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 <size_t I, class T> class tuple_element; // undefined
84template <size_t I, class... T> class tuple_element<I, tuple<T...>>;
85template <size_t I, class T>
86  using tuple_element_t = typename tuple_element <I, T>::type; // C++14
87
88// 20.4.1.5, element access:
89template <size_t I, class... T>
90    typename tuple_element<I, tuple<T...>>::type&
91    get(tuple<T...>&) noexcept; // constexpr in C++14
92template <size_t I, class... T>
93    const typename tuple_element<I, tuple<T...>>::type&
94    get(const tuple<T...>&) noexcept; // constexpr in C++14
95template <size_t I, class... T>
96    typename tuple_element<I, tuple<T...>>::type&&
97    get(tuple<T...>&&) noexcept; // constexpr in C++14
98template <size_t I, class... T>
99    const typename tuple_element<I, tuple<T...>>::type&&
100    get(const tuple<T...>&&) noexcept; // constexpr in C++14
101
102template <class T1, class... T>
103    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
104template <class T1, class... T>
105    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14
106template <class T1, class... T>
107    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
108template <class T1, class... T>
109    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14
110
111// 20.4.1.6, relational operators:
112template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
113template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
114template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
115template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
116template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
117template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
118
119template <class... Types, class Alloc>
120  struct uses_allocator<tuple<Types...>, Alloc>;
121
122template <class... Types>
123  void
124  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
125
126}  // std
127
128*/
129
130#include <__config>
131#include <__tuple>
132#include <cstddef>
133#include <type_traits>
134#include <__functional_base>
135#include <utility>
136
137#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
138#pragma GCC system_header
139#endif
140
141_LIBCPP_BEGIN_NAMESPACE_STD
142
143#ifndef _LIBCPP_HAS_NO_VARIADICS
144
145// tuple_size
146
147template <class ..._Tp>
148class _LIBCPP_TYPE_VIS_ONLY tuple_size<tuple<_Tp...> >
149    : public integral_constant<size_t, sizeof...(_Tp)>
150{
151};
152
153// tuple_element
154
155template <size_t _Ip, class ..._Tp>
156class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, tuple<_Tp...> >
157{
158public:
159    typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
160};
161
162#if _LIBCPP_STD_VER > 11
163template <size_t _Ip, class ..._Tp>
164using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type;
165#endif
166
167// __tuple_leaf
168
169template <size_t _Ip, class _Hp,
170          bool=is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value
171         >
172class __tuple_leaf;
173
174template <size_t _Ip, class _Hp, bool _Ep>
175inline _LIBCPP_INLINE_VISIBILITY
176void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
177    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
178{
179    swap(__x.get(), __y.get());
180}
181
182template <size_t _Ip, class _Hp, bool>
183class __tuple_leaf
184{
185    _Hp value;
186
187    __tuple_leaf& operator=(const __tuple_leaf&);
188public:
189    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
190             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : value()
191       {static_assert(!is_reference<_Hp>::value,
192              "Attempted to default construct a reference element in a tuple");}
193
194    template <class _Alloc>
195        _LIBCPP_INLINE_VISIBILITY
196        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
197            : value()
198        {static_assert(!is_reference<_Hp>::value,
199              "Attempted to default construct a reference element in a tuple");}
200
201    template <class _Alloc>
202        _LIBCPP_INLINE_VISIBILITY
203        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
204            : value(allocator_arg_t(), __a)
205        {static_assert(!is_reference<_Hp>::value,
206              "Attempted to default construct a reference element in a tuple");}
207
208    template <class _Alloc>
209        _LIBCPP_INLINE_VISIBILITY
210        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
211            : value(__a)
212        {static_assert(!is_reference<_Hp>::value,
213              "Attempted to default construct a reference element in a tuple");}
214
215    template <class _Tp,
216              class = typename enable_if<
217                  __lazy_and<
218                      __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
219                    , is_constructible<_Hp, _Tp>
220                    >::value
221                >::type
222            >
223        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
224        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
225            : value(_VSTD::forward<_Tp>(__t))
226        {static_assert(!is_reference<_Hp>::value ||
227                       (is_lvalue_reference<_Hp>::value &&
228                        (is_lvalue_reference<_Tp>::value ||
229                         is_same<typename remove_reference<_Tp>::type,
230                                 reference_wrapper<
231                                    typename remove_reference<_Hp>::type
232                                 >
233                                >::value)) ||
234                        (is_rvalue_reference<_Hp>::value &&
235                         !is_lvalue_reference<_Tp>::value),
236       "Attempted to construct a reference element in a tuple with an rvalue");}
237
238    template <class _Tp, class _Alloc>
239        _LIBCPP_INLINE_VISIBILITY
240        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
241            : value(_VSTD::forward<_Tp>(__t))
242        {static_assert(!is_lvalue_reference<_Hp>::value ||
243                       (is_lvalue_reference<_Hp>::value &&
244                        (is_lvalue_reference<_Tp>::value ||
245                         is_same<typename remove_reference<_Tp>::type,
246                                 reference_wrapper<
247                                    typename remove_reference<_Hp>::type
248                                 >
249                                >::value)),
250       "Attempted to construct a reference element in a tuple with an rvalue");}
251
252    template <class _Tp, class _Alloc>
253        _LIBCPP_INLINE_VISIBILITY
254        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
255            : value(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
256        {static_assert(!is_lvalue_reference<_Hp>::value ||
257                       (is_lvalue_reference<_Hp>::value &&
258                        (is_lvalue_reference<_Tp>::value ||
259                         is_same<typename remove_reference<_Tp>::type,
260                                 reference_wrapper<
261                                    typename remove_reference<_Hp>::type
262                                 >
263                                >::value)),
264       "Attempted to construct a reference element in a tuple with an rvalue");}
265
266    template <class _Tp, class _Alloc>
267        _LIBCPP_INLINE_VISIBILITY
268        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
269            : value(_VSTD::forward<_Tp>(__t), __a)
270        {static_assert(!is_lvalue_reference<_Hp>::value ||
271                       (is_lvalue_reference<_Hp>::value &&
272                        (is_lvalue_reference<_Tp>::value ||
273                         is_same<typename remove_reference<_Tp>::type,
274                                 reference_wrapper<
275                                    typename remove_reference<_Hp>::type
276                                 >
277                                >::value)),
278       "Attempted to construct a reference element in a tuple with an rvalue");}
279
280    __tuple_leaf(const __tuple_leaf& __t) = default;
281    __tuple_leaf(__tuple_leaf&& __t) = default;
282
283    template <class _Tp>
284        _LIBCPP_INLINE_VISIBILITY
285        __tuple_leaf&
286        operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
287        {
288            value = _VSTD::forward<_Tp>(__t);
289            return *this;
290        }
291
292    _LIBCPP_INLINE_VISIBILITY
293    int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
294    {
295        _VSTD::swap(*this, __t);
296        return 0;
297    }
298
299    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return value;}
300    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return value;}
301};
302
303template <size_t _Ip, class _Hp>
304class __tuple_leaf<_Ip, _Hp, true>
305    : private _Hp
306{
307
308    __tuple_leaf& operator=(const __tuple_leaf&);
309public:
310    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
311             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
312
313    template <class _Alloc>
314        _LIBCPP_INLINE_VISIBILITY
315        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
316
317    template <class _Alloc>
318        _LIBCPP_INLINE_VISIBILITY
319        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
320            : _Hp(allocator_arg_t(), __a) {}
321
322    template <class _Alloc>
323        _LIBCPP_INLINE_VISIBILITY
324        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
325            : _Hp(__a) {}
326
327    template <class _Tp,
328              class = typename enable_if<
329                  __lazy_and<
330                        __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
331                      , is_constructible<_Hp, _Tp>
332                    >::value
333                >::type
334            >
335        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
336        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
337            : _Hp(_VSTD::forward<_Tp>(__t)) {}
338
339    template <class _Tp, class _Alloc>
340        _LIBCPP_INLINE_VISIBILITY
341        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
342            : _Hp(_VSTD::forward<_Tp>(__t)) {}
343
344    template <class _Tp, class _Alloc>
345        _LIBCPP_INLINE_VISIBILITY
346        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
347            : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
348
349    template <class _Tp, class _Alloc>
350        _LIBCPP_INLINE_VISIBILITY
351        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
352            : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
353
354    __tuple_leaf(__tuple_leaf const &) = default;
355    __tuple_leaf(__tuple_leaf &&) = default;
356
357    template <class _Tp>
358        _LIBCPP_INLINE_VISIBILITY
359        __tuple_leaf&
360        operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
361        {
362            _Hp::operator=(_VSTD::forward<_Tp>(__t));
363            return *this;
364        }
365
366    _LIBCPP_INLINE_VISIBILITY
367    int
368    swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
369    {
370        _VSTD::swap(*this, __t);
371        return 0;
372    }
373
374    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
375    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
376};
377
378template <class ..._Tp>
379_LIBCPP_INLINE_VISIBILITY
380void __swallow(_Tp&&...) _NOEXCEPT {}
381
382template <bool ..._Pred>
383struct __all
384    : is_same<__all<_Pred...>, __all<(_Pred, true)...>>
385{ };
386
387template <class _Tp>
388struct __all_default_constructible;
389
390template <class ..._Tp>
391struct __all_default_constructible<__tuple_types<_Tp...>>
392    : __all<is_default_constructible<_Tp>::value...>
393{ };
394
395// __tuple_impl
396
397template<class _Indx, class ..._Tp> struct __tuple_impl;
398
399template<size_t ..._Indx, class ..._Tp>
400struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
401    : public __tuple_leaf<_Indx, _Tp>...
402{
403    _LIBCPP_INLINE_VISIBILITY
404    _LIBCPP_CONSTEXPR __tuple_impl()
405        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
406
407    template <size_t ..._Uf, class ..._Tf,
408              size_t ..._Ul, class ..._Tl, class ..._Up>
409        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
410        explicit
411        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
412                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
413                     _Up&&... __u)
414                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
415                                 __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
416            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
417            __tuple_leaf<_Ul, _Tl>()...
418            {}
419
420    template <class _Alloc, size_t ..._Uf, class ..._Tf,
421              size_t ..._Ul, class ..._Tl, class ..._Up>
422        _LIBCPP_INLINE_VISIBILITY
423        explicit
424        __tuple_impl(allocator_arg_t, const _Alloc& __a,
425                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
426                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
427                     _Up&&... __u) :
428            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
429            _VSTD::forward<_Up>(__u))...,
430            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
431            {}
432
433    template <class _Tuple,
434              class = typename enable_if
435                      <
436                         __tuple_constructible<_Tuple, tuple<_Tp...> >::value
437                      >::type
438             >
439        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
440        __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
441                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
442            : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
443                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
444            {}
445
446    template <class _Alloc, class _Tuple,
447              class = typename enable_if
448                      <
449                         __tuple_convertible<_Tuple, tuple<_Tp...> >::value
450                      >::type
451             >
452        _LIBCPP_INLINE_VISIBILITY
453        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
454            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
455                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a,
456                                       _VSTD::forward<typename tuple_element<_Indx,
457                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
458            {}
459
460    template <class _Tuple>
461        _LIBCPP_INLINE_VISIBILITY
462        typename enable_if
463        <
464            __tuple_assignable<_Tuple, tuple<_Tp...> >::value,
465            __tuple_impl&
466        >::type
467        operator=(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_assignable<_Tp&, typename tuple_element<_Indx,
468                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
469        {
470            __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<typename tuple_element<_Indx,
471                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...);
472            return *this;
473        }
474
475    __tuple_impl(const __tuple_impl&) = default;
476    __tuple_impl(__tuple_impl&&) = default;
477
478    _LIBCPP_INLINE_VISIBILITY
479    __tuple_impl&
480    operator=(const __tuple_impl& __t) _NOEXCEPT_((__all<is_nothrow_copy_assignable<_Tp>::value...>::value))
481    {
482        __swallow(__tuple_leaf<_Indx, _Tp>::operator=(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t).get())...);
483        return *this;
484    }
485
486    _LIBCPP_INLINE_VISIBILITY
487    __tuple_impl&
488    operator=(__tuple_impl&& __t) _NOEXCEPT_((__all<is_nothrow_move_assignable<_Tp>::value...>::value))
489    {
490        __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<_Tp>(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t).get()))...);
491        return *this;
492    }
493
494    _LIBCPP_INLINE_VISIBILITY
495    void swap(__tuple_impl& __t)
496        _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
497    {
498        __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
499    }
500};
501
502template <class ..._Tp>
503class _LIBCPP_TYPE_VIS_ONLY tuple
504{
505    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
506
507    base base_;
508
509    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
510        typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
511    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
512        const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
513    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
514        typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
515    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
516        const typename tuple_element<_Jp, tuple<_Up...> >::type&& get(const tuple<_Up...>&&) _NOEXCEPT;
517public:
518
519    template <bool _Dummy = true, class = typename enable_if<
520        __all<__dependent_type<is_default_constructible<_Tp>, _Dummy>::value...>::value
521    >::type>
522    _LIBCPP_INLINE_VISIBILITY
523    _LIBCPP_CONSTEXPR tuple()
524        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
525
526    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
527    explicit tuple(const _Tp& ... __t) _NOEXCEPT_((__all<is_nothrow_copy_constructible<_Tp>::value...>::value)) 
528        : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
529                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
530                typename __make_tuple_indices<0>::type(),
531                typename __make_tuple_types<tuple, 0>::type(),
532                __t...
533               ) {}
534
535    template <class _Alloc>
536      _LIBCPP_INLINE_VISIBILITY
537      tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
538        : base_(allocator_arg_t(), __a,
539                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
540                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
541                typename __make_tuple_indices<0>::type(),
542                typename __make_tuple_types<tuple, 0>::type(),
543                __t...
544               ) {}
545
546    template <class ..._Up,
547              typename enable_if
548                      <
549                         sizeof...(_Up) <= sizeof...(_Tp) &&
550                         __tuple_convertible
551                         <
552                            tuple<_Up...>,
553                            typename __make_tuple_types<tuple,
554                                     sizeof...(_Up) < sizeof...(_Tp) ?
555                                        sizeof...(_Up) :
556                                        sizeof...(_Tp)>::type
557                         >::value &&
558                         __all_default_constructible<
559                            typename __make_tuple_types<tuple, sizeof...(_Tp),
560                                sizeof...(_Up) < sizeof...(_Tp) ?
561                                    sizeof...(_Up) :
562                                    sizeof...(_Tp)>::type
563                         >::value,
564                         bool
565                      >::type = false
566             >
567        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
568        tuple(_Up&&... __u)
569            _NOEXCEPT_((
570                is_nothrow_constructible<base,
571                    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                    _Up...
576                >::value
577            ))
578            : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
579                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
580                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
581                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
582                    _VSTD::forward<_Up>(__u)...) {}
583
584    template <class ..._Up,
585              typename enable_if
586                      <
587                         sizeof...(_Up) <= sizeof...(_Tp) &&
588                         __tuple_constructible
589                         <
590                            tuple<_Up...>,
591                            typename __make_tuple_types<tuple,
592                                     sizeof...(_Up) < sizeof...(_Tp) ?
593                                        sizeof...(_Up) :
594                                        sizeof...(_Tp)>::type
595                         >::value &&
596                         !__tuple_convertible
597                         <
598                            tuple<_Up...>,
599                            typename __make_tuple_types<tuple,
600                                     sizeof...(_Up) < sizeof...(_Tp) ?
601                                        sizeof...(_Up) :
602                                        sizeof...(_Tp)>::type
603                         >::value &&
604                         __all_default_constructible<
605                            typename __make_tuple_types<tuple, sizeof...(_Tp),
606                                sizeof...(_Up) < sizeof...(_Tp) ?
607                                    sizeof...(_Up) :
608                                    sizeof...(_Tp)>::type
609                         >::value,
610                         bool
611                      >::type =false
612             >
613        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
614        explicit
615        tuple(_Up&&... __u)
616            _NOEXCEPT_((
617                is_nothrow_constructible<base,
618                    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                    _Up...
623                >::value
624            ))
625            : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
626                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
627                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
628                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
629                    _VSTD::forward<_Up>(__u)...) {}
630
631    template <class _Alloc, class ..._Up,
632              class = typename enable_if
633                      <
634                         sizeof...(_Up) <= sizeof...(_Tp) &&
635                         __tuple_convertible
636                         <
637                            tuple<_Up...>,
638                            typename __make_tuple_types<tuple,
639                                     sizeof...(_Up) < sizeof...(_Tp) ?
640                                        sizeof...(_Up) :
641                                        sizeof...(_Tp)>::type
642                         >::value &&
643                         __all_default_constructible<
644                            typename __make_tuple_types<tuple, sizeof...(_Tp),
645                                sizeof...(_Up) < sizeof...(_Tp) ?
646                                    sizeof...(_Up) :
647                                    sizeof...(_Tp)>::type
648                         >::value
649                      >::type
650             >
651        _LIBCPP_INLINE_VISIBILITY
652        tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
653            : base_(allocator_arg_t(), __a,
654                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
655                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
656                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
657                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
658                    _VSTD::forward<_Up>(__u)...) {}
659
660    template <class _Tuple,
661              typename enable_if
662                      <
663                         __tuple_convertible<_Tuple, tuple>::value,
664                         bool
665                      >::type = false
666             >
667        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
668        tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
669            : base_(_VSTD::forward<_Tuple>(__t)) {}
670
671    template <class _Tuple,
672              typename enable_if
673                      <
674                         __tuple_constructible<_Tuple, tuple>::value &&
675                         !__tuple_convertible<_Tuple, tuple>::value,
676                         bool
677                      >::type = false
678             >
679        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
680        explicit
681        tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
682            : base_(_VSTD::forward<_Tuple>(__t)) {}
683
684    template <class _Alloc, class _Tuple,
685              class = typename enable_if
686                      <
687                         __tuple_convertible<_Tuple, tuple>::value
688                      >::type
689             >
690        _LIBCPP_INLINE_VISIBILITY
691        tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
692            : base_(allocator_arg_t(), __a, _VSTD::forward<_Tuple>(__t)) {}
693
694    template <class _Tuple,
695              class = typename enable_if
696                      <
697                         __tuple_assignable<_Tuple, tuple>::value
698                      >::type
699             >
700        _LIBCPP_INLINE_VISIBILITY
701        tuple&
702        operator=(_Tuple&& __t) _NOEXCEPT_((is_nothrow_assignable<base&, _Tuple>::value))
703        {
704            base_.operator=(_VSTD::forward<_Tuple>(__t));
705            return *this;
706        }
707
708    _LIBCPP_INLINE_VISIBILITY
709    void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
710        {base_.swap(__t.base_);}
711};
712
713template <>
714class _LIBCPP_TYPE_VIS_ONLY tuple<>
715{
716public:
717    _LIBCPP_INLINE_VISIBILITY
718    _LIBCPP_CONSTEXPR tuple() _NOEXCEPT {}
719    template <class _Alloc>
720    _LIBCPP_INLINE_VISIBILITY
721        tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
722    template <class _Alloc>
723    _LIBCPP_INLINE_VISIBILITY
724        tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
725    template <class _Up>
726    _LIBCPP_INLINE_VISIBILITY
727        tuple(array<_Up, 0>) _NOEXCEPT {}
728    template <class _Alloc, class _Up>
729    _LIBCPP_INLINE_VISIBILITY
730        tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
731    _LIBCPP_INLINE_VISIBILITY
732    void swap(tuple&) _NOEXCEPT {}
733};
734
735template <class ..._Tp>
736inline _LIBCPP_INLINE_VISIBILITY
737typename enable_if
738<
739    __all<__is_swappable<_Tp>::value...>::value,
740    void
741>::type
742swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
743                 _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
744    {__t.swap(__u);}
745
746// get
747
748template <size_t _Ip, class ..._Tp>
749inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
750typename tuple_element<_Ip, tuple<_Tp...> >::type&
751get(tuple<_Tp...>& __t) _NOEXCEPT
752{
753    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
754    return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
755}
756
757template <size_t _Ip, class ..._Tp>
758inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
759const typename tuple_element<_Ip, tuple<_Tp...> >::type&
760get(const tuple<_Tp...>& __t) _NOEXCEPT
761{
762    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
763    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
764}
765
766template <size_t _Ip, class ..._Tp>
767inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
768typename tuple_element<_Ip, tuple<_Tp...> >::type&&
769get(tuple<_Tp...>&& __t) _NOEXCEPT
770{
771    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
772    return static_cast<type&&>(
773             static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
774}
775
776template <size_t _Ip, class ..._Tp>
777inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
778const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
779get(const tuple<_Tp...>&& __t) _NOEXCEPT
780{
781    typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
782    return static_cast<const type&&>(
783             static_cast<const __tuple_leaf<_Ip, type>&&>(__t.base_).get());
784}
785
786#if _LIBCPP_STD_VER > 11
787// get by type
788template <typename _T1, size_t _Idx, typename... _Args>
789struct __find_exactly_one_t_helper;
790
791// -- find exactly one
792template <typename _T1, size_t _Idx, typename... _Args>
793struct __find_exactly_one_t_checker {
794    static constexpr size_t value = _Idx;
795//  Check the rest of the list to make sure there's only one
796    static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
797    };
798
799
800template <typename _T1, size_t _Idx>
801struct __find_exactly_one_t_helper <_T1, _Idx> {
802    static constexpr size_t value = -1;
803    };
804
805template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
806struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
807    static constexpr size_t value =
808        std::conditional<
809            std::is_same<_T1, _Head>::value,
810            __find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
811            __find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
812        >::type::value;
813    };
814
815template <typename _T1, typename... _Args>
816struct __find_exactly_one_t {
817    static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
818    static_assert ( value != -1, "type not found in type list" );
819    };
820
821template <class _T1, class... _Args>
822inline _LIBCPP_INLINE_VISIBILITY
823constexpr _T1& get(tuple<_Args...>& __tup) noexcept
824{
825    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
826}
827
828template <class _T1, class... _Args>
829inline _LIBCPP_INLINE_VISIBILITY
830constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
831{
832    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
833}
834
835template <class _T1, class... _Args>
836inline _LIBCPP_INLINE_VISIBILITY
837constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
838{
839    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
840}
841
842template <class _T1, class... _Args>
843inline _LIBCPP_INLINE_VISIBILITY
844constexpr _T1 const&& get(tuple<_Args...> const&& __tup) noexcept
845{
846    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
847}
848
849#endif
850
851// tie
852
853template <class ..._Tp>
854inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
855tuple<_Tp&...>
856tie(_Tp&... __t) _NOEXCEPT
857{
858    return tuple<_Tp&...>(__t...);
859}
860
861template <class _Up>
862struct __ignore_t
863{
864    template <class _Tp>
865        _LIBCPP_INLINE_VISIBILITY
866        const __ignore_t& operator=(_Tp&&) const {return *this;}
867};
868
869namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
870
871template <class _Tp>
872struct __make_tuple_return_impl
873{
874    typedef _Tp type;
875};
876
877template <class _Tp>
878struct __make_tuple_return_impl<reference_wrapper<_Tp> >
879{
880    typedef _Tp& type;
881};
882
883template <class _Tp>
884struct __make_tuple_return
885{
886    typedef typename __make_tuple_return_impl<typename decay<_Tp>::type>::type type;
887};
888
889template <class... _Tp>
890inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
891tuple<typename __make_tuple_return<_Tp>::type...>
892make_tuple(_Tp&&... __t)
893{
894    return tuple<typename __make_tuple_return<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
895}
896
897template <class... _Tp>
898inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
899tuple<_Tp&&...>
900forward_as_tuple(_Tp&&... __t) _NOEXCEPT
901{
902    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
903}
904
905template <size_t _Ip>
906struct __tuple_equal
907{
908    template <class _Tp, class _Up>
909    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
910    bool operator()(const _Tp& __x, const _Up& __y)
911    {
912        return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
913    }
914};
915
916template <>
917struct __tuple_equal<0>
918{
919    template <class _Tp, class _Up>
920    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
921    bool operator()(const _Tp&, const _Up&)
922    {
923        return true;
924    }
925};
926
927template <class ..._Tp, class ..._Up>
928inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
929bool
930operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
931{
932    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
933}
934
935template <class ..._Tp, class ..._Up>
936inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
937bool
938operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
939{
940    return !(__x == __y);
941}
942
943template <size_t _Ip>
944struct __tuple_less
945{
946    template <class _Tp, class _Up>
947    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
948    bool operator()(const _Tp& __x, const _Up& __y)
949    {
950        const size_t __idx = tuple_size<_Tp>::value - _Ip;
951        if (_VSTD::get<__idx>(__x) < _VSTD::get<__idx>(__y))
952            return true;
953        if (_VSTD::get<__idx>(__y) < _VSTD::get<__idx>(__x))
954            return false;
955        return __tuple_less<_Ip-1>()(__x, __y);
956    }
957};
958
959template <>
960struct __tuple_less<0>
961{
962    template <class _Tp, class _Up>
963    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
964    bool operator()(const _Tp&, const _Up&)
965    {
966        return false;
967    }
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 __tuple_less<sizeof...(_Tp)>()(__x, __y);
976}
977
978template <class ..._Tp, class ..._Up>
979inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
980bool
981operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
982{
983    return __y < __x;
984}
985
986template <class ..._Tp, class ..._Up>
987inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
988bool
989operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
990{
991    return !(__x < __y);
992}
993
994template <class ..._Tp, class ..._Up>
995inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
996bool
997operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
998{
999    return !(__y < __x);
1000}
1001
1002// tuple_cat
1003
1004template <class _Tp, class _Up> struct __tuple_cat_type;
1005
1006template <class ..._Ttypes, class ..._Utypes>
1007struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
1008{
1009    typedef tuple<_Ttypes..., _Utypes...> type;
1010};
1011
1012template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
1013struct __tuple_cat_return_1
1014{
1015};
1016
1017template <class ..._Types, class _Tuple0>
1018struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
1019{
1020    typedef typename __tuple_cat_type<tuple<_Types...>,
1021            typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type>::type
1022                                                                           type;
1023};
1024
1025template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
1026struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
1027    : public __tuple_cat_return_1<
1028                 typename __tuple_cat_type<
1029                     tuple<_Types...>,
1030                     typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type
1031                 >::type,
1032                 __tuple_like<typename remove_reference<_Tuple1>::type>::value,
1033                 _Tuple1, _Tuples...>
1034{
1035};
1036
1037template <class ..._Tuples> struct __tuple_cat_return;
1038
1039template <class _Tuple0, class ..._Tuples>
1040struct __tuple_cat_return<_Tuple0, _Tuples...>
1041    : public __tuple_cat_return_1<tuple<>,
1042         __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
1043                                                                     _Tuples...>
1044{
1045};
1046
1047template <>
1048struct __tuple_cat_return<>
1049{
1050    typedef tuple<> type;
1051};
1052
1053inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1054tuple<>
1055tuple_cat()
1056{
1057    return tuple<>();
1058}
1059
1060template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1061struct __tuple_cat_return_ref_imp;
1062
1063template <class ..._Types, size_t ..._I0, class _Tuple0>
1064struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1065{
1066    typedef typename remove_reference<_Tuple0>::type _T0;
1067    typedef tuple<_Types..., typename __apply_cv<_Tuple0,
1068                          typename tuple_element<_I0, _T0>::type>::type&&...> type;
1069};
1070
1071template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1072struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1073                                  _Tuple0, _Tuple1, _Tuples...>
1074    : public __tuple_cat_return_ref_imp<
1075         tuple<_Types..., typename __apply_cv<_Tuple0,
1076               typename tuple_element<_I0,
1077                  typename remove_reference<_Tuple0>::type>::type>::type&&...>,
1078         typename __make_tuple_indices<tuple_size<typename
1079                                 remove_reference<_Tuple1>::type>::value>::type,
1080         _Tuple1, _Tuples...>
1081{
1082};
1083
1084template <class _Tuple0, class ..._Tuples>
1085struct __tuple_cat_return_ref
1086    : public __tuple_cat_return_ref_imp<tuple<>,
1087               typename __make_tuple_indices<
1088                        tuple_size<typename remove_reference<_Tuple0>::type>::value
1089               >::type, _Tuple0, _Tuples...>
1090{
1091};
1092
1093template <class _Types, class _I0, class _J0>
1094struct __tuple_cat;
1095
1096template <class ..._Types, size_t ..._I0, size_t ..._J0>
1097struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1098{
1099    template <class _Tuple0>
1100    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1101    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1102    operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1103    {
1104        return forward_as_tuple(_VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1105                                      _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1106    }
1107
1108    template <class _Tuple0, class _Tuple1, class ..._Tuples>
1109    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1110    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1111    operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1112    {
1113        typedef typename remove_reference<_Tuple0>::type _T0;
1114        typedef typename remove_reference<_Tuple1>::type _T1;
1115        return __tuple_cat<
1116           tuple<_Types..., typename __apply_cv<_Tuple0, typename tuple_element<_J0, _T0>::type>::type&&...>,
1117           typename __make_tuple_indices<sizeof ...(_Types) + tuple_size<_T0>::value>::type,
1118           typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
1119                           (forward_as_tuple(
1120                              _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1121                              _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
1122                            ),
1123                            _VSTD::forward<_Tuple1>(__t1),
1124                            _VSTD::forward<_Tuples>(__tpls)...);
1125    }
1126};
1127
1128template <class _Tuple0, class... _Tuples>
1129inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1130typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1131tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1132{
1133    typedef typename remove_reference<_Tuple0>::type _T0;
1134    return __tuple_cat<tuple<>, __tuple_indices<>,
1135                  typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1136                  (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1137                                            _VSTD::forward<_Tuples>(__tpls)...);
1138}
1139
1140template <class ..._Tp, class _Alloc>
1141struct _LIBCPP_TYPE_VIS_ONLY uses_allocator<tuple<_Tp...>, _Alloc>
1142    : true_type {};
1143
1144template <class _T1, class _T2>
1145template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1146inline _LIBCPP_INLINE_VISIBILITY
1147pair<_T1, _T2>::pair(piecewise_construct_t,
1148                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1149                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1150    :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
1151      second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
1152{
1153}
1154
1155#endif  // _LIBCPP_HAS_NO_VARIADICS
1156
1157_LIBCPP_END_NAMESPACE_STD
1158
1159#endif  // _LIBCPP_TUPLE
1160