11.2.0/bits/stl_tempbuf.h

// Temporary buffer implementation -*- C++ -*-

// Copyright (C) 2001-2021 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/>.

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996,1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

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

#ifndef _STL_TEMPBUF_H
#define _STL_TEMPBUF_H 1

#include <bits/stl_algobase.h>
#include <bits/stl_construct.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  namespace __detail
  {
    template<typename _Tp>
      inline void
      __return_temporary_buffer(_Tp* __p,
                                size_t __len __attribute__((__unused__)))
      {
#if __cpp_sized_deallocation
        ::operator delete(__p, __len * sizeof(_Tp));
#else
        ::operator delete(__p);
#endif
      }
  }

  /**
   *  @brief Allocates a temporary buffer.
   *  @param  __len  The number of objects of type Tp.
   *  @return See full description.
   *
   *  Reinventing the wheel, but this time with prettier spokes!
   *
   *  This function tries to obtain storage for @c __len adjacent Tp
   *  objects.  The objects themselves are not constructed, of course.
   *  A pair<> is returned containing <em>the buffer s address and
   *  capacity (in the units of sizeof(_Tp)), or a pair of 0 values if
   *  no storage can be obtained.</em>  Note that the capacity obtained
   *  may be less than that requested if the memory is unavailable;
   *  you should compare len with the .second return value.
   *
   * Provides the nothrow exception guarantee.
   */
  template<typename _Tp>
    pair<_Tp*, ptrdiff_t>
    get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT
    {
      const ptrdiff_t __max =
        __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp);
      if (__len > __max)
        __len = __max;

      while (__len > 0)
        {
          _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp),
                                                        std::nothrow));
          if (__tmp != 0)
            return std::pair<_Tp*, ptrdiff_t>(__tmp, __len);
          __len = __len == 1 ? 0 : ((__len + 1) / 2);
        }
      return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0);
    }

  /**
   *  @brief The companion to get_temporary_buffer().
   *  @param  __p  A buffer previously allocated by get_temporary_buffer.
   *  @return   None.
   *
   *  Frees the memory pointed to by __p.
   */
  template<typename _Tp>
    inline void
    return_temporary_buffer(_Tp* __p)
    { ::operator delete(__p); }

  /**
   *  This class is used in two places: stl_algo.h and ext/memory,
   *  where it is wrapped as the temporary_buffer class.  See
   *  temporary_buffer docs for more notes.
   */
  template<typename _ForwardIterator, typename _Tp>
    class _Temporary_buffer
    {
      // concept requirements
      __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept)

    public:
      typedef _Tp         value_type;
      typedef value_type* pointer;
      typedef pointer     iterator;
      typedef ptrdiff_t   size_type;

    protected:
      size_type  _M_original_len;
      size_type  _M_len;
      pointer    _M_buffer;

    public:
      /// As per Table mumble.
      size_type
      size() const
      { return _M_len; }

      /// Returns the size requested by the constructor; may be >size().
      size_type
      requested_size() const
      { return _M_original_len; }

      /// As per Table mumble.
      iterator
      begin()
      { return _M_buffer; }

      /// As per Table mumble.
      iterator
      end()
      { return _M_buffer + _M_len; }

      /**
       * Constructs a temporary buffer of a size somewhere between
       * zero and the given length.
       */
      _Temporary_buffer(_ForwardIterator __seed, size_type __original_len);

      ~_Temporary_buffer()
      {
        std::_Destroy(_M_buffer, _M_buffer + _M_len);
        std::__detail::__return_temporary_buffer(_M_buffer, _M_len);
      }

    private:
      // Disable copy constructor and assignment operator.
      _Temporary_buffer(const _Temporary_buffer&);

      void
      operator=(const _Temporary_buffer&);
    };


  template<bool>
    struct __uninitialized_construct_buf_dispatch
    {
      template<typename _Pointer, typename _ForwardIterator>
        static void
        __ucr(_Pointer __first, _Pointer __last,
              _ForwardIterator __seed)
        {
          if (__first == __last)
            return;

          _Pointer __cur = __first;
          __try
            {
              std::_Construct(std::__addressof(*__first),
                              _GLIBCXX_MOVE(*__seed));
              _Pointer __prev = __cur;
              ++__cur;
              for(; __cur != __last; ++__cur, ++__prev)
                std::_Construct(std::__addressof(*__cur),
                                _GLIBCXX_MOVE(*__prev));
              *__seed = _GLIBCXX_MOVE(*__prev);
            }
          __catch(...)
            {
              std::_Destroy(__first, __cur);
              __throw_exception_again;
            }
        }
    };

  template<>
    struct __uninitialized_construct_buf_dispatch<true>
    {
      template<typename _Pointer, typename _ForwardIterator>
        static void
        __ucr(_Pointer, _Pointer, _ForwardIterator) { }
    };

  // Constructs objects in the range [first, last).
  // Note that while these new objects will take valid values,
  // their exact value is not defined. In particular they may
  // be 'moved from'.
  //
  // While *__seed may be altered during this algorithm, it will have
  // the same value when the algorithm finishes, unless one of the
  // constructions throws.
  //
  // Requirements: _Pointer::value_type(_Tp&&) is valid.
  template<typename _Pointer, typename _ForwardIterator>
    inline void
    __uninitialized_construct_buf(_Pointer __first, _Pointer __last,
                                  _ForwardIterator __seed)
    {
      typedef typename std::iterator_traits<_Pointer>::value_type
        _ValueType;

      std::__uninitialized_construct_buf_dispatch<
        __has_trivial_constructor(_ValueType)>::
          __ucr(__first, __last, __seed);
    }

  template<typename _ForwardIterator, typename _Tp>
    _Temporary_buffer<_ForwardIterator, _Tp>::
    _Temporary_buffer(_ForwardIterator __seed, size_type __original_len)
    : _M_original_len(__original_len), _M_len(0), _M_buffer(0)
    {
      std::pair<pointer, size_type> __p(
                std::get_temporary_buffer<value_type>(_M_original_len));

      if (__p.first)
        {
          __try
            {
              std::__uninitialized_construct_buf(__p.first, __p.first + __p.second,
                                                 __seed);
              _M_buffer = __p.first;
              _M_len = __p.second;
            }
          __catch(...)
            {
              std::__detail::__return_temporary_buffer(__p.first, __p.second);
              __throw_exception_again;
            }
        }
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif /* _STL_TEMPBUF_H */
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	8655 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// Temporary buffer implementation -- C++ --
2
3	// Copyright (C) 2001-2021 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	/*
26	*
27	* Copyright (c) 1994
28	* Hewlett-Packard Company
29	*
30	* Permission to use, copy, modify, distribute and sell this software
31	* and its documentation for any purpose is hereby granted without fee,
32	* provided that the above copyright notice appear in all copies and
33	* that both that copyright notice and this permission notice appear
34	* in supporting documentation. Hewlett-Packard Company makes no
35	* representations about the suitability of this software for any
36	* purpose. It is provided "as is" without express or implied warranty.
37	*
38	*
39	* Copyright (c) 1996,1997
40	* Silicon Graphics Computer Systems, Inc.
41	*
42	* Permission to use, copy, modify, distribute and sell this software
43	* and its documentation for any purpose is hereby granted without fee,
44	* provided that the above copyright notice appear in all copies and
45	* that both that copyright notice and this permission notice appear
46	* in supporting documentation. Silicon Graphics makes no
47	* representations about the suitability of this software for any
48	* purpose. It is provided "as is" without express or implied warranty.
49	*/
50
51	/** @file bits/stl_tempbuf.h
52	* This is an internal header file, included by other library headers.
53	* Do not attempt to use it directly. @headername{memory}
54	*/
55
56	#ifndef _STL_TEMPBUF_H
57	#define _STL_TEMPBUF_H 1
58
59	#include <bits/stl_algobase.h>
60	#include <bits/stl_construct.h>
61
62	namespace std _GLIBCXX_VISIBILITY(default)
63	{
64	_GLIBCXX_BEGIN_NAMESPACE_VERSION
65
66	namespace __detail
67	{
68	template<typename _Tp>
69	inline void
70	__return_temporary_buffer(_Tp* __p,
71	size_t __len __attribute__((__unused__)))
72	{
73	#if __cpp_sized_deallocation
74	::operator delete(__p, __len * sizeof(_Tp));
75	#else
76	::operator delete(__p);
77	#endif
78	}
79	}
80
81	/**
82	* @brief Allocates a temporary buffer.
83	* @param __len The number of objects of type Tp.
84	* @return See full description.
85	*
86	* Reinventing the wheel, but this time with prettier spokes!
87	*
88	* This function tries to obtain storage for @c __len adjacent Tp
89	* objects. The objects themselves are not constructed, of course.
90	* A pair<> is returned containing <em>the buffer s address and
91	* capacity (in the units of sizeof(_Tp)), or a pair of 0 values if
92	* no storage can be obtained.</em> Note that the capacity obtained
93	* may be less than that requested if the memory is unavailable;
94	* you should compare len with the .second return value.
95	*
96	* Provides the nothrow exception guarantee.
97	*/
98	template<typename _Tp>
99	pair<_Tp*, ptrdiff_t>
100	get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT
101	{
102	const ptrdiff_t __max =
103	__gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp);
104	if (__len > __max)
105	__len = __max;
106
107	while (__len > 0)
108	{
109	_Tp* __tmp = static_cast<_Tp>(::operator new(__len sizeof(_Tp),
110	std::nothrow));
111	if (__tmp != 0)
112	return std::pair<_Tp*, ptrdiff_t>(__tmp, __len);
113	__len = __len == 1 ? 0 : ((__len + 1) / 2);
114	}
115	return std::pair<_Tp, ptrdiff_t>(static_cast<_Tp>(0), 0);
116	}
117
118	/**
119	* @brief The companion to get_temporary_buffer().
120	* @param __p A buffer previously allocated by get_temporary_buffer.
121	* @return None.
122	*
123	* Frees the memory pointed to by __p.
124	*/
125	template<typename _Tp>
126	inline void
127	return_temporary_buffer(_Tp* __p)
128	{ ::operator delete(__p); }
129
130	/**
131	* This class is used in two places: stl_algo.h and ext/memory,
132	* where it is wrapped as the temporary_buffer class. See
133	* temporary_buffer docs for more notes.
134	*/
135	template<typename _ForwardIterator, typename _Tp>
136	class _Temporary_buffer
137	{
138	// concept requirements
139	__glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept)
140
141	public:
142	typedef _Tp value_type;
143	typedef value_type* pointer;
144	typedef pointer iterator;
145	typedef ptrdiff_t size_type;
146
147	protected:
148	size_type _M_original_len;
149	size_type _M_len;
150	pointer _M_buffer;
151
152	public:
153	/// As per Table mumble.
154	size_type
155	size() const
156	{ return _M_len; }
157
158	/// Returns the size requested by the constructor; may be >size().
159	size_type
160	requested_size() const
161	{ return _M_original_len; }
162
163	/// As per Table mumble.
164	iterator
165	begin()
166	{ return _M_buffer; }
167
168	/// As per Table mumble.
169	iterator
170	end()
171	{ return _M_buffer + _M_len; }
172
173	/**
174	* Constructs a temporary buffer of a size somewhere between
175	* zero and the given length.
176	*/
177	_Temporary_buffer(_ForwardIterator __seed, size_type __original_len);
178
179	~_Temporary_buffer()
180	{
181	std::_Destroy(_M_buffer, _M_buffer + _M_len);
182	std::__detail::__return_temporary_buffer(_M_buffer, _M_len);
183	}
184
185	private:
186	// Disable copy constructor and assignment operator.
187	_Temporary_buffer(const _Temporary_buffer&);
188
189	void
190	operator=(const _Temporary_buffer&);
191	};
192
193
194	template<bool>
195	struct __uninitialized_construct_buf_dispatch
196	{
197	template<typename _Pointer, typename _ForwardIterator>
198	static void
199	__ucr(_Pointer __first, _Pointer __last,
200	_ForwardIterator __seed)
201	{
202	if (__first == __last)
203	return;
204
205	_Pointer __cur = __first;
206	__try
207	{
208	std::_Construct(std::__addressof(*__first),
209	_GLIBCXX_MOVE(*__seed));
210	_Pointer __prev = __cur;
211	++__cur;
212	for(; __cur != __last; ++__cur, ++__prev)
213	std::_Construct(std::__addressof(*__cur),
214	_GLIBCXX_MOVE(*__prev));
215	__seed = _GLIBCXX_MOVE(__prev);
216	}
217	__catch(...)
218	{
219	std::_Destroy(__first, __cur);
220	__throw_exception_again;
221	}
222	}
223	};
224
225	template<>
226	struct __uninitialized_construct_buf_dispatch<true>
227	{
228	template<typename _Pointer, typename _ForwardIterator>
229	static void
230	__ucr(_Pointer, _Pointer, _ForwardIterator) { }
231	};
232
233	// Constructs objects in the range [first, last).
234	// Note that while these new objects will take valid values,
235	// their exact value is not defined. In particular they may
236	// be 'moved from'.
237	//
238	// While *__seed may be altered during this algorithm, it will have
239	// the same value when the algorithm finishes, unless one of the
240	// constructions throws.
241	//
242	// Requirements: _Pointer::value_type(_Tp&&) is valid.
243	template<typename _Pointer, typename _ForwardIterator>
244	inline void
245	__uninitialized_construct_buf(_Pointer __first, _Pointer __last,
246	_ForwardIterator __seed)
247	{
248	typedef typename std::iterator_traits<_Pointer>::value_type
249	_ValueType;
250
251	std::__uninitialized_construct_buf_dispatch<
252	__has_trivial_constructor(_ValueType)>::
253	__ucr(__first, __last, __seed);
254	}
255
256	template<typename _ForwardIterator, typename _Tp>
257	_Temporary_buffer<_ForwardIterator, _Tp>::
258	_Temporary_buffer(_ForwardIterator __seed, size_type __original_len)
259	: _M_original_len(__original_len), _M_len(0), _M_buffer(0)
260	{
261	std::pair<pointer, size_type> __p(
262	std::get_temporary_buffer<value_type>(_M_original_len));
263
264	if (__p.first)
265	{
266	__try
267	{
268	std::__uninitialized_construct_buf(__p.first, __p.first + __p.second,
269	__seed);
270	_M_buffer = __p.first;
271	_M_len = __p.second;
272	}
273	__catch(...)
274	{
275	std::__detail::__return_temporary_buffer(__p.first, __p.second);
276	__throw_exception_again;
277	}
278	}
279	}
280
281	_GLIBCXX_END_NAMESPACE_VERSION
282	} // namespace
283
284	#endif /* _STL_TEMPBUF_H */