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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 | ||
304 | namespace boost{ | |
305 | namespace move_detail{ | |
306 | ||
307 | template <typename T> | |
308 | typename 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 |