11.2.0/backward/auto_ptr.h

// auto_ptr implementation -*- C++ -*-

// Copyright (C) 2007-2021 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) { }
    } _GLIBCXX11_DEPRECATED;

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"

  /**
   *  @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_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_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 are supposed to convert an %auto_ptr into and from
       *  an auto_ptr_ref automatically as needed.  This would allow
       *  constructs such as
       *  @code
       *    auto_ptr<Derived>  func_returning_auto_ptr(.....);
       *    ...
       *    auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
       *  @endcode
       *
       *  But it doesn't work, and won't be fixed. For further details see
       *  http://cplusplus.github.io/LWG/lwg-closed.html#463
       */
      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()); }
    } _GLIBCXX11_DEPRECATED_SUGGEST("std::unique_ptr");

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 541. shared_ptr template assignment and void
  template<>
    class auto_ptr<void>
    {
    public:
      typedef void element_type;
    } _GLIBCXX11_DEPRECATED;

#if __cplusplus >= 201103L
  template<_Lock_policy _Lp>
  template<typename _Tp>
    inline
    __shared_count<_Lp>::__shared_count(std::auto_ptr<_Tp>&& __r)
    : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get()))
    { __r.release(); }

  template<typename _Tp, _Lock_policy _Lp>
  template<typename _Tp1, typename>
    inline
    __shared_ptr<_Tp, _Lp>::__shared_ptr(std::auto_ptr<_Tp1>&& __r)
    : _M_ptr(__r.get()), _M_refcount()
    {
      __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
      static_assert( sizeof(_Tp1) > 0, "incomplete type" );
      _Tp1* __tmp = __r.get();
      _M_refcount = __shared_count<_Lp>(std::move(__r));
      _M_enable_shared_from_this_with(__tmp);
    }

  template<typename _Tp>
  template<typename _Tp1, typename>
    inline
    shared_ptr<_Tp>::shared_ptr(std::auto_ptr<_Tp1>&& __r)
    : __shared_ptr<_Tp>(std::move(__r)) { }

  template<typename _Tp, typename _Dp>
  template<typename _Up, typename>
    inline
    unique_ptr<_Tp, _Dp>::unique_ptr(auto_ptr<_Up>&& __u) noexcept
    : _M_t(__u.release(), deleter_type()) { }
#endif

#pragma GCC diagnostic pop

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif /* _BACKWARD_AUTO_PTR_H */
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	10837 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// auto_ptr implementation -- C++ --
2
3	// Copyright (C) 2007-2021 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/** @file backward/auto_ptr.h
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly. @headername{memory}
28	*/
29
30	#ifndef _BACKWARD_AUTO_PTR_H
31	#define _BACKWARD_AUTO_PTR_H 1
32
33	#include <bits/c++config.h>
34	#include <debug/debug.h>
35
36	namespace std _GLIBCXX_VISIBILITY(default)
37	{
38	_GLIBCXX_BEGIN_NAMESPACE_VERSION
39
40	/**
41	* A wrapper class to provide auto_ptr with reference semantics.
42	* For example, an auto_ptr can be assigned (or constructed from)
43	* the result of a function which returns an auto_ptr by value.
44	*
45	* All the auto_ptr_ref stuff should happen behind the scenes.
46	*/
47	template<typename _Tp1>
48	struct auto_ptr_ref
49	{
50	_Tp1* _M_ptr;
51
52	explicit
53	auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { }
54	} _GLIBCXX11_DEPRECATED;
55
56	#pragma GCC diagnostic push
57	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
58
59	/**
60	* @brief A simple smart pointer providing strict ownership semantics.
61	*
62	* The Standard says:
63	* <pre>
64	* An @c auto_ptr owns the object it holds a pointer to. Copying
65	* an @c auto_ptr copies the pointer and transfers ownership to the
66	* destination. If more than one @c auto_ptr owns the same object
67	* at the same time the behavior of the program is undefined.
68	*
69	* The uses of @c auto_ptr include providing temporary
70	* exception-safety for dynamically allocated memory, passing
71	* ownership of dynamically allocated memory to a function, and
72	* returning dynamically allocated memory from a function. @c
73	* auto_ptr does not meet the CopyConstructible and Assignable
74	* requirements for Standard Library <a
75	* href="tables.html#65">container</a> elements and thus
76	* instantiating a Standard Library container with an @c auto_ptr
77	* results in undefined behavior.
78	* </pre>
79	* Quoted from [20.4.5]/3.
80	*
81	* Good examples of what can and cannot be done with auto_ptr can
82	* be found in the libstdc++ testsuite.
83	*
84	* _GLIBCXX_RESOLVE_LIB_DEFECTS
85	* 127. auto_ptr<> conversion issues
86	* These resolutions have all been incorporated.
87	*/
88	template<typename _Tp>
89	class auto_ptr
90	{
91	private:
92	_Tp* _M_ptr;
93
94	public:
95	/// The pointed-to type.
96	typedef _Tp element_type;
97
98	/**
99	* @brief An %auto_ptr is usually constructed from a raw pointer.
100	* @param __p A pointer (defaults to NULL).
101	*
102	* This object now @e owns the object pointed to by @a __p.
103	*/
104	explicit
105	auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { }
106
107	/**
108	* @brief An %auto_ptr can be constructed from another %auto_ptr.
109	* @param __a Another %auto_ptr of the same type.
110	*
111	* This object now @e owns the object previously owned by @a __a,
112	* which has given up ownership.
113	*/
114	auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { }
115
116	/**
117	* @brief An %auto_ptr can be constructed from another %auto_ptr.
118	* @param __a Another %auto_ptr of a different but related type.
119	*
120	* A pointer-to-Tp1 must be convertible to a
121	* pointer-to-Tp/element_type.
122	*
123	* This object now @e owns the object previously owned by @a __a,
124	* which has given up ownership.
125	*/
126	template<typename _Tp1>
127	auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { }
128
129	/**
130	* @brief %auto_ptr assignment operator.
131	* @param __a Another %auto_ptr of the same type.
132	*
133	* This object now @e owns the object previously owned by @a __a,
134	* which has given up ownership. The object that this one @e
135	* used to own and track has been deleted.
136	*/
137	auto_ptr&
138	operator=(auto_ptr& __a) throw()
139	{
140	reset(__a.release());
141	return *this;
142	}
143
144	/**
145	* @brief %auto_ptr assignment operator.
146	* @param __a Another %auto_ptr of a different but related type.
147	*
148	* A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.
149	*
150	* This object now @e owns the object previously owned by @a __a,
151	* which has given up ownership. The object that this one @e
152	* used to own and track has been deleted.
153	*/
154	template<typename _Tp1>
155	auto_ptr&
156	operator=(auto_ptr<_Tp1>& __a) throw()
157	{
158	reset(__a.release());
159	return *this;
160	}
161
162	/**
163	* When the %auto_ptr goes out of scope, the object it owns is
164	* deleted. If it no longer owns anything (i.e., @c get() is
165	* @c NULL), then this has no effect.
166	*
167	* The C++ standard says there is supposed to be an empty throw
168	* specification here, but omitting it is standard conforming. Its
169	* presence can be detected only if _Tp::~_Tp() throws, but this is
170	* prohibited. [17.4.3.6]/2
171	*/
172	~auto_ptr() { delete _M_ptr; }
173
174	/**
175	* @brief Smart pointer dereferencing.
176	*
177	* If this %auto_ptr no longer owns anything, then this
178	* operation will crash. (For a smart pointer, <em>no longer owns
179	* anything</em> is the same as being a null pointer, and you know
180	* what happens when you dereference one of those...)
181	*/
182	element_type&
183	operator*() const throw()
184	{
185	__glibcxx_assert(_M_ptr != 0);
186	return *_M_ptr;
187	}
188
189	/**
190	* @brief Smart pointer dereferencing.
191	*
192	* This returns the pointer itself, which the language then will
193	* automatically cause to be dereferenced.
194	*/
195	element_type*
196	operator->() const throw()
197	{
198	__glibcxx_assert(_M_ptr != 0);
199	return _M_ptr;
200	}
201
202	/**
203	* @brief Bypassing the smart pointer.
204	* @return The raw pointer being managed.
205	*
206	* You can get a copy of the pointer that this object owns, for
207	* situations such as passing to a function which only accepts
208	* a raw pointer.
209	*
210	* @note This %auto_ptr still owns the memory.
211	*/
212	element_type*
213	get() const throw() { return _M_ptr; }
214
215	/**
216	* @brief Bypassing the smart pointer.
217	* @return The raw pointer being managed.
218	*
219	* You can get a copy of the pointer that this object owns, for
220	* situations such as passing to a function which only accepts
221	* a raw pointer.
222	*
223	* @note This %auto_ptr no longer owns the memory. When this object
224	* goes out of scope, nothing will happen.
225	*/
226	element_type*
227	release() throw()
228	{
229	element_type* __tmp = _M_ptr;
230	_M_ptr = 0;
231	return __tmp;
232	}
233
234	/**
235	* @brief Forcibly deletes the managed object.
236	* @param __p A pointer (defaults to NULL).
237	*
238	* This object now @e owns the object pointed to by @a __p. The
239	* previous object has been deleted.
240	*/
241	void
242	reset(element_type* __p = 0) throw()
243	{
244	if (__p != _M_ptr)
245	{
246	delete _M_ptr;
247	_M_ptr = __p;
248	}
249	}
250
251	/**
252	* @brief Automatic conversions
253	*
254	* These operations are supposed to convert an %auto_ptr into and from
255	* an auto_ptr_ref automatically as needed. This would allow
256	* constructs such as
257	* @code
258	* auto_ptr<Derived> func_returning_auto_ptr(.....);
259	* ...
260	* auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
261	* @endcode
262	*
263	* But it doesn't work, and won't be fixed. For further details see
264	* http://cplusplus.github.io/LWG/lwg-closed.html#463
265	*/
266	auto_ptr(auto_ptr_ref<element_type> __ref) throw()
267	: _M_ptr(__ref._M_ptr) { }
268
269	auto_ptr&
270	operator=(auto_ptr_ref<element_type> __ref) throw()
271	{
272	if (__ref._M_ptr != this->get())
273	{
274	delete _M_ptr;
275	_M_ptr = __ref._M_ptr;
276	}
277	return *this;
278	}
279
280	template<typename _Tp1>
281	operator auto_ptr_ref<_Tp1>() throw()
282	{ return auto_ptr_ref<_Tp1>(this->release()); }
283
284	template<typename _Tp1>
285	operator auto_ptr<_Tp1>() throw()
286	{ return auto_ptr<_Tp1>(this->release()); }
287	} _GLIBCXX11_DEPRECATED_SUGGEST("std::unique_ptr");
288
289	// _GLIBCXX_RESOLVE_LIB_DEFECTS
290	// 541. shared_ptr template assignment and void
291	template<>
292	class auto_ptr<void>
293	{
294	public:
295	typedef void element_type;
296	} _GLIBCXX11_DEPRECATED;
297
298	#if __cplusplus >= 201103L
299	template<_Lock_policy _Lp>
300	template<typename _Tp>
301	inline
302	__shared_count<_Lp>::__shared_count(std::auto_ptr<_Tp>&& __r)
303	: _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get()))
304	{ __r.release(); }
305
306	template<typename _Tp, _Lock_policy _Lp>
307	template<typename _Tp1, typename>
308	inline
309	__shared_ptr<_Tp, _Lp>::__shared_ptr(std::auto_ptr<_Tp1>&& __r)
310	: _M_ptr(__r.get()), _M_refcount()
311	{
312	__glibcxx_function_requires(_ConvertibleConcept<_Tp1, _Tp>)
313	static_assert( sizeof(_Tp1) > 0, "incomplete type" );
314	_Tp1* __tmp = __r.get();
315	_M_refcount = __shared_count<_Lp>(std::move(__r));
316	_M_enable_shared_from_this_with(__tmp);
317	}
318
319	template<typename _Tp>
320	template<typename _Tp1, typename>
321	inline
322	shared_ptr<_Tp>::shared_ptr(std::auto_ptr<_Tp1>&& __r)
323	: __shared_ptr<_Tp>(std::move(__r)) { }
324
325	template<typename _Tp, typename _Dp>
326	template<typename _Up, typename>
327	inline
328	unique_ptr<_Tp, _Dp>::unique_ptr(auto_ptr<_Up>&& __u) noexcept
329	: _M_t(__u.release(), deleter_type()) { }
330	#endif
331
332	#pragma GCC diagnostic pop
333
334	_GLIBCXX_END_NAMESPACE_VERSION
335	} // namespace
336
337	#endif /* _BACKWARD_AUTO_PTR_H */