tuple revision 288943 
1// -*- C++ -*-
2//===--------------------------- tuple ------------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is distributed under the University of Illinois Open Source
7// License. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_TUPLE
12#define _LIBCPP_TUPLE
13
14/*
15    tuple synopsis
16
17namespace std
18{
19
20template <class... T>
21class tuple {
22public:
23    constexpr tuple();
24    explicit tuple(const T&...);  // constexpr in C++14
25    template <class... U>
26        explicit tuple(U&&...);  // constexpr in C++14
27    tuple(const tuple&) = default;
28    tuple(tuple&&) = default;
29    template <class... U>
30        tuple(const tuple<U...>&);  // constexpr in C++14
31    template <class... U>
32        tuple(tuple<U...>&&);  // constexpr in C++14
33    template <class U1, class U2>
34        tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14
35    template <class U1, class U2>
36        tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14
37
38    // allocator-extended constructors
39    template <class Alloc>
40        tuple(allocator_arg_t, const Alloc& a);
41    template <class Alloc>
42        tuple(allocator_arg_t, const Alloc& a, const T&...);
43    template <class Alloc, class... U>
44        tuple(allocator_arg_t, const Alloc& a, U&&...);
45    template <class Alloc>
46        tuple(allocator_arg_t, const Alloc& a, const tuple&);
47    template <class Alloc>
48        tuple(allocator_arg_t, const Alloc& a, tuple&&);
49    template <class Alloc, class... U>
50        tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);
51    template <class Alloc, class... U>
52        tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);
53    template <class Alloc, class U1, class U2>
54        tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);
55    template <class Alloc, class U1, class U2>
56        tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);
57
58    tuple& operator=(const tuple&);
59    tuple&
60        operator=(tuple&&) noexcept(AND(is_nothrow_move_assignable<T>::value ...));
61    template <class... U>
62        tuple& operator=(const tuple<U...>&);
63    template <class... U>
64        tuple& operator=(tuple<U...>&&);
65    template <class U1, class U2>
66        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2
67    template <class U1, class U2>
68        tuple& operator=(pair<U1, U2>&&); //iffsizeof...(T) == 2
69
70    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));
71};
72
73const unspecified ignore;
74
75template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
76template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
77template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14
78template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
79  
80// 20.4.1.4, tuple helper classes:
81template <class T> class tuple_size; // undefined
82template <class... T> class tuple_size<tuple<T...>>;
83template <intsize_t I, class T> class tuple_element; // undefined
84template <intsize_t I, class... T> class tuple_element<I, tuple<T...>>;
85template <size_t _Ip, class ..._Tp>
86  using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type; // C++14
87
88// 20.4.1.5, element access:
89template <intsize_t I, class... T>
90    typename tuple_element<I, tuple<T...>>::type&
91    get(tuple<T...>&) noexcept; // constexpr in C++14
92template <intsize_t I, class... T>
93    typename const tuple_element<I, tuple<T...>>::type &
94    get(const tuple<T...>&) noexcept; // constexpr in C++14
95template <intsize_t I, class... T>
96    typename tuple_element<I, tuple<T...>>::type&&
97    get(tuple<T...>&&) noexcept; // constexpr in C++14
98
99template <class T1, class... T>
100    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
101template <class T1, class... T>
102    constexpr T1 const& get(const tuple<T...>&) noexcept;   // C++14
103template <class T1, class... T>
104    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
105
106// 20.4.1.6, relational operators:
107template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
108template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
109template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
110template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
111template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
112template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
113
114template <class... Types, class Alloc>
115  struct uses_allocator<tuple<Types...>, Alloc>;
116
117template <class... Types>
118  void
119  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
120
121}  // std
122
123*/
124
125#include <__config>
126#include <__tuple>
127#include <cstddef>
128#include <type_traits>
129#include <__functional_base>
130#include <utility>
131
132#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
133#pragma GCC system_header
134#endif
135
136_LIBCPP_BEGIN_NAMESPACE_STD
137
138#ifndef _LIBCPP_HAS_NO_VARIADICS
139
140// tuple_size
141
142template <class ..._Tp>
143class _LIBCPP_TYPE_VIS_ONLY tuple_size<tuple<_Tp...> >
144    : public integral_constant<size_t, sizeof...(_Tp)>
145{
146};
147
148// tuple_element
149
150template <size_t _Ip, class ..._Tp>
151class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, tuple<_Tp...> >
152{
153public:
154    typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
155};
156
157#if _LIBCPP_STD_VER > 11
158template <size_t _Ip, class ..._Tp>
159using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type;
160#endif
161
162// __tuple_leaf
163
164template <size_t _Ip, class _Hp,
165          bool=is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value
166         >
167class __tuple_leaf;
168
169template <size_t _Ip, class _Hp, bool _Ep>
170inline _LIBCPP_INLINE_VISIBILITY
171void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
172    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
173{
174    swap(__x.get(), __y.get());
175}
176
177template <size_t _Ip, class _Hp, bool>
178class __tuple_leaf
179{
180    _Hp value;
181
182    __tuple_leaf& operator=(const __tuple_leaf&);
183public:
184    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
185             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : value()
186       {static_assert(!is_reference<_Hp>::value,
187              "Attempted to default construct a reference element in a tuple");}
188
189    template <class _Alloc>
190        _LIBCPP_INLINE_VISIBILITY
191        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
192            : value()
193        {static_assert(!is_reference<_Hp>::value,
194              "Attempted to default construct a reference element in a tuple");}
195
196    template <class _Alloc>
197        _LIBCPP_INLINE_VISIBILITY
198        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
199            : value(allocator_arg_t(), __a)
200        {static_assert(!is_reference<_Hp>::value,
201              "Attempted to default construct a reference element in a tuple");}
202
203    template <class _Alloc>
204        _LIBCPP_INLINE_VISIBILITY
205        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
206            : value(__a)
207        {static_assert(!is_reference<_Hp>::value,
208              "Attempted to default construct a reference element in a tuple");}
209
210    template <class _Tp,
211              class = typename enable_if<
212                  __lazy_and<
213                      __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
214                    , is_constructible<_Hp, _Tp>
215                    >::value
216                >::type
217            >
218        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
219        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
220            : value(_VSTD::forward<_Tp>(__t))
221        {static_assert(!is_reference<_Hp>::value ||
222                       (is_lvalue_reference<_Hp>::value &&
223                        (is_lvalue_reference<_Tp>::value ||
224                         is_same<typename remove_reference<_Tp>::type,
225                                 reference_wrapper<
226                                    typename remove_reference<_Hp>::type
227                                 >
228                                >::value)) ||
229                        (is_rvalue_reference<_Hp>::value &&
230                         !is_lvalue_reference<_Tp>::value),
231       "Attempted to construct a reference element in a tuple with an rvalue");}
232
233    template <class _Tp, class _Alloc>
234        _LIBCPP_INLINE_VISIBILITY
235        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
236            : value(_VSTD::forward<_Tp>(__t))
237        {static_assert(!is_lvalue_reference<_Hp>::value ||
238                       (is_lvalue_reference<_Hp>::value &&
239                        (is_lvalue_reference<_Tp>::value ||
240                         is_same<typename remove_reference<_Tp>::type,
241                                 reference_wrapper<
242                                    typename remove_reference<_Hp>::type
243                                 >
244                                >::value)),
245       "Attempted to construct a reference element in a tuple with an rvalue");}
246
247    template <class _Tp, class _Alloc>
248        _LIBCPP_INLINE_VISIBILITY
249        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
250            : value(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
251        {static_assert(!is_lvalue_reference<_Hp>::value ||
252                       (is_lvalue_reference<_Hp>::value &&
253                        (is_lvalue_reference<_Tp>::value ||
254                         is_same<typename remove_reference<_Tp>::type,
255                                 reference_wrapper<
256                                    typename remove_reference<_Hp>::type
257                                 >
258                                >::value)),
259       "Attempted to construct a reference element in a tuple with an rvalue");}
260
261    template <class _Tp, class _Alloc>
262        _LIBCPP_INLINE_VISIBILITY
263        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
264            : value(_VSTD::forward<_Tp>(__t), __a)
265        {static_assert(!is_lvalue_reference<_Hp>::value ||
266                       (is_lvalue_reference<_Hp>::value &&
267                        (is_lvalue_reference<_Tp>::value ||
268                         is_same<typename remove_reference<_Tp>::type,
269                                 reference_wrapper<
270                                    typename remove_reference<_Hp>::type
271                                 >
272                                >::value)),
273       "Attempted to construct a reference element in a tuple with an rvalue");}
274
275    __tuple_leaf(const __tuple_leaf& __t) = default;
276    __tuple_leaf(__tuple_leaf&& __t) = default;
277
278    template <class _Tp>
279        _LIBCPP_INLINE_VISIBILITY
280        __tuple_leaf&
281        operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
282        {
283            value = _VSTD::forward<_Tp>(__t);
284            return *this;
285        }
286
287    _LIBCPP_INLINE_VISIBILITY
288    int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
289    {
290        _VSTD::swap(*this, __t);
291        return 0;
292    }
293
294    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return value;}
295    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return value;}
296};
297
298template <size_t _Ip, class _Hp>
299class __tuple_leaf<_Ip, _Hp, true>
300    : private _Hp
301{
302
303    __tuple_leaf& operator=(const __tuple_leaf&);
304public:
305    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
306             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
307
308    template <class _Alloc>
309        _LIBCPP_INLINE_VISIBILITY
310        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
311
312    template <class _Alloc>
313        _LIBCPP_INLINE_VISIBILITY
314        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
315            : _Hp(allocator_arg_t(), __a) {}
316
317    template <class _Alloc>
318        _LIBCPP_INLINE_VISIBILITY
319        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
320            : _Hp(__a) {}
321
322    template <class _Tp,
323              class = typename enable_if<
324                  __lazy_and<
325                        __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
326                      , is_constructible<_Hp, _Tp>
327                    >::value
328                >::type
329            >
330        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
331        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
332            : _Hp(_VSTD::forward<_Tp>(__t)) {}
333
334    template <class _Tp, class _Alloc>
335        _LIBCPP_INLINE_VISIBILITY
336        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
337            : _Hp(_VSTD::forward<_Tp>(__t)) {}
338
339    template <class _Tp, class _Alloc>
340        _LIBCPP_INLINE_VISIBILITY
341        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
342            : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
343
344    template <class _Tp, class _Alloc>
345        _LIBCPP_INLINE_VISIBILITY
346        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
347            : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
348
349    __tuple_leaf(__tuple_leaf const &) = default;
350    __tuple_leaf(__tuple_leaf &&) = default;
351
352    template <class _Tp>
353        _LIBCPP_INLINE_VISIBILITY
354        __tuple_leaf&
355        operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
356        {
357            _Hp::operator=(_VSTD::forward<_Tp>(__t));
358            return *this;
359        }
360
361    _LIBCPP_INLINE_VISIBILITY
362    int
363    swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
364    {
365        _VSTD::swap(*this, __t);
366        return 0;
367    }
368
369    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
370    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
371};
372
373template <class ..._Tp>
374_LIBCPP_INLINE_VISIBILITY
375void __swallow(_Tp&&...) _NOEXCEPT {}
376
377template <bool ..._Pred>
378struct __all
379    : is_same<__all<_Pred...>, __all<(_Pred, true)...>>
380{ };
381
382template <class _Tp>
383struct __all_default_constructible;
384
385template <class ..._Tp>
386struct __all_default_constructible<__tuple_types<_Tp...>>
387    : __all<is_default_constructible<_Tp>::value...>
388{ };
389
390// __tuple_impl
391
392template<class _Indx, class ..._Tp> struct __tuple_impl;
393
394template<size_t ..._Indx, class ..._Tp>
395struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
396    : public __tuple_leaf<_Indx, _Tp>...
397{
398    _LIBCPP_INLINE_VISIBILITY
399    _LIBCPP_CONSTEXPR __tuple_impl()
400        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
401
402    template <size_t ..._Uf, class ..._Tf,
403              size_t ..._Ul, class ..._Tl, class ..._Up>
404        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
405        explicit
406        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
407                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
408                     _Up&&... __u)
409                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
410                                 __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
411            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
412            __tuple_leaf<_Ul, _Tl>()...
413            {}
414
415    template <class _Alloc, size_t ..._Uf, class ..._Tf,
416              size_t ..._Ul, class ..._Tl, class ..._Up>
417        _LIBCPP_INLINE_VISIBILITY
418        explicit
419        __tuple_impl(allocator_arg_t, const _Alloc& __a,
420                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
421                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
422                     _Up&&... __u) :
423            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
424            _VSTD::forward<_Up>(__u))...,
425            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
426            {}
427
428    template <class _Tuple,
429              class = typename enable_if
430                      <
431                         __tuple_constructible<_Tuple, tuple<_Tp...> >::value
432                      >::type
433             >
434        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
435        __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
436                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
437            : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
438                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
439            {}
440
441    template <class _Alloc, class _Tuple,
442              class = typename enable_if
443                      <
444                         __tuple_convertible<_Tuple, tuple<_Tp...> >::value
445                      >::type
446             >
447        _LIBCPP_INLINE_VISIBILITY
448        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
449            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
450                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a,
451                                       _VSTD::forward<typename tuple_element<_Indx,
452                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
453            {}
454
455    template <class _Tuple>
456        _LIBCPP_INLINE_VISIBILITY
457        typename enable_if
458        <
459            __tuple_assignable<_Tuple, tuple<_Tp...> >::value,
460            __tuple_impl&
461        >::type
462        operator=(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_assignable<_Tp&, typename tuple_element<_Indx,
463                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
464        {
465            __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<typename tuple_element<_Indx,
466                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...);
467            return *this;
468        }
469
470    __tuple_impl(const __tuple_impl&) = default;
471    __tuple_impl(__tuple_impl&&) = default;
472
473    _LIBCPP_INLINE_VISIBILITY
474    __tuple_impl&
475    operator=(const __tuple_impl& __t) _NOEXCEPT_((__all<is_nothrow_copy_assignable<_Tp>::value...>::value))
476    {
477        __swallow(__tuple_leaf<_Indx, _Tp>::operator=(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t).get())...);
478        return *this;
479    }
480
481    _LIBCPP_INLINE_VISIBILITY
482    __tuple_impl&
483    operator=(__tuple_impl&& __t) _NOEXCEPT_((__all<is_nothrow_move_assignable<_Tp>::value...>::value))
484    {
485        __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<_Tp>(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t).get()))...);
486        return *this;
487    }
488
489    _LIBCPP_INLINE_VISIBILITY
490    void swap(__tuple_impl& __t)
491        _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
492    {
493        __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
494    }
495};
496
497template <class ..._Tp>
498class _LIBCPP_TYPE_VIS_ONLY tuple
499{
500    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
501
502    base base_;
503
504    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
505        typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
506    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
507        const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
508    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
509        typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
510public:
511
512    template <bool _Dummy = true, class = typename enable_if<
513        __all<__dependent_type<is_default_constructible<_Tp>, _Dummy>::value...>::value
514    >::type>
515    _LIBCPP_INLINE_VISIBILITY
516    _LIBCPP_CONSTEXPR tuple()
517        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
518
519    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
520    explicit tuple(const _Tp& ... __t) _NOEXCEPT_((__all<is_nothrow_copy_constructible<_Tp>::value...>::value)) 
521        : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
522                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
523                typename __make_tuple_indices<0>::type(),
524                typename __make_tuple_types<tuple, 0>::type(),
525                __t...
526               ) {}
527
528    template <class _Alloc>
529      _LIBCPP_INLINE_VISIBILITY
530      tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
531        : base_(allocator_arg_t(), __a,
532                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
533                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
534                typename __make_tuple_indices<0>::type(),
535                typename __make_tuple_types<tuple, 0>::type(),
536                __t...
537               ) {}
538
539    template <class ..._Up,
540              typename enable_if
541                      <
542                         sizeof...(_Up) <= sizeof...(_Tp) &&
543                         __tuple_convertible
544                         <
545                            tuple<_Up...>,
546                            typename __make_tuple_types<tuple,
547                                     sizeof...(_Up) < sizeof...(_Tp) ?
548                                        sizeof...(_Up) :
549                                        sizeof...(_Tp)>::type
550                         >::value &&
551                         __all_default_constructible<
552                            typename __make_tuple_types<tuple, sizeof...(_Tp),
553                                sizeof...(_Up) < sizeof...(_Tp) ?
554                                    sizeof...(_Up) :
555                                    sizeof...(_Tp)>::type
556                         >::value,
557                         bool
558                      >::type = false
559             >
560        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
561        tuple(_Up&&... __u)
562            _NOEXCEPT_((
563                is_nothrow_constructible<base,
564                    typename __make_tuple_indices<sizeof...(_Up)>::type,
565                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
566                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
567                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
568                    _Up...
569                >::value
570            ))
571            : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
572                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
573                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
574                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
575                    _VSTD::forward<_Up>(__u)...) {}
576
577    template <class ..._Up,
578              typename enable_if
579                      <
580                         sizeof...(_Up) <= sizeof...(_Tp) &&
581                         __tuple_constructible
582                         <
583                            tuple<_Up...>,
584                            typename __make_tuple_types<tuple,
585                                     sizeof...(_Up) < sizeof...(_Tp) ?
586                                        sizeof...(_Up) :
587                                        sizeof...(_Tp)>::type
588                         >::value &&
589                         !__tuple_convertible
590                         <
591                            tuple<_Up...>,
592                            typename __make_tuple_types<tuple,
593                                     sizeof...(_Up) < sizeof...(_Tp) ?
594                                        sizeof...(_Up) :
595                                        sizeof...(_Tp)>::type
596                         >::value &&
597                         __all_default_constructible<
598                            typename __make_tuple_types<tuple, sizeof...(_Tp),
599                                sizeof...(_Up) < sizeof...(_Tp) ?
600                                    sizeof...(_Up) :
601                                    sizeof...(_Tp)>::type
602                         >::value,
603                         bool
604                      >::type =false
605             >
606        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
607        explicit
608        tuple(_Up&&... __u)
609            _NOEXCEPT_((
610                is_nothrow_constructible<base,
611                    typename __make_tuple_indices<sizeof...(_Up)>::type,
612                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
613                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
614                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
615                    _Up...
616                >::value
617            ))
618            : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
619                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
620                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
621                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
622                    _VSTD::forward<_Up>(__u)...) {}
623
624    template <class _Alloc, class ..._Up,
625              class = typename enable_if
626                      <
627                         sizeof...(_Up) <= sizeof...(_Tp) &&
628                         __tuple_convertible
629                         <
630                            tuple<_Up...>,
631                            typename __make_tuple_types<tuple,
632                                     sizeof...(_Up) < sizeof...(_Tp) ?
633                                        sizeof...(_Up) :
634                                        sizeof...(_Tp)>::type
635                         >::value &&
636                         __all_default_constructible<
637                            typename __make_tuple_types<tuple, sizeof...(_Tp),
638                                sizeof...(_Up) < sizeof...(_Tp) ?
639                                    sizeof...(_Up) :
640                                    sizeof...(_Tp)>::type
641                         >::value
642                      >::type
643             >
644        _LIBCPP_INLINE_VISIBILITY
645        tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
646            : base_(allocator_arg_t(), __a,
647                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
648                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
649                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
650                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
651                    _VSTD::forward<_Up>(__u)...) {}
652
653    template <class _Tuple,
654              typename enable_if
655                      <
656                         __tuple_convertible<_Tuple, tuple>::value,
657                         bool
658                      >::type = false
659             >
660        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
661        tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
662            : base_(_VSTD::forward<_Tuple>(__t)) {}
663
664    template <class _Tuple,
665              typename enable_if
666                      <
667                         __tuple_constructible<_Tuple, tuple>::value &&
668                         !__tuple_convertible<_Tuple, tuple>::value,
669                         bool
670                      >::type = false
671             >
672        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
673        explicit
674        tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
675            : base_(_VSTD::forward<_Tuple>(__t)) {}
676
677    template <class _Alloc, class _Tuple,
678              class = typename enable_if
679                      <
680                         __tuple_convertible<_Tuple, tuple>::value
681                      >::type
682             >
683        _LIBCPP_INLINE_VISIBILITY
684        tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
685            : base_(allocator_arg_t(), __a, _VSTD::forward<_Tuple>(__t)) {}
686
687    template <class _Tuple,
688              class = typename enable_if
689                      <
690                         __tuple_assignable<_Tuple, tuple>::value
691                      >::type
692             >
693        _LIBCPP_INLINE_VISIBILITY
694        tuple&
695        operator=(_Tuple&& __t) _NOEXCEPT_((is_nothrow_assignable<base&, _Tuple>::value))
696        {
697            base_.operator=(_VSTD::forward<_Tuple>(__t));
698            return *this;
699        }
700
701    _LIBCPP_INLINE_VISIBILITY
702    void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
703        {base_.swap(__t.base_);}
704};
705
706template <>
707class _LIBCPP_TYPE_VIS_ONLY tuple<>
708{
709public:
710    _LIBCPP_INLINE_VISIBILITY
711    _LIBCPP_CONSTEXPR tuple() _NOEXCEPT {}
712    template <class _Alloc>
713    _LIBCPP_INLINE_VISIBILITY
714        tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
715    template <class _Alloc>
716    _LIBCPP_INLINE_VISIBILITY
717        tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
718    template <class _Up>
719    _LIBCPP_INLINE_VISIBILITY
720        tuple(array<_Up, 0>) _NOEXCEPT {}
721    template <class _Alloc, class _Up>
722    _LIBCPP_INLINE_VISIBILITY
723        tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
724    _LIBCPP_INLINE_VISIBILITY
725    void swap(tuple&) _NOEXCEPT {}
726};
727
728template <class ..._Tp>
729inline _LIBCPP_INLINE_VISIBILITY
730typename enable_if
731<
732    __all<__is_swappable<_Tp>::value...>::value,
733    void
734>::type
735swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
736                 _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
737    {__t.swap(__u);}
738
739// get
740
741template <size_t _Ip, class ..._Tp>
742inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
743typename tuple_element<_Ip, tuple<_Tp...> >::type&
744get(tuple<_Tp...>& __t) _NOEXCEPT
745{
746    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
747    return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
748}
749
750template <size_t _Ip, class ..._Tp>
751inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
752const typename tuple_element<_Ip, tuple<_Tp...> >::type&
753get(const tuple<_Tp...>& __t) _NOEXCEPT
754{
755    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
756    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
757}
758
759template <size_t _Ip, class ..._Tp>
760inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
761typename tuple_element<_Ip, tuple<_Tp...> >::type&&
762get(tuple<_Tp...>&& __t) _NOEXCEPT
763{
764    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
765    return static_cast<type&&>(
766             static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
767}
768
769#if _LIBCPP_STD_VER > 11
770// get by type
771template <typename _T1, size_t _Idx, typename... _Args>
772struct __find_exactly_one_t_helper;
773
774// -- find exactly one
775template <typename _T1, size_t _Idx, typename... _Args>
776struct __find_exactly_one_t_checker {
777    static constexpr size_t value = _Idx;
778//  Check the rest of the list to make sure there's only one
779    static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
780    };
781
782
783template <typename _T1, size_t _Idx>
784struct __find_exactly_one_t_helper <_T1, _Idx> {
785    static constexpr size_t value = -1;
786    };
787
788template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
789struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
790    static constexpr size_t value =
791        std::conditional<
792            std::is_same<_T1, _Head>::value,
793            __find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
794            __find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
795        >::type::value;
796    };
797
798template <typename _T1, typename... _Args>
799struct __find_exactly_one_t {
800    static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
801    static_assert ( value != -1, "type not found in type list" );
802    };
803
804template <class _T1, class... _Args>
805inline _LIBCPP_INLINE_VISIBILITY
806constexpr _T1& get(tuple<_Args...>& __tup) noexcept
807{
808    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
809}
810
811template <class _T1, class... _Args>
812inline _LIBCPP_INLINE_VISIBILITY
813constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
814{
815    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
816}
817
818template <class _T1, class... _Args>
819inline _LIBCPP_INLINE_VISIBILITY
820constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
821{
822    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
823}
824
825#endif
826
827// tie
828
829template <class ..._Tp>
830inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
831tuple<_Tp&...>
832tie(_Tp&... __t) _NOEXCEPT
833{
834    return tuple<_Tp&...>(__t...);
835}
836
837template <class _Up>
838struct __ignore_t
839{
840    template <class _Tp>
841        _LIBCPP_INLINE_VISIBILITY
842        const __ignore_t& operator=(_Tp&&) const {return *this;}
843};
844
845namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
846
847template <class _Tp>
848struct __make_tuple_return_impl
849{
850    typedef _Tp type;
851};
852
853template <class _Tp>
854struct __make_tuple_return_impl<reference_wrapper<_Tp> >
855{
856    typedef _Tp& type;
857};
858
859template <class _Tp>
860struct __make_tuple_return
861{
862    typedef typename __make_tuple_return_impl<typename decay<_Tp>::type>::type type;
863};
864
865template <class... _Tp>
866inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
867tuple<typename __make_tuple_return<_Tp>::type...>
868make_tuple(_Tp&&... __t)
869{
870    return tuple<typename __make_tuple_return<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
871}
872
873template <class... _Tp>
874inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
875tuple<_Tp&&...>
876forward_as_tuple(_Tp&&... __t) _NOEXCEPT
877{
878    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
879}
880
881template <size_t _Ip>
882struct __tuple_equal
883{
884    template <class _Tp, class _Up>
885    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
886    bool operator()(const _Tp& __x, const _Up& __y)
887    {
888        return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
889    }
890};
891
892template <>
893struct __tuple_equal<0>
894{
895    template <class _Tp, class _Up>
896    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
897    bool operator()(const _Tp&, const _Up&)
898    {
899        return true;
900    }
901};
902
903template <class ..._Tp, class ..._Up>
904inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
905bool
906operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
907{
908    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
909}
910
911template <class ..._Tp, class ..._Up>
912inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
913bool
914operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
915{
916    return !(__x == __y);
917}
918
919template <size_t _Ip>
920struct __tuple_less
921{
922    template <class _Tp, class _Up>
923    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
924    bool operator()(const _Tp& __x, const _Up& __y)
925    {
926        const size_t __idx = tuple_size<_Tp>::value - _Ip;
927        if (_VSTD::get<__idx>(__x) < _VSTD::get<__idx>(__y))
928            return true;
929        if (_VSTD::get<__idx>(__y) < _VSTD::get<__idx>(__x))
930            return false;
931        return __tuple_less<_Ip-1>()(__x, __y);
932    }
933};
934
935template <>
936struct __tuple_less<0>
937{
938    template <class _Tp, class _Up>
939    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
940    bool operator()(const _Tp&, const _Up&)
941    {
942        return false;
943    }
944};
945
946template <class ..._Tp, class ..._Up>
947inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
948bool
949operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
950{
951    return __tuple_less<sizeof...(_Tp)>()(__x, __y);
952}
953
954template <class ..._Tp, class ..._Up>
955inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
956bool
957operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
958{
959    return __y < __x;
960}
961
962template <class ..._Tp, class ..._Up>
963inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
964bool
965operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
966{
967    return !(__x < __y);
968}
969
970template <class ..._Tp, class ..._Up>
971inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
972bool
973operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
974{
975    return !(__y < __x);
976}
977
978// tuple_cat
979
980template <class _Tp, class _Up> struct __tuple_cat_type;
981
982template <class ..._Ttypes, class ..._Utypes>
983struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
984{
985    typedef tuple<_Ttypes..., _Utypes...> type;
986};
987
988template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
989struct __tuple_cat_return_1
990{
991};
992
993template <class ..._Types, class _Tuple0>
994struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
995{
996    typedef typename __tuple_cat_type<tuple<_Types...>,
997            typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type>::type
998                                                                           type;
999};
1000
1001template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
1002struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
1003    : public __tuple_cat_return_1<
1004                 typename __tuple_cat_type<
1005                     tuple<_Types...>,
1006                     typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type
1007                 >::type,
1008                 __tuple_like<typename remove_reference<_Tuple1>::type>::value,
1009                 _Tuple1, _Tuples...>
1010{
1011};
1012
1013template <class ..._Tuples> struct __tuple_cat_return;
1014
1015template <class _Tuple0, class ..._Tuples>
1016struct __tuple_cat_return<_Tuple0, _Tuples...>
1017    : public __tuple_cat_return_1<tuple<>,
1018         __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
1019                                                                     _Tuples...>
1020{
1021};
1022
1023template <>
1024struct __tuple_cat_return<>
1025{
1026    typedef tuple<> type;
1027};
1028
1029inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1030tuple<>
1031tuple_cat()
1032{
1033    return tuple<>();
1034}
1035
1036template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1037struct __tuple_cat_return_ref_imp;
1038
1039template <class ..._Types, size_t ..._I0, class _Tuple0>
1040struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1041{
1042    typedef typename remove_reference<_Tuple0>::type _T0;
1043    typedef tuple<_Types..., typename __apply_cv<_Tuple0,
1044                          typename tuple_element<_I0, _T0>::type>::type&&...> type;
1045};
1046
1047template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1048struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1049                                  _Tuple0, _Tuple1, _Tuples...>
1050    : public __tuple_cat_return_ref_imp<
1051         tuple<_Types..., typename __apply_cv<_Tuple0,
1052               typename tuple_element<_I0,
1053                  typename remove_reference<_Tuple0>::type>::type>::type&&...>,
1054         typename __make_tuple_indices<tuple_size<typename
1055                                 remove_reference<_Tuple1>::type>::value>::type,
1056         _Tuple1, _Tuples...>
1057{
1058};
1059
1060template <class _Tuple0, class ..._Tuples>
1061struct __tuple_cat_return_ref
1062    : public __tuple_cat_return_ref_imp<tuple<>,
1063               typename __make_tuple_indices<
1064                        tuple_size<typename remove_reference<_Tuple0>::type>::value
1065               >::type, _Tuple0, _Tuples...>
1066{
1067};
1068
1069template <class _Types, class _I0, class _J0>
1070struct __tuple_cat;
1071
1072template <class ..._Types, size_t ..._I0, size_t ..._J0>
1073struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1074{
1075    template <class _Tuple0>
1076    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1077    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1078    operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1079    {
1080        return forward_as_tuple(_VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1081                                      _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1082    }
1083
1084    template <class _Tuple0, class _Tuple1, class ..._Tuples>
1085    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1086    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1087    operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1088    {
1089        typedef typename remove_reference<_Tuple0>::type _T0;
1090        typedef typename remove_reference<_Tuple1>::type _T1;
1091        return __tuple_cat<
1092           tuple<_Types..., typename __apply_cv<_Tuple0, typename tuple_element<_J0, _T0>::type>::type&&...>,
1093           typename __make_tuple_indices<sizeof ...(_Types) + tuple_size<_T0>::value>::type,
1094           typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
1095                           (forward_as_tuple(
1096                              _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1097                              _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
1098                            ),
1099                            _VSTD::forward<_Tuple1>(__t1),
1100                            _VSTD::forward<_Tuples>(__tpls)...);
1101    }
1102};
1103
1104template <class _Tuple0, class... _Tuples>
1105inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1106typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1107tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1108{
1109    typedef typename remove_reference<_Tuple0>::type _T0;
1110    return __tuple_cat<tuple<>, __tuple_indices<>,
1111                  typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1112                  (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1113                                            _VSTD::forward<_Tuples>(__tpls)...);
1114}
1115
1116template <class ..._Tp, class _Alloc>
1117struct _LIBCPP_TYPE_VIS_ONLY uses_allocator<tuple<_Tp...>, _Alloc>
1118    : true_type {};
1119
1120template <class _T1, class _T2>
1121template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1122inline _LIBCPP_INLINE_VISIBILITY
1123pair<_T1, _T2>::pair(piecewise_construct_t,
1124                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1125                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1126    :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
1127      second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
1128{
1129}
1130
1131#endif  // _LIBCPP_HAS_NO_VARIADICS
1132
1133_LIBCPP_END_NAMESPACE_STD
1134
1135#endif  // _LIBCPP_TUPLE
1136