1//////////////////////////////////////////////////////////////////////////////
2//
3// (C) Copyright Ion Gaztanaga 2012-2012.
4// Distributed under the Boost Software License, Version 1.0.
5// (See accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt)
7//
8// See http://www.boost.org/libs/move for documentation.
9//
10//////////////////////////////////////////////////////////////////////////////
11
12//! \file
13//! This header defines core utilities to ease the development
14//! of move-aware functions. This header minimizes dependencies
15//! from other libraries.
16
17#ifndef BOOST_MOVE_MOVE_UTILITY_CORE_HPP
18#define BOOST_MOVE_MOVE_UTILITY_CORE_HPP
19
20#ifndef BOOST_CONFIG_HPP
21# include <boost/config.hpp>
22#endif
23#
24#if defined(BOOST_HAS_PRAGMA_ONCE)
25# pragma once
26#endif
27
28#include <boost/move/detail/config_begin.hpp>
29#include <boost/move/detail/workaround.hpp> //forceinline
30#include <boost/move/core.hpp>
31#include <boost/move/detail/meta_utils.hpp>
32#include <boost/static_assert.hpp>
33
34#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_MOVE_DOXYGEN_INVOKED)
35
36 namespace boost {
37
38 template<class T>
39 struct enable_move_utility_emulation
40 {
41 static const bool value = true;
42 };
43
44 //////////////////////////////////////////////////////////////////////////////
45 //
46 // move()
47 //
48 //////////////////////////////////////////////////////////////////////////////
49
50 template <class T>
51 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
52 < T &
53 , enable_move_utility_emulation<T>
54 , has_move_emulation_disabled<T>
55 >::type
56 move(T& x) BOOST_NOEXCEPT
57 {
58 return x;
59 }
60
61 template <class T>
62 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
63 < rv<T>&
64 , enable_move_utility_emulation<T>
65 , has_move_emulation_enabled<T>
66 >::type
67 move(T& x) BOOST_NOEXCEPT
68 {
69 return *BOOST_MOVE_TO_RV_CAST(::boost::rv<T>*, ::boost::move_detail::addressof(x) );
70 }
71
72 template <class T>
73 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
74 < rv<T>&
75 , enable_move_utility_emulation<T>
76 , has_move_emulation_enabled<T>
77 >::type
78 move(rv<T>& x) BOOST_NOEXCEPT
79 {
80 return x;
81 }
82
83 //////////////////////////////////////////////////////////////////////////////
84 //
85 // forward()
86 //
87 //////////////////////////////////////////////////////////////////////////////
88
89 template <class T>
90 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
91 < T &
92 , enable_move_utility_emulation<T>
93 , ::boost::move_detail::is_rv<T>
94 >::type
95 forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
96 {
97 return const_cast<T&>(x);
98 }
99
100 template <class T>
101 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
102 < const T &
103 , enable_move_utility_emulation<T>
104 , ::boost::move_detail::is_not_rv<T>
105 >::type
106 forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
107 {
108 return x;
109 }
110
111 //////////////////////////////////////////////////////////////////////////////
112 //
113 // move_if_not_lvalue_reference()
114 //
115 //////////////////////////////////////////////////////////////////////////////
116
117 template <class T>
118 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
119 < T &
120 , enable_move_utility_emulation<T>
121 , ::boost::move_detail::is_rv<T>
122 >::type
123 move_if_not_lvalue_reference(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
124 {
125 return const_cast<T&>(x);
126 }
127
128 template <class T>
129 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
130 < typename ::boost::move_detail::add_lvalue_reference<T>::type
131 , enable_move_utility_emulation<T>
132 , ::boost::move_detail::is_not_rv<T>
133 , ::boost::move_detail::or_
134 < ::boost::move_detail::is_lvalue_reference<T>
135 , has_move_emulation_disabled<T>
136 >
137 >::type
138 move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type &x) BOOST_NOEXCEPT
139 {
140 return x;
141 }
142
143 template <class T>
144 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
145 < rv<T>&
146 , enable_move_utility_emulation<T>
147 , ::boost::move_detail::is_not_rv<T>
148 , ::boost::move_detail::and_
149 < ::boost::move_detail::not_< ::boost::move_detail::is_lvalue_reference<T> >
150 , has_move_emulation_enabled<T>
151 >
152 >::type
153 move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type &x) BOOST_NOEXCEPT
154 {
155 return move(x);
156 }
157
158 } //namespace boost
159
160#else //#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_MOVE_DOXYGEN_INVOKED)
161
162 #if defined(BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
163 #include <utility>
164
165 namespace boost{
166
167 using ::std::move;
168 using ::std::forward;
169
170 } //namespace boost
171
172 #else //!BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE
173
174 namespace boost {
175
176 //! This trait's internal boolean `value` is false in compilers with rvalue references
177 //! and true in compilers without rvalue references.
178 //!
179 //! A user can specialize this trait for a type T to false to SFINAE out `move` and `forward`
180 //! so that the user can define a different move emulation for that type in namespace boost
181 //! (e.g. another Boost library for its types) and avoid any overload ambiguity.
182 template<class T>
183 struct enable_move_utility_emulation
184 {
185 static const bool value = false;
186 };
187
188 //////////////////////////////////////////////////////////////////////////////
189 //
190 // move
191 //
192 //////////////////////////////////////////////////////////////////////////////
193
194 #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
195 //! This function provides a way to convert a reference into a rvalue reference
196 //! in compilers with rvalue references. For other compilers if `T` is Boost.Move
197 //! enabled type then it converts `T&` into <tt>::boost::rv<T> &</tt> so that
198 //! move emulation is activated, else it returns `T &`.
199 template <class T>
200 rvalue_reference move(input_reference) noexcept;
201
202 #elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
203
204 //Old move approach, lvalues could bind to rvalue references
205 template <class T>
206 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::remove_reference<T>::type && move(T&& t) BOOST_NOEXCEPT
207 { return t; }
208
209 #else //BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES
210
211 template <class T>
212 BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::remove_reference<T>::type && move(T&& t) BOOST_NOEXCEPT
213 { return static_cast<typename ::boost::move_detail::remove_reference<T>::type &&>(t); }
214
215 #endif //BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES
216
217 //////////////////////////////////////////////////////////////////////////////
218 //
219 // forward
220 //
221 //////////////////////////////////////////////////////////////////////////////
222
223
224 #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
225 //! This function provides limited form of forwarding that is usually enough for
226 //! in-place construction and avoids the exponential overloading for
227 //! achieve the limited forwarding in C++03.
228 //!
229 //! For compilers with rvalue references this function provides perfect forwarding.
230 //!
231 //! Otherwise:
232 //! * If input_reference binds to const ::boost::rv<T> & then it output_reference is
233 //! ::boost::rv<T> &
234 //!
235 //! * Else, output_reference is equal to input_reference.
236 template <class T> output_reference forward(input_reference) noexcept;
237 #elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
238
239 //Old move approach, lvalues could bind to rvalue references
240
241 template <class T>
242 BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
243 { return t; }
244
245 #else //Old move
246
247 template <class T>
248 BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
249 { return static_cast<T&&>(t); }
250
251 template <class T>
252 BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
253 {
254 //"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
255 BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
256 return static_cast<T&&>(t);
257 }
258
259 #endif //BOOST_MOVE_DOXYGEN_INVOKED
260
261 //////////////////////////////////////////////////////////////////////////////
262 //
263 // move_if_not_lvalue_reference
264 //
265 //////////////////////////////////////////////////////////////////////////////
266
267
268 #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
269 //! <b>Effects</b>: Calls `boost::move` if `input_reference` is not a lvalue reference.
270 //! Otherwise returns the reference
271 template <class T> output_reference move_if_not_lvalue_reference(input_reference) noexcept;
272 #elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
273
274 //Old move approach, lvalues could bind to rvalue references
275
276 template <class T>
277 BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
278 { return t; }
279
280 #else //Old move
281
282 template <class T>
283 BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
284 { return static_cast<T&&>(t); }
285
286 template <class T>
287 BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
288 {
289 //"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
290 BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
291 return static_cast<T&&>(t);
292 }
293
294 #endif //BOOST_MOVE_DOXYGEN_INVOKED
295
296 } //namespace boost {
297
298 #endif //#if defined(BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
299
300#endif //BOOST_NO_CXX11_RVALUE_REFERENCES
301
302#if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
303
304namespace boost{
305namespace move_detail{
306
307template <typename T>
308typename boost::move_detail::add_rvalue_reference<T>::type declval();
309
310} //namespace move_detail{
311} //namespace boost{
312
313#endif //#if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
314
315
316#include <boost/move/detail/config_end.hpp>
317
318#endif //#ifndef BOOST_MOVE_MOVE_UTILITY_CORE_HPP
319

source code of include/boost/move/utility_core.hpp