11.2.0/bits/allocator.h

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

#ifndef _ALLOCATOR_H
#define _ALLOCATOR_H 1

#include <bits/c++allocator.h> // Define the base class to std::allocator.
#include <bits/memoryfwd.h>
#if __cplusplus >= 201103L
#include <type_traits>
#endif

#define __cpp_lib_incomplete_container_elements 201505

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   *  @addtogroup allocators
   *  @{
   */

  // Since C++20 the primary template should be used for allocator<void>,
  // but then it would have a non-trivial default ctor and dtor, which
  // would be an ABI change. So C++20 still uses the allocator<void> explicit
  // specialization, with the historical ABI properties, but with the same
  // members that are present in the primary template.

#if ! _GLIBCXX_INLINE_VERSION
  /// allocator<void> specialization.
  template<>
    class allocator<void>
    {
    public:
      typedef void        value_type;
      typedef size_t      size_type;
      typedef ptrdiff_t   difference_type;

#if __cplusplus <= 201703L
      // These were removed for C++20.
      typedef void*       pointer;
      typedef const void* const_pointer;

      template<typename _Tp1>
        struct rebind
        { typedef allocator<_Tp1> other; };
#endif

#if __cplusplus >= 201103L
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2103. std::allocator propagate_on_container_move_assignment
      typedef true_type propagate_on_container_move_assignment;

      typedef true_type is_always_equal;

#if __cplusplus >= 202002L
      allocator() = default;

      template<typename _Up>
        constexpr
        allocator(const allocator<_Up>&) noexcept { }

      // No allocate member because it's ill-formed by LWG 3307.
      // No deallocate member because it would be undefined to call it
      // with any pointer which wasn't obtained from allocate.

#else // ! C++20
    private:
      // This uses construct and destroy in C++11/14/17 modes.
      friend allocator_traits<allocator<void>>;

      template<typename _Up, typename... _Args>
        void
        construct(_Up* __p, _Args&&... __args)
        noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
        { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }

      template<typename _Up>
        void
        destroy(_Up* __p)
        noexcept(std::is_nothrow_destructible<_Up>::value)
        { __p->~_Up(); }
#endif // C++17
#endif // C++11

    };
#endif // ! _GLIBCXX_INLINE_VERSION

  /**
   * @brief  The @a standard allocator, as per C++03 [20.4.1].
   *
   *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
   *  for further details.
   *
   *  @tparam  _Tp  Type of allocated object.
   */
  template<typename _Tp>
    class allocator : public __allocator_base<_Tp>
    {
    public:
      typedef _Tp        value_type;
      typedef size_t     size_type;
      typedef ptrdiff_t  difference_type;

#if __cplusplus <= 201703L
      // These were removed for C++20.
      typedef _Tp*       pointer;
      typedef const _Tp* const_pointer;
      typedef _Tp&       reference;
      typedef const _Tp& const_reference;

      template<typename _Tp1>
        struct rebind
        { typedef allocator<_Tp1> other; };
#endif

#if __cplusplus >= 201103L
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2103. std::allocator propagate_on_container_move_assignment
      typedef true_type propagate_on_container_move_assignment;

      typedef true_type is_always_equal;
#endif

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 3035. std::allocator's constructors should be constexpr
      _GLIBCXX20_CONSTEXPR
      allocator() _GLIBCXX_NOTHROW { }

      _GLIBCXX20_CONSTEXPR
      allocator(const allocator& __a) _GLIBCXX_NOTHROW
      : __allocator_base<_Tp>(__a) { }

#if __cplusplus >= 201103L
      // Avoid implicit deprecation.
      allocator& operator=(const allocator&) = default;
#endif

      template<typename _Tp1>
        _GLIBCXX20_CONSTEXPR
        allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { }

#if __cpp_constexpr_dynamic_alloc
      constexpr
#endif
      ~allocator() _GLIBCXX_NOTHROW { }

#if __cplusplus > 201703L
      [[nodiscard,__gnu__::__always_inline__]]
      constexpr _Tp*
      allocate(size_t __n)
      {
#ifdef __cpp_lib_is_constant_evaluated
        if (std::is_constant_evaluated())
          return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
#endif
        return __allocator_base<_Tp>::allocate(__n, 0);
      }

      [[__gnu__::__always_inline__]]
      constexpr void
      deallocate(_Tp* __p, size_t __n)
      {
#ifdef __cpp_lib_is_constant_evaluated
        if (std::is_constant_evaluated())
          {
            ::operator delete(__p);
            return;
          }
#endif
          __allocator_base<_Tp>::deallocate(__p, __n);
      }
#endif // C++20

      friend _GLIBCXX20_CONSTEXPR bool
      operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
      { return true; }

#if __cpp_impl_three_way_comparison < 201907L
      friend _GLIBCXX20_CONSTEXPR bool
      operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW
      { return false; }
#endif

      // Inherit everything else.
    };

  template<typename _T1, typename _T2>
    inline _GLIBCXX20_CONSTEXPR bool
    operator==(const allocator<_T1>&, const allocator<_T2>&)
    _GLIBCXX_NOTHROW
    { return true; }

#if __cpp_impl_three_way_comparison < 201907L
  template<typename _T1, typename _T2>
    inline _GLIBCXX20_CONSTEXPR bool
    operator!=(const allocator<_T1>&, const allocator<_T2>&)
    _GLIBCXX_NOTHROW
    { return false; }
#endif

  // Invalid allocator<cv T> partial specializations.
  // allocator_traits::rebind_alloc can be used to form a valid allocator type.
  template<typename _Tp>
    class allocator<const _Tp>
    {
    public:
      typedef _Tp value_type;
      template<typename _Up> allocator(const allocator<_Up>&) { }
    };

  template<typename _Tp>
    class allocator<volatile _Tp>
    {
    public:
      typedef _Tp value_type;
      template<typename _Up> allocator(const allocator<_Up>&) { }
    };

  template<typename _Tp>
    class allocator<const volatile _Tp>
    {
    public:
      typedef _Tp value_type;
      template<typename _Up> allocator(const allocator<_Up>&) { }
    };

  /// @} group allocator

  // Inhibit implicit instantiations for required instantiations,
  // which are defined via explicit instantiations elsewhere.
#if _GLIBCXX_EXTERN_TEMPLATE
  extern template class allocator<char>;
  extern template class allocator<wchar_t>;
#endif

  // Undefine.
#undef __allocator_base

  // To implement Option 3 of DR 431.
  template<typename _Alloc, bool = __is_empty(_Alloc)>
    struct __alloc_swap
    { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };

  template<typename _Alloc>
    struct __alloc_swap<_Alloc, false>
    {
      static void
      _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
      {
        // Precondition: swappable allocators.
        if (__one != __two)
          swap(__one, __two);
      }
    };

  // Optimize for stateless allocators.
  template<typename _Alloc, bool = __is_empty(_Alloc)>
    struct __alloc_neq
    {
      static bool
      _S_do_it(const _Alloc&, const _Alloc&)
      { return false; }
    };

  template<typename _Alloc>
    struct __alloc_neq<_Alloc, false>
    {
      static bool
      _S_do_it(const _Alloc& __one, const _Alloc& __two)
      { return __one != __two; }
    };

#if __cplusplus >= 201103L
  template<typename _Tp, bool
    = __or_<is_copy_constructible<typename _Tp::value_type>,
            is_nothrow_move_constructible<typename _Tp::value_type>>::value>
    struct __shrink_to_fit_aux
    { static bool _S_do_it(_Tp&) noexcept { return false; } };

  template<typename _Tp>
    struct __shrink_to_fit_aux<_Tp, true>
    {
      static bool
      _S_do_it(_Tp& __c) noexcept
      {
#if __cpp_exceptions
        try
          {
            _Tp(__make_move_if_noexcept_iterator(__c.begin()),
                __make_move_if_noexcept_iterator(__c.end()),
                __c.get_allocator()).swap(__c);
            return true;
          }
        catch(...)
          { return false; }
#else
        return false;
#endif
      }
    };
#endif

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	9836 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// Allocators -- 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	* Copyright (c) 1996-1997
27	* Silicon Graphics Computer Systems, Inc.
28	*
29	* Permission to use, copy, modify, distribute and sell this software
30	* and its documentation for any purpose is hereby granted without fee,
31	* provided that the above copyright notice appear in all copies and
32	* that both that copyright notice and this permission notice appear
33	* in supporting documentation. Silicon Graphics makes no
34	* representations about the suitability of this software for any
35	* purpose. It is provided "as is" without express or implied warranty.
36	*/
37
38	/** @file bits/allocator.h
39	* This is an internal header file, included by other library headers.
40	* Do not attempt to use it directly. @headername{memory}
41	*/
42
43	#ifndef _ALLOCATOR_H
44	#define _ALLOCATOR_H 1
45
46	#include <bits/c++allocator.h> // Define the base class to std::allocator.
47	#include <bits/memoryfwd.h>
48	#if __cplusplus >= 201103L
49	#include <type_traits>
50	#endif
51
52	#define __cpp_lib_incomplete_container_elements 201505
53
54	namespace std _GLIBCXX_VISIBILITY(default)
55	{
56	_GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58	/**
59	* @addtogroup allocators
60	* @{
61	*/
62
63	// Since C++20 the primary template should be used for allocator<void>,
64	// but then it would have a non-trivial default ctor and dtor, which
65	// would be an ABI change. So C++20 still uses the allocator<void> explicit
66	// specialization, with the historical ABI properties, but with the same
67	// members that are present in the primary template.
68
69	#if ! _GLIBCXX_INLINE_VERSION
70	/// allocator<void> specialization.
71	template<>
72	class allocator<void>
73	{
74	public:
75	typedef void value_type;
76	typedef size_t size_type;
77	typedef ptrdiff_t difference_type;
78
79	#if __cplusplus <= 201703L
80	// These were removed for C++20.
81	typedef void* pointer;
82	typedef const void* const_pointer;
83
84	template<typename _Tp1>
85	struct rebind
86	{ typedef allocator<_Tp1> other; };
87	#endif
88
89	#if __cplusplus >= 201103L
90	// _GLIBCXX_RESOLVE_LIB_DEFECTS
91	// 2103. std::allocator propagate_on_container_move_assignment
92	typedef true_type propagate_on_container_move_assignment;
93
94	typedef true_type is_always_equal;
95
96	#if __cplusplus >= 202002L
97	allocator() = default;
98
99	template<typename _Up>
100	constexpr
101	allocator(const allocator<_Up>&) noexcept { }
102
103	// No allocate member because it's ill-formed by LWG 3307.
104	// No deallocate member because it would be undefined to call it
105	// with any pointer which wasn't obtained from allocate.
106
107	#else // ! C++20
108	private:
109	// This uses construct and destroy in C++11/14/17 modes.
110	friend allocator_traits<allocator<void>>;
111
112	template<typename _Up, typename... _Args>
113	void
114	construct(_Up* __p, _Args&&... __args)
115	noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
116	{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
117
118	template<typename _Up>
119	void
120	destroy(_Up* __p)
121	noexcept(std::is_nothrow_destructible<_Up>::value)
122	{ __p->~_Up(); }
123	#endif // C++17
124	#endif // C++11
125
126	};
127	#endif // ! _GLIBCXX_INLINE_VERSION
128
129	/**
130	* @brief The @a standard allocator, as per C++03 [20.4.1].
131	*
132	* See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
133	* for further details.
134	*
135	* @tparam _Tp Type of allocated object.
136	*/
137	template<typename _Tp>
138	class allocator : public __allocator_base<_Tp>
139	{
140	public:
141	typedef _Tp value_type;
142	typedef size_t size_type;
143	typedef ptrdiff_t difference_type;
144
145	#if __cplusplus <= 201703L
146	// These were removed for C++20.
147	typedef _Tp* pointer;
148	typedef const _Tp* const_pointer;
149	typedef _Tp& reference;
150	typedef const _Tp& const_reference;
151
152	template<typename _Tp1>
153	struct rebind
154	{ typedef allocator<_Tp1> other; };
155	#endif
156
157	#if __cplusplus >= 201103L
158	// _GLIBCXX_RESOLVE_LIB_DEFECTS
159	// 2103. std::allocator propagate_on_container_move_assignment
160	typedef true_type propagate_on_container_move_assignment;
161
162	typedef true_type is_always_equal;
163	#endif
164
165	// _GLIBCXX_RESOLVE_LIB_DEFECTS
166	// 3035. std::allocator's constructors should be constexpr
167	_GLIBCXX20_CONSTEXPR
168	allocator() _GLIBCXX_NOTHROW { }
169
170	_GLIBCXX20_CONSTEXPR
171	allocator(const allocator& __a) _GLIBCXX_NOTHROW
172	: __allocator_base<_Tp>(__a) { }
173
174	#if __cplusplus >= 201103L
175	// Avoid implicit deprecation.
176	allocator& operator=(const allocator&) = default;
177	#endif
178
179	template<typename _Tp1>
180	_GLIBCXX20_CONSTEXPR
181	allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { }
182
183	#if __cpp_constexpr_dynamic_alloc
184	constexpr
185	#endif
186	~allocator() _GLIBCXX_NOTHROW { }
187
188	#if __cplusplus > 201703L
189	[[nodiscard,__gnu__::__always_inline__]]
190	constexpr _Tp*
191	allocate(size_t __n)
192	{
193	#ifdef __cpp_lib_is_constant_evaluated
194	if (std::is_constant_evaluated())
195	return static_cast<_Tp>(::operator new(__n sizeof(_Tp)));
196	#endif
197	return __allocator_base<_Tp>::allocate(__n, 0);
198	}
199
200	[[__gnu__::__always_inline__]]
201	constexpr void
202	deallocate(_Tp* __p, size_t __n)
203	{
204	#ifdef __cpp_lib_is_constant_evaluated
205	if (std::is_constant_evaluated())
206	{
207	::operator delete(__p);
208	return;
209	}
210	#endif
211	__allocator_base<_Tp>::deallocate(__p, __n);
212	}
213	#endif // C++20
214
215	friend _GLIBCXX20_CONSTEXPR bool
216	operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
217	{ return true; }
218
219	#if __cpp_impl_three_way_comparison < 201907L
220	friend _GLIBCXX20_CONSTEXPR bool
221	operator!=(const allocator&, const allocator&) _GLIBCXX_NOTHROW
222	{ return false; }
223	#endif
224
225	// Inherit everything else.
226	};
227
228	template<typename _T1, typename _T2>
229	inline _GLIBCXX20_CONSTEXPR bool
230	operator==(const allocator<_T1>&, const allocator<_T2>&)
231	_GLIBCXX_NOTHROW
232	{ return true; }
233
234	#if __cpp_impl_three_way_comparison < 201907L
235	template<typename _T1, typename _T2>
236	inline _GLIBCXX20_CONSTEXPR bool
237	operator!=(const allocator<_T1>&, const allocator<_T2>&)
238	_GLIBCXX_NOTHROW
239	{ return false; }
240	#endif
241
242	// Invalid allocator<cv T> partial specializations.
243	// allocator_traits::rebind_alloc can be used to form a valid allocator type.
244	template<typename _Tp>
245	class allocator<const _Tp>
246	{
247	public:
248	typedef _Tp value_type;
249	template<typename _Up> allocator(const allocator<_Up>&) { }
250	};
251
252	template<typename _Tp>
253	class allocator<volatile _Tp>
254	{
255	public:
256	typedef _Tp value_type;
257	template<typename _Up> allocator(const allocator<_Up>&) { }
258	};
259
260	template<typename _Tp>
261	class allocator<const volatile _Tp>
262	{
263	public:
264	typedef _Tp value_type;
265	template<typename _Up> allocator(const allocator<_Up>&) { }
266	};
267
268	/// @} group allocator
269
270	// Inhibit implicit instantiations for required instantiations,
271	// which are defined via explicit instantiations elsewhere.
272	#if _GLIBCXX_EXTERN_TEMPLATE
273	extern template class allocator<char>;
274	extern template class allocator<wchar_t>;
275	#endif
276
277	// Undefine.
278	#undef __allocator_base
279
280	// To implement Option 3 of DR 431.
281	template<typename _Alloc, bool = __is_empty(_Alloc)>
282	struct __alloc_swap
283	{ static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
284
285	template<typename _Alloc>
286	struct __alloc_swap<_Alloc, false>
287	{
288	static void
289	_S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
290	{
291	// Precondition: swappable allocators.
292	if (__one != __two)
293	swap(__one, __two);
294	}
295	};
296
297	// Optimize for stateless allocators.
298	template<typename _Alloc, bool = __is_empty(_Alloc)>
299	struct __alloc_neq
300	{
301	static bool
302	_S_do_it(const _Alloc&, const _Alloc&)
303	{ return false; }
304	};
305
306	template<typename _Alloc>
307	struct __alloc_neq<_Alloc, false>
308	{
309	static bool
310	_S_do_it(const _Alloc& __one, const _Alloc& __two)
311	{ return __one != __two; }
312	};
313
314	#if __cplusplus >= 201103L
315	template<typename _Tp, bool
316	= __or_<is_copy_constructible<typename _Tp::value_type>,
317	is_nothrow_move_constructible<typename _Tp::value_type>>::value>
318	struct __shrink_to_fit_aux
319	{ static bool _S_do_it(_Tp&) noexcept { return false; } };
320
321	template<typename _Tp>
322	struct __shrink_to_fit_aux<_Tp, true>
323	{
324	static bool
325	_S_do_it(_Tp& __c) noexcept
326	{
327	#if __cpp_exceptions
328	try
329	{
330	_Tp(__make_move_if_noexcept_iterator(__c.begin()),
331	__make_move_if_noexcept_iterator(__c.end()),
332	__c.get_allocator()).swap(__c);
333	return true;
334	}
335	catch(...)
336	{ return false; }
337	#else
338	return false;
339	#endif
340	}
341	};
342	#endif
343
344	_GLIBCXX_END_NAMESPACE_VERSION
345	} // namespace std
346
347	#endif