1>(this->release()); }

      template<typename _Tp1>
        operator auto_ptr<_Tp1>() throw()
        { return auto_ptr<_Tp1>(this->release()); }
    } _GLIBCXX_DEPRECATED;

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 541. shared_ptr template assignment and void
  template<>
    class auto_ptr<void>
    {
    public:
      typedef void element_type;
    } _GLIBCXX_DEPRECATED;

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif /* _BACKWARD_AUTO_PTR_H */