1 | //----------------------------------------------------------------------------- |
2 | // boost variant/variant.hpp header file |
3 | // See http://www.boost.org for updates, documentation, and revision history. |
4 | //----------------------------------------------------------------------------- |
5 | // |
6 | // Copyright (c) 2002-2003 Eric Friedman, Itay Maman |
7 | // Copyright (c) 2012-2024 Antony Polukhin |
8 | // |
9 | // Distributed under the Boost Software License, Version 1.0. (See |
10 | // accompanying file LICENSE_1_0.txt or copy at |
11 | // http://www.boost.org/LICENSE_1_0.txt) |
12 | |
13 | // Thanks to Adam Romanek for providing patches for exception-disabled env. |
14 | |
15 | #ifndef BOOST_VARIANT_VARIANT_HPP |
16 | #define BOOST_VARIANT_VARIANT_HPP |
17 | |
18 | #include <cstddef> // for std::size_t |
19 | #include <new> // for placement new |
20 | |
21 | #include <boost/type_index.hpp> |
22 | |
23 | #include <boost/variant/detail/config.hpp> |
24 | #include <boost/mpl/aux_/value_wknd.hpp> |
25 | |
26 | #include <boost/variant/variant_fwd.hpp> |
27 | #include <boost/variant/detail/backup_holder.hpp> |
28 | #include <boost/variant/detail/enable_recursive_fwd.hpp> |
29 | #include <boost/variant/detail/forced_return.hpp> |
30 | #include <boost/variant/detail/initializer.hpp> |
31 | #include <boost/variant/detail/make_variant_list.hpp> |
32 | #include <boost/variant/detail/over_sequence.hpp> |
33 | #include <boost/variant/detail/visitation_impl.hpp> |
34 | #include <boost/variant/detail/hash_variant.hpp> |
35 | #include <boost/variant/detail/std_hash.hpp> |
36 | |
37 | #include <boost/variant/detail/move.hpp> |
38 | |
39 | #include <boost/detail/reference_content.hpp> |
40 | #include <boost/blank.hpp> |
41 | #include <boost/integer/common_factor_ct.hpp> |
42 | #include <boost/static_assert.hpp> |
43 | #include <boost/type_traits/aligned_storage.hpp> |
44 | #include <boost/type_traits/alignment_of.hpp> |
45 | #include <boost/type_traits/add_const.hpp> |
46 | #include <boost/type_traits/has_nothrow_constructor.hpp> |
47 | #include <boost/type_traits/has_nothrow_copy.hpp> |
48 | #include <boost/type_traits/is_nothrow_move_assignable.hpp> |
49 | #include <boost/type_traits/is_nothrow_move_constructible.hpp> |
50 | #include <boost/type_traits/is_const.hpp> |
51 | #include <boost/type_traits/is_same.hpp> |
52 | #include <boost/type_traits/is_rvalue_reference.hpp> |
53 | #include <boost/type_traits/is_constructible.hpp> |
54 | #include <boost/type_traits/add_lvalue_reference.hpp> |
55 | #include <boost/type_traits/declval.hpp> |
56 | #include <boost/core/no_exceptions_support.hpp> |
57 | #include <boost/core/enable_if.hpp> |
58 | #include <boost/variant/recursive_wrapper_fwd.hpp> |
59 | #include <boost/variant/static_visitor.hpp> |
60 | |
61 | #include <boost/mpl/assert.hpp> |
62 | #include <boost/mpl/begin_end.hpp> |
63 | #include <boost/mpl/bool.hpp> |
64 | #include <boost/mpl/deref.hpp> |
65 | #include <boost/mpl/empty.hpp> |
66 | #include <boost/mpl/eval_if.hpp> |
67 | #include <boost/mpl/find_if.hpp> |
68 | #include <boost/mpl/fold.hpp> |
69 | #include <boost/mpl/front.hpp> |
70 | #include <boost/mpl/identity.hpp> |
71 | #include <boost/mpl/if.hpp> |
72 | #include <boost/mpl/insert_range.hpp> |
73 | #include <boost/mpl/int.hpp> |
74 | #include <boost/mpl/is_sequence.hpp> |
75 | #include <boost/mpl/iterator_range.hpp> |
76 | #include <boost/mpl/iter_fold_if.hpp> |
77 | #include <boost/mpl/list.hpp> |
78 | #include <boost/mpl/logical.hpp> |
79 | #include <boost/mpl/max_element.hpp> |
80 | #include <boost/mpl/next.hpp> |
81 | #include <boost/mpl/not.hpp> |
82 | #include <boost/mpl/pair.hpp> |
83 | #include <boost/mpl/protect.hpp> |
84 | #include <boost/mpl/push_front.hpp> |
85 | #include <boost/mpl/same_as.hpp> |
86 | #include <boost/mpl/size_t.hpp> |
87 | #include <boost/mpl/sizeof.hpp> |
88 | #include <boost/mpl/transform.hpp> |
89 | |
90 | /////////////////////////////////////////////////////////////////////////////// |
91 | // Implementation Macros: |
92 | // |
93 | // BOOST_VARIANT_VISITATION_UNROLLING_LIMIT |
94 | // Defined in boost/variant/detail/visitation_impl.hpp. |
95 | // |
96 | // BOOST_VARIANT_MINIMIZE_SIZE |
97 | // When #defined, implementation employs all known means to minimize the |
98 | // size of variant obje cts. However, often unsuccessful due to alignment |
99 | // issues, and potentially harmful to runtime speed, so not enabled by |
100 | // default. (TODO: Investigate further.) |
101 | |
102 | #if defined(BOOST_VARIANT_MINIMIZE_SIZE) |
103 | # include <climits> // for SCHAR_MAX |
104 | # include <boost/mpl/eval_if.hpp> |
105 | # include <boost/mpl/equal_to.hpp> |
106 | # include <boost/mpl/identity.hpp> |
107 | # include <boost/mpl/int.hpp> |
108 | # include <boost/mpl/if.hpp> |
109 | # include <boost/mpl/less.hpp> |
110 | # include <boost/mpl/long.hpp> |
111 | # include <boost/mpl/O1_size.hpp> |
112 | #endif |
113 | |
114 | |
115 | namespace boost { |
116 | |
117 | namespace detail { namespace variant { |
118 | |
119 | /////////////////////////////////////////////////////////////////////////////// |
120 | // (detail) metafunction max_value |
121 | // |
122 | // Finds the maximum value of the unary metafunction F over Sequence. |
123 | // |
124 | template <typename Sequence, typename F> |
125 | struct max_value |
126 | { |
127 | private: // helpers, for metafunction result (below) |
128 | |
129 | typedef typename mpl::transform1<Sequence, F>::type transformed_; |
130 | typedef typename mpl::max_element<transformed_ |
131 | |
132 | >::type max_it; |
133 | |
134 | public: // metafunction result |
135 | |
136 | typedef typename mpl::deref<max_it>::type |
137 | type; |
138 | |
139 | }; |
140 | |
141 | struct add_alignment |
142 | { |
143 | template <typename State, typename Item> |
144 | struct apply |
145 | : mpl::size_t< |
146 | ::boost::integer::static_lcm< |
147 | BOOST_MPL_AUX_VALUE_WKND(State)::value |
148 | , ::boost::alignment_of<Item>::value |
149 | >::value |
150 | > |
151 | {}; |
152 | }; |
153 | |
154 | /////////////////////////////////////////////////////////////////////////////// |
155 | // (detail) metafunction find_fallback_type |
156 | // |
157 | // Provides a fallback (i.e., nothrow default-constructible) type from the |
158 | // specified sequence, or no_fallback_type if not found. |
159 | // |
160 | // This implementation is designed to prefer boost::blank over other potential |
161 | // fallback types, regardless of its position in the specified sequence. |
162 | // |
163 | |
164 | class no_fallback_type; |
165 | |
166 | struct find_fallback_type_pred |
167 | { |
168 | template <typename Iterator> |
169 | struct apply |
170 | { |
171 | private: |
172 | typedef typename mpl::deref<Iterator>::type t_; |
173 | |
174 | public: |
175 | typedef mpl::not_< has_nothrow_constructor<t_> > type; |
176 | }; |
177 | }; |
178 | |
179 | template <typename Types> |
180 | struct find_fallback_type |
181 | { |
182 | private: // helpers, for metafunction result (below) |
183 | |
184 | typedef typename mpl::end<Types>::type end_it; |
185 | |
186 | // [Find the first suitable fallback type...] |
187 | |
188 | typedef typename mpl::iter_fold_if< |
189 | Types |
190 | , mpl::int_<0>, mpl::protect< mpl::next<> > |
191 | , mpl::protect< find_fallback_type_pred > |
192 | >::type first_result_; |
193 | |
194 | typedef typename first_result_::first first_result_index; |
195 | typedef typename first_result_::second first_result_it; |
196 | |
197 | // [...now search the rest of the sequence for boost::blank...] |
198 | |
199 | typedef typename mpl::iter_fold_if< |
200 | mpl::iterator_range< first_result_it,end_it > |
201 | , first_result_index, mpl::protect< mpl::next<> > |
202 | , mpl::protect< mpl::not_same_as<boost::blank> > |
203 | >::type second_result_; |
204 | |
205 | typedef typename second_result_::second second_result_it; |
206 | |
207 | public: // metafunction result |
208 | |
209 | // [...and return the results of the search:] |
210 | typedef typename mpl::eval_if< |
211 | is_same< second_result_it,end_it > |
212 | , mpl::if_< |
213 | is_same< first_result_it,end_it > |
214 | , mpl::pair< no_fallback_type,no_fallback_type > |
215 | , first_result_ |
216 | > |
217 | , mpl::identity< second_result_ > |
218 | >::type type; |
219 | |
220 | }; |
221 | |
222 | /////////////////////////////////////////////////////////////////////////////// |
223 | // (detail) metafunction is_variant_move_noexcept_constructible |
224 | // |
225 | // Returns true_type if all the types are nothrow move constructible. |
226 | // |
227 | template <class Types> |
228 | struct is_variant_move_noexcept_constructible { |
229 | typedef typename boost::mpl::find_if< |
230 | Types, mpl::not_<boost::is_nothrow_move_constructible<boost::mpl::_1> > |
231 | >::type iterator_t; |
232 | |
233 | typedef typename boost::mpl::end<Types>::type end_t; |
234 | typedef typename boost::is_same< |
235 | iterator_t, end_t |
236 | >::type type; |
237 | }; |
238 | |
239 | /////////////////////////////////////////////////////////////////////////////// |
240 | // (detail) metafunction is_variant_move_noexcept_assignable |
241 | // |
242 | // Returns true_type if all the types are nothrow move constructible. |
243 | // |
244 | template <class Types> |
245 | struct is_variant_move_noexcept_assignable { |
246 | typedef typename boost::mpl::find_if< |
247 | Types, mpl::not_<boost::is_nothrow_move_assignable<boost::mpl::_1> > |
248 | >::type iterator_t; |
249 | |
250 | typedef typename boost::mpl::end<Types>::type end_t; |
251 | typedef typename boost::is_same< |
252 | iterator_t, end_t |
253 | >::type type; |
254 | }; |
255 | |
256 | /////////////////////////////////////////////////////////////////////////////// |
257 | // (detail) metafunction is_variant_constructible_from |
258 | // |
259 | // Derives from true_type if at least one variant's type is constructible from T. |
260 | // |
261 | template <class T1, class T2> |
262 | struct is_constructible_ext: |
263 | boost::mpl::or_< |
264 | boost::is_constructible< |
265 | T1, |
266 | T2 |
267 | >, |
268 | boost::is_constructible< |
269 | T1, |
270 | typename boost::add_lvalue_reference<T2>::type |
271 | > |
272 | > |
273 | {}; |
274 | |
275 | template <class T, class Types> |
276 | struct is_variant_constructible_from: |
277 | boost::mpl::not_< boost::is_same< |
278 | typename boost::mpl::find_if< |
279 | Types, |
280 | is_constructible_ext<boost::mpl::_1, T> |
281 | >::type, |
282 | typename boost::mpl::end<Types>::type |
283 | > > |
284 | {}; |
285 | |
286 | template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types> |
287 | struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >: |
288 | boost::is_same< |
289 | typename boost::mpl::find_if< |
290 | typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types, |
291 | mpl::not_< is_variant_constructible_from< boost::mpl::_1, Types> > |
292 | >::type, |
293 | typename boost::mpl::end< typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types >::type |
294 | > |
295 | {}; |
296 | |
297 | template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types> |
298 | struct is_variant_constructible_from< const boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >: |
299 | is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types > |
300 | {}; |
301 | |
302 | template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types> |
303 | struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >: |
304 | is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types > |
305 | {}; |
306 | |
307 | template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types> |
308 | struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>&& , Types >: |
309 | is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types > |
310 | {}; |
311 | |
312 | template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types> |
313 | struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const && , Types >: |
314 | is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types > |
315 | {}; |
316 | |
317 | |
318 | /////////////////////////////////////////////////////////////////////////////// |
319 | // (detail) metafunction make_storage |
320 | // |
321 | // Provides an aligned storage type capable of holding any of the types |
322 | // specified in the given type-sequence. |
323 | // |
324 | |
325 | template <typename Types, typename NeverUsesBackupFlag> |
326 | struct make_storage |
327 | { |
328 | private: // helpers, for metafunction result (below) |
329 | |
330 | typedef typename mpl::eval_if< |
331 | NeverUsesBackupFlag |
332 | , mpl::identity< Types > |
333 | , mpl::push_front< |
334 | Types, backup_holder<void*> |
335 | > |
336 | >::type types; |
337 | |
338 | typedef typename max_value< |
339 | types, mpl::sizeof_<mpl::_1> |
340 | >::type max_size; |
341 | |
342 | #if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551)) |
343 | |
344 | typedef typename mpl::fold< |
345 | types |
346 | , mpl::size_t<1> |
347 | , add_alignment |
348 | >::type max_alignment; |
349 | |
350 | #else // borland |
351 | |
352 | // temporary workaround -- use maximal alignment |
353 | typedef mpl::size_t< -1 > max_alignment; |
354 | |
355 | #endif // borland workaround |
356 | |
357 | public: // metafunction result |
358 | |
359 | typedef ::boost::aligned_storage< |
360 | BOOST_MPL_AUX_VALUE_WKND(max_size)::value |
361 | , BOOST_MPL_AUX_VALUE_WKND(max_alignment)::value |
362 | > type; |
363 | }; |
364 | |
365 | /////////////////////////////////////////////////////////////////////////////// |
366 | // (detail) class destroyer |
367 | // |
368 | // Internal visitor that destroys the value it visits. |
369 | // |
370 | struct destroyer |
371 | : public static_visitor<> |
372 | { |
373 | public: // visitor interfaces |
374 | |
375 | template <typename T> |
376 | void internal_visit(T& operand, int) const BOOST_NOEXCEPT |
377 | { |
378 | operand.~T(); // must be noexcept |
379 | |
380 | #if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551)) || \ |
381 | BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
382 | (void)operand; // suppresses warnings |
383 | #endif |
384 | } |
385 | |
386 | }; |
387 | |
388 | /////////////////////////////////////////////////////////////////////////////// |
389 | // (detail) class template known_get |
390 | // |
391 | // Visitor that returns a reference to content of the specified type. |
392 | // |
393 | // Precondition: visited variant MUST contain logical content of type T. |
394 | // |
395 | template <typename T> |
396 | class known_get |
397 | : public static_visitor<T&> |
398 | { |
399 | |
400 | public: // visitor interface |
401 | |
402 | T& operator()(T& operand) const BOOST_NOEXCEPT |
403 | { |
404 | return operand; |
405 | } |
406 | |
407 | template <typename U> |
408 | T& operator()(U&) const |
409 | { |
410 | // logical error to be here: see precondition above |
411 | return ::boost::detail::variant::forced_return< T& >(); |
412 | } |
413 | }; |
414 | |
415 | /////////////////////////////////////////////////////////////////////////////// |
416 | // (detail) class copy_into |
417 | // |
418 | // Internal visitor that copies the value it visits into the given buffer. |
419 | // |
420 | class copy_into |
421 | : public static_visitor<> |
422 | { |
423 | private: // representation |
424 | |
425 | void* storage_; |
426 | |
427 | public: // structors |
428 | |
429 | explicit copy_into(void* storage) BOOST_NOEXCEPT |
430 | : storage_(storage) |
431 | { |
432 | } |
433 | |
434 | public: // internal visitor interface |
435 | |
436 | template <typename T> |
437 | void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const |
438 | { |
439 | new(storage_) T( operand.get() ); |
440 | } |
441 | |
442 | template <typename T> |
443 | void internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const |
444 | { |
445 | new(storage_) T( operand.get() ); |
446 | } |
447 | |
448 | template <typename T> |
449 | void internal_visit(const T& operand, int) const |
450 | { |
451 | new(storage_) T(operand); |
452 | } |
453 | |
454 | }; |
455 | |
456 | /////////////////////////////////////////////////////////////////////////////// |
457 | // (detail) class move_into |
458 | // |
459 | // Internal visitor that moves the value it visits into the given buffer. |
460 | // |
461 | class move_into |
462 | : public static_visitor<> |
463 | { |
464 | private: // representation |
465 | |
466 | void* storage_; |
467 | |
468 | public: // structors |
469 | |
470 | explicit move_into(void* storage) BOOST_NOEXCEPT |
471 | : storage_(storage) |
472 | { |
473 | } |
474 | |
475 | public: // internal visitor interface |
476 | |
477 | template <typename T> |
478 | void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const |
479 | { |
480 | new(storage_) T( ::boost::detail::variant::move(operand.get()) ); |
481 | } |
482 | |
483 | template <typename T> |
484 | void internal_visit(T& operand, int) const BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(T(boost::declval<T>()))) |
485 | { |
486 | new(storage_) T(::boost::detail::variant::move(operand)); |
487 | } |
488 | }; |
489 | |
490 | /////////////////////////////////////////////////////////////////////////////// |
491 | // (detail) class assign_storage |
492 | // |
493 | // Internal visitor that assigns the given storage (which must be a |
494 | // constructed value of the same type) to the value it visits. |
495 | // |
496 | struct assign_storage |
497 | : public static_visitor<> |
498 | { |
499 | private: // representation |
500 | |
501 | const void* rhs_storage_; |
502 | |
503 | public: // structors |
504 | |
505 | explicit assign_storage(const void* rhs_storage) BOOST_NOEXCEPT |
506 | : rhs_storage_(rhs_storage) |
507 | { |
508 | } |
509 | |
510 | public: // internal visitor interfaces |
511 | |
512 | template <typename T> |
513 | void internal_visit(backup_holder<T>& lhs_content, long) const |
514 | { |
515 | lhs_content.get() |
516 | = static_cast< const backup_holder<T>* >(rhs_storage_)->get(); |
517 | } |
518 | |
519 | template <typename T> |
520 | void internal_visit(const backup_holder<T>& lhs_content, long) const |
521 | { |
522 | lhs_content.get() |
523 | = static_cast< const backup_holder<T>* >(rhs_storage_)->get(); |
524 | } |
525 | |
526 | template <typename T> |
527 | void internal_visit(T& lhs_content, int) const |
528 | { |
529 | // NOTE TO USER : |
530 | // Compile error here indicates one of variant's bounded types does |
531 | // not meet the requirements of the Assignable concept. Thus, |
532 | // variant is not Assignable. |
533 | // |
534 | // Hint: Are any of the bounded types const-qualified or references? |
535 | // |
536 | lhs_content = *static_cast< const T* >(rhs_storage_); |
537 | } |
538 | |
539 | }; |
540 | |
541 | /////////////////////////////////////////////////////////////////////////////// |
542 | // (detail) class move_storage |
543 | // |
544 | // Internal visitor that moves the given storage (which must be a |
545 | // constructed value of the same type) to the value it visits. |
546 | // |
547 | struct move_storage |
548 | : public static_visitor<> |
549 | { |
550 | private: // representation |
551 | |
552 | void* rhs_storage_; |
553 | |
554 | public: // structors |
555 | |
556 | explicit move_storage(void* rhs_storage) BOOST_NOEXCEPT |
557 | : rhs_storage_(rhs_storage) |
558 | { |
559 | } |
560 | |
561 | public: // internal visitor interfaces |
562 | |
563 | template <typename T> |
564 | void internal_visit(backup_holder<T>& lhs_content, long) const |
565 | { |
566 | lhs_content.get() |
567 | = ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get()); |
568 | } |
569 | |
570 | template <typename T> |
571 | void internal_visit(const backup_holder<T>& lhs_content, long) const |
572 | { |
573 | lhs_content.get() |
574 | = ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get()); |
575 | } |
576 | |
577 | template <typename T> |
578 | void internal_visit(T& lhs_content, int) const |
579 | { |
580 | // NOTE TO USER : |
581 | // Compile error here indicates one of variant's bounded types does |
582 | // not meet the requirements of the Assignable concept. Thus, |
583 | // variant is not Assignable. |
584 | // |
585 | // Hint: Are any of the bounded types const-qualified or references? |
586 | // |
587 | lhs_content = ::boost::detail::variant::move(*static_cast<T* >(rhs_storage_)); |
588 | } |
589 | |
590 | }; |
591 | |
592 | /////////////////////////////////////////////////////////////////////////////// |
593 | // (detail) class direct_assigner |
594 | // |
595 | // Generic static visitor that: if and only if the visited value is of the |
596 | // specified type, assigns the given value to the visited value and returns |
597 | // true; else returns false. |
598 | // |
599 | template <typename T> |
600 | class direct_assigner |
601 | : public static_visitor<bool> |
602 | { |
603 | private: // representation |
604 | |
605 | const T& rhs_; |
606 | |
607 | public: // structors |
608 | |
609 | explicit direct_assigner(const T& rhs) BOOST_NOEXCEPT |
610 | : rhs_(rhs) |
611 | { |
612 | } |
613 | |
614 | public: // visitor interface |
615 | |
616 | bool operator()(T& lhs) |
617 | { |
618 | lhs = rhs_; |
619 | return true; |
620 | } |
621 | |
622 | template <typename U> |
623 | bool operator()(U&) BOOST_NOEXCEPT |
624 | { |
625 | return false; |
626 | } |
627 | |
628 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
629 | private: |
630 | // silence MSVC warning C4512: assignment operator could not be generated |
631 | direct_assigner& operator= (direct_assigner const&); |
632 | #endif |
633 | }; |
634 | |
635 | /////////////////////////////////////////////////////////////////////////////// |
636 | // (detail) class direct_mover |
637 | // |
638 | // Generic static visitor that: if and only if the visited value is of the |
639 | // specified type, move assigns the given value to the visited value and returns |
640 | // true; else returns false. |
641 | // |
642 | template <typename T> |
643 | class direct_mover |
644 | : public static_visitor<bool> |
645 | { |
646 | private: // representation |
647 | |
648 | T& rhs_; |
649 | |
650 | public: // structors |
651 | |
652 | explicit direct_mover(T& rhs) BOOST_NOEXCEPT |
653 | : rhs_(rhs) |
654 | { |
655 | } |
656 | |
657 | public: // visitor interface |
658 | |
659 | bool operator()(T& lhs) |
660 | { |
661 | lhs = ::boost::detail::variant::move(rhs_); |
662 | return true; |
663 | } |
664 | |
665 | template <typename U> |
666 | bool operator()(U&) BOOST_NOEXCEPT |
667 | { |
668 | return false; |
669 | } |
670 | |
671 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
672 | private: |
673 | // silence MSVC warning C4512: assignment operator could not be generated |
674 | direct_mover& operator= (direct_mover const&); |
675 | #endif |
676 | }; |
677 | |
678 | |
679 | /////////////////////////////////////////////////////////////////////////////// |
680 | // (detail) class backup_assigner |
681 | // |
682 | // Internal visitor that "assigns" the given value to the visited value, |
683 | // using backup to recover if the destroy-copy sequence fails. |
684 | // |
685 | // NOTE: This needs to be a friend of variant, as it needs access to |
686 | // indicate_which, indicate_backup_which, etc. |
687 | // |
688 | template <typename Variant> |
689 | class backup_assigner |
690 | : public static_visitor<> |
691 | { |
692 | private: // representation |
693 | |
694 | Variant& lhs_; |
695 | int rhs_which_; |
696 | const void* rhs_content_; |
697 | void (*copy_rhs_content_)(void*, const void*); |
698 | |
699 | public: // structors |
700 | |
701 | template<class RhsT> |
702 | backup_assigner(Variant& lhs, int rhs_which, const RhsT& rhs_content) |
703 | : lhs_(lhs) |
704 | , rhs_which_(rhs_which) |
705 | , rhs_content_(&rhs_content) |
706 | , copy_rhs_content_(&construct_impl<RhsT>) |
707 | { |
708 | } |
709 | |
710 | private: // helpers, for visitor interface (below) |
711 | |
712 | template<class RhsT> |
713 | static void construct_impl(void* addr, const void* obj) |
714 | { |
715 | new(addr) RhsT(*static_cast<const RhsT*>(obj)); |
716 | } |
717 | |
718 | template <typename LhsT> |
719 | void backup_assign_impl( |
720 | backup_holder<LhsT>& lhs_content |
721 | , mpl::false_ // is_nothrow_move_constructible |
722 | , long |
723 | ) |
724 | { |
725 | // Move lhs content to backup... |
726 | backup_holder<LhsT> backup_lhs_content(0); |
727 | backup_lhs_content.swap(lhs_content); // nothrow |
728 | |
729 | // ...destroy lhs content... |
730 | lhs_content.~backup_holder<LhsT>(); // nothrow |
731 | |
732 | BOOST_TRY |
733 | { |
734 | // ...and attempt to copy rhs content into lhs storage: |
735 | copy_rhs_content_(lhs_.storage_.address(), rhs_content_); |
736 | } |
737 | BOOST_CATCH (...) |
738 | { |
739 | // In case of failure, copy backup pointer to lhs storage... |
740 | new(lhs_.storage_.address()) |
741 | backup_holder<LhsT>( 0 ); // nothrow |
742 | |
743 | static_cast<backup_holder<LhsT>* >(lhs_.storage_.address()) |
744 | ->swap(backup_lhs_content); // nothrow |
745 | |
746 | // ...and rethrow: |
747 | BOOST_RETHROW; |
748 | } |
749 | BOOST_CATCH_END |
750 | |
751 | // In case of success, indicate new content type: |
752 | lhs_.indicate_which(rhs_which_); // nothrow |
753 | } |
754 | |
755 | template <typename LhsT> |
756 | void backup_assign_impl( |
757 | LhsT& lhs_content |
758 | , mpl::true_ // is_nothrow_move_constructible |
759 | , int |
760 | ) |
761 | { |
762 | // Move lhs content to backup... |
763 | LhsT backup_lhs_content( |
764 | ::boost::detail::variant::move(lhs_content) |
765 | ); // nothrow |
766 | |
767 | // ...destroy lhs content... |
768 | lhs_content.~LhsT(); // nothrow |
769 | |
770 | BOOST_TRY |
771 | { |
772 | // ...and attempt to copy rhs content into lhs storage: |
773 | copy_rhs_content_(lhs_.storage_.address(), rhs_content_); |
774 | } |
775 | BOOST_CATCH (...) |
776 | { |
777 | // In case of failure, restore backup content to lhs storage... |
778 | new(lhs_.storage_.address()) |
779 | LhsT( |
780 | ::boost::detail::variant::move(backup_lhs_content) |
781 | ); // nothrow |
782 | |
783 | // ...and rethrow: |
784 | BOOST_RETHROW; |
785 | } |
786 | BOOST_CATCH_END |
787 | |
788 | // In case of success, indicate new content type: |
789 | lhs_.indicate_which(rhs_which_); // nothrow |
790 | } |
791 | |
792 | template <typename LhsT> |
793 | void backup_assign_impl( |
794 | LhsT& lhs_content |
795 | , mpl::false_ // is_nothrow_move_constructible |
796 | , int |
797 | ) |
798 | { |
799 | // Backup lhs content... |
800 | LhsT* backup_lhs_ptr = new LhsT(lhs_content); |
801 | |
802 | // ...destroy lhs content... |
803 | lhs_content.~LhsT(); // nothrow |
804 | |
805 | BOOST_TRY |
806 | { |
807 | // ...and attempt to copy rhs content into lhs storage: |
808 | copy_rhs_content_(lhs_.storage_.address(), rhs_content_); |
809 | } |
810 | BOOST_CATCH (...) |
811 | { |
812 | // In case of failure, copy backup pointer to lhs storage... |
813 | new(lhs_.storage_.address()) |
814 | backup_holder<LhsT>( backup_lhs_ptr ); // nothrow |
815 | |
816 | // ...indicate now using backup... |
817 | lhs_.indicate_backup_which( lhs_.which() ); // nothrow |
818 | |
819 | // ...and rethrow: |
820 | BOOST_RETHROW; |
821 | } |
822 | BOOST_CATCH_END |
823 | |
824 | // In case of success, indicate new content type... |
825 | lhs_.indicate_which(rhs_which_); // nothrow |
826 | |
827 | // ...and delete backup: |
828 | delete backup_lhs_ptr; // nothrow |
829 | } |
830 | |
831 | public: // visitor interface |
832 | |
833 | template <typename LhsT> |
834 | void internal_visit(LhsT& lhs_content, int) |
835 | { |
836 | typedef typename is_nothrow_move_constructible<LhsT>::type |
837 | nothrow_move; |
838 | |
839 | backup_assign_impl( lhs_content, nothrow_move(), 1L); |
840 | } |
841 | |
842 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
843 | private: |
844 | // silence MSVC warning C4512: assignment operator could not be generated |
845 | backup_assigner& operator= (backup_assigner const&); |
846 | #endif |
847 | }; |
848 | |
849 | /////////////////////////////////////////////////////////////////////////////// |
850 | // (detail) class swap_with |
851 | // |
852 | // Visitor that swaps visited value with content of given variant. |
853 | // |
854 | // Precondition: Given variant MUST have same logical type as visited value. |
855 | // |
856 | template <typename Variant> |
857 | struct swap_with |
858 | : public static_visitor<> |
859 | { |
860 | private: // representation |
861 | |
862 | Variant& toswap_; |
863 | |
864 | public: // structors |
865 | |
866 | explicit swap_with(Variant& toswap) BOOST_NOEXCEPT |
867 | : toswap_(toswap) |
868 | { |
869 | } |
870 | |
871 | public: // internal visitor interfaces |
872 | |
873 | template <typename T> |
874 | void operator()(T& operand) const |
875 | { |
876 | // Since the precondition ensures types are same, get T... |
877 | known_get<T> getter; |
878 | T& other = toswap_.apply_visitor(getter); |
879 | |
880 | // ...and swap: |
881 | ::boost::detail::variant::move_swap( operand, other ); |
882 | } |
883 | |
884 | private: |
885 | swap_with& operator=(const swap_with&); |
886 | |
887 | }; |
888 | |
889 | /////////////////////////////////////////////////////////////////////////////// |
890 | // (detail) class reflect |
891 | // |
892 | // Generic static visitor that performs a typeid on the value it visits. |
893 | // |
894 | |
895 | class reflect |
896 | : public static_visitor<const boost::typeindex::type_info&> |
897 | { |
898 | public: // visitor interfaces |
899 | |
900 | template <typename T> |
901 | const boost::typeindex::type_info& operator()(const T&) const BOOST_NOEXCEPT |
902 | { |
903 | return boost::typeindex::type_id<T>().type_info(); |
904 | } |
905 | |
906 | }; |
907 | |
908 | /////////////////////////////////////////////////////////////////////////////// |
909 | // (detail) class comparer |
910 | // |
911 | // Generic static visitor that compares the content of the given lhs variant |
912 | // with the visited rhs content using Comp. |
913 | // |
914 | // Precondition: lhs.which() == rhs.which() |
915 | // |
916 | template <typename Variant, typename Comp> |
917 | class comparer |
918 | : public static_visitor<bool> |
919 | { |
920 | private: // representation |
921 | |
922 | const Variant& lhs_; |
923 | |
924 | public: // structors |
925 | |
926 | explicit comparer(const Variant& lhs) BOOST_NOEXCEPT |
927 | : lhs_(lhs) |
928 | { |
929 | } |
930 | |
931 | public: // visitor interfaces |
932 | |
933 | template <typename T> |
934 | bool operator()(T& rhs_content) const |
935 | { |
936 | // Since the precondition ensures lhs and rhs types are same, get T... |
937 | known_get<T> getter; |
938 | const T& lhs_content = lhs_.apply_visitor(getter); |
939 | |
940 | // ...and compare lhs and rhs contents: |
941 | return Comp()(lhs_content, rhs_content); |
942 | } |
943 | |
944 | private: |
945 | comparer& operator=(const comparer&); |
946 | |
947 | }; |
948 | |
949 | /////////////////////////////////////////////////////////////////////////////// |
950 | // (detail) class equal_comp |
951 | // |
952 | // Generic function object compares lhs with rhs using operator==. |
953 | // |
954 | struct equal_comp |
955 | { |
956 | template <typename T> |
957 | bool operator()(const T& lhs, const T& rhs) const |
958 | { |
959 | return lhs == rhs; |
960 | } |
961 | }; |
962 | |
963 | /////////////////////////////////////////////////////////////////////////////// |
964 | // (detail) class less_comp |
965 | // |
966 | // Generic function object compares lhs with rhs using operator<. |
967 | // |
968 | struct less_comp |
969 | { |
970 | template <typename T> |
971 | bool operator()(const T& lhs, const T& rhs) const |
972 | { |
973 | return lhs < rhs; |
974 | } |
975 | }; |
976 | |
977 | /////////////////////////////////////////////////////////////////////////////// |
978 | // (detail) class template invoke_visitor |
979 | // |
980 | // Internal visitor that invokes the given visitor using: |
981 | // * for wrappers (e.g., recursive_wrapper), the wrapper's held value. |
982 | // * for all other values, the value itself. |
983 | // |
984 | template <typename Visitor, bool MoveSemantics> |
985 | class invoke_visitor |
986 | { |
987 | private: // representation |
988 | |
989 | Visitor& visitor_; |
990 | |
991 | public: // visitor typedefs |
992 | |
993 | typedef typename Visitor::result_type |
994 | result_type; |
995 | |
996 | public: // structors |
997 | |
998 | explicit invoke_visitor(Visitor& visitor) BOOST_NOEXCEPT |
999 | : visitor_(visitor) |
1000 | { |
1001 | } |
1002 | |
1003 | public: // internal visitor interfaces |
1004 | |
1005 | //using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work |
1006 | template <typename T> |
1007 | typename enable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int) |
1008 | { |
1009 | return visitor_(std::move(operand)); |
1010 | } |
1011 | |
1012 | //using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work |
1013 | template <typename T> |
1014 | typename disable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int) |
1015 | { |
1016 | return visitor_(operand); |
1017 | } |
1018 | |
1019 | public: // internal visitor interfaces, cont. |
1020 | |
1021 | template <typename T> |
1022 | result_type internal_visit(boost::recursive_wrapper<T>& operand, long) |
1023 | { |
1024 | return internal_visit( operand.get(), 1L ); |
1025 | } |
1026 | |
1027 | template <typename T> |
1028 | result_type internal_visit(const boost::recursive_wrapper<T>& operand, long) |
1029 | { |
1030 | return internal_visit( operand.get(), 1L ); |
1031 | } |
1032 | |
1033 | template <typename T> |
1034 | result_type internal_visit(boost::detail::reference_content<T>& operand, long) |
1035 | { |
1036 | return internal_visit( operand.get(), 1L ); |
1037 | } |
1038 | |
1039 | template <typename T> |
1040 | result_type internal_visit(const boost::detail::reference_content<T>& operand, long) |
1041 | { |
1042 | return internal_visit( operand.get(), 1L ); |
1043 | } |
1044 | |
1045 | template <typename T> |
1046 | result_type internal_visit(boost::detail::variant::backup_holder<T>& operand, long) |
1047 | { |
1048 | return internal_visit( operand.get(), 1L ); |
1049 | } |
1050 | |
1051 | template <typename T> |
1052 | result_type internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) |
1053 | { |
1054 | return internal_visit( operand.get(), 1L ); |
1055 | } |
1056 | |
1057 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
1058 | private: |
1059 | // silence MSVC warning C4512: assignment operator could not be generated |
1060 | invoke_visitor& operator= (invoke_visitor const&); |
1061 | #endif |
1062 | }; |
1063 | |
1064 | }} // namespace detail::variant |
1065 | |
1066 | /////////////////////////////////////////////////////////////////////////////// |
1067 | // class template variant (concept inspired by Andrei Alexandrescu) |
1068 | // |
1069 | // See docs and boost/variant/variant_fwd.hpp for more information. |
1070 | // |
1071 | template < |
1072 | typename T0_ |
1073 | , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T) |
1074 | > |
1075 | class variant |
1076 | { |
1077 | private: // helpers, for typedefs (below) |
1078 | |
1079 | typedef variant wknd_self_t; |
1080 | |
1081 | struct is_recursive_ |
1082 | : detail::variant::is_recursive_flag<T0_> |
1083 | { |
1084 | }; |
1085 | |
1086 | typedef typename mpl::eval_if< |
1087 | is_recursive_ |
1088 | , T0_ |
1089 | , mpl::identity< T0_ > |
1090 | >::type unwrapped_T0_; |
1091 | |
1092 | struct is_sequence_based_ |
1093 | : detail::variant::is_over_sequence<unwrapped_T0_> |
1094 | { |
1095 | }; |
1096 | |
1097 | private: // helpers, for typedefs (below) |
1098 | |
1099 | typedef typename mpl::eval_if< |
1100 | is_sequence_based_ |
1101 | , unwrapped_T0_ // over_sequence<...>::type |
1102 | , detail::variant::make_variant_list< |
1103 | unwrapped_T0_ |
1104 | , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
1105 | > |
1106 | >::type specified_types; |
1107 | |
1108 | BOOST_STATIC_ASSERT(( |
1109 | ::boost::mpl::not_< mpl::empty<specified_types> >::value |
1110 | )); |
1111 | |
1112 | public: // public typedefs |
1113 | typedef typename mpl::eval_if< |
1114 | is_recursive_ |
1115 | , mpl::transform< |
1116 | specified_types |
1117 | , mpl::protect< |
1118 | detail::variant::quoted_enable_recursive<wknd_self_t> |
1119 | > |
1120 | > |
1121 | , mpl::identity< specified_types > |
1122 | >::type recursive_enabled_types; // used by is_variant_constructible_from<> trait |
1123 | |
1124 | typedef typename mpl::transform< |
1125 | recursive_enabled_types |
1126 | , unwrap_recursive<mpl::_1> |
1127 | >::type types; |
1128 | |
1129 | private: // internal typedefs |
1130 | |
1131 | typedef typename mpl::transform< |
1132 | recursive_enabled_types |
1133 | , mpl::protect< detail::make_reference_content<> > |
1134 | >::type internal_types; |
1135 | |
1136 | typedef typename mpl::front< |
1137 | internal_types |
1138 | >::type internal_T0; |
1139 | |
1140 | private: // helpers, for representation (below) |
1141 | |
1142 | typedef typename detail::variant::find_fallback_type< |
1143 | internal_types |
1144 | >::type fallback_type_result_; |
1145 | |
1146 | typedef typename fallback_type_result_::first |
1147 | fallback_type_index_; |
1148 | typedef typename fallback_type_result_::second |
1149 | fallback_type_; |
1150 | |
1151 | struct has_fallback_type_ |
1152 | : mpl::not_< |
1153 | is_same< fallback_type_, detail::variant::no_fallback_type > |
1154 | > |
1155 | { |
1156 | }; |
1157 | |
1158 | typedef has_fallback_type_ |
1159 | never_uses_backup_flag; |
1160 | |
1161 | typedef typename detail::variant::make_storage< |
1162 | internal_types, never_uses_backup_flag |
1163 | >::type storage_t; |
1164 | |
1165 | typedef typename detail::variant::is_variant_move_noexcept_constructible< |
1166 | internal_types |
1167 | > variant_move_noexcept_constructible; |
1168 | |
1169 | typedef typename detail::variant::is_variant_move_noexcept_assignable< |
1170 | internal_types |
1171 | > variant_move_noexcept_assignable; |
1172 | |
1173 | private: // helpers, for representation (below) |
1174 | |
1175 | // which_ on: |
1176 | // * [0, size<internal_types>) indicates stack content |
1177 | // * [-size<internal_types>, 0) indicates pointer to heap backup |
1178 | // if which_ >= 0: |
1179 | // * then which() -> which_ |
1180 | // * else which() -> -(which_ + 1) |
1181 | |
1182 | #if !defined(BOOST_VARIANT_MINIMIZE_SIZE) |
1183 | |
1184 | typedef int which_t; |
1185 | |
1186 | #else // defined(BOOST_VARIANT_MINIMIZE_SIZE) |
1187 | |
1188 | // [if O1_size available, then attempt which_t size optimization...] |
1189 | // [select signed char if fewer than SCHAR_MAX types, else signed int:] |
1190 | typedef typename mpl::eval_if< |
1191 | mpl::equal_to< mpl::O1_size<internal_types>, mpl::long_<-1> > |
1192 | , mpl::identity< int > |
1193 | , mpl::if_< |
1194 | mpl::less< mpl::O1_size<internal_types>, mpl::int_<SCHAR_MAX> > |
1195 | , signed char |
1196 | , int |
1197 | > |
1198 | >::type which_t; |
1199 | |
1200 | #endif // BOOST_VARIANT_MINIMIZE_SIZE switch |
1201 | |
1202 | // representation -- private when possible |
1203 | #if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) |
1204 | private: |
1205 | #else |
1206 | public: |
1207 | #endif |
1208 | |
1209 | which_t which_; |
1210 | storage_t storage_; |
1211 | |
1212 | void indicate_which(int which_arg) BOOST_NOEXCEPT |
1213 | { |
1214 | which_ = static_cast<which_t>( which_arg ); |
1215 | } |
1216 | |
1217 | void indicate_backup_which(int which_arg) BOOST_NOEXCEPT |
1218 | { |
1219 | which_ = static_cast<which_t>( -(which_arg + 1) ); |
1220 | } |
1221 | |
1222 | private: // helpers, for queries (below) |
1223 | |
1224 | bool using_backup() const BOOST_NOEXCEPT |
1225 | { |
1226 | return which_ < 0; |
1227 | } |
1228 | |
1229 | public: // queries |
1230 | |
1231 | int which() const BOOST_NOEXCEPT |
1232 | { |
1233 | // If using heap backup... |
1234 | if (using_backup()) |
1235 | // ...then return adjusted which_: |
1236 | return -(which_ + 1); |
1237 | |
1238 | // Otherwise, return which_ directly: |
1239 | return which_; |
1240 | } |
1241 | |
1242 | private: // helpers, for structors (below) |
1243 | |
1244 | struct initializer |
1245 | : BOOST_VARIANT_AUX_INITIALIZER_T( |
1246 | recursive_enabled_types, recursive_enabled_T |
1247 | ) |
1248 | { |
1249 | }; |
1250 | |
1251 | void destroy_content() BOOST_NOEXCEPT |
1252 | { |
1253 | detail::variant::destroyer visitor; |
1254 | this->internal_apply_visitor(visitor); |
1255 | } |
1256 | |
1257 | public: // structors |
1258 | |
1259 | ~variant() BOOST_NOEXCEPT |
1260 | { |
1261 | destroy_content(); |
1262 | } |
1263 | |
1264 | variant() |
1265 | #if !(defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x5130)) |
1266 | BOOST_NOEXCEPT_IF(boost::has_nothrow_constructor<internal_T0>::value) |
1267 | #endif |
1268 | { |
1269 | #ifdef _MSC_VER |
1270 | #pragma warning( push ) |
1271 | // behavior change: an object of POD type constructed with an initializer of the form () will be default-initialized |
1272 | #pragma warning( disable : 4345 ) |
1273 | #endif |
1274 | // NOTE TO USER : |
1275 | // Compile error from here indicates that the first bound |
1276 | // type is not default-constructible, and so variant cannot |
1277 | // support its own default-construction. |
1278 | // |
1279 | new( storage_.address() ) internal_T0(); |
1280 | indicate_which(which_arg: 0); // zero is the index of the first bounded type |
1281 | #ifdef _MSC_VER |
1282 | #pragma warning( pop ) |
1283 | #endif |
1284 | } |
1285 | |
1286 | private: // helpers, for structors, cont. (below) |
1287 | |
1288 | class convert_copy_into |
1289 | : public static_visitor<int> |
1290 | { |
1291 | private: // representation |
1292 | |
1293 | void* storage_; |
1294 | |
1295 | public: // structors |
1296 | |
1297 | explicit convert_copy_into(void* storage) BOOST_NOEXCEPT |
1298 | : storage_(storage) |
1299 | { |
1300 | } |
1301 | |
1302 | public: // internal visitor interfaces (below) |
1303 | |
1304 | template <typename T> |
1305 | int internal_visit(T& operand, int) const |
1306 | { |
1307 | // NOTE TO USER : |
1308 | // Compile error here indicates one of the source variant's types |
1309 | // cannot be unambiguously converted to the destination variant's |
1310 | // types (or that no conversion exists). |
1311 | // |
1312 | return initializer::initialize(storage_, operand); |
1313 | } |
1314 | |
1315 | # if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0564)) |
1316 | template <typename T> |
1317 | result_type internal_visit(const T& operand, int) const |
1318 | { |
1319 | return initializer::initialize(storage_, operand); |
1320 | } |
1321 | # endif |
1322 | |
1323 | template <typename T> |
1324 | int internal_visit(boost::detail::reference_content<T>& operand, long) const |
1325 | { |
1326 | return internal_visit( operand.get(), 1L ); |
1327 | } |
1328 | |
1329 | template <typename T> |
1330 | int internal_visit(const boost::detail::reference_content<T>& operand, long) const |
1331 | { |
1332 | return internal_visit( operand.get(), 1L ); |
1333 | } |
1334 | |
1335 | template <typename T> |
1336 | int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const |
1337 | { |
1338 | return internal_visit( operand.get(), 1L ); |
1339 | } |
1340 | |
1341 | template <typename T> |
1342 | int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const |
1343 | { |
1344 | return internal_visit( operand.get(), 1L ); |
1345 | } |
1346 | |
1347 | template <typename T> |
1348 | int internal_visit(boost::recursive_wrapper<T>& operand, long) const |
1349 | { |
1350 | return internal_visit( operand.get(), 1L ); |
1351 | } |
1352 | |
1353 | template <typename T> |
1354 | int internal_visit(const boost::recursive_wrapper<T>& operand, long) const |
1355 | { |
1356 | return internal_visit( operand.get(), 1L ); |
1357 | } |
1358 | |
1359 | }; |
1360 | |
1361 | friend class convert_copy_into; |
1362 | |
1363 | class convert_move_into |
1364 | : public static_visitor<int> |
1365 | { |
1366 | private: // representation |
1367 | |
1368 | void* storage_; |
1369 | |
1370 | public: // structors |
1371 | |
1372 | explicit convert_move_into(void* storage) BOOST_NOEXCEPT |
1373 | : storage_(storage) |
1374 | { |
1375 | } |
1376 | |
1377 | public: // internal visitor interfaces (below) |
1378 | |
1379 | template <typename T> |
1380 | int internal_visit(T& operand, int) const |
1381 | { |
1382 | // NOTE TO USER : |
1383 | // Compile error here indicates one of the source variant's types |
1384 | // cannot be unambiguously converted to the destination variant's |
1385 | // types (or that no conversion exists). |
1386 | // |
1387 | return initializer::initialize(storage_, detail::variant::move(operand) ); |
1388 | } |
1389 | |
1390 | template <typename T> |
1391 | int internal_visit(boost::detail::reference_content<T>& operand, long) const |
1392 | { |
1393 | return internal_visit( operand.get(), 1L ); |
1394 | } |
1395 | |
1396 | template <typename T> |
1397 | int internal_visit(const boost::detail::reference_content<T>& operand, long) const |
1398 | { |
1399 | return internal_visit( operand.get(), 1L ); |
1400 | } |
1401 | |
1402 | template <typename T> |
1403 | int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const |
1404 | { |
1405 | return internal_visit( operand.get(), 1L ); |
1406 | } |
1407 | |
1408 | template <typename T> |
1409 | int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const |
1410 | { |
1411 | return internal_visit( operand.get(), 1L ); |
1412 | } |
1413 | |
1414 | template <typename T> |
1415 | int internal_visit(boost::recursive_wrapper<T>& operand, long) const |
1416 | { |
1417 | return internal_visit( operand.get(), 1L ); |
1418 | } |
1419 | |
1420 | template <typename T> |
1421 | int internal_visit(const boost::recursive_wrapper<T>& operand, long) const |
1422 | { |
1423 | return internal_visit( operand.get(), 1L ); |
1424 | } |
1425 | }; |
1426 | |
1427 | friend class convert_move_into; |
1428 | |
1429 | private: // helpers, for structors, below |
1430 | |
1431 | template <typename T> |
1432 | void convert_construct( |
1433 | T& operand |
1434 | , int |
1435 | , mpl::false_ = mpl::false_() // is_foreign_variant |
1436 | ) |
1437 | { |
1438 | // NOTE TO USER : |
1439 | // Compile error here indicates that the given type is not |
1440 | // unambiguously convertible to one of the variant's types |
1441 | // (or that no conversion exists). |
1442 | // |
1443 | indicate_which( |
1444 | which_arg: initializer::initialize( |
1445 | storage_.address() |
1446 | , operand |
1447 | ) |
1448 | ); |
1449 | } |
1450 | |
1451 | template <typename T> |
1452 | typename boost::enable_if<boost::is_rvalue_reference<T&&> >::type convert_construct( |
1453 | T&& operand |
1454 | , int |
1455 | , mpl::false_ = mpl::false_() // is_foreign_variant |
1456 | ) |
1457 | { |
1458 | // NOTE TO USER : |
1459 | // Compile error here indicates that the given type is not |
1460 | // unambiguously convertible to one of the variant's types |
1461 | // (or that no conversion exists). |
1462 | // |
1463 | indicate_which( |
1464 | which_arg: initializer::initialize( |
1465 | storage_.address() |
1466 | , detail::variant::move(operand) |
1467 | ) |
1468 | ); |
1469 | } |
1470 | |
1471 | template <typename Variant> |
1472 | void convert_construct( |
1473 | Variant& operand |
1474 | , long |
1475 | , mpl::true_// is_foreign_variant |
1476 | ) |
1477 | { |
1478 | convert_copy_into visitor(storage_.address()); |
1479 | indicate_which( |
1480 | which_arg: operand.internal_apply_visitor(visitor) |
1481 | ); |
1482 | } |
1483 | |
1484 | template <typename Variant> |
1485 | typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct( |
1486 | Variant&& operand |
1487 | , long |
1488 | , mpl::true_// is_foreign_variant |
1489 | ) |
1490 | { |
1491 | convert_move_into visitor(storage_.address()); |
1492 | indicate_which( |
1493 | which_arg: operand.internal_apply_visitor(visitor) |
1494 | ); |
1495 | } |
1496 | |
1497 | template <typename Variant> |
1498 | void convert_construct_variant(Variant& operand) |
1499 | { |
1500 | // [Determine if the given variant is itself a bounded type, or if its |
1501 | // content needs to be converted (i.e., it is a 'foreign' variant):] |
1502 | // |
1503 | |
1504 | typedef typename mpl::find_if< |
1505 | types |
1506 | , is_same< |
1507 | add_const<mpl::_1> |
1508 | , const Variant |
1509 | > |
1510 | >::type found_it; |
1511 | |
1512 | typedef typename mpl::end<types>::type not_found; |
1513 | typedef typename is_same< |
1514 | found_it, not_found |
1515 | >::type is_foreign_variant; |
1516 | |
1517 | // Convert construct from operand: |
1518 | convert_construct( |
1519 | operand, 1L |
1520 | , is_foreign_variant() |
1521 | ); |
1522 | } |
1523 | |
1524 | template <typename Variant> |
1525 | typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct_variant(Variant&& operand) |
1526 | { |
1527 | // [Determine if the given variant is itself a bounded type, or if its |
1528 | // content needs to be converted (i.e., it is a 'foreign' variant):] |
1529 | // |
1530 | |
1531 | typedef typename mpl::find_if< |
1532 | types |
1533 | , is_same< |
1534 | add_const<mpl::_1> |
1535 | , const Variant |
1536 | > |
1537 | >::type found_it; |
1538 | |
1539 | typedef typename mpl::end<types>::type not_found; |
1540 | typedef typename is_same< |
1541 | found_it, not_found |
1542 | >::type is_foreign_variant; |
1543 | |
1544 | // Convert move construct from operand: |
1545 | convert_construct( |
1546 | detail::variant::move(operand), 1L |
1547 | , is_foreign_variant() |
1548 | ); |
1549 | } |
1550 | |
1551 | template <BOOST_VARIANT_ENUM_PARAMS(typename U)> |
1552 | typename boost::enable_if<mpl::or_< |
1553 | boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>, |
1554 | boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types> |
1555 | > >::type convert_construct( |
1556 | boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand |
1557 | , long |
1558 | ) |
1559 | { |
1560 | convert_construct_variant(operand); |
1561 | } |
1562 | |
1563 | template <BOOST_VARIANT_ENUM_PARAMS(typename U)> |
1564 | typename boost::enable_if<mpl::or_< |
1565 | boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>, |
1566 | boost::detail::variant::is_variant_constructible_from<const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types> |
1567 | > >::type convert_construct( |
1568 | const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand |
1569 | , long |
1570 | ) |
1571 | { |
1572 | convert_construct_variant(operand); |
1573 | } |
1574 | |
1575 | template <BOOST_VARIANT_ENUM_PARAMS(typename U)> |
1576 | typename boost::enable_if<mpl::or_< |
1577 | boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>, |
1578 | boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&&, internal_types> |
1579 | > >::type convert_construct( |
1580 | boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&& operand |
1581 | , long |
1582 | ) |
1583 | { |
1584 | convert_construct_variant( detail::variant::move(operand) ); |
1585 | } |
1586 | |
1587 | public: // structors, cont. |
1588 | |
1589 | template <typename T> |
1590 | variant(const T& operand, |
1591 | typename boost::enable_if<mpl::or_< |
1592 | mpl::and_< |
1593 | mpl::not_< boost::is_same<T, variant> >, |
1594 | boost::detail::variant::is_variant_constructible_from<const T&, internal_types> |
1595 | >, |
1596 | boost::is_same<T, boost::recursive_variant_> >, |
1597 | bool >::type = true) |
1598 | { |
1599 | convert_construct(operand, 1L); |
1600 | } |
1601 | |
1602 | template <typename T> |
1603 | variant( |
1604 | T& operand |
1605 | , typename boost::enable_if<mpl::or_< |
1606 | mpl::and_< |
1607 | mpl::not_< is_const<T> >, |
1608 | mpl::not_< boost::is_same<T, variant> >, |
1609 | boost::detail::variant::is_variant_constructible_from<T&, internal_types> |
1610 | >, |
1611 | boost::is_same<T, boost::recursive_variant_> >, |
1612 | bool >::type = true |
1613 | ) |
1614 | { |
1615 | convert_construct(operand, 1L); |
1616 | } |
1617 | |
1618 | template <class T> |
1619 | variant(T&& operand, |
1620 | typename boost::enable_if<mpl::or_< |
1621 | mpl::and_< |
1622 | boost::is_rvalue_reference<T&&>, |
1623 | mpl::not_< boost::is_const<T> >, |
1624 | mpl::not_< boost::is_same<T, variant> >, |
1625 | boost::detail::variant::is_variant_constructible_from<T&&, internal_types> |
1626 | >, |
1627 | boost::is_same<T, boost::recursive_variant_> >, |
1628 | bool >::type = true) |
1629 | { |
1630 | convert_construct( detail::variant::move(operand), 1L); |
1631 | } |
1632 | |
1633 | public: // structors, cont. |
1634 | |
1635 | // [MSVC6 requires copy constructor appear after template constructors] |
1636 | variant(const variant& operand) |
1637 | { |
1638 | // Copy the value of operand into *this... |
1639 | detail::variant::copy_into visitor( storage_.address() ); |
1640 | operand.internal_apply_visitor(visitor); |
1641 | |
1642 | // ...and activate the *this's primary storage on success: |
1643 | indicate_which(which_arg: operand.which()); |
1644 | } |
1645 | |
1646 | variant(variant&& operand) BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value) |
1647 | { |
1648 | // Move the value of operand into *this... |
1649 | detail::variant::move_into visitor( storage_.address() ); |
1650 | operand.internal_apply_visitor(visitor); |
1651 | |
1652 | // ...and activate the *this's primary storage on success: |
1653 | indicate_which(which_arg: operand.which()); |
1654 | } |
1655 | |
1656 | private: // helpers, for modifiers (below) |
1657 | |
1658 | template <typename Variant> |
1659 | friend class detail::variant::backup_assigner; |
1660 | |
1661 | // class assigner |
1662 | // |
1663 | // Internal visitor that "assigns" the visited value to the given variant |
1664 | // by appropriate destruction and copy-construction. |
1665 | // |
1666 | |
1667 | class assigner |
1668 | : public static_visitor<> |
1669 | { |
1670 | protected: // representation |
1671 | |
1672 | variant& lhs_; |
1673 | const int rhs_which_; |
1674 | |
1675 | public: // structors |
1676 | |
1677 | assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT |
1678 | : lhs_(lhs) |
1679 | , rhs_which_(rhs_which) |
1680 | { |
1681 | } |
1682 | |
1683 | protected: // helpers, for internal visitor interface (below) |
1684 | |
1685 | template <typename RhsT, typename B1, typename B2> |
1686 | void assign_impl( |
1687 | const RhsT& rhs_content |
1688 | , mpl::true_ // has_nothrow_copy |
1689 | , B1 // is_nothrow_move_constructible |
1690 | , B2 // has_fallback_type |
1691 | ) const BOOST_NOEXCEPT |
1692 | { |
1693 | // Destroy lhs's content... |
1694 | lhs_.destroy_content(); // nothrow |
1695 | |
1696 | // ...copy rhs content into lhs's storage... |
1697 | new(lhs_.storage_.address()) |
1698 | RhsT( rhs_content ); // nothrow |
1699 | |
1700 | // ...and indicate new content type: |
1701 | lhs_.indicate_which(rhs_which_); // nothrow |
1702 | } |
1703 | |
1704 | template <typename RhsT, typename B> |
1705 | void assign_impl( |
1706 | const RhsT& rhs_content |
1707 | , mpl::false_ // has_nothrow_copy |
1708 | , mpl::true_ // is_nothrow_move_constructible |
1709 | , B // has_fallback_type |
1710 | ) const |
1711 | { |
1712 | // Attempt to make a temporary copy (so as to move it below)... |
1713 | RhsT temp(rhs_content); |
1714 | |
1715 | // ...and upon success destroy lhs's content... |
1716 | lhs_.destroy_content(); // nothrow |
1717 | |
1718 | // ...move the temporary copy into lhs's storage... |
1719 | new(lhs_.storage_.address()) |
1720 | RhsT( detail::variant::move(temp) ); // nothrow |
1721 | |
1722 | // ...and indicate new content type: |
1723 | lhs_.indicate_which(rhs_which_); // nothrow |
1724 | } |
1725 | |
1726 | void construct_fallback() const BOOST_NOEXCEPT { |
1727 | // In case of failure, default-construct fallback type in lhs's storage... |
1728 | new (lhs_.storage_.address()) |
1729 | fallback_type_; // nothrow |
1730 | |
1731 | // ...indicate construction of fallback type... |
1732 | lhs_.indicate_which( |
1733 | BOOST_MPL_AUX_VALUE_WKND(fallback_type_index_)::value |
1734 | ); // nothrow |
1735 | } |
1736 | |
1737 | template <typename RhsT> |
1738 | void assign_impl( |
1739 | const RhsT& rhs_content |
1740 | , mpl::false_ // has_nothrow_copy |
1741 | , mpl::false_ // is_nothrow_move_constructible |
1742 | , mpl::true_ // has_fallback_type |
1743 | ) const |
1744 | { |
1745 | // Destroy lhs's content... |
1746 | lhs_.destroy_content(); // nothrow |
1747 | |
1748 | BOOST_TRY |
1749 | { |
1750 | // ...and attempt to copy rhs's content into lhs's storage: |
1751 | new(lhs_.storage_.address()) |
1752 | RhsT( rhs_content ); |
1753 | } |
1754 | BOOST_CATCH (...) |
1755 | { |
1756 | construct_fallback(); |
1757 | |
1758 | // ...and rethrow: |
1759 | BOOST_RETHROW; |
1760 | } |
1761 | BOOST_CATCH_END |
1762 | |
1763 | // In the event of success, indicate new content type: |
1764 | lhs_.indicate_which(rhs_which_); // nothrow |
1765 | } |
1766 | |
1767 | template <typename RhsT> |
1768 | void assign_impl( |
1769 | const RhsT& rhs_content |
1770 | , mpl::false_ // has_nothrow_copy |
1771 | , mpl::false_ // is_nothrow_move_constructible |
1772 | , mpl::false_ // has_fallback_type |
1773 | ) const |
1774 | { |
1775 | detail::variant::backup_assigner<wknd_self_t> |
1776 | visitor(lhs_, rhs_which_, rhs_content); |
1777 | lhs_.internal_apply_visitor(visitor); |
1778 | } |
1779 | |
1780 | public: // internal visitor interfaces |
1781 | |
1782 | template <typename RhsT> |
1783 | void internal_visit(const RhsT& rhs_content, int) const |
1784 | { |
1785 | typedef typename has_nothrow_copy<RhsT>::type |
1786 | nothrow_copy; |
1787 | typedef typename mpl::or_< // reduces compile-time |
1788 | nothrow_copy |
1789 | , is_nothrow_move_constructible<RhsT> |
1790 | >::type nothrow_move_constructor; |
1791 | |
1792 | assign_impl( |
1793 | rhs_content |
1794 | , nothrow_copy() |
1795 | , nothrow_move_constructor() |
1796 | , has_fallback_type_() |
1797 | ); |
1798 | } |
1799 | |
1800 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
1801 | private: |
1802 | // silence MSVC warning C4512: assignment operator could not be generated |
1803 | assigner& operator= (assigner const&); |
1804 | #endif |
1805 | }; |
1806 | |
1807 | friend class assigner; |
1808 | |
1809 | // class move_assigner |
1810 | // |
1811 | // Internal visitor that "move assigns" the visited value to the given variant |
1812 | // by appropriate destruction and move-construction. |
1813 | // |
1814 | |
1815 | class move_assigner |
1816 | : public assigner |
1817 | { |
1818 | public: // structors |
1819 | |
1820 | move_assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT |
1821 | : assigner(lhs, rhs_which) |
1822 | { |
1823 | } |
1824 | |
1825 | private: // helpers, for internal visitor interface (below) |
1826 | |
1827 | template <typename RhsT, typename B2> |
1828 | void assign_impl( |
1829 | RhsT& rhs_content |
1830 | , mpl::true_ // has_nothrow_copy |
1831 | , mpl::false_ // is_nothrow_move_constructible |
1832 | , B2 // has_fallback_type |
1833 | ) const BOOST_NOEXCEPT |
1834 | { |
1835 | assigner::assign_impl(rhs_content, mpl::true_(), mpl::false_(), B2()); |
1836 | } |
1837 | |
1838 | template <typename RhsT, typename B, typename B2> |
1839 | void assign_impl( |
1840 | RhsT& rhs_content |
1841 | , B // has_nothrow_copy |
1842 | , mpl::true_ // is_nothrow_move_constructible |
1843 | , B2 // has_fallback_type |
1844 | ) const BOOST_NOEXCEPT |
1845 | { |
1846 | // ...destroy lhs's content... |
1847 | assigner::lhs_.destroy_content(); // nothrow |
1848 | |
1849 | // ...move the rhs_content into lhs's storage... |
1850 | new(assigner::lhs_.storage_.address()) |
1851 | RhsT( detail::variant::move(rhs_content) ); // nothrow |
1852 | |
1853 | // ...and indicate new content type: |
1854 | assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow |
1855 | } |
1856 | |
1857 | template <typename RhsT> |
1858 | void assign_impl( |
1859 | RhsT& rhs_content |
1860 | , mpl::false_ // has_nothrow_copy |
1861 | , mpl::false_ // is_nothrow_move_constructible |
1862 | , mpl::true_ // has_fallback_type |
1863 | ) const |
1864 | { |
1865 | // Destroy lhs's content... |
1866 | assigner::lhs_.destroy_content(); // nothrow |
1867 | |
1868 | BOOST_TRY |
1869 | { |
1870 | // ...and attempt to copy rhs's content into lhs's storage: |
1871 | new(assigner::lhs_.storage_.address()) |
1872 | RhsT( detail::variant::move(rhs_content) ); |
1873 | } |
1874 | BOOST_CATCH (...) |
1875 | { |
1876 | assigner::construct_fallback(); |
1877 | |
1878 | // ...and rethrow: |
1879 | BOOST_RETHROW; |
1880 | } |
1881 | BOOST_CATCH_END |
1882 | |
1883 | // In the event of success, indicate new content type: |
1884 | assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow |
1885 | } |
1886 | |
1887 | template <typename RhsT> |
1888 | void assign_impl( |
1889 | RhsT& rhs_content |
1890 | , mpl::false_ // has_nothrow_copy |
1891 | , mpl::false_ // is_nothrow_move_constructible |
1892 | , mpl::false_ // has_fallback_type |
1893 | ) const |
1894 | { |
1895 | assigner::assign_impl(rhs_content, mpl::false_(), mpl::false_(), mpl::false_()); |
1896 | } |
1897 | |
1898 | public: // internal visitor interfaces |
1899 | |
1900 | template <typename RhsT> |
1901 | void internal_visit(RhsT& rhs_content, int) const |
1902 | { |
1903 | typedef typename is_nothrow_move_constructible<RhsT>::type |
1904 | nothrow_move_constructor; |
1905 | typedef typename mpl::or_< // reduces compile-time |
1906 | nothrow_move_constructor |
1907 | , has_nothrow_copy<RhsT> |
1908 | >::type nothrow_copy; |
1909 | |
1910 | assign_impl( |
1911 | rhs_content |
1912 | , nothrow_copy() |
1913 | , nothrow_move_constructor() |
1914 | , has_fallback_type_() |
1915 | ); |
1916 | } |
1917 | |
1918 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600)) |
1919 | private: |
1920 | // silence MSVC warning C4512: assignment operator could not be generated |
1921 | move_assigner& operator= (move_assigner const&); |
1922 | #endif |
1923 | }; |
1924 | |
1925 | friend class move_assigner; |
1926 | |
1927 | void variant_assign(const variant& rhs) |
1928 | { |
1929 | // If the contained types are EXACTLY the same... |
1930 | if (which_ == rhs.which_) |
1931 | { |
1932 | // ...then assign rhs's storage to lhs's content: |
1933 | detail::variant::assign_storage visitor(rhs.storage_.address()); |
1934 | this->internal_apply_visitor(visitor); |
1935 | } |
1936 | else |
1937 | { |
1938 | // Otherwise, perform general (copy-based) variant assignment: |
1939 | assigner visitor(*this, rhs.which()); |
1940 | rhs.internal_apply_visitor(visitor); |
1941 | } |
1942 | } |
1943 | |
1944 | void variant_assign(variant&& rhs) |
1945 | { |
1946 | // If the contained types are EXACTLY the same... |
1947 | if (which_ == rhs.which_) |
1948 | { |
1949 | // ...then move rhs's storage to lhs's content: |
1950 | detail::variant::move_storage visitor(rhs.storage_.address()); |
1951 | this->internal_apply_visitor(visitor); |
1952 | } |
1953 | else |
1954 | { |
1955 | // Otherwise, perform general (move-based) variant assignment: |
1956 | move_assigner visitor(*this, rhs.which()); |
1957 | rhs.internal_apply_visitor(visitor); |
1958 | } |
1959 | } |
1960 | |
1961 | private: // helpers, for modifiers (below) |
1962 | |
1963 | template <typename T> |
1964 | void assign(const T& rhs) |
1965 | { |
1966 | // If direct T-to-T assignment is not possible... |
1967 | detail::variant::direct_assigner<T> direct_assign(rhs); |
1968 | if (this->apply_visitor(direct_assign) == false) |
1969 | { |
1970 | // ...then convert rhs to variant and assign: |
1971 | // |
1972 | // While potentially inefficient, the following construction of a |
1973 | // variant allows T as any type convertible to one of the bounded |
1974 | // types without excessive code redundancy. |
1975 | // |
1976 | variant temp(rhs); |
1977 | variant_assign( detail::variant::move(temp) ); |
1978 | } |
1979 | } |
1980 | |
1981 | template <typename T> |
1982 | void move_assign(T&& rhs) |
1983 | { |
1984 | // If direct T-to-T move assignment is not possible... |
1985 | detail::variant::direct_mover<T> direct_move(rhs); |
1986 | if (this->apply_visitor(direct_move) == false) |
1987 | { |
1988 | // ...then convert rhs to variant and assign: |
1989 | // |
1990 | // While potentially inefficient, the following construction of a |
1991 | // variant allows T as any type convertible to one of the bounded |
1992 | // types without excessive code redundancy. |
1993 | // |
1994 | variant temp( detail::variant::move(rhs) ); |
1995 | variant_assign( detail::variant::move(temp) ); |
1996 | } |
1997 | } |
1998 | |
1999 | public: // modifiers |
2000 | |
2001 | #if !BOOST_WORKAROUND(BOOST_CLANG_VERSION, BOOST_TESTED_AT(150000)) || BOOST_CXX_VERSION <= 202002L |
2002 | template <class T> |
2003 | typename boost::enable_if< |
2004 | boost::mpl::and_< |
2005 | boost::is_rvalue_reference<T&&>, |
2006 | mpl::not_< boost::is_const<T> >, |
2007 | boost::detail::variant::is_variant_constructible_from<T&&, internal_types> |
2008 | >, |
2009 | variant& |
2010 | >::type operator=(T&& rhs) |
2011 | { |
2012 | move_assign( detail::variant::move(rhs) ); |
2013 | return *this; |
2014 | } |
2015 | #endif |
2016 | |
2017 | template <typename T> |
2018 | typename boost::enable_if< |
2019 | mpl::or_< |
2020 | boost::is_same<T, variant>, |
2021 | boost::detail::variant::is_variant_constructible_from<const T&, internal_types> |
2022 | >, |
2023 | variant& |
2024 | >::type operator=(const T& rhs) |
2025 | { |
2026 | assign(rhs); |
2027 | return *this; |
2028 | } |
2029 | |
2030 | // [MSVC6 requires copy assign appear after templated operator=] |
2031 | variant& operator=(const variant& rhs) |
2032 | { |
2033 | variant_assign(rhs); |
2034 | return *this; |
2035 | } |
2036 | |
2037 | variant& operator=(variant&& rhs) |
2038 | #if !defined(__GNUC__) || (__GNUC__ != 4) || (__GNUC_MINOR__ > 6) || defined(__clang__) |
2039 | BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value && variant_move_noexcept_assignable::type::value) |
2040 | #endif |
2041 | { |
2042 | variant_assign( detail::variant::move(rhs) ); |
2043 | return *this; |
2044 | } |
2045 | |
2046 | void swap(variant& rhs) |
2047 | { |
2048 | // If the contained types are the same... |
2049 | if (which() == rhs.which()) |
2050 | { |
2051 | // ...then swap the values directly: |
2052 | detail::variant::swap_with<variant> visitor(rhs); |
2053 | this->apply_visitor(visitor); |
2054 | } |
2055 | else |
2056 | { |
2057 | // ...otherwise, perform general variant swap: |
2058 | variant tmp( detail::variant::move(rhs) ); |
2059 | rhs = detail::variant::move(*this); |
2060 | *this = detail::variant::move(tmp); |
2061 | } |
2062 | } |
2063 | |
2064 | public: // queries |
2065 | |
2066 | // |
2067 | // NOTE: member which() defined above. |
2068 | // |
2069 | |
2070 | bool empty() const BOOST_NOEXCEPT |
2071 | { |
2072 | return false; |
2073 | } |
2074 | |
2075 | const boost::typeindex::type_info& type() const |
2076 | { |
2077 | detail::variant::reflect visitor; |
2078 | return this->apply_visitor(visitor); |
2079 | } |
2080 | |
2081 | public: // prevent comparison with foreign types |
2082 | |
2083 | template <typename U> |
2084 | void operator==(const U&) const |
2085 | { |
2086 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2087 | } |
2088 | |
2089 | template <typename U> |
2090 | void operator<(const U&) const |
2091 | { |
2092 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2093 | } |
2094 | |
2095 | template <typename U> |
2096 | void operator!=(const U&) const |
2097 | { |
2098 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2099 | } |
2100 | |
2101 | template <typename U> |
2102 | void operator>(const U&) const |
2103 | { |
2104 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2105 | } |
2106 | |
2107 | template <typename U> |
2108 | void operator<=(const U&) const |
2109 | { |
2110 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2111 | } |
2112 | |
2113 | template <typename U> |
2114 | void operator>=(const U&) const |
2115 | { |
2116 | BOOST_STATIC_ASSERT( false && sizeof(U) ); |
2117 | } |
2118 | |
2119 | public: // comparison operators |
2120 | |
2121 | // [MSVC6 requires these operators appear after template operators] |
2122 | |
2123 | bool operator==(const variant& rhs) const |
2124 | { |
2125 | if (this->which() != rhs.which()) |
2126 | return false; |
2127 | |
2128 | detail::variant::comparer< |
2129 | variant, detail::variant::equal_comp |
2130 | > visitor(*this); |
2131 | return rhs.apply_visitor(visitor); |
2132 | } |
2133 | |
2134 | bool operator<(const variant& rhs) const |
2135 | { |
2136 | // |
2137 | // Dirk Schreib suggested this collating order. |
2138 | // |
2139 | |
2140 | if (this->which() != rhs.which()) |
2141 | return this->which() < rhs.which(); |
2142 | |
2143 | detail::variant::comparer< |
2144 | variant, detail::variant::less_comp |
2145 | > visitor(*this); |
2146 | return rhs.apply_visitor(visitor); |
2147 | } |
2148 | |
2149 | /////////////////////////////////////////////////////////////////////////////// |
2150 | // comparison operators != > <= >= |
2151 | inline bool operator!=(const variant& rhs) const |
2152 | { |
2153 | return !(*this == rhs); |
2154 | } |
2155 | |
2156 | inline bool operator>(const variant& rhs) const |
2157 | { |
2158 | return rhs < *this; |
2159 | } |
2160 | |
2161 | inline bool operator<=(const variant& rhs) const |
2162 | { |
2163 | return !(*this > rhs); |
2164 | } |
2165 | |
2166 | inline bool operator>=(const variant& rhs) const |
2167 | { |
2168 | return !(*this < rhs); |
2169 | } |
2170 | |
2171 | // helpers, for visitation support (below) -- private when possible |
2172 | #if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) |
2173 | |
2174 | template < BOOST_VARIANT_ENUM_PARAMS(typename U) > |
2175 | friend class variant; |
2176 | |
2177 | private: |
2178 | |
2179 | #else// defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) |
2180 | |
2181 | public: |
2182 | |
2183 | #endif// !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) |
2184 | |
2185 | template <typename Visitor, typename VoidPtrCV> |
2186 | BOOST_FORCEINLINE static typename Visitor::result_type |
2187 | internal_apply_visitor_impl( |
2188 | int internal_which |
2189 | , int logical_which |
2190 | , Visitor& visitor |
2191 | , VoidPtrCV storage |
2192 | ) |
2193 | { |
2194 | typedef mpl::int_<0> first_which; |
2195 | typedef typename mpl::begin<internal_types>::type first_it; |
2196 | typedef typename mpl::end<internal_types>::type last_it; |
2197 | |
2198 | typedef detail::variant::visitation_impl_step< |
2199 | first_it, last_it |
2200 | > first_step; |
2201 | |
2202 | return detail::variant::visitation_impl( |
2203 | internal_which, logical_which |
2204 | , visitor, storage, mpl::false_() |
2205 | , never_uses_backup_flag() |
2206 | , static_cast<first_which*>(0), static_cast<first_step*>(0) |
2207 | ); |
2208 | } |
2209 | |
2210 | template <typename Visitor> |
2211 | BOOST_FORCEINLINE typename Visitor::result_type |
2212 | internal_apply_visitor(Visitor& visitor) |
2213 | { |
2214 | return internal_apply_visitor_impl( |
2215 | which_, which(), visitor, storage_.address() |
2216 | ); |
2217 | } |
2218 | |
2219 | template <typename Visitor> |
2220 | BOOST_FORCEINLINE typename Visitor::result_type |
2221 | internal_apply_visitor(Visitor& visitor) const |
2222 | { |
2223 | return internal_apply_visitor_impl( |
2224 | which_, which(), visitor, storage_.address() |
2225 | ); |
2226 | } |
2227 | |
2228 | public: // visitation support |
2229 | |
2230 | template <typename Visitor> |
2231 | typename Visitor::result_type |
2232 | apply_visitor(Visitor& visitor) && |
2233 | { |
2234 | detail::variant::invoke_visitor<Visitor, true> invoker(visitor); |
2235 | return this->internal_apply_visitor(invoker); |
2236 | } |
2237 | |
2238 | template <typename Visitor> |
2239 | typename Visitor::result_type |
2240 | apply_visitor(Visitor& visitor) const&& |
2241 | { |
2242 | detail::variant::invoke_visitor<Visitor, true> invoker(visitor); |
2243 | return this->internal_apply_visitor(invoker); |
2244 | } |
2245 | |
2246 | template <typename Visitor> |
2247 | typename Visitor::result_type |
2248 | apply_visitor(Visitor& visitor) & |
2249 | { |
2250 | detail::variant::invoke_visitor<Visitor, false> invoker(visitor); |
2251 | return this->internal_apply_visitor(invoker); |
2252 | } |
2253 | |
2254 | template <typename Visitor> |
2255 | typename Visitor::result_type |
2256 | apply_visitor(Visitor& visitor) const & |
2257 | { |
2258 | detail::variant::invoke_visitor<Visitor, false> invoker(visitor); |
2259 | return this->internal_apply_visitor(invoker); |
2260 | } |
2261 | |
2262 | }; // class variant |
2263 | |
2264 | /////////////////////////////////////////////////////////////////////////////// |
2265 | // metafunction make_variant_over |
2266 | // |
2267 | // See docs and boost/variant/variant_fwd.hpp for more information. |
2268 | // |
2269 | template <typename Types> |
2270 | struct make_variant_over |
2271 | { |
2272 | private: // precondition assertions |
2273 | |
2274 | BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value )); |
2275 | typedef typename boost::mpl::insert_range< |
2276 | boost::mpl::list<> |
2277 | , boost::mpl::end< boost::mpl::list<> >::type |
2278 | , Types |
2279 | >::type copied_sequence_t; |
2280 | |
2281 | public: // metafunction result |
2282 | |
2283 | typedef variant< |
2284 | detail::variant::over_sequence<copied_sequence_t> |
2285 | > type; |
2286 | |
2287 | }; |
2288 | |
2289 | /////////////////////////////////////////////////////////////////////////////// |
2290 | // function template swap |
2291 | // |
2292 | // Swaps two variants of the same type (i.e., identical specification). |
2293 | // |
2294 | template < BOOST_VARIANT_ENUM_PARAMS(typename T) > |
2295 | inline void swap( |
2296 | variant< BOOST_VARIANT_ENUM_PARAMS(T) >& lhs |
2297 | , variant< BOOST_VARIANT_ENUM_PARAMS(T) >& rhs |
2298 | ) |
2299 | { |
2300 | lhs.swap(rhs); |
2301 | } |
2302 | |
2303 | } // namespace boost |
2304 | |
2305 | // implementation additions |
2306 | |
2307 | #if !defined(BOOST_NO_IOSTREAM) |
2308 | #include <boost/variant/detail/variant_io.hpp> |
2309 | #endif // BOOST_NO_IOSTREAM |
2310 | |
2311 | #endif // BOOST_VARIANT_VARIANT_HPP |
2312 | |