11.2.0/bits/move.h

// Move, forward and identity for C++11 + swap -*- 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 bits/move.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{utility}
 */

#ifndef _MOVE_H
#define _MOVE_H 1

#include <bits/c++config.h>
#if __cplusplus < 201103L
# include <bits/concept_check.h>
#endif

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // Used, in C++03 mode too, by allocators, etc.
  /**
   *  @brief Same as C++11 std::addressof
   *  @ingroup utilities
   */
  template<typename _Tp>
    inline _GLIBCXX_CONSTEXPR _Tp*
    __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
    { return __builtin_addressof(__r); }

#if __cplusplus >= 201103L

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#include <type_traits> // Brings in std::declval too.

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   *  @addtogroup utilities
   *  @{
   */

  /**
   *  @brief  Forward an lvalue.
   *  @return The parameter cast to the specified type.
   *
   *  This function is used to implement "perfect forwarding".
   */
  template<typename _Tp>
    _GLIBCXX_NODISCARD
    constexpr _Tp&&
    forward(typename std::remove_reference<_Tp>::type& __t) noexcept
    { return static_cast<_Tp&&>(__t); }

  /**
   *  @brief  Forward an rvalue.
   *  @return The parameter cast to the specified type.
   *
   *  This function is used to implement "perfect forwarding".
   */
  template<typename _Tp>
    _GLIBCXX_NODISCARD
    constexpr _Tp&&
    forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
    {
      static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
                    " substituting _Tp must not be an lvalue reference type");
      return static_cast<_Tp&&>(__t);
    }

  /**
   *  @brief  Convert a value to an rvalue.
   *  @param  __t  A thing of arbitrary type.
   *  @return The parameter cast to an rvalue-reference to allow moving it.
  */
  template<typename _Tp>
    _GLIBCXX_NODISCARD
    constexpr typename std::remove_reference<_Tp>::type&&
    move(_Tp&& __t) noexcept
    { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }


  template<typename _Tp>
    struct __move_if_noexcept_cond
    : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
                    is_copy_constructible<_Tp>>::type { };

  /**
   *  @brief  Conditionally convert a value to an rvalue.
   *  @param  __x  A thing of arbitrary type.
   *  @return The parameter, possibly cast to an rvalue-reference.
   *
   *  Same as std::move unless the type's move constructor could throw and the
   *  type is copyable, in which case an lvalue-reference is returned instead.
   */
  template<typename _Tp>
    _GLIBCXX_NODISCARD
    constexpr typename
    conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
    move_if_noexcept(_Tp& __x) noexcept
    { return std::move(__x); }

  // declval, from type_traits.

#if __cplusplus > 201402L
  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 2296. std::addressof should be constexpr
# define __cpp_lib_addressof_constexpr 201603
#endif
  /**
   *  @brief Returns the actual address of the object or function
   *         referenced by r, even in the presence of an overloaded
   *         operator&.
   *  @param  __r  Reference to an object or function.
   *  @return   The actual address.
  */
  template<typename _Tp>
    _GLIBCXX_NODISCARD
    inline _GLIBCXX17_CONSTEXPR _Tp*
    addressof(_Tp& __r) noexcept
    { return std::__addressof(__r); }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 2598. addressof works on temporaries
  template<typename _Tp>
    const _Tp* addressof(const _Tp&&) = delete;

  // C++11 version of std::exchange for internal use.
  template <typename _Tp, typename _Up = _Tp>
    _GLIBCXX20_CONSTEXPR
    inline _Tp
    __exchange(_Tp& __obj, _Up&& __new_val)
    {
      _Tp __old_val = std::move(__obj);
      __obj = std::forward<_Up>(__new_val);
      return __old_val;
    }

  /// @} group utilities

#define _GLIBCXX_FWDREF(_Tp) _Tp&&
#define _GLIBCXX_MOVE(__val) std::move(__val)
#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
#else
#define _GLIBCXX_FWDREF(_Tp) const _Tp&
#define _GLIBCXX_MOVE(__val) (__val)
#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
#endif

  /**
   *  @addtogroup utilities
   *  @{
   */

  /**
   *  @brief Swaps two values.
   *  @param  __a  A thing of arbitrary type.
   *  @param  __b  Another thing of arbitrary type.
   *  @return   Nothing.
  */
  template<typename _Tp>
    _GLIBCXX20_CONSTEXPR
    inline
#if __cplusplus >= 201103L
    typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
                              is_move_constructible<_Tp>,
                              is_move_assignable<_Tp>>::value>::type
#else
    void
#endif
    swap(_Tp& __a, _Tp& __b)
    _GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>,
                                is_nothrow_move_assignable<_Tp>>::value)
    {
#if __cplusplus < 201103L
      // concept requirements
      __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
#endif
      _Tp __tmp = _GLIBCXX_MOVE(__a);
      __a = _GLIBCXX_MOVE(__b);
      __b = _GLIBCXX_MOVE(__tmp);
    }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // DR 809. std::swap should be overloaded for array types.
  /// Swap the contents of two arrays.
  template<typename _Tp, size_t _Nm>
    _GLIBCXX20_CONSTEXPR
    inline
#if __cplusplus >= 201103L
    typename enable_if<__is_swappable<_Tp>::value>::type
#else
    void
#endif
    swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
    _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value)
    {
      for (size_t __n = 0; __n < _Nm; ++__n)
        swap(__a[__n], __b[__n]);
    }

  /// @} group utilities
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif /* _MOVE_H */
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	6812 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// Move, forward and identity for C++11 + swap -- 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 bits/move.h
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly. @headername{utility}
28	*/
29
30	#ifndef _MOVE_H
31	#define _MOVE_H 1
32
33	#include <bits/c++config.h>
34	#if __cplusplus < 201103L
35	# include <bits/concept_check.h>
36	#endif
37
38	namespace std _GLIBCXX_VISIBILITY(default)
39	{
40	_GLIBCXX_BEGIN_NAMESPACE_VERSION
41
42	// Used, in C++03 mode too, by allocators, etc.
43	/**
44	* @brief Same as C++11 std::addressof
45	* @ingroup utilities
46	*/
47	template<typename _Tp>
48	inline _GLIBCXX_CONSTEXPR _Tp*
49	__addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
50	{ return __builtin_addressof(__r); }
51
52	#if __cplusplus >= 201103L
53
54	_GLIBCXX_END_NAMESPACE_VERSION
55	} // namespace
56
57	#include <type_traits> // Brings in std::declval too.
58
59	namespace std _GLIBCXX_VISIBILITY(default)
60	{
61	_GLIBCXX_BEGIN_NAMESPACE_VERSION
62
63	/**
64	* @addtogroup utilities
65	* @{
66	*/
67
68	/**
69	* @brief Forward an lvalue.
70	* @return The parameter cast to the specified type.
71	*
72	* This function is used to implement "perfect forwarding".
73	*/
74	template<typename _Tp>
75	_GLIBCXX_NODISCARD
76	constexpr _Tp&&
77	forward(typename std::remove_reference<_Tp>::type& __t) noexcept
78	{ return static_cast<_Tp&&>(__t); }
79
80	/**
81	* @brief Forward an rvalue.
82	* @return The parameter cast to the specified type.
83	*
84	* This function is used to implement "perfect forwarding".
85	*/
86	template<typename _Tp>
87	_GLIBCXX_NODISCARD
88	constexpr _Tp&&
89	forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
90	{
91	static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
92	" substituting _Tp must not be an lvalue reference type");
93	return static_cast<_Tp&&>(__t);
94	}
95
96	/**
97	* @brief Convert a value to an rvalue.
98	* @param __t A thing of arbitrary type.
99	* @return The parameter cast to an rvalue-reference to allow moving it.
100	*/
101	template<typename _Tp>
102	_GLIBCXX_NODISCARD
103	constexpr typename std::remove_reference<_Tp>::type&&
104	move(_Tp&& __t) noexcept
105	{ return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
106
107
108	template<typename _Tp>
109	struct __move_if_noexcept_cond
110	: public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
111	is_copy_constructible<_Tp>>::type { };
112
113	/**
114	* @brief Conditionally convert a value to an rvalue.
115	* @param __x A thing of arbitrary type.
116	* @return The parameter, possibly cast to an rvalue-reference.
117	*
118	* Same as std::move unless the type's move constructor could throw and the
119	* type is copyable, in which case an lvalue-reference is returned instead.
120	*/
121	template<typename _Tp>
122	_GLIBCXX_NODISCARD
123	constexpr typename
124	conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
125	move_if_noexcept(_Tp& __x) noexcept
126	{ return std::move(__x); }
127
128	// declval, from type_traits.
129
130	#if __cplusplus > 201402L
131	// _GLIBCXX_RESOLVE_LIB_DEFECTS
132	// 2296. std::addressof should be constexpr
133	# define __cpp_lib_addressof_constexpr 201603
134	#endif
135	/**
136	* @brief Returns the actual address of the object or function
137	* referenced by r, even in the presence of an overloaded
138	* operator&.
139	* @param __r Reference to an object or function.
140	* @return The actual address.
141	*/
142	template<typename _Tp>
143	_GLIBCXX_NODISCARD
144	inline _GLIBCXX17_CONSTEXPR _Tp*
145	addressof(_Tp& __r) noexcept
146	{ return std::__addressof(__r); }
147
148	// _GLIBCXX_RESOLVE_LIB_DEFECTS
149	// 2598. addressof works on temporaries
150	template<typename _Tp>
151	const _Tp* addressof(const _Tp&&) = delete;
152
153	// C++11 version of std::exchange for internal use.
154	template <typename _Tp, typename _Up = _Tp>
155	_GLIBCXX20_CONSTEXPR
156	inline _Tp
157	__exchange(_Tp& __obj, _Up&& __new_val)
158	{
159	_Tp __old_val = std::move(__obj);
160	__obj = std::forward<_Up>(__new_val);
161	return __old_val;
162	}
163
164	/// @} group utilities
165
166	#define _GLIBCXX_FWDREF(_Tp) _Tp&&
167	#define _GLIBCXX_MOVE(__val) std::move(__val)
168	#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
169	#else
170	#define _GLIBCXX_FWDREF(_Tp) const _Tp&
171	#define _GLIBCXX_MOVE(__val) (__val)
172	#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
173	#endif
174
175	/**
176	* @addtogroup utilities
177	* @{
178	*/
179
180	/**
181	* @brief Swaps two values.
182	* @param __a A thing of arbitrary type.
183	* @param __b Another thing of arbitrary type.
184	* @return Nothing.
185	*/
186	template<typename _Tp>
187	_GLIBCXX20_CONSTEXPR
188	inline
189	#if __cplusplus >= 201103L
190	typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
191	is_move_constructible<_Tp>,
192	is_move_assignable<_Tp>>::value>::type
193	#else
194	void
195	#endif
196	swap(_Tp& __a, _Tp& __b)
197	_GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>,
198	is_nothrow_move_assignable<_Tp>>::value)
199	{
200	#if __cplusplus < 201103L
201	// concept requirements
202	__glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
203	#endif
204	_Tp __tmp = _GLIBCXX_MOVE(__a);
205	__a = _GLIBCXX_MOVE(__b);
206	__b = _GLIBCXX_MOVE(__tmp);
207	}
208
209	// _GLIBCXX_RESOLVE_LIB_DEFECTS
210	// DR 809. std::swap should be overloaded for array types.
211	/// Swap the contents of two arrays.
212	template<typename _Tp, size_t _Nm>
213	_GLIBCXX20_CONSTEXPR
214	inline
215	#if __cplusplus >= 201103L
216	typename enable_if<__is_swappable<_Tp>::value>::type
217	#else
218	void
219	#endif
220	swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
221	_GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value)
222	{
223	for (size_t __n = 0; __n < _Nm; ++__n)
224	swap(__a[__n], __b[__n]);
225	}
226
227	/// @} group utilities
228	_GLIBCXX_END_NAMESPACE_VERSION
229	} // namespace
230
231	#endif /* _MOVE_H */