1*38fd1498Szrj // Move, forward and identity for C++11 + swap -*- C++ -*-
2*38fd1498Szrj
3*38fd1498Szrj // Copyright (C) 2007-2018 Free Software Foundation, Inc.
4*38fd1498Szrj //
5*38fd1498Szrj // This file is part of the GNU ISO C++ Library. This library is free
6*38fd1498Szrj // software; you can redistribute it and/or modify it under the
7*38fd1498Szrj // terms of the GNU General Public License as published by the
8*38fd1498Szrj // Free Software Foundation; either version 3, or (at your option)
9*38fd1498Szrj // any later version.
10*38fd1498Szrj
11*38fd1498Szrj // This library is distributed in the hope that it will be useful,
12*38fd1498Szrj // but WITHOUT ANY WARRANTY; without even the implied warranty of
13*38fd1498Szrj // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14*38fd1498Szrj // GNU General Public License for more details.
15*38fd1498Szrj
16*38fd1498Szrj // Under Section 7 of GPL version 3, you are granted additional
17*38fd1498Szrj // permissions described in the GCC Runtime Library Exception, version
18*38fd1498Szrj // 3.1, as published by the Free Software Foundation.
19*38fd1498Szrj
20*38fd1498Szrj // You should have received a copy of the GNU General Public License and
21*38fd1498Szrj // a copy of the GCC Runtime Library Exception along with this program;
22*38fd1498Szrj // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23*38fd1498Szrj // <http://www.gnu.org/licenses/>.
24*38fd1498Szrj
25*38fd1498Szrj /** @file bits/move.h
26*38fd1498Szrj * This is an internal header file, included by other library headers.
27*38fd1498Szrj * Do not attempt to use it directly. @headername{utility}
28*38fd1498Szrj */
29*38fd1498Szrj
30*38fd1498Szrj #ifndef _MOVE_H
31*38fd1498Szrj #define _MOVE_H 1
32*38fd1498Szrj
33*38fd1498Szrj #include <bits/c++config.h>
34*38fd1498Szrj #include <bits/concept_check.h>
35*38fd1498Szrj
_GLIBCXX_VISIBILITY(default)36*38fd1498Szrj namespace std _GLIBCXX_VISIBILITY(default)
37*38fd1498Szrj {
38*38fd1498Szrj _GLIBCXX_BEGIN_NAMESPACE_VERSION
39*38fd1498Szrj
40*38fd1498Szrj // Used, in C++03 mode too, by allocators, etc.
41*38fd1498Szrj /**
42*38fd1498Szrj * @brief Same as C++11 std::addressof
43*38fd1498Szrj * @ingroup utilities
44*38fd1498Szrj */
45*38fd1498Szrj template<typename _Tp>
46*38fd1498Szrj inline _GLIBCXX_CONSTEXPR _Tp*
47*38fd1498Szrj __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
48*38fd1498Szrj { return __builtin_addressof(__r); }
49*38fd1498Szrj
50*38fd1498Szrj #if __cplusplus >= 201103L
51*38fd1498Szrj
52*38fd1498Szrj _GLIBCXX_END_NAMESPACE_VERSION
53*38fd1498Szrj } // namespace
54*38fd1498Szrj
55*38fd1498Szrj #include <type_traits> // Brings in std::declval too.
56*38fd1498Szrj
_GLIBCXX_VISIBILITY(default)57*38fd1498Szrj namespace std _GLIBCXX_VISIBILITY(default)
58*38fd1498Szrj {
59*38fd1498Szrj _GLIBCXX_BEGIN_NAMESPACE_VERSION
60*38fd1498Szrj
61*38fd1498Szrj /**
62*38fd1498Szrj * @addtogroup utilities
63*38fd1498Szrj * @{
64*38fd1498Szrj */
65*38fd1498Szrj
66*38fd1498Szrj /**
67*38fd1498Szrj * @brief Forward an lvalue.
68*38fd1498Szrj * @return The parameter cast to the specified type.
69*38fd1498Szrj *
70*38fd1498Szrj * This function is used to implement "perfect forwarding".
71*38fd1498Szrj */
72*38fd1498Szrj template<typename _Tp>
73*38fd1498Szrj constexpr _Tp&&
74*38fd1498Szrj forward(typename std::remove_reference<_Tp>::type& __t) noexcept
75*38fd1498Szrj { return static_cast<_Tp&&>(__t); }
76*38fd1498Szrj
77*38fd1498Szrj /**
78*38fd1498Szrj * @brief Forward an rvalue.
79*38fd1498Szrj * @return The parameter cast to the specified type.
80*38fd1498Szrj *
81*38fd1498Szrj * This function is used to implement "perfect forwarding".
82*38fd1498Szrj */
83*38fd1498Szrj template<typename _Tp>
84*38fd1498Szrj constexpr _Tp&&
85*38fd1498Szrj forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
86*38fd1498Szrj {
87*38fd1498Szrj static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
88*38fd1498Szrj " substituting _Tp is an lvalue reference type");
89*38fd1498Szrj return static_cast<_Tp&&>(__t);
90*38fd1498Szrj }
91*38fd1498Szrj
92*38fd1498Szrj /**
93*38fd1498Szrj * @brief Convert a value to an rvalue.
94*38fd1498Szrj * @param __t A thing of arbitrary type.
95*38fd1498Szrj * @return The parameter cast to an rvalue-reference to allow moving it.
96*38fd1498Szrj */
97*38fd1498Szrj template<typename _Tp>
98*38fd1498Szrj constexpr typename std::remove_reference<_Tp>::type&&
99*38fd1498Szrj move(_Tp&& __t) noexcept
100*38fd1498Szrj { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
101*38fd1498Szrj
102*38fd1498Szrj
103*38fd1498Szrj template<typename _Tp>
104*38fd1498Szrj struct __move_if_noexcept_cond
105*38fd1498Szrj : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
106*38fd1498Szrj is_copy_constructible<_Tp>>::type { };
107*38fd1498Szrj
108*38fd1498Szrj /**
109*38fd1498Szrj * @brief Conditionally convert a value to an rvalue.
110*38fd1498Szrj * @param __x A thing of arbitrary type.
111*38fd1498Szrj * @return The parameter, possibly cast to an rvalue-reference.
112*38fd1498Szrj *
113*38fd1498Szrj * Same as std::move unless the type's move constructor could throw and the
114*38fd1498Szrj * type is copyable, in which case an lvalue-reference is returned instead.
115*38fd1498Szrj */
116*38fd1498Szrj template<typename _Tp>
117*38fd1498Szrj constexpr typename
118*38fd1498Szrj conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
119*38fd1498Szrj move_if_noexcept(_Tp& __x) noexcept
120*38fd1498Szrj { return std::move(__x); }
121*38fd1498Szrj
122*38fd1498Szrj // declval, from type_traits.
123*38fd1498Szrj
124*38fd1498Szrj #if __cplusplus > 201402L
125*38fd1498Szrj // _GLIBCXX_RESOLVE_LIB_DEFECTS
126*38fd1498Szrj // 2296. std::addressof should be constexpr
127*38fd1498Szrj # define __cpp_lib_addressof_constexpr 201603
128*38fd1498Szrj #endif
129*38fd1498Szrj /**
130*38fd1498Szrj * @brief Returns the actual address of the object or function
131*38fd1498Szrj * referenced by r, even in the presence of an overloaded
132*38fd1498Szrj * operator&.
133*38fd1498Szrj * @param __r Reference to an object or function.
134*38fd1498Szrj * @return The actual address.
135*38fd1498Szrj */
136*38fd1498Szrj template<typename _Tp>
137*38fd1498Szrj inline _GLIBCXX17_CONSTEXPR _Tp*
138*38fd1498Szrj addressof(_Tp& __r) noexcept
139*38fd1498Szrj { return std::__addressof(__r); }
140*38fd1498Szrj
141*38fd1498Szrj // _GLIBCXX_RESOLVE_LIB_DEFECTS
142*38fd1498Szrj // 2598. addressof works on temporaries
143*38fd1498Szrj template<typename _Tp>
144*38fd1498Szrj const _Tp* addressof(const _Tp&&) = delete;
145*38fd1498Szrj
146*38fd1498Szrj // C++11 version of std::exchange for internal use.
147*38fd1498Szrj template <typename _Tp, typename _Up = _Tp>
148*38fd1498Szrj inline _Tp
149*38fd1498Szrj __exchange(_Tp& __obj, _Up&& __new_val)
150*38fd1498Szrj {
151*38fd1498Szrj _Tp __old_val = std::move(__obj);
152*38fd1498Szrj __obj = std::forward<_Up>(__new_val);
153*38fd1498Szrj return __old_val;
154*38fd1498Szrj }
155*38fd1498Szrj
156*38fd1498Szrj /// @} group utilities
157*38fd1498Szrj
158*38fd1498Szrj #define _GLIBCXX_MOVE(__val) std::move(__val)
159*38fd1498Szrj #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
160*38fd1498Szrj #else
161*38fd1498Szrj #define _GLIBCXX_MOVE(__val) (__val)
162*38fd1498Szrj #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
163*38fd1498Szrj #endif
164*38fd1498Szrj
165*38fd1498Szrj /**
166*38fd1498Szrj * @addtogroup utilities
167*38fd1498Szrj * @{
168*38fd1498Szrj */
169*38fd1498Szrj
170*38fd1498Szrj /**
171*38fd1498Szrj * @brief Swaps two values.
172*38fd1498Szrj * @param __a A thing of arbitrary type.
173*38fd1498Szrj * @param __b Another thing of arbitrary type.
174*38fd1498Szrj * @return Nothing.
175*38fd1498Szrj */
176*38fd1498Szrj template<typename _Tp>
177*38fd1498Szrj inline
178*38fd1498Szrj #if __cplusplus >= 201103L
179*38fd1498Szrj typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
180*38fd1498Szrj is_move_constructible<_Tp>,
181*38fd1498Szrj is_move_assignable<_Tp>>::value>::type
182*38fd1498Szrj swap(_Tp& __a, _Tp& __b)
183*38fd1498Szrj noexcept(__and_<is_nothrow_move_constructible<_Tp>,
184*38fd1498Szrj is_nothrow_move_assignable<_Tp>>::value)
185*38fd1498Szrj #else
186*38fd1498Szrj void
187*38fd1498Szrj swap(_Tp& __a, _Tp& __b)
188*38fd1498Szrj #endif
189*38fd1498Szrj {
190*38fd1498Szrj // concept requirements
191*38fd1498Szrj __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
192*38fd1498Szrj
193*38fd1498Szrj _Tp __tmp = _GLIBCXX_MOVE(__a);
194*38fd1498Szrj __a = _GLIBCXX_MOVE(__b);
195*38fd1498Szrj __b = _GLIBCXX_MOVE(__tmp);
196*38fd1498Szrj }
197*38fd1498Szrj
198*38fd1498Szrj // _GLIBCXX_RESOLVE_LIB_DEFECTS
199*38fd1498Szrj // DR 809. std::swap should be overloaded for array types.
200*38fd1498Szrj /// Swap the contents of two arrays.
201*38fd1498Szrj template<typename _Tp, size_t _Nm>
202*38fd1498Szrj inline
203*38fd1498Szrj #if __cplusplus >= 201103L
204*38fd1498Szrj typename enable_if<__is_swappable<_Tp>::value>::type
205*38fd1498Szrj swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
206*38fd1498Szrj noexcept(__is_nothrow_swappable<_Tp>::value)
207*38fd1498Szrj #else
208*38fd1498Szrj void
209*38fd1498Szrj swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
210*38fd1498Szrj #endif
211*38fd1498Szrj {
212*38fd1498Szrj for (size_t __n = 0; __n < _Nm; ++__n)
213*38fd1498Szrj swap(__a[__n], __b[__n]);
214*38fd1498Szrj }
215*38fd1498Szrj
216*38fd1498Szrj /// @} group utilities
217*38fd1498Szrj _GLIBCXX_END_NAMESPACE_VERSION
218*38fd1498Szrj } // namespace
219*38fd1498Szrj
220*38fd1498Szrj #endif /* _MOVE_H */
221