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) 2012-2023 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/preprocessor/cat.hpp>
44#include <boost/preprocessor/repeat.hpp>
45#include <boost/type_traits/aligned_storage.hpp>
46#include <boost/type_traits/alignment_of.hpp>
47#include <boost/type_traits/add_const.hpp>
48#include <boost/type_traits/has_nothrow_constructor.hpp>
49#include <boost/type_traits/has_nothrow_copy.hpp>
50#include <boost/type_traits/is_nothrow_move_assignable.hpp>
51#include <boost/type_traits/is_nothrow_move_constructible.hpp>
52#include <boost/type_traits/is_const.hpp>
53#include <boost/type_traits/is_same.hpp>
54#include <boost/type_traits/is_rvalue_reference.hpp>
55#include <boost/type_traits/is_constructible.hpp>
56#include <boost/type_traits/add_lvalue_reference.hpp>
57#include <boost/type_traits/declval.hpp>
58#include <boost/core/no_exceptions_support.hpp>
59#include <boost/core/enable_if.hpp>
60#include <boost/variant/recursive_wrapper_fwd.hpp>
61#include <boost/variant/static_visitor.hpp>
62
63#include <boost/mpl/assert.hpp>
64#include <boost/mpl/begin_end.hpp>
65#include <boost/mpl/bool.hpp>
66#include <boost/mpl/deref.hpp>
67#include <boost/mpl/empty.hpp>
68#include <boost/mpl/eval_if.hpp>
69#include <boost/mpl/find_if.hpp>
70#include <boost/mpl/fold.hpp>
71#include <boost/mpl/front.hpp>
72#include <boost/mpl/identity.hpp>
73#include <boost/mpl/if.hpp>
74#include <boost/mpl/insert_range.hpp>
75#include <boost/mpl/int.hpp>
76#include <boost/mpl/is_sequence.hpp>
77#include <boost/mpl/iterator_range.hpp>
78#include <boost/mpl/iter_fold_if.hpp>
79#include <boost/mpl/list.hpp>
80#include <boost/mpl/logical.hpp>
81#include <boost/mpl/max_element.hpp>
82#include <boost/mpl/next.hpp>
83#include <boost/mpl/not.hpp>
84#include <boost/mpl/pair.hpp>
85#include <boost/mpl/protect.hpp>
86#include <boost/mpl/push_front.hpp>
87#include <boost/mpl/same_as.hpp>
88#include <boost/mpl/size_t.hpp>
89#include <boost/mpl/sizeof.hpp>
90#include <boost/mpl/transform.hpp>
91
92///////////////////////////////////////////////////////////////////////////////
93// Implementation Macros:
94//
95// BOOST_VARIANT_VISITATION_UNROLLING_LIMIT
96// Defined in boost/variant/detail/visitation_impl.hpp.
97//
98// BOOST_VARIANT_MINIMIZE_SIZE
99// When #defined, implementation employs all known means to minimize the
100// size of variant obje cts. However, often unsuccessful due to alignment
101// issues, and potentially harmful to runtime speed, so not enabled by
102// default. (TODO: Investigate further.)
103
104#if defined(BOOST_VARIANT_MINIMIZE_SIZE)
105# include <climits> // for SCHAR_MAX
106# include <boost/mpl/eval_if.hpp>
107# include <boost/mpl/equal_to.hpp>
108# include <boost/mpl/identity.hpp>
109# include <boost/mpl/int.hpp>
110# include <boost/mpl/if.hpp>
111# include <boost/mpl/less.hpp>
112# include <boost/mpl/long.hpp>
113# include <boost/mpl/O1_size.hpp>
114#endif
115
116
117namespace boost {
118
119namespace detail { namespace variant {
120
121///////////////////////////////////////////////////////////////////////////////
122// (detail) metafunction max_value
123//
124// Finds the maximum value of the unary metafunction F over Sequence.
125//
126template <typename Sequence, typename F>
127struct max_value
128{
129private: // helpers, for metafunction result (below)
130
131 typedef typename mpl::transform1<Sequence, F>::type transformed_;
132 typedef typename mpl::max_element<transformed_
133
134 >::type max_it;
135
136public: // metafunction result
137
138 typedef typename mpl::deref<max_it>::type
139 type;
140
141};
142
143struct add_alignment
144{
145 template <typename State, typename Item>
146 struct apply
147 : mpl::size_t<
148 ::boost::integer::static_lcm<
149 BOOST_MPL_AUX_VALUE_WKND(State)::value
150 , ::boost::alignment_of<Item>::value
151 >::value
152 >
153 {};
154};
155
156///////////////////////////////////////////////////////////////////////////////
157// (detail) metafunction find_fallback_type
158//
159// Provides a fallback (i.e., nothrow default-constructible) type from the
160// specified sequence, or no_fallback_type if not found.
161//
162// This implementation is designed to prefer boost::blank over other potential
163// fallback types, regardless of its position in the specified sequence.
164//
165
166class no_fallback_type;
167
168struct find_fallback_type_pred
169{
170 template <typename Iterator>
171 struct apply
172 {
173 private:
174 typedef typename mpl::deref<Iterator>::type t_;
175
176 public:
177 typedef mpl::not_< has_nothrow_constructor<t_> > type;
178 };
179};
180
181template <typename Types>
182struct find_fallback_type
183{
184private: // helpers, for metafunction result (below)
185
186 typedef typename mpl::end<Types>::type end_it;
187
188 // [Find the first suitable fallback type...]
189
190 typedef typename mpl::iter_fold_if<
191 Types
192 , mpl::int_<0>, mpl::protect< mpl::next<> >
193 , mpl::protect< find_fallback_type_pred >
194 >::type first_result_;
195
196 typedef typename first_result_::first first_result_index;
197 typedef typename first_result_::second first_result_it;
198
199 // [...now search the rest of the sequence for boost::blank...]
200
201 typedef typename mpl::iter_fold_if<
202 mpl::iterator_range< first_result_it,end_it >
203 , first_result_index, mpl::protect< mpl::next<> >
204 , mpl::protect< mpl::not_same_as<boost::blank> >
205 >::type second_result_;
206
207 typedef typename second_result_::second second_result_it;
208
209public: // metafunction result
210
211 // [...and return the results of the search:]
212 typedef typename mpl::eval_if<
213 is_same< second_result_it,end_it >
214 , mpl::if_<
215 is_same< first_result_it,end_it >
216 , mpl::pair< no_fallback_type,no_fallback_type >
217 , first_result_
218 >
219 , mpl::identity< second_result_ >
220 >::type type;
221
222};
223
224#ifndef BOOST_NO_CXX11_NOEXCEPT
225///////////////////////////////////////////////////////////////////////////////
226// (detail) metafunction is_variant_move_noexcept_constructible
227//
228// Returns true_type if all the types are nothrow move constructible.
229//
230template <class Types>
231struct is_variant_move_noexcept_constructible {
232 typedef typename boost::mpl::find_if<
233 Types, mpl::not_<boost::is_nothrow_move_constructible<boost::mpl::_1> >
234 >::type iterator_t;
235
236 typedef typename boost::mpl::end<Types>::type end_t;
237 typedef typename boost::is_same<
238 iterator_t, end_t
239 >::type type;
240};
241
242///////////////////////////////////////////////////////////////////////////////
243// (detail) metafunction is_variant_move_noexcept_assignable
244//
245// Returns true_type if all the types are nothrow move constructible.
246//
247template <class Types>
248struct is_variant_move_noexcept_assignable {
249 typedef typename boost::mpl::find_if<
250 Types, mpl::not_<boost::is_nothrow_move_assignable<boost::mpl::_1> >
251 >::type iterator_t;
252
253 typedef typename boost::mpl::end<Types>::type end_t;
254 typedef typename boost::is_same<
255 iterator_t, end_t
256 >::type type;
257};
258#endif // BOOST_NO_CXX11_NOEXCEPT
259
260///////////////////////////////////////////////////////////////////////////////
261// (detail) metafunction is_variant_constructible_from
262//
263// Derives from true_type if at least one variant's type is constructible from T.
264//
265template <class T1, class T2>
266struct is_constructible_ext:
267 boost::mpl::or_<
268 boost::is_constructible<
269 T1,
270 T2
271 >,
272 boost::is_constructible<
273 T1,
274 typename boost::add_lvalue_reference<T2>::type
275 >
276 >
277{};
278
279template <class T, class Types>
280struct is_variant_constructible_from:
281 boost::mpl::not_< boost::is_same<
282 typename boost::mpl::find_if<
283 Types,
284 is_constructible_ext<boost::mpl::_1, T>
285 >::type,
286 typename boost::mpl::end<Types>::type
287 > >
288{};
289
290template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
291struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >:
292 boost::is_same<
293 typename boost::mpl::find_if<
294 typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types,
295 mpl::not_< is_variant_constructible_from< boost::mpl::_1, Types> >
296 >::type,
297 typename boost::mpl::end< typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types >::type
298 >
299{};
300
301template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
302struct is_variant_constructible_from< const boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >:
303 is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
304{};
305
306template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
307struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >:
308 is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
309{};
310
311#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
312
313template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
314struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>&& , Types >:
315 is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
316{};
317
318template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
319struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const && , Types >:
320 is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
321{};
322
323#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCE
324
325
326///////////////////////////////////////////////////////////////////////////////
327// (detail) metafunction make_storage
328//
329// Provides an aligned storage type capable of holding any of the types
330// specified in the given type-sequence.
331//
332
333template <typename Types, typename NeverUsesBackupFlag>
334struct make_storage
335{
336private: // helpers, for metafunction result (below)
337
338 typedef typename mpl::eval_if<
339 NeverUsesBackupFlag
340 , mpl::identity< Types >
341 , mpl::push_front<
342 Types, backup_holder<void*>
343 >
344 >::type types;
345
346 typedef typename max_value<
347 types, mpl::sizeof_<mpl::_1>
348 >::type max_size;
349
350#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551))
351
352 typedef typename mpl::fold<
353 types
354 , mpl::size_t<1>
355 , add_alignment
356 >::type max_alignment;
357
358#else // borland
359
360 // temporary workaround -- use maximal alignment
361 typedef mpl::size_t< -1 > max_alignment;
362
363#endif // borland workaround
364
365public: // metafunction result
366
367 typedef ::boost::aligned_storage<
368 BOOST_MPL_AUX_VALUE_WKND(max_size)::value
369 , BOOST_MPL_AUX_VALUE_WKND(max_alignment)::value
370 > type;
371};
372
373///////////////////////////////////////////////////////////////////////////////
374// (detail) class destroyer
375//
376// Internal visitor that destroys the value it visits.
377//
378struct destroyer
379 : public static_visitor<>
380{
381public: // visitor interfaces
382
383 template <typename T>
384 void internal_visit(T& operand, int) const BOOST_NOEXCEPT
385 {
386 operand.~T(); // must be noexcept
387
388#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551)) || \
389 BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
390 (void)operand; // suppresses warnings
391#endif
392 }
393
394};
395
396///////////////////////////////////////////////////////////////////////////////
397// (detail) class template known_get
398//
399// Visitor that returns a reference to content of the specified type.
400//
401// Precondition: visited variant MUST contain logical content of type T.
402//
403template <typename T>
404class known_get
405 : public static_visitor<T&>
406{
407
408public: // visitor interface
409
410 T& operator()(T& operand) const BOOST_NOEXCEPT
411 {
412 return operand;
413 }
414
415 template <typename U>
416 T& operator()(U&) const
417 {
418 // logical error to be here: see precondition above
419 return ::boost::detail::variant::forced_return< T& >();
420 }
421};
422
423///////////////////////////////////////////////////////////////////////////////
424// (detail) class copy_into
425//
426// Internal visitor that copies the value it visits into the given buffer.
427//
428class copy_into
429 : public static_visitor<>
430{
431private: // representation
432
433 void* storage_;
434
435public: // structors
436
437 explicit copy_into(void* storage) BOOST_NOEXCEPT
438 : storage_(storage)
439 {
440 }
441
442public: // internal visitor interface
443
444 template <typename T>
445 void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
446 {
447 new(storage_) T( operand.get() );
448 }
449
450 template <typename T>
451 void internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
452 {
453 new(storage_) T( operand.get() );
454 }
455
456 template <typename T>
457 void internal_visit(const T& operand, int) const
458 {
459 new(storage_) T(operand);
460 }
461
462};
463
464///////////////////////////////////////////////////////////////////////////////
465// (detail) class move_into
466//
467// Internal visitor that moves the value it visits into the given buffer.
468//
469#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
470class move_into
471 : public static_visitor<>
472{
473private: // representation
474
475 void* storage_;
476
477public: // structors
478
479 explicit move_into(void* storage) BOOST_NOEXCEPT
480 : storage_(storage)
481 {
482 }
483
484public: // internal visitor interface
485
486 template <typename T>
487 void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
488 {
489 new(storage_) T( ::boost::detail::variant::move(operand.get()) );
490 }
491
492 template <typename T>
493 void internal_visit(T& operand, int) const BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(T(boost::declval<T>())))
494 {
495 new(storage_) T(::boost::detail::variant::move(operand));
496 }
497};
498#endif
499
500///////////////////////////////////////////////////////////////////////////////
501// (detail) class assign_storage
502//
503// Internal visitor that assigns the given storage (which must be a
504// constructed value of the same type) to the value it visits.
505//
506struct assign_storage
507 : public static_visitor<>
508{
509private: // representation
510
511 const void* rhs_storage_;
512
513public: // structors
514
515 explicit assign_storage(const void* rhs_storage) BOOST_NOEXCEPT
516 : rhs_storage_(rhs_storage)
517 {
518 }
519
520public: // internal visitor interfaces
521
522 template <typename T>
523 void internal_visit(backup_holder<T>& lhs_content, long) const
524 {
525 lhs_content.get()
526 = static_cast< const backup_holder<T>* >(rhs_storage_)->get();
527 }
528
529 template <typename T>
530 void internal_visit(const backup_holder<T>& lhs_content, long) const
531 {
532 lhs_content.get()
533 = static_cast< const backup_holder<T>* >(rhs_storage_)->get();
534 }
535
536 template <typename T>
537 void internal_visit(T& lhs_content, int) const
538 {
539 // NOTE TO USER :
540 // Compile error here indicates one of variant's bounded types does
541 // not meet the requirements of the Assignable concept. Thus,
542 // variant is not Assignable.
543 //
544 // Hint: Are any of the bounded types const-qualified or references?
545 //
546 lhs_content = *static_cast< const T* >(rhs_storage_);
547 }
548
549};
550
551///////////////////////////////////////////////////////////////////////////////
552// (detail) class move_storage
553//
554// Internal visitor that moves the given storage (which must be a
555// constructed value of the same type) to the value it visits.
556//
557struct move_storage
558 : public static_visitor<>
559{
560private: // representation
561
562 void* rhs_storage_;
563
564public: // structors
565
566 explicit move_storage(void* rhs_storage) BOOST_NOEXCEPT
567 : rhs_storage_(rhs_storage)
568 {
569 }
570
571public: // internal visitor interfaces
572
573 template <typename T>
574 void internal_visit(backup_holder<T>& lhs_content, long) const
575 {
576 lhs_content.get()
577 = ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get());
578 }
579
580 template <typename T>
581 void internal_visit(const backup_holder<T>& lhs_content, long) const
582 {
583 lhs_content.get()
584 = ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get());
585 }
586
587 template <typename T>
588 void internal_visit(T& lhs_content, int) const
589 {
590 // NOTE TO USER :
591 // Compile error here indicates one of variant's bounded types does
592 // not meet the requirements of the Assignable concept. Thus,
593 // variant is not Assignable.
594 //
595 // Hint: Are any of the bounded types const-qualified or references?
596 //
597 lhs_content = ::boost::detail::variant::move(*static_cast<T* >(rhs_storage_));
598 }
599
600};
601
602///////////////////////////////////////////////////////////////////////////////
603// (detail) class direct_assigner
604//
605// Generic static visitor that: if and only if the visited value is of the
606// specified type, assigns the given value to the visited value and returns
607// true; else returns false.
608//
609template <typename T>
610class direct_assigner
611 : public static_visitor<bool>
612{
613private: // representation
614
615 const T& rhs_;
616
617public: // structors
618
619 explicit direct_assigner(const T& rhs) BOOST_NOEXCEPT
620 : rhs_(rhs)
621 {
622 }
623
624public: // visitor interface
625
626 bool operator()(T& lhs)
627 {
628 lhs = rhs_;
629 return true;
630 }
631
632 template <typename U>
633 bool operator()(U&) BOOST_NOEXCEPT
634 {
635 return false;
636 }
637
638#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
639private:
640 // silence MSVC warning C4512: assignment operator could not be generated
641 direct_assigner& operator= (direct_assigner const&);
642#endif
643};
644
645///////////////////////////////////////////////////////////////////////////////
646// (detail) class direct_mover
647//
648// Generic static visitor that: if and only if the visited value is of the
649// specified type, move assigns the given value to the visited value and returns
650// true; else returns false.
651//
652template <typename T>
653class direct_mover
654 : public static_visitor<bool>
655{
656private: // representation
657
658 T& rhs_;
659
660public: // structors
661
662 explicit direct_mover(T& rhs) BOOST_NOEXCEPT
663 : rhs_(rhs)
664 {
665 }
666
667public: // visitor interface
668
669 bool operator()(T& lhs)
670 {
671 lhs = ::boost::detail::variant::move(rhs_);
672 return true;
673 }
674
675 template <typename U>
676 bool operator()(U&) BOOST_NOEXCEPT
677 {
678 return false;
679 }
680
681#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
682private:
683 // silence MSVC warning C4512: assignment operator could not be generated
684 direct_mover& operator= (direct_mover const&);
685#endif
686};
687
688
689///////////////////////////////////////////////////////////////////////////////
690// (detail) class backup_assigner
691//
692// Internal visitor that "assigns" the given value to the visited value,
693// using backup to recover if the destroy-copy sequence fails.
694//
695// NOTE: This needs to be a friend of variant, as it needs access to
696// indicate_which, indicate_backup_which, etc.
697//
698template <typename Variant>
699class backup_assigner
700 : public static_visitor<>
701{
702private: // representation
703
704 Variant& lhs_;
705 int rhs_which_;
706 const void* rhs_content_;
707 void (*copy_rhs_content_)(void*, const void*);
708
709public: // structors
710
711 template<class RhsT>
712 backup_assigner(Variant& lhs, int rhs_which, const RhsT& rhs_content)
713 : lhs_(lhs)
714 , rhs_which_(rhs_which)
715 , rhs_content_(&rhs_content)
716 , copy_rhs_content_(&construct_impl<RhsT>)
717 {
718 }
719
720private: // helpers, for visitor interface (below)
721
722 template<class RhsT>
723 static void construct_impl(void* addr, const void* obj)
724 {
725 new(addr) RhsT(*static_cast<const RhsT*>(obj));
726 }
727
728 template <typename LhsT>
729 void backup_assign_impl(
730 backup_holder<LhsT>& lhs_content
731 , mpl::false_ // is_nothrow_move_constructible
732 , long
733 )
734 {
735 // Move lhs content to backup...
736 backup_holder<LhsT> backup_lhs_content(0);
737 backup_lhs_content.swap(lhs_content); // nothrow
738
739 // ...destroy lhs content...
740 lhs_content.~backup_holder<LhsT>(); // nothrow
741
742 BOOST_TRY
743 {
744 // ...and attempt to copy rhs content into lhs storage:
745 copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
746 }
747 BOOST_CATCH (...)
748 {
749 // In case of failure, copy backup pointer to lhs storage...
750 new(lhs_.storage_.address())
751 backup_holder<LhsT>( 0 ); // nothrow
752
753 static_cast<backup_holder<LhsT>* >(lhs_.storage_.address())
754 ->swap(backup_lhs_content); // nothrow
755
756 // ...and rethrow:
757 BOOST_RETHROW;
758 }
759 BOOST_CATCH_END
760
761 // In case of success, indicate new content type:
762 lhs_.indicate_which(rhs_which_); // nothrow
763 }
764
765 template <typename LhsT>
766 void backup_assign_impl(
767 LhsT& lhs_content
768 , mpl::true_ // is_nothrow_move_constructible
769 , int
770 )
771 {
772 // Move lhs content to backup...
773 LhsT backup_lhs_content(
774 ::boost::detail::variant::move(lhs_content)
775 ); // nothrow
776
777 // ...destroy lhs content...
778 lhs_content.~LhsT(); // nothrow
779
780 BOOST_TRY
781 {
782 // ...and attempt to copy rhs content into lhs storage:
783 copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
784 }
785 BOOST_CATCH (...)
786 {
787 // In case of failure, restore backup content to lhs storage...
788 new(lhs_.storage_.address())
789 LhsT(
790 ::boost::detail::variant::move(backup_lhs_content)
791 ); // nothrow
792
793 // ...and rethrow:
794 BOOST_RETHROW;
795 }
796 BOOST_CATCH_END
797
798 // In case of success, indicate new content type:
799 lhs_.indicate_which(rhs_which_); // nothrow
800 }
801
802 template <typename LhsT>
803 void backup_assign_impl(
804 LhsT& lhs_content
805 , mpl::false_ // is_nothrow_move_constructible
806 , int
807 )
808 {
809 // Backup lhs content...
810 LhsT* backup_lhs_ptr = new LhsT(lhs_content);
811
812 // ...destroy lhs content...
813 lhs_content.~LhsT(); // nothrow
814
815 BOOST_TRY
816 {
817 // ...and attempt to copy rhs content into lhs storage:
818 copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
819 }
820 BOOST_CATCH (...)
821 {
822 // In case of failure, copy backup pointer to lhs storage...
823 new(lhs_.storage_.address())
824 backup_holder<LhsT>( backup_lhs_ptr ); // nothrow
825
826 // ...indicate now using backup...
827 lhs_.indicate_backup_which( lhs_.which() ); // nothrow
828
829 // ...and rethrow:
830 BOOST_RETHROW;
831 }
832 BOOST_CATCH_END
833
834 // In case of success, indicate new content type...
835 lhs_.indicate_which(rhs_which_); // nothrow
836
837 // ...and delete backup:
838 delete backup_lhs_ptr; // nothrow
839 }
840
841public: // visitor interface
842
843 template <typename LhsT>
844 void internal_visit(LhsT& lhs_content, int)
845 {
846 typedef typename is_nothrow_move_constructible<LhsT>::type
847 nothrow_move;
848
849 backup_assign_impl( lhs_content, nothrow_move(), 1L);
850 }
851
852#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
853private:
854 // silence MSVC warning C4512: assignment operator could not be generated
855 backup_assigner& operator= (backup_assigner const&);
856#endif
857};
858
859///////////////////////////////////////////////////////////////////////////////
860// (detail) class swap_with
861//
862// Visitor that swaps visited value with content of given variant.
863//
864// Precondition: Given variant MUST have same logical type as visited value.
865//
866template <typename Variant>
867struct swap_with
868 : public static_visitor<>
869{
870private: // representation
871
872 Variant& toswap_;
873
874public: // structors
875
876 explicit swap_with(Variant& toswap) BOOST_NOEXCEPT
877 : toswap_(toswap)
878 {
879 }
880
881public: // internal visitor interfaces
882
883 template <typename T>
884 void operator()(T& operand) const
885 {
886 // Since the precondition ensures types are same, get T...
887 known_get<T> getter;
888 T& other = toswap_.apply_visitor(getter);
889
890 // ...and swap:
891 ::boost::detail::variant::move_swap( operand, other );
892 }
893
894private:
895 swap_with& operator=(const swap_with&);
896
897};
898
899///////////////////////////////////////////////////////////////////////////////
900// (detail) class reflect
901//
902// Generic static visitor that performs a typeid on the value it visits.
903//
904
905class reflect
906 : public static_visitor<const boost::typeindex::type_info&>
907{
908public: // visitor interfaces
909
910 template <typename T>
911 const boost::typeindex::type_info& operator()(const T&) const BOOST_NOEXCEPT
912 {
913 return boost::typeindex::type_id<T>().type_info();
914 }
915
916};
917
918///////////////////////////////////////////////////////////////////////////////
919// (detail) class comparer
920//
921// Generic static visitor that compares the content of the given lhs variant
922// with the visited rhs content using Comp.
923//
924// Precondition: lhs.which() == rhs.which()
925//
926template <typename Variant, typename Comp>
927class comparer
928 : public static_visitor<bool>
929{
930private: // representation
931
932 const Variant& lhs_;
933
934public: // structors
935
936 explicit comparer(const Variant& lhs) BOOST_NOEXCEPT
937 : lhs_(lhs)
938 {
939 }
940
941public: // visitor interfaces
942
943 template <typename T>
944 bool operator()(T& rhs_content) const
945 {
946 // Since the precondition ensures lhs and rhs types are same, get T...
947 known_get<T> getter;
948 const T& lhs_content = lhs_.apply_visitor(getter);
949
950 // ...and compare lhs and rhs contents:
951 return Comp()(lhs_content, rhs_content);
952 }
953
954private:
955 comparer& operator=(const comparer&);
956
957};
958
959///////////////////////////////////////////////////////////////////////////////
960// (detail) class equal_comp
961//
962// Generic function object compares lhs with rhs using operator==.
963//
964struct equal_comp
965{
966 template <typename T>
967 bool operator()(const T& lhs, const T& rhs) const
968 {
969 return lhs == rhs;
970 }
971};
972
973///////////////////////////////////////////////////////////////////////////////
974// (detail) class less_comp
975//
976// Generic function object compares lhs with rhs using operator<.
977//
978struct less_comp
979{
980 template <typename T>
981 bool operator()(const T& lhs, const T& rhs) const
982 {
983 return lhs < rhs;
984 }
985};
986
987///////////////////////////////////////////////////////////////////////////////
988// (detail) class template invoke_visitor
989//
990// Internal visitor that invokes the given visitor using:
991// * for wrappers (e.g., recursive_wrapper), the wrapper's held value.
992// * for all other values, the value itself.
993//
994template <typename Visitor, bool MoveSemantics>
995class invoke_visitor
996{
997private: // representation
998
999 Visitor& visitor_;
1000
1001public: // visitor typedefs
1002
1003 typedef typename Visitor::result_type
1004 result_type;
1005
1006public: // structors
1007
1008 explicit invoke_visitor(Visitor& visitor) BOOST_NOEXCEPT
1009 : visitor_(visitor)
1010 {
1011 }
1012
1013public: // internal visitor interfaces
1014
1015#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1016
1017 //using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work
1018 template <typename T>
1019 typename enable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int)
1020 {
1021 return visitor_(::boost::move(operand));
1022 }
1023
1024 //using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work
1025 template <typename T>
1026 typename disable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int)
1027 {
1028 return visitor_(operand);
1029 }
1030
1031#else
1032
1033 template <typename T>
1034 result_type internal_visit(T& operand, int)
1035 {
1036 return visitor_(operand);
1037 }
1038
1039# if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0564))
1040 template <typename T>
1041 result_type internal_visit(const T& operand, int)
1042 {
1043 return visitor_(operand);
1044 }
1045# endif //BORLAND
1046
1047#endif //RVALUE REFERENCES
1048
1049public: // internal visitor interfaces, cont.
1050
1051 template <typename T>
1052 result_type internal_visit(boost::recursive_wrapper<T>& operand, long)
1053 {
1054 return internal_visit( operand.get(), 1L );
1055 }
1056
1057 template <typename T>
1058 result_type internal_visit(const boost::recursive_wrapper<T>& operand, long)
1059 {
1060 return internal_visit( operand.get(), 1L );
1061 }
1062
1063 template <typename T>
1064 result_type internal_visit(boost::detail::reference_content<T>& operand, long)
1065 {
1066 return internal_visit( operand.get(), 1L );
1067 }
1068
1069 template <typename T>
1070 result_type internal_visit(const boost::detail::reference_content<T>& operand, long)
1071 {
1072 return internal_visit( operand.get(), 1L );
1073 }
1074
1075 template <typename T>
1076 result_type internal_visit(boost::detail::variant::backup_holder<T>& operand, long)
1077 {
1078 return internal_visit( operand.get(), 1L );
1079 }
1080
1081 template <typename T>
1082 result_type internal_visit(const boost::detail::variant::backup_holder<T>& operand, long)
1083 {
1084 return internal_visit( operand.get(), 1L );
1085 }
1086
1087#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
1088private:
1089 // silence MSVC warning C4512: assignment operator could not be generated
1090 invoke_visitor& operator= (invoke_visitor const&);
1091#endif
1092};
1093
1094}} // namespace detail::variant
1095
1096///////////////////////////////////////////////////////////////////////////////
1097// class template variant (concept inspired by Andrei Alexandrescu)
1098//
1099// See docs and boost/variant/variant_fwd.hpp for more information.
1100//
1101template <
1102 typename T0_
1103 , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T)
1104 >
1105class variant
1106{
1107private: // helpers, for typedefs (below)
1108
1109 typedef variant wknd_self_t;
1110
1111 struct is_recursive_
1112 : detail::variant::is_recursive_flag<T0_>
1113 {
1114 };
1115
1116 typedef typename mpl::eval_if<
1117 is_recursive_
1118 , T0_
1119 , mpl::identity< T0_ >
1120 >::type unwrapped_T0_;
1121
1122 struct is_sequence_based_
1123 : detail::variant::is_over_sequence<unwrapped_T0_>
1124 {
1125 };
1126
1127#if !defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
1128
1129private: // helpers, for typedefs (below)
1130
1131 typedef typename mpl::eval_if<
1132 is_sequence_based_
1133 , unwrapped_T0_ // over_sequence<...>::type
1134 , detail::variant::make_variant_list<
1135 unwrapped_T0_
1136 , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
1137 >
1138 >::type specified_types;
1139
1140 BOOST_STATIC_ASSERT((
1141 ::boost::mpl::not_< mpl::empty<specified_types> >::value
1142 ));
1143
1144public: // public typedefs
1145 typedef typename mpl::eval_if<
1146 is_recursive_
1147 , mpl::transform<
1148 specified_types
1149 , mpl::protect<
1150 detail::variant::quoted_enable_recursive<wknd_self_t>
1151 >
1152 >
1153 , mpl::identity< specified_types >
1154 >::type recursive_enabled_types; // used by is_variant_constructible_from<> trait
1155
1156 typedef typename mpl::transform<
1157 recursive_enabled_types
1158 , unwrap_recursive<mpl::_1>
1159 >::type types;
1160
1161private: // internal typedefs
1162
1163 typedef typename mpl::transform<
1164 recursive_enabled_types
1165 , mpl::protect< detail::make_reference_content<> >
1166 >::type internal_types;
1167
1168 typedef typename mpl::front<
1169 internal_types
1170 >::type internal_T0;
1171
1172#else // defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
1173
1174private: // helpers, for typedefs (below)
1175
1176 typedef unwrapped_T0_ T0;
1177
1178 #define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS(z,N,_) \
1179 typedef typename mpl::eval_if< \
1180 is_recursive_ \
1181 , detail::variant::enable_recursive< \
1182 BOOST_PP_CAT(T,N) \
1183 , wknd_self_t \
1184 > \
1185 , mpl::identity< BOOST_PP_CAT(T,N) > \
1186 >::type BOOST_PP_CAT(recursive_enabled_T,N); \
1187 /**/
1188
1189 BOOST_PP_REPEAT(
1190 BOOST_VARIANT_LIMIT_TYPES
1191 , BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
1192 , _
1193 )
1194
1195 #undef BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
1196
1197 #define BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS(z,N,_) \
1198 typedef typename unwrap_recursive< \
1199 BOOST_PP_CAT(recursive_enabled_T,N) \
1200 >::type BOOST_PP_CAT(public_T,N); \
1201 /**/
1202
1203 BOOST_PP_REPEAT(
1204 BOOST_VARIANT_LIMIT_TYPES
1205 , BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
1206 , _
1207 )
1208
1209 #undef BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
1210
1211public: // public typedefs
1212
1213 typedef typename detail::variant::make_variant_list<
1214 BOOST_VARIANT_ENUM_PARAMS(public_T)
1215 >::type types;
1216
1217private: // helpers, for internal typedefs (below)
1218
1219 #define BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS(z,N,_) \
1220 typedef detail::make_reference_content< \
1221 BOOST_PP_CAT(recursive_enabled_T,N) \
1222 >::type BOOST_PP_CAT(internal_T,N); \
1223 /**/
1224
1225 BOOST_PP_REPEAT(
1226 BOOST_VARIANT_LIMIT_TYPES
1227 , BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
1228 , _
1229 )
1230
1231 #undef BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
1232
1233private: // internal typedefs
1234
1235 typedef typename detail::variant::make_variant_list<
1236 BOOST_VARIANT_ENUM_PARAMS(internal_T)
1237 >::type internal_types;
1238
1239private: // static precondition assertions
1240
1241 // NOTE TO USER :
1242 // variant< type-sequence > syntax is not supported on this compiler!
1243 //
1244 BOOST_MPL_ASSERT_NOT(( is_sequence_based_ ));
1245
1246#endif // BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT workaround
1247
1248private: // helpers, for representation (below)
1249
1250 typedef typename detail::variant::find_fallback_type<
1251 internal_types
1252 >::type fallback_type_result_;
1253
1254 typedef typename fallback_type_result_::first
1255 fallback_type_index_;
1256 typedef typename fallback_type_result_::second
1257 fallback_type_;
1258
1259 struct has_fallback_type_
1260 : mpl::not_<
1261 is_same< fallback_type_, detail::variant::no_fallback_type >
1262 >
1263 {
1264 };
1265
1266 typedef has_fallback_type_
1267 never_uses_backup_flag;
1268
1269 typedef typename detail::variant::make_storage<
1270 internal_types, never_uses_backup_flag
1271 >::type storage_t;
1272
1273#ifndef BOOST_NO_CXX11_NOEXCEPT
1274 typedef typename detail::variant::is_variant_move_noexcept_constructible<
1275 internal_types
1276 > variant_move_noexcept_constructible;
1277
1278 typedef typename detail::variant::is_variant_move_noexcept_assignable<
1279 internal_types
1280 > variant_move_noexcept_assignable;
1281
1282#endif
1283
1284private: // helpers, for representation (below)
1285
1286 // which_ on:
1287 // * [0, size<internal_types>) indicates stack content
1288 // * [-size<internal_types>, 0) indicates pointer to heap backup
1289 // if which_ >= 0:
1290 // * then which() -> which_
1291 // * else which() -> -(which_ + 1)
1292
1293#if !defined(BOOST_VARIANT_MINIMIZE_SIZE)
1294
1295 typedef int which_t;
1296
1297#else // defined(BOOST_VARIANT_MINIMIZE_SIZE)
1298
1299 // [if O1_size available, then attempt which_t size optimization...]
1300 // [select signed char if fewer than SCHAR_MAX types, else signed int:]
1301 typedef typename mpl::eval_if<
1302 mpl::equal_to< mpl::O1_size<internal_types>, mpl::long_<-1> >
1303 , mpl::identity< int >
1304 , mpl::if_<
1305 mpl::less< mpl::O1_size<internal_types>, mpl::int_<SCHAR_MAX> >
1306 , signed char
1307 , int
1308 >
1309 >::type which_t;
1310
1311#endif // BOOST_VARIANT_MINIMIZE_SIZE switch
1312
1313// representation -- private when possible
1314#if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
1315 private:
1316#else
1317 public:
1318#endif
1319
1320 which_t which_;
1321 storage_t storage_;
1322
1323 void indicate_which(int which_arg) BOOST_NOEXCEPT
1324 {
1325 which_ = static_cast<which_t>( which_arg );
1326 }
1327
1328 void indicate_backup_which(int which_arg) BOOST_NOEXCEPT
1329 {
1330 which_ = static_cast<which_t>( -(which_arg + 1) );
1331 }
1332
1333private: // helpers, for queries (below)
1334
1335 bool using_backup() const BOOST_NOEXCEPT
1336 {
1337 return which_ < 0;
1338 }
1339
1340public: // queries
1341
1342 int which() const BOOST_NOEXCEPT
1343 {
1344 // If using heap backup...
1345 if (using_backup())
1346 // ...then return adjusted which_:
1347 return -(which_ + 1);
1348
1349 // Otherwise, return which_ directly:
1350 return which_;
1351 }
1352
1353private: // helpers, for structors (below)
1354
1355 struct initializer
1356 : BOOST_VARIANT_AUX_INITIALIZER_T(
1357 recursive_enabled_types, recursive_enabled_T
1358 )
1359 {
1360 };
1361
1362 void destroy_content() BOOST_NOEXCEPT
1363 {
1364 detail::variant::destroyer visitor;
1365 this->internal_apply_visitor(visitor);
1366 }
1367
1368public: // structors
1369
1370 ~variant() BOOST_NOEXCEPT
1371 {
1372 destroy_content();
1373 }
1374
1375 variant()
1376#if !(defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x5130))
1377 BOOST_NOEXCEPT_IF(boost::has_nothrow_constructor<internal_T0>::value)
1378#endif
1379 {
1380#ifdef _MSC_VER
1381#pragma warning( push )
1382// behavior change: an object of POD type constructed with an initializer of the form () will be default-initialized
1383#pragma warning( disable : 4345 )
1384#endif
1385 // NOTE TO USER :
1386 // Compile error from here indicates that the first bound
1387 // type is not default-constructible, and so variant cannot
1388 // support its own default-construction.
1389 //
1390 new( storage_.address() ) internal_T0();
1391 indicate_which(which_arg: 0); // zero is the index of the first bounded type
1392#ifdef _MSC_VER
1393#pragma warning( pop )
1394#endif
1395 }
1396
1397private: // helpers, for structors, cont. (below)
1398
1399 class convert_copy_into
1400 : public static_visitor<int>
1401 {
1402 private: // representation
1403
1404 void* storage_;
1405
1406 public: // structors
1407
1408 explicit convert_copy_into(void* storage) BOOST_NOEXCEPT
1409 : storage_(storage)
1410 {
1411 }
1412
1413 public: // internal visitor interfaces (below)
1414
1415 template <typename T>
1416 int internal_visit(T& operand, int) const
1417 {
1418 // NOTE TO USER :
1419 // Compile error here indicates one of the source variant's types
1420 // cannot be unambiguously converted to the destination variant's
1421 // types (or that no conversion exists).
1422 //
1423 return initializer::initialize(storage_, operand);
1424 }
1425
1426# if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0564))
1427 template <typename T>
1428 result_type internal_visit(const T& operand, int) const
1429 {
1430 return initializer::initialize(storage_, operand);
1431 }
1432# endif
1433
1434 template <typename T>
1435 int internal_visit(boost::detail::reference_content<T>& operand, long) const
1436 {
1437 return internal_visit( operand.get(), 1L );
1438 }
1439
1440 template <typename T>
1441 int internal_visit(const boost::detail::reference_content<T>& operand, long) const
1442 {
1443 return internal_visit( operand.get(), 1L );
1444 }
1445
1446 template <typename T>
1447 int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
1448 {
1449 return internal_visit( operand.get(), 1L );
1450 }
1451
1452 template <typename T>
1453 int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
1454 {
1455 return internal_visit( operand.get(), 1L );
1456 }
1457
1458 template <typename T>
1459 int internal_visit(boost::recursive_wrapper<T>& operand, long) const
1460 {
1461 return internal_visit( operand.get(), 1L );
1462 }
1463
1464 template <typename T>
1465 int internal_visit(const boost::recursive_wrapper<T>& operand, long) const
1466 {
1467 return internal_visit( operand.get(), 1L );
1468 }
1469
1470 };
1471
1472 friend class convert_copy_into;
1473
1474#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1475 class convert_move_into
1476 : public static_visitor<int>
1477 {
1478 private: // representation
1479
1480 void* storage_;
1481
1482 public: // structors
1483
1484 explicit convert_move_into(void* storage) BOOST_NOEXCEPT
1485 : storage_(storage)
1486 {
1487 }
1488
1489 public: // internal visitor interfaces (below)
1490
1491 template <typename T>
1492 int internal_visit(T& operand, int) const
1493 {
1494 // NOTE TO USER :
1495 // Compile error here indicates one of the source variant's types
1496 // cannot be unambiguously converted to the destination variant's
1497 // types (or that no conversion exists).
1498 //
1499 return initializer::initialize(storage_, detail::variant::move(operand) );
1500 }
1501
1502 template <typename T>
1503 int internal_visit(boost::detail::reference_content<T>& operand, long) const
1504 {
1505 return internal_visit( operand.get(), 1L );
1506 }
1507
1508 template <typename T>
1509 int internal_visit(const boost::detail::reference_content<T>& operand, long) const
1510 {
1511 return internal_visit( operand.get(), 1L );
1512 }
1513
1514 template <typename T>
1515 int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
1516 {
1517 return internal_visit( operand.get(), 1L );
1518 }
1519
1520 template <typename T>
1521 int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
1522 {
1523 return internal_visit( operand.get(), 1L );
1524 }
1525
1526 template <typename T>
1527 int internal_visit(boost::recursive_wrapper<T>& operand, long) const
1528 {
1529 return internal_visit( operand.get(), 1L );
1530 }
1531
1532 template <typename T>
1533 int internal_visit(const boost::recursive_wrapper<T>& operand, long) const
1534 {
1535 return internal_visit( operand.get(), 1L );
1536 }
1537 };
1538
1539 friend class convert_move_into;
1540#endif
1541
1542private: // helpers, for structors, below
1543
1544 template <typename T>
1545 void convert_construct(
1546 T& operand
1547 , int
1548 , mpl::false_ = mpl::false_() // is_foreign_variant
1549 )
1550 {
1551 // NOTE TO USER :
1552 // Compile error here indicates that the given type is not
1553 // unambiguously convertible to one of the variant's types
1554 // (or that no conversion exists).
1555 //
1556 indicate_which(
1557 which_arg: initializer::initialize(
1558 storage_.address()
1559 , operand
1560 )
1561 );
1562 }
1563
1564#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1565 template <typename T>
1566 typename boost::enable_if<boost::is_rvalue_reference<T&&> >::type convert_construct(
1567 T&& operand
1568 , int
1569 , mpl::false_ = mpl::false_() // is_foreign_variant
1570 )
1571 {
1572 // NOTE TO USER :
1573 // Compile error here indicates that the given type is not
1574 // unambiguously convertible to one of the variant's types
1575 // (or that no conversion exists).
1576 //
1577 indicate_which(
1578 which_arg: initializer::initialize(
1579 storage_.address()
1580 , detail::variant::move(operand)
1581 )
1582 );
1583 }
1584#endif
1585
1586 template <typename Variant>
1587 void convert_construct(
1588 Variant& operand
1589 , long
1590 , mpl::true_// is_foreign_variant
1591 )
1592 {
1593 convert_copy_into visitor(storage_.address());
1594 indicate_which(
1595 which_arg: operand.internal_apply_visitor(visitor)
1596 );
1597 }
1598
1599#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1600 template <typename Variant>
1601 typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct(
1602 Variant&& operand
1603 , long
1604 , mpl::true_// is_foreign_variant
1605 )
1606 {
1607 convert_move_into visitor(storage_.address());
1608 indicate_which(
1609 which_arg: operand.internal_apply_visitor(visitor)
1610 );
1611 }
1612#endif
1613
1614 template <typename Variant>
1615 void convert_construct_variant(Variant& operand)
1616 {
1617 // [Determine if the given variant is itself a bounded type, or if its
1618 // content needs to be converted (i.e., it is a 'foreign' variant):]
1619 //
1620
1621 typedef typename mpl::find_if<
1622 types
1623 , is_same<
1624 add_const<mpl::_1>
1625 , const Variant
1626 >
1627 >::type found_it;
1628
1629 typedef typename mpl::end<types>::type not_found;
1630 typedef typename is_same<
1631 found_it, not_found
1632 >::type is_foreign_variant;
1633
1634 // Convert construct from operand:
1635 convert_construct(
1636 operand, 1L
1637 , is_foreign_variant()
1638 );
1639 }
1640
1641#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1642 template <typename Variant>
1643 typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct_variant(Variant&& operand)
1644 {
1645 // [Determine if the given variant is itself a bounded type, or if its
1646 // content needs to be converted (i.e., it is a 'foreign' variant):]
1647 //
1648
1649 typedef typename mpl::find_if<
1650 types
1651 , is_same<
1652 add_const<mpl::_1>
1653 , const Variant
1654 >
1655 >::type found_it;
1656
1657 typedef typename mpl::end<types>::type not_found;
1658 typedef typename is_same<
1659 found_it, not_found
1660 >::type is_foreign_variant;
1661
1662 // Convert move construct from operand:
1663 convert_construct(
1664 detail::variant::move(operand), 1L
1665 , is_foreign_variant()
1666 );
1667 }
1668#endif
1669
1670 template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
1671 typename boost::enable_if<mpl::or_<
1672 boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
1673 boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types>
1674 > >::type convert_construct(
1675 boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
1676 , long
1677 )
1678 {
1679 convert_construct_variant(operand);
1680 }
1681
1682 template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
1683 typename boost::enable_if<mpl::or_<
1684 boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
1685 boost::detail::variant::is_variant_constructible_from<const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types>
1686 > >::type convert_construct(
1687 const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
1688 , long
1689 )
1690 {
1691 convert_construct_variant(operand);
1692 }
1693
1694#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1695 template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
1696 typename boost::enable_if<mpl::or_<
1697 boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
1698 boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&&, internal_types>
1699 > >::type convert_construct(
1700 boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&& operand
1701 , long
1702 )
1703 {
1704 convert_construct_variant( detail::variant::move(operand) );
1705 }
1706#endif
1707
1708public: // structors, cont.
1709
1710 template <typename T>
1711 variant(const T& operand,
1712 typename boost::enable_if<mpl::or_<
1713 mpl::and_<
1714 mpl::not_< boost::is_same<T, variant> >,
1715 boost::detail::variant::is_variant_constructible_from<const T&, internal_types>
1716 >,
1717 boost::is_same<T, boost::recursive_variant_> >,
1718 bool >::type = true)
1719 {
1720 convert_construct(operand, 1L);
1721 }
1722
1723 template <typename T>
1724 variant(
1725 T& operand
1726 , typename boost::enable_if<mpl::or_<
1727 mpl::and_<
1728 mpl::not_< is_const<T> >,
1729 mpl::not_< boost::is_same<T, variant> >,
1730 boost::detail::variant::is_variant_constructible_from<T&, internal_types>
1731 >,
1732 boost::is_same<T, boost::recursive_variant_> >,
1733 bool >::type = true
1734 )
1735 {
1736 convert_construct(operand, 1L);
1737 }
1738
1739#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1740 template <class T>
1741 variant(T&& operand,
1742 typename boost::enable_if<mpl::or_<
1743 mpl::and_<
1744 boost::is_rvalue_reference<T&&>,
1745 mpl::not_< boost::is_const<T> >,
1746 mpl::not_< boost::is_same<T, variant> >,
1747 boost::detail::variant::is_variant_constructible_from<T&&, internal_types>
1748 >,
1749 boost::is_same<T, boost::recursive_variant_> >,
1750 bool >::type = true)
1751 {
1752 convert_construct( detail::variant::move(operand), 1L);
1753 }
1754#endif
1755
1756public: // structors, cont.
1757
1758 // [MSVC6 requires copy constructor appear after template constructors]
1759 variant(const variant& operand)
1760 {
1761 // Copy the value of operand into *this...
1762 detail::variant::copy_into visitor( storage_.address() );
1763 operand.internal_apply_visitor(visitor);
1764
1765 // ...and activate the *this's primary storage on success:
1766 indicate_which(which_arg: operand.which());
1767 }
1768
1769#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1770 variant(variant&& operand) BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value)
1771 {
1772 // Move the value of operand into *this...
1773 detail::variant::move_into visitor( storage_.address() );
1774 operand.internal_apply_visitor(visitor);
1775
1776 // ...and activate the *this's primary storage on success:
1777 indicate_which(which_arg: operand.which());
1778 }
1779#endif
1780
1781private: // helpers, for modifiers (below)
1782
1783# if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
1784 template <typename Variant>
1785 friend class detail::variant::backup_assigner;
1786# endif
1787
1788 // class assigner
1789 //
1790 // Internal visitor that "assigns" the visited value to the given variant
1791 // by appropriate destruction and copy-construction.
1792 //
1793
1794 class assigner
1795 : public static_visitor<>
1796 {
1797 protected: // representation
1798
1799 variant& lhs_;
1800 const int rhs_which_;
1801
1802 public: // structors
1803
1804 assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT
1805 : lhs_(lhs)
1806 , rhs_which_(rhs_which)
1807 {
1808 }
1809
1810 protected: // helpers, for internal visitor interface (below)
1811
1812 template <typename RhsT, typename B1, typename B2>
1813 void assign_impl(
1814 const RhsT& rhs_content
1815 , mpl::true_ // has_nothrow_copy
1816 , B1 // is_nothrow_move_constructible
1817 , B2 // has_fallback_type
1818 ) const BOOST_NOEXCEPT
1819 {
1820 // Destroy lhs's content...
1821 lhs_.destroy_content(); // nothrow
1822
1823 // ...copy rhs content into lhs's storage...
1824 new(lhs_.storage_.address())
1825 RhsT( rhs_content ); // nothrow
1826
1827 // ...and indicate new content type:
1828 lhs_.indicate_which(rhs_which_); // nothrow
1829 }
1830
1831 template <typename RhsT, typename B>
1832 void assign_impl(
1833 const RhsT& rhs_content
1834 , mpl::false_ // has_nothrow_copy
1835 , mpl::true_ // is_nothrow_move_constructible
1836 , B // has_fallback_type
1837 ) const
1838 {
1839 // Attempt to make a temporary copy (so as to move it below)...
1840 RhsT temp(rhs_content);
1841
1842 // ...and upon success destroy lhs's content...
1843 lhs_.destroy_content(); // nothrow
1844
1845 // ...move the temporary copy into lhs's storage...
1846 new(lhs_.storage_.address())
1847 RhsT( detail::variant::move(temp) ); // nothrow
1848
1849 // ...and indicate new content type:
1850 lhs_.indicate_which(rhs_which_); // nothrow
1851 }
1852
1853 void construct_fallback() const BOOST_NOEXCEPT {
1854 // In case of failure, default-construct fallback type in lhs's storage...
1855 new (lhs_.storage_.address())
1856 fallback_type_; // nothrow
1857
1858 // ...indicate construction of fallback type...
1859 lhs_.indicate_which(
1860 BOOST_MPL_AUX_VALUE_WKND(fallback_type_index_)::value
1861 ); // nothrow
1862 }
1863
1864 template <typename RhsT>
1865 void assign_impl(
1866 const RhsT& rhs_content
1867 , mpl::false_ // has_nothrow_copy
1868 , mpl::false_ // is_nothrow_move_constructible
1869 , mpl::true_ // has_fallback_type
1870 ) const
1871 {
1872 // Destroy lhs's content...
1873 lhs_.destroy_content(); // nothrow
1874
1875 BOOST_TRY
1876 {
1877 // ...and attempt to copy rhs's content into lhs's storage:
1878 new(lhs_.storage_.address())
1879 RhsT( rhs_content );
1880 }
1881 BOOST_CATCH (...)
1882 {
1883 construct_fallback();
1884
1885 // ...and rethrow:
1886 BOOST_RETHROW;
1887 }
1888 BOOST_CATCH_END
1889
1890 // In the event of success, indicate new content type:
1891 lhs_.indicate_which(rhs_which_); // nothrow
1892 }
1893
1894 template <typename RhsT>
1895 void assign_impl(
1896 const RhsT& rhs_content
1897 , mpl::false_ // has_nothrow_copy
1898 , mpl::false_ // is_nothrow_move_constructible
1899 , mpl::false_ // has_fallback_type
1900 ) const
1901 {
1902 detail::variant::backup_assigner<wknd_self_t>
1903 visitor(lhs_, rhs_which_, rhs_content);
1904 lhs_.internal_apply_visitor(visitor);
1905 }
1906
1907 public: // internal visitor interfaces
1908
1909 template <typename RhsT>
1910 void internal_visit(const RhsT& rhs_content, int) const
1911 {
1912 typedef typename has_nothrow_copy<RhsT>::type
1913 nothrow_copy;
1914 typedef typename mpl::or_< // reduces compile-time
1915 nothrow_copy
1916 , is_nothrow_move_constructible<RhsT>
1917 >::type nothrow_move_constructor;
1918
1919 assign_impl(
1920 rhs_content
1921 , nothrow_copy()
1922 , nothrow_move_constructor()
1923 , has_fallback_type_()
1924 );
1925 }
1926
1927#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
1928 private:
1929 // silence MSVC warning C4512: assignment operator could not be generated
1930 assigner& operator= (assigner const&);
1931#endif
1932 };
1933
1934 friend class assigner;
1935
1936#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
1937 // class move_assigner
1938 //
1939 // Internal visitor that "move assigns" the visited value to the given variant
1940 // by appropriate destruction and move-construction.
1941 //
1942
1943 class move_assigner
1944 : public assigner
1945 {
1946 public: // structors
1947
1948 move_assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT
1949 : assigner(lhs, rhs_which)
1950 {
1951 }
1952
1953 private: // helpers, for internal visitor interface (below)
1954
1955 template <typename RhsT, typename B2>
1956 void assign_impl(
1957 RhsT& rhs_content
1958 , mpl::true_ // has_nothrow_copy
1959 , mpl::false_ // is_nothrow_move_constructible
1960 , B2 // has_fallback_type
1961 ) const BOOST_NOEXCEPT
1962 {
1963 assigner::assign_impl(rhs_content, mpl::true_(), mpl::false_(), B2());
1964 }
1965
1966 template <typename RhsT, typename B, typename B2>
1967 void assign_impl(
1968 RhsT& rhs_content
1969 , B // has_nothrow_copy
1970 , mpl::true_ // is_nothrow_move_constructible
1971 , B2 // has_fallback_type
1972 ) const BOOST_NOEXCEPT
1973 {
1974 // ...destroy lhs's content...
1975 assigner::lhs_.destroy_content(); // nothrow
1976
1977 // ...move the rhs_content into lhs's storage...
1978 new(assigner::lhs_.storage_.address())
1979 RhsT( detail::variant::move(rhs_content) ); // nothrow
1980
1981 // ...and indicate new content type:
1982 assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow
1983 }
1984
1985 template <typename RhsT>
1986 void assign_impl(
1987 RhsT& rhs_content
1988 , mpl::false_ // has_nothrow_copy
1989 , mpl::false_ // is_nothrow_move_constructible
1990 , mpl::true_ // has_fallback_type
1991 ) const
1992 {
1993 // Destroy lhs's content...
1994 assigner::lhs_.destroy_content(); // nothrow
1995
1996 BOOST_TRY
1997 {
1998 // ...and attempt to copy rhs's content into lhs's storage:
1999 new(assigner::lhs_.storage_.address())
2000 RhsT( detail::variant::move(rhs_content) );
2001 }
2002 BOOST_CATCH (...)
2003 {
2004 assigner::construct_fallback();
2005
2006 // ...and rethrow:
2007 BOOST_RETHROW;
2008 }
2009 BOOST_CATCH_END
2010
2011 // In the event of success, indicate new content type:
2012 assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow
2013 }
2014
2015 template <typename RhsT>
2016 void assign_impl(
2017 RhsT& rhs_content
2018 , mpl::false_ // has_nothrow_copy
2019 , mpl::false_ // is_nothrow_move_constructible
2020 , mpl::false_ // has_fallback_type
2021 ) const
2022 {
2023 assigner::assign_impl(rhs_content, mpl::false_(), mpl::false_(), mpl::false_());
2024 }
2025
2026 public: // internal visitor interfaces
2027
2028 template <typename RhsT>
2029 void internal_visit(RhsT& rhs_content, int) const
2030 {
2031 typedef typename is_nothrow_move_constructible<RhsT>::type
2032 nothrow_move_constructor;
2033 typedef typename mpl::or_< // reduces compile-time
2034 nothrow_move_constructor
2035 , has_nothrow_copy<RhsT>
2036 >::type nothrow_copy;
2037
2038 assign_impl(
2039 rhs_content
2040 , nothrow_copy()
2041 , nothrow_move_constructor()
2042 , has_fallback_type_()
2043 );
2044 }
2045
2046#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
2047 private:
2048 // silence MSVC warning C4512: assignment operator could not be generated
2049 move_assigner& operator= (move_assigner const&);
2050#endif
2051 };
2052
2053 friend class move_assigner;
2054#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
2055
2056 void variant_assign(const variant& rhs)
2057 {
2058 // If the contained types are EXACTLY the same...
2059 if (which_ == rhs.which_)
2060 {
2061 // ...then assign rhs's storage to lhs's content:
2062 detail::variant::assign_storage visitor(rhs.storage_.address());
2063 this->internal_apply_visitor(visitor);
2064 }
2065 else
2066 {
2067 // Otherwise, perform general (copy-based) variant assignment:
2068 assigner visitor(*this, rhs.which());
2069 rhs.internal_apply_visitor(visitor);
2070 }
2071 }
2072
2073#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
2074 void variant_assign(variant&& rhs)
2075 {
2076 // If the contained types are EXACTLY the same...
2077 if (which_ == rhs.which_)
2078 {
2079 // ...then move rhs's storage to lhs's content:
2080 detail::variant::move_storage visitor(rhs.storage_.address());
2081 this->internal_apply_visitor(visitor);
2082 }
2083 else
2084 {
2085 // Otherwise, perform general (move-based) variant assignment:
2086 move_assigner visitor(*this, rhs.which());
2087 rhs.internal_apply_visitor(visitor);
2088 }
2089 }
2090#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
2091
2092private: // helpers, for modifiers (below)
2093
2094 template <typename T>
2095 void assign(const T& rhs)
2096 {
2097 // If direct T-to-T assignment is not possible...
2098 detail::variant::direct_assigner<T> direct_assign(rhs);
2099 if (this->apply_visitor(direct_assign) == false)
2100 {
2101 // ...then convert rhs to variant and assign:
2102 //
2103 // While potentially inefficient, the following construction of a
2104 // variant allows T as any type convertible to one of the bounded
2105 // types without excessive code redundancy.
2106 //
2107 variant temp(rhs);
2108 variant_assign( detail::variant::move(temp) );
2109 }
2110 }
2111
2112#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
2113 template <typename T>
2114 void move_assign(T&& rhs)
2115 {
2116 // If direct T-to-T move assignment is not possible...
2117 detail::variant::direct_mover<T> direct_move(rhs);
2118 if (this->apply_visitor(direct_move) == false)
2119 {
2120 // ...then convert rhs to variant and assign:
2121 //
2122 // While potentially inefficient, the following construction of a
2123 // variant allows T as any type convertible to one of the bounded
2124 // types without excessive code redundancy.
2125 //
2126 variant temp( detail::variant::move(rhs) );
2127 variant_assign( detail::variant::move(temp) );
2128 }
2129 }
2130#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
2131
2132public: // modifiers
2133
2134#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && \
2135 (!BOOST_WORKAROUND(BOOST_CLANG_VERSION, BOOST_TESTED_AT(150000)) || BOOST_CXX_VERSION <= 202002L)
2136 template <class T>
2137 typename boost::enable_if<
2138 boost::mpl::and_<
2139 boost::is_rvalue_reference<T&&>,
2140 mpl::not_< boost::is_const<T> >,
2141 boost::detail::variant::is_variant_constructible_from<T&&, internal_types>
2142 >,
2143 variant&
2144 >::type operator=(T&& rhs)
2145 {
2146 move_assign( detail::variant::move(rhs) );
2147 return *this;
2148 }
2149#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
2150
2151 template <typename T>
2152 typename boost::enable_if<
2153 mpl::or_<
2154 boost::is_same<T, variant>,
2155 boost::detail::variant::is_variant_constructible_from<const T&, internal_types>
2156 >,
2157 variant&
2158 >::type operator=(const T& rhs)
2159 {
2160 assign(rhs);
2161 return *this;
2162 }
2163
2164 // [MSVC6 requires copy assign appear after templated operator=]
2165 variant& operator=(const variant& rhs)
2166 {
2167 variant_assign(rhs);
2168 return *this;
2169 }
2170
2171#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
2172 variant& operator=(variant&& rhs)
2173#if !defined(__GNUC__) || (__GNUC__ != 4) || (__GNUC_MINOR__ > 6) || defined(__clang__)
2174 BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value && variant_move_noexcept_assignable::type::value)
2175#endif
2176 {
2177 variant_assign( detail::variant::move(rhs) );
2178 return *this;
2179 }
2180#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
2181
2182 void swap(variant& rhs)
2183 {
2184 // If the contained types are the same...
2185 if (which() == rhs.which())
2186 {
2187 // ...then swap the values directly:
2188 detail::variant::swap_with<variant> visitor(rhs);
2189 this->apply_visitor(visitor);
2190 }
2191 else
2192 {
2193 // ...otherwise, perform general variant swap:
2194 variant tmp( detail::variant::move(rhs) );
2195 rhs = detail::variant::move(*this);
2196 *this = detail::variant::move(tmp);
2197 }
2198 }
2199
2200public: // queries
2201
2202 //
2203 // NOTE: member which() defined above.
2204 //
2205
2206 bool empty() const BOOST_NOEXCEPT
2207 {
2208 return false;
2209 }
2210
2211 const boost::typeindex::type_info& type() const
2212 {
2213 detail::variant::reflect visitor;
2214 return this->apply_visitor(visitor);
2215 }
2216
2217public: // prevent comparison with foreign types
2218
2219 template <typename U>
2220 void operator==(const U&) const
2221 {
2222 BOOST_STATIC_ASSERT( false && sizeof(U) );
2223 }
2224
2225 template <typename U>
2226 void operator<(const U&) const
2227 {
2228 BOOST_STATIC_ASSERT( false && sizeof(U) );
2229 }
2230
2231 template <typename U>
2232 void operator!=(const U&) const
2233 {
2234 BOOST_STATIC_ASSERT( false && sizeof(U) );
2235 }
2236
2237 template <typename U>
2238 void operator>(const U&) const
2239 {
2240 BOOST_STATIC_ASSERT( false && sizeof(U) );
2241 }
2242
2243 template <typename U>
2244 void operator<=(const U&) const
2245 {
2246 BOOST_STATIC_ASSERT( false && sizeof(U) );
2247 }
2248
2249 template <typename U>
2250 void operator>=(const U&) const
2251 {
2252 BOOST_STATIC_ASSERT( false && sizeof(U) );
2253 }
2254
2255public: // comparison operators
2256
2257 // [MSVC6 requires these operators appear after template operators]
2258
2259 bool operator==(const variant& rhs) const
2260 {
2261 if (this->which() != rhs.which())
2262 return false;
2263
2264 detail::variant::comparer<
2265 variant, detail::variant::equal_comp
2266 > visitor(*this);
2267 return rhs.apply_visitor(visitor);
2268 }
2269
2270 bool operator<(const variant& rhs) const
2271 {
2272 //
2273 // Dirk Schreib suggested this collating order.
2274 //
2275
2276 if (this->which() != rhs.which())
2277 return this->which() < rhs.which();
2278
2279 detail::variant::comparer<
2280 variant, detail::variant::less_comp
2281 > visitor(*this);
2282 return rhs.apply_visitor(visitor);
2283 }
2284
2285 ///////////////////////////////////////////////////////////////////////////////
2286 // comparison operators != > <= >=
2287 inline bool operator!=(const variant& rhs) const
2288 {
2289 return !(*this == rhs);
2290 }
2291
2292 inline bool operator>(const variant& rhs) const
2293 {
2294 return rhs < *this;
2295 }
2296
2297 inline bool operator<=(const variant& rhs) const
2298 {
2299 return !(*this > rhs);
2300 }
2301
2302 inline bool operator>=(const variant& rhs) const
2303 {
2304 return !(*this < rhs);
2305 }
2306
2307// helpers, for visitation support (below) -- private when possible
2308#if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
2309
2310 template < BOOST_VARIANT_ENUM_PARAMS(typename U) >
2311 friend class variant;
2312
2313private:
2314
2315#else// defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
2316
2317public:
2318
2319#endif// !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
2320
2321 template <typename Visitor, typename VoidPtrCV>
2322 BOOST_FORCEINLINE static typename Visitor::result_type
2323 internal_apply_visitor_impl(
2324 int internal_which
2325 , int logical_which
2326 , Visitor& visitor
2327 , VoidPtrCV storage
2328 )
2329 {
2330 typedef mpl::int_<0> first_which;
2331 typedef typename mpl::begin<internal_types>::type first_it;
2332 typedef typename mpl::end<internal_types>::type last_it;
2333
2334 typedef detail::variant::visitation_impl_step<
2335 first_it, last_it
2336 > first_step;
2337
2338 return detail::variant::visitation_impl(
2339 internal_which, logical_which
2340 , visitor, storage, mpl::false_()
2341 , never_uses_backup_flag()
2342 , static_cast<first_which*>(0), static_cast<first_step*>(0)
2343 );
2344 }
2345
2346 template <typename Visitor>
2347 BOOST_FORCEINLINE typename Visitor::result_type
2348 internal_apply_visitor(Visitor& visitor)
2349 {
2350 return internal_apply_visitor_impl(
2351 which_, which(), visitor, storage_.address()
2352 );
2353 }
2354
2355 template <typename Visitor>
2356 BOOST_FORCEINLINE typename Visitor::result_type
2357 internal_apply_visitor(Visitor& visitor) const
2358 {
2359 return internal_apply_visitor_impl(
2360 which_, which(), visitor, storage_.address()
2361 );
2362 }
2363
2364public: // visitation support
2365
2366#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
2367
2368 template <typename Visitor>
2369 typename Visitor::result_type
2370 apply_visitor(Visitor& visitor) &&
2371 {
2372 detail::variant::invoke_visitor<Visitor, true> invoker(visitor);
2373 return this->internal_apply_visitor(invoker);
2374 }
2375
2376 template <typename Visitor>
2377 typename Visitor::result_type
2378 apply_visitor(Visitor& visitor) const&&
2379 {
2380 detail::variant::invoke_visitor<Visitor, true> invoker(visitor);
2381 return this->internal_apply_visitor(invoker);
2382 }
2383
2384#endif
2385
2386 template <typename Visitor>
2387 typename Visitor::result_type
2388 apply_visitor(Visitor& visitor)
2389#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
2390 &
2391#endif
2392 {
2393 detail::variant::invoke_visitor<Visitor, false> invoker(visitor);
2394 return this->internal_apply_visitor(invoker);
2395 }
2396
2397 template <typename Visitor>
2398 typename Visitor::result_type
2399 apply_visitor(Visitor& visitor) const
2400#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
2401 &
2402#endif
2403 {
2404 detail::variant::invoke_visitor<Visitor, false> invoker(visitor);
2405 return this->internal_apply_visitor(invoker);
2406 }
2407
2408}; // class variant
2409
2410///////////////////////////////////////////////////////////////////////////////
2411// metafunction make_variant_over
2412//
2413// See docs and boost/variant/variant_fwd.hpp for more information.
2414//
2415template <typename Types>
2416struct make_variant_over
2417{
2418private: // precondition assertions
2419
2420 BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value ));
2421 typedef typename boost::mpl::insert_range<
2422 boost::mpl::list<>
2423 , boost::mpl::end< boost::mpl::list<> >::type
2424 , Types
2425 >::type copied_sequence_t;
2426
2427public: // metafunction result
2428
2429 typedef variant<
2430 detail::variant::over_sequence<copied_sequence_t>
2431 > type;
2432
2433};
2434
2435///////////////////////////////////////////////////////////////////////////////
2436// function template swap
2437//
2438// Swaps two variants of the same type (i.e., identical specification).
2439//
2440template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
2441inline void swap(
2442 variant< BOOST_VARIANT_ENUM_PARAMS(T) >& lhs
2443 , variant< BOOST_VARIANT_ENUM_PARAMS(T) >& rhs
2444 )
2445{
2446 lhs.swap(rhs);
2447}
2448
2449} // namespace boost
2450
2451// implementation additions
2452
2453#if !defined(BOOST_NO_IOSTREAM)
2454#include <boost/variant/detail/variant_io.hpp>
2455#endif // BOOST_NO_IOSTREAM
2456
2457#endif // BOOST_VARIANT_VARIANT_HPP
2458