contrib/libc++/include/tuple

   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
  17 namespace std
  18 {
  19
  20 template <class... T>
  21 class tuple {
  22 public:
  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
  73 const unspecified ignore;
  74
  75 template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
  76 template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
  77 template <class... T> tuple<T&...> tie(T&...) noexcept;
  78 template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
  79
  80 // 20.4.1.4, tuple helper classes:
  81 template <class T> class tuple_size; // undefined
  82 template <class... T> class tuple_size<tuple<T...>>;
  83 template <intsize_t I, class T> class tuple_element; // undefined
  84 template <intsize_t I, class... T> class tuple_element<I, tuple<T...>>;
  85
  86 // 20.4.1.5, element access:
  87 template <intsize_t I, class... T>
  88     typename tuple_element<I, tuple<T...>>::type&
  89     get(tuple<T...>&) noexcept; // constexpr in C++14
  90 template <intsize_t I, class... T>
  91     typename tuple_element<I, tuple<T...>>::type const&
  92     get(const tuple<T...>&) noexcept; // constexpr in C++14
  93 template <intsize_t I, class... T>
  94     typename tuple_element<I, tuple<T...>>::type&&
  95     get(tuple<T...>&&) noexcept; // constexpr in C++14
  96
  97 template <class T1, class... T>
  98     constexpr T1& get(tuple<T...>&) noexcept;  // C++14
  99 template <class T1, class... T>
 100     constexpr T1 const& get(const tuple<T...>&) noexcept;   // C++14
 101 template <class T1, class... T>
 102     constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
 103
 104 // 20.4.1.6, relational operators:
 105 template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 106 template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
 107 template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 108 template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
 109 template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 110 template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 111
 112 template <class... Types, class Alloc>
 113   struct uses_allocator<tuple<Types...>, Alloc>;
 114
 115 template <class... Types>
 116   void
 117   swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
 118
 119 }  // std
 120
 121 */
 122
 123 #include <__config>
 124 #include <__tuple>
 125 #include <cstddef>
 126 #include <type_traits>
 127 #include <__functional_base>
 128 #include <utility>
 129
 130 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 131 #pragma GCC system_header
 132 #endif
 133
 134 _LIBCPP_BEGIN_NAMESPACE_STD
 135
 136 #ifndef _LIBCPP_HAS_NO_VARIADICS
 137
 138 // tuple_size
 139
 140 template <class ..._Tp>
 141 class _LIBCPP_TYPE_VIS_ONLY tuple_size<tuple<_Tp...> >
 142     : public integral_constant<size_t, sizeof...(_Tp)>
 143 {
 144 };
 145
 146 // tuple_element
 147
 148 template <size_t _Ip, class ..._Tp>
 149 class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, tuple<_Tp...> >
 150 {
 151 public:
 152     typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
 153 };
 154
 155 // __tuple_leaf
 156
 157 template <size_t _Ip, class _Hp, bool=is_empty<_Hp>::value
 158 #if __has_feature(is_final)
 159                                  && !__is_final(_Hp)
 160 #endif
 161          >
 162 class __tuple_leaf;
 163
 164 template <size_t _Ip, class _Hp, bool _Ep>
 165 inline _LIBCPP_INLINE_VISIBILITY
 166 void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
 167     _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
 168 {
 169     swap(__x.get(), __y.get());
 170 }
 171
 172 template <size_t _Ip, class _Hp, bool>
 173 class __tuple_leaf
 174 {
 175     _Hp value;
 176
 177     __tuple_leaf& operator=(const __tuple_leaf&);
 178 public:
 179     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
 180              _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : value()
 181        {static_assert(!is_reference<_Hp>::value,
 182               "Attempted to default construct a reference element in a tuple");}
 183
 184     template <class _Alloc>
 185         _LIBCPP_INLINE_VISIBILITY
 186         __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
 187             : value()
 188         {static_assert(!is_reference<_Hp>::value,
 189               "Attempted to default construct a reference element in a tuple");}
 190
 191     template <class _Alloc>
 192         _LIBCPP_INLINE_VISIBILITY
 193         __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
 194             : value(allocator_arg_t(), __a)
 195         {static_assert(!is_reference<_Hp>::value,
 196               "Attempted to default construct a reference element in a tuple");}
 197
 198     template <class _Alloc>
 199         _LIBCPP_INLINE_VISIBILITY
 200         __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
 201             : value(__a)
 202         {static_assert(!is_reference<_Hp>::value,
 203               "Attempted to default construct a reference element in a tuple");}
 204
 205     template <class _Tp,
 206               class = typename enable_if<is_constructible<_Hp, _Tp>::value>::type>
 207         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 208         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
 209             : value(_VSTD::forward<_Tp>(__t))
 210         {static_assert(!is_reference<_Hp>::value ||
 211                        (is_lvalue_reference<_Hp>::value &&
 212                         (is_lvalue_reference<_Tp>::value ||
 213                          is_same<typename remove_reference<_Tp>::type,
 214                                  reference_wrapper<
 215                                     typename remove_reference<_Hp>::type
 216                                  >
 217                                 >::value)) ||
 218                         (is_rvalue_reference<_Hp>::value &&
 219                          !is_lvalue_reference<_Tp>::value),
 220        "Attempted to construct a reference element in a tuple with an rvalue");}
 221
 222     template <class _Tp, class _Alloc>
 223         _LIBCPP_INLINE_VISIBILITY
 224         explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
 225             : value(_VSTD::forward<_Tp>(__t))
 226         {static_assert(!is_lvalue_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        "Attempted to construct a reference element in a tuple with an rvalue");}
 235
 236     template <class _Tp, class _Alloc>
 237         _LIBCPP_INLINE_VISIBILITY
 238         explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
 239             : value(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
 240         {static_assert(!is_lvalue_reference<_Hp>::value ||
 241                        (is_lvalue_reference<_Hp>::value &&
 242                         (is_lvalue_reference<_Tp>::value ||
 243                          is_same<typename remove_reference<_Tp>::type,
 244                                  reference_wrapper<
 245                                     typename remove_reference<_Hp>::type
 246                                  >
 247                                 >::value)),
 248        "Attempted to construct a reference element in a tuple with an rvalue");}
 249
 250     template <class _Tp, class _Alloc>
 251         _LIBCPP_INLINE_VISIBILITY
 252         explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
 253             : value(_VSTD::forward<_Tp>(__t), __a)
 254         {static_assert(!is_lvalue_reference<_Hp>::value ||
 255                        (is_lvalue_reference<_Hp>::value &&
 256                         (is_lvalue_reference<_Tp>::value ||
 257                          is_same<typename remove_reference<_Tp>::type,
 258                                  reference_wrapper<
 259                                     typename remove_reference<_Hp>::type
 260                                  >
 261                                 >::value)),
 262        "Attempted to construct a reference element in a tuple with an rvalue");}
 263
 264     _LIBCPP_INLINE_VISIBILITY
 265     _LIBCPP_CONSTEXPR_AFTER_CXX11
 266     __tuple_leaf(const __tuple_leaf& __t) _NOEXCEPT_(is_nothrow_copy_constructible<_Hp>::value)
 267         : value(__t.get())
 268         {static_assert(!is_rvalue_reference<_Hp>::value, "Can not copy a tuple with rvalue reference member");}
 269
 270     _LIBCPP_INLINE_VISIBILITY
 271     _LIBCPP_CONSTEXPR_AFTER_CXX11
 272     __tuple_leaf(__tuple_leaf&& __t) _NOEXCEPT_(is_nothrow_move_constructible<_Hp>::value)
 273         : value(_VSTD::forward<_Hp>(__t.get()))
 274         {}
 275
 276     template <class _Tp>
 277         _LIBCPP_INLINE_VISIBILITY
 278         __tuple_leaf&
 279         operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
 280         {
 281             value = _VSTD::forward<_Tp>(__t);
 282             return *this;
 283         }
 284
 285     _LIBCPP_INLINE_VISIBILITY
 286     int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
 287     {
 288         _VSTD::swap(*this, __t);
 289         return 0;
 290     }
 291
 292     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return value;}
 293     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return value;}
 294 };
 295
 296 template <size_t _Ip, class _Hp>
 297 class __tuple_leaf<_Ip, _Hp, true>
 298     : private _Hp
 299 {
 300
 301     __tuple_leaf& operator=(const __tuple_leaf&);
 302 public:
 303     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
 304              _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
 305
 306     template <class _Alloc>
 307         _LIBCPP_INLINE_VISIBILITY
 308         __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
 309
 310     template <class _Alloc>
 311         _LIBCPP_INLINE_VISIBILITY
 312         __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
 313             : _Hp(allocator_arg_t(), __a) {}
 314
 315     template <class _Alloc>
 316         _LIBCPP_INLINE_VISIBILITY
 317         __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
 318             : _Hp(__a) {}
 319
 320     template <class _Tp,
 321               class = typename enable_if<is_constructible<_Hp, _Tp>::value>::type>
 322         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 323         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
 324             : _Hp(_VSTD::forward<_Tp>(__t)) {}
 325
 326     template <class _Tp, class _Alloc>
 327         _LIBCPP_INLINE_VISIBILITY
 328         explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
 329             : _Hp(_VSTD::forward<_Tp>(__t)) {}
 330
 331     template <class _Tp, class _Alloc>
 332         _LIBCPP_INLINE_VISIBILITY
 333         explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
 334             : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
 335
 336     template <class _Tp, class _Alloc>
 337         _LIBCPP_INLINE_VISIBILITY
 338         explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
 339             : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
 340
 341     template <class _Tp>
 342         _LIBCPP_INLINE_VISIBILITY
 343         __tuple_leaf&
 344         operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
 345         {
 346             _Hp::operator=(_VSTD::forward<_Tp>(__t));
 347             return *this;
 348         }
 349
 350     _LIBCPP_INLINE_VISIBILITY
 351     int
 352     swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
 353     {
 354         _VSTD::swap(*this, __t);
 355         return 0;
 356     }
 357
 358     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
 359     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
 360 };
 361
 362 template <class ..._Tp>
 363 _LIBCPP_INLINE_VISIBILITY
 364 void __swallow(_Tp&&...) _NOEXCEPT {}
 365
 366 template <bool ...> struct __all;
 367
 368 template <>
 369 struct __all<>
 370 {
 371     static const bool value = true;
 372 };
 373
 374 template <bool _B0, bool ... _Bp>
 375 struct __all<_B0, _Bp...>
 376 {
 377     static const bool value = _B0 && __all<_Bp...>::value;
 378 };
 379
 380 // __tuple_impl
 381
 382 template<class _Indx, class ..._Tp> struct __tuple_impl;
 383
 384 template<size_t ..._Indx, class ..._Tp>
 385 struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
 386     : public __tuple_leaf<_Indx, _Tp>...
 387 {
 388     _LIBCPP_INLINE_VISIBILITY
 389     _LIBCPP_CONSTEXPR __tuple_impl()
 390         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 391
 392     template <size_t ..._Uf, class ..._Tf,
 393               size_t ..._Ul, class ..._Tl, class ..._Up>
 394         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 395         explicit
 396         __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 397                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 398                      _Up&&... __u)
 399                      _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
 400                                  __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
 401             __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
 402             __tuple_leaf<_Ul, _Tl>()...
 403             {}
 404
 405     template <class _Alloc, size_t ..._Uf, class ..._Tf,
 406               size_t ..._Ul, class ..._Tl, class ..._Up>
 407         _LIBCPP_INLINE_VISIBILITY
 408         explicit
 409         __tuple_impl(allocator_arg_t, const _Alloc& __a,
 410                      __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 411                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 412                      _Up&&... __u) :
 413             __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
 414             _VSTD::forward<_Up>(__u))...,
 415             __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
 416             {}
 417
 418     template <class _Tuple,
 419               class = typename enable_if
 420                       <
 421                          __tuple_constructible<_Tuple, tuple<_Tp...> >::value
 422                       >::type
 423              >
 424         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 425         __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
 426                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 427             : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
 428                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 429             {}
 430
 431     template <class _Alloc, class _Tuple,
 432               class = typename enable_if
 433                       <
 434                          __tuple_convertible<_Tuple, tuple<_Tp...> >::value
 435                       >::type
 436              >
 437         _LIBCPP_INLINE_VISIBILITY
 438         __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 439             : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
 440                                        typename __make_tuple_types<_Tuple>::type>::type>(), __a,
 441                                        _VSTD::forward<typename tuple_element<_Indx,
 442                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 443             {}
 444
 445     template <class _Tuple>
 446         _LIBCPP_INLINE_VISIBILITY
 447         typename enable_if
 448         <
 449             __tuple_assignable<_Tuple, tuple<_Tp...> >::value,
 450             __tuple_impl&
 451         >::type
 452         operator=(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_assignable<_Tp&, typename tuple_element<_Indx,
 453                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 454         {
 455             __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<typename tuple_element<_Indx,
 456                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...);
 457             return *this;
 458         }
 459
 460     __tuple_impl(const __tuple_impl&) = default;
 461     __tuple_impl(__tuple_impl&&) = default;
 462
 463     _LIBCPP_INLINE_VISIBILITY
 464     __tuple_impl&
 465     operator=(const __tuple_impl& __t) _NOEXCEPT_((__all<is_nothrow_copy_assignable<_Tp>::value...>::value))
 466     {
 467         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t).get())...);
 468         return *this;
 469     }
 470
 471     _LIBCPP_INLINE_VISIBILITY
 472     __tuple_impl&
 473     operator=(__tuple_impl&& __t) _NOEXCEPT_((__all<is_nothrow_move_assignable<_Tp>::value...>::value))
 474     {
 475         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<_Tp>(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t).get()))...);
 476         return *this;
 477     }
 478
 479     _LIBCPP_INLINE_VISIBILITY
 480     void swap(__tuple_impl& __t)
 481         _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 482     {
 483         __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
 484     }
 485 };
 486
 487 template <class ..._Tp>
 488 class _LIBCPP_TYPE_VIS_ONLY tuple
 489 {
 490     typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
 491
 492     base base_;
 493
 494     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 495         typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
 496     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 497         const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
 498     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 499         typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
 500 public:
 501
 502     _LIBCPP_INLINE_VISIBILITY
 503     _LIBCPP_CONSTEXPR tuple()
 504         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 505
 506     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 507     explicit tuple(const _Tp& ... __t) _NOEXCEPT_((__all<is_nothrow_copy_constructible<_Tp>::value...>::value))
 508         : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 509                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 510                 typename __make_tuple_indices<0>::type(),
 511                 typename __make_tuple_types<tuple, 0>::type(),
 512                 __t...
 513                ) {}
 514
 515     template <class _Alloc>
 516       _LIBCPP_INLINE_VISIBILITY
 517       tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
 518         : base_(allocator_arg_t(), __a,
 519                 typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 520                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 521                 typename __make_tuple_indices<0>::type(),
 522                 typename __make_tuple_types<tuple, 0>::type(),
 523                 __t...
 524                ) {}
 525
 526     template <class ..._Up,
 527               typename enable_if
 528                       <
 529                          sizeof...(_Up) <= sizeof...(_Tp) &&
 530                          __tuple_convertible
 531                          <
 532                             tuple<_Up...>,
 533                             typename __make_tuple_types<tuple,
 534                                      sizeof...(_Up) < sizeof...(_Tp) ?
 535                                         sizeof...(_Up) :
 536                                         sizeof...(_Tp)>::type
 537                          >::value,
 538                          bool
 539                       >::type = false
 540              >
 541         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 542         tuple(_Up&&... __u)
 543             _NOEXCEPT_((
 544                 is_nothrow_constructible<
 545                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 546                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 547                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 548                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 549                     _Up...
 550                 >::value
 551             ))
 552             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 553                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 554                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 555                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 556                     _VSTD::forward<_Up>(__u)...) {}
 557
 558     template <class ..._Up,
 559               typename enable_if
 560                       <
 561                          sizeof...(_Up) <= sizeof...(_Tp) &&
 562                          __tuple_constructible
 563                          <
 564                             tuple<_Up...>,
 565                             typename __make_tuple_types<tuple,
 566                                      sizeof...(_Up) < sizeof...(_Tp) ?
 567                                         sizeof...(_Up) :
 568                                         sizeof...(_Tp)>::type
 569                          >::value &&
 570                          !__tuple_convertible
 571                          <
 572                             tuple<_Up...>,
 573                             typename __make_tuple_types<tuple,
 574                                      sizeof...(_Up) < sizeof...(_Tp) ?
 575                                         sizeof...(_Up) :
 576                                         sizeof...(_Tp)>::type
 577                          >::value,
 578                          bool
 579                       >::type =false
 580              >
 581         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 582         explicit
 583         tuple(_Up&&... __u)
 584             _NOEXCEPT_((
 585                 is_nothrow_constructible<
 586                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 587                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 588                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 589                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 590                     _Up...
 591                 >::value
 592             ))
 593             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 594                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 595                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 596                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 597                     _VSTD::forward<_Up>(__u)...) {}
 598
 599     template <class _Alloc, class ..._Up,
 600               class = typename enable_if
 601                       <
 602                          sizeof...(_Up) <= sizeof...(_Tp) &&
 603                          __tuple_convertible
 604                          <
 605                             tuple<_Up...>,
 606                             typename __make_tuple_types<tuple,
 607                                      sizeof...(_Up) < sizeof...(_Tp) ?
 608                                         sizeof...(_Up) :
 609                                         sizeof...(_Tp)>::type
 610                          >::value
 611                       >::type
 612              >
 613         _LIBCPP_INLINE_VISIBILITY
 614         tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
 615             : base_(allocator_arg_t(), __a,
 616                     typename __make_tuple_indices<sizeof...(_Up)>::type(),
 617                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 618                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 619                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 620                     _VSTD::forward<_Up>(__u)...) {}
 621
 622     template <class _Tuple,
 623               typename enable_if
 624                       <
 625                          __tuple_convertible<_Tuple, tuple>::value,
 626                          bool
 627                       >::type = false
 628              >
 629         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 630         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 631             : base_(_VSTD::forward<_Tuple>(__t)) {}
 632
 633     template <class _Tuple,
 634               typename enable_if
 635                       <
 636                          __tuple_constructible<_Tuple, tuple>::value &&
 637                          !__tuple_convertible<_Tuple, tuple>::value,
 638                          bool
 639                       >::type = false
 640              >
 641         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 642         explicit
 643         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 644             : base_(_VSTD::forward<_Tuple>(__t)) {}
 645
 646     template <class _Alloc, class _Tuple,
 647               class = typename enable_if
 648                       <
 649                          __tuple_convertible<_Tuple, tuple>::value
 650                       >::type
 651              >
 652         _LIBCPP_INLINE_VISIBILITY
 653         tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 654             : base_(allocator_arg_t(), __a, _VSTD::forward<_Tuple>(__t)) {}
 655
 656     template <class _Tuple,
 657               class = typename enable_if
 658                       <
 659                          __tuple_assignable<_Tuple, tuple>::value
 660                       >::type
 661              >
 662         _LIBCPP_INLINE_VISIBILITY
 663         tuple&
 664         operator=(_Tuple&& __t) _NOEXCEPT_((is_nothrow_assignable<base&, _Tuple>::value))
 665         {
 666             base_.operator=(_VSTD::forward<_Tuple>(__t));
 667             return *this;
 668         }
 669
 670     _LIBCPP_INLINE_VISIBILITY
 671     void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 672         {base_.swap(__t.base_);}
 673 };
 674
 675 template <>
 676 class _LIBCPP_TYPE_VIS_ONLY tuple<>
 677 {
 678 public:
 679     _LIBCPP_INLINE_VISIBILITY
 680     _LIBCPP_CONSTEXPR tuple() _NOEXCEPT {}
 681     template <class _Alloc>
 682     _LIBCPP_INLINE_VISIBILITY
 683         tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
 684     template <class _Alloc>
 685     _LIBCPP_INLINE_VISIBILITY
 686         tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
 687     template <class _Up>
 688     _LIBCPP_INLINE_VISIBILITY
 689         tuple(array<_Up, 0>) _NOEXCEPT {}
 690     template <class _Alloc, class _Up>
 691     _LIBCPP_INLINE_VISIBILITY
 692         tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
 693     _LIBCPP_INLINE_VISIBILITY
 694     void swap(tuple&) _NOEXCEPT {}
 695 };
 696
 697 template <class ..._Tp>
 698 inline _LIBCPP_INLINE_VISIBILITY
 699 typename enable_if
 700 <
 701     __all<__is_swappable<_Tp>::value...>::value,
 702     void
 703 >::type
 704 swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
 705                  _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 706     {__t.swap(__u);}
 707
 708 // get
 709
 710 template <size_t _Ip, class ..._Tp>
 711 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 712 typename tuple_element<_Ip, tuple<_Tp...> >::type&
 713 get(tuple<_Tp...>& __t) _NOEXCEPT
 714 {
 715     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 716     return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
 717 }
 718
 719 template <size_t _Ip, class ..._Tp>
 720 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 721 const typename tuple_element<_Ip, tuple<_Tp...> >::type&
 722 get(const tuple<_Tp...>& __t) _NOEXCEPT
 723 {
 724     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 725     return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
 726 }
 727
 728 template <size_t _Ip, class ..._Tp>
 729 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 730 typename tuple_element<_Ip, tuple<_Tp...> >::type&&
 731 get(tuple<_Tp...>&& __t) _NOEXCEPT
 732 {
 733     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 734     return static_cast<type&&>(
 735              static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
 736 }
 737
 738 #if _LIBCPP_STD_VER > 11
 739 // get by type
 740 template <typename _T1, size_t _Idx, typename... _Args>
 741 struct __find_exactly_one_t_helper;
 742
 743 // -- find exactly one
 744 template <typename _T1, size_t _Idx, typename... _Args>
 745 struct __find_exactly_one_t_checker {
 746     static constexpr size_t value = _Idx;
 747 //  Check the rest of the list to make sure there's only one
 748     static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
 749     };
 750
 751
 752 template <typename _T1, size_t _Idx>
 753 struct __find_exactly_one_t_helper <_T1, _Idx> {
 754     static constexpr size_t value = -1;
 755     };
 756
 757 template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
 758 struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
 759     static constexpr size_t value =
 760         std::conditional<
 761             std::is_same<_T1, _Head>::value,
 762             __find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
 763             __find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
 764         >::type::value;
 765     };
 766
 767 template <typename _T1, typename... _Args>
 768 struct __find_exactly_one_t {
 769     static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
 770     static_assert ( value != -1, "type not found in type list" );
 771     };
 772
 773 template <class _T1, class... _Args>
 774 inline _LIBCPP_INLINE_VISIBILITY
 775 constexpr _T1& get(tuple<_Args...>& __tup) noexcept
 776 {
 777     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 778 }
 779
 780 template <class _T1, class... _Args>
 781 inline _LIBCPP_INLINE_VISIBILITY
 782 constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
 783 {
 784     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 785 }
 786
 787 template <class _T1, class... _Args>
 788 inline _LIBCPP_INLINE_VISIBILITY
 789 constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
 790 {
 791     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
 792 }
 793
 794 #endif
 795
 796 // tie
 797
 798 template <class ..._Tp>
 799 inline _LIBCPP_INLINE_VISIBILITY
 800 tuple<_Tp&...>
 801 tie(_Tp&... __t) _NOEXCEPT
 802 {
 803     return tuple<_Tp&...>(__t...);
 804 }
 805
 806 template <class _Up>
 807 struct __ignore_t
 808 {
 809     template <class _Tp>
 810         _LIBCPP_INLINE_VISIBILITY
 811         const __ignore_t& operator=(_Tp&&) const {return *this;}
 812 };
 813
 814 namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
 815
 816 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
 817
 818 template <class _Tp>
 819 struct ___make_tuple_return
 820 {
 821     typedef _Tp type;
 822 };
 823
 824 template <class _Tp>
 825 struct ___make_tuple_return<reference_wrapper<_Tp> >
 826 {
 827     typedef _Tp& type;
 828 };
 829
 830 template <class _Tp>
 831 struct __make_tuple_return
 832 {
 833     typedef typename ___make_tuple_return<typename decay<_Tp>::type>::type type;
 834 };
 835
 836 template <class... _Tp>
 837 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 838 tuple<typename __make_tuple_return<_Tp>::type...>
 839 make_tuple(_Tp&&... __t)
 840 {
 841     return tuple<typename __make_tuple_return<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
 842 }
 843
 844 template <class... _Tp>
 845 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 846 tuple<_Tp&&...>
 847 forward_as_tuple(_Tp&&... __t) _NOEXCEPT
 848 {
 849     return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
 850 }
 851
 852 template <size_t _Ip>
 853 struct __tuple_equal
 854 {
 855     template <class _Tp, class _Up>
 856     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 857     bool operator()(const _Tp& __x, const _Up& __y)
 858     {
 859         return __tuple_equal<_Ip - 1>()(__x, __y) && get<_Ip-1>(__x) == get<_Ip-1>(__y);
 860     }
 861 };
 862
 863 template <>
 864 struct __tuple_equal<0>
 865 {
 866     template <class _Tp, class _Up>
 867     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 868     bool operator()(const _Tp&, const _Up&)
 869     {
 870         return true;
 871     }
 872 };
 873
 874 template <class ..._Tp, class ..._Up>
 875 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 876 bool
 877 operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 878 {
 879     return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
 880 }
 881
 882 template <class ..._Tp, class ..._Up>
 883 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 884 bool
 885 operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 886 {
 887     return !(__x == __y);
 888 }
 889
 890 template <size_t _Ip>
 891 struct __tuple_less
 892 {
 893     template <class _Tp, class _Up>
 894     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 895     bool operator()(const _Tp& __x, const _Up& __y)
 896     {
 897         return __tuple_less<_Ip-1>()(__x, __y) ||
 898              (!__tuple_less<_Ip-1>()(__y, __x) && get<_Ip-1>(__x) < get<_Ip-1>(__y));
 899     }
 900 };
 901
 902 template <>
 903 struct __tuple_less<0>
 904 {
 905     template <class _Tp, class _Up>
 906     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 907     bool operator()(const _Tp&, const _Up&)
 908     {
 909         return false;
 910     }
 911 };
 912
 913 template <class ..._Tp, class ..._Up>
 914 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 915 bool
 916 operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 917 {
 918     return __tuple_less<sizeof...(_Tp)>()(__x, __y);
 919 }
 920
 921 template <class ..._Tp, class ..._Up>
 922 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 923 bool
 924 operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 925 {
 926     return __y < __x;
 927 }
 928
 929 template <class ..._Tp, class ..._Up>
 930 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 931 bool
 932 operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 933 {
 934     return !(__x < __y);
 935 }
 936
 937 template <class ..._Tp, class ..._Up>
 938 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 939 bool
 940 operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 941 {
 942     return !(__y < __x);
 943 }
 944
 945 // tuple_cat
 946
 947 template <class _Tp, class _Up> struct __tuple_cat_type;
 948
 949 template <class ..._Ttypes, class ..._Utypes>
 950 struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
 951 {
 952     typedef tuple<_Ttypes..., _Utypes...> type;
 953 };
 954
 955 template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
 956 struct __tuple_cat_return_1
 957 {
 958 };
 959
 960 template <class ..._Types, class _Tuple0>
 961 struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
 962 {
 963     typedef typename __tuple_cat_type<tuple<_Types...>,
 964             typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type>::type
 965                                                                            type;
 966 };
 967
 968 template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
 969 struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
 970     : public __tuple_cat_return_1<
 971                  typename __tuple_cat_type<
 972                      tuple<_Types...>,
 973                      typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type
 974                  >::type,
 975                  __tuple_like<typename remove_reference<_Tuple1>::type>::value,
 976                  _Tuple1, _Tuples...>
 977 {
 978 };
 979
 980 template <class ..._Tuples> struct __tuple_cat_return;
 981
 982 template <class _Tuple0, class ..._Tuples>
 983 struct __tuple_cat_return<_Tuple0, _Tuples...>
 984     : public __tuple_cat_return_1<tuple<>,
 985          __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
 986                                                                      _Tuples...>
 987 {
 988 };
 989
 990 template <>
 991 struct __tuple_cat_return<>
 992 {
 993     typedef tuple<> type;
 994 };
 995
 996 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 997 tuple<>
 998 tuple_cat()
 999 {
1000     return tuple<>();
1001 }
1002
1003 template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1004 struct __tuple_cat_return_ref_imp;
1005
1006 template <class ..._Types, size_t ..._I0, class _Tuple0>
1007 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1008 {
1009     typedef typename remove_reference<_Tuple0>::type _T0;
1010     typedef tuple<_Types..., typename __apply_cv<_Tuple0,
1011                           typename tuple_element<_I0, _T0>::type>::type&&...> type;
1012 };
1013
1014 template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1015 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1016                                   _Tuple0, _Tuple1, _Tuples...>
1017     : public __tuple_cat_return_ref_imp<
1018          tuple<_Types..., typename __apply_cv<_Tuple0,
1019                typename tuple_element<_I0,
1020                   typename remove_reference<_Tuple0>::type>::type>::type&&...>,
1021          typename __make_tuple_indices<tuple_size<typename
1022                                  remove_reference<_Tuple1>::type>::value>::type,
1023          _Tuple1, _Tuples...>
1024 {
1025 };
1026
1027 template <class _Tuple0, class ..._Tuples>
1028 struct __tuple_cat_return_ref
1029     : public __tuple_cat_return_ref_imp<tuple<>,
1030                typename __make_tuple_indices<
1031                         tuple_size<typename remove_reference<_Tuple0>::type>::value
1032                >::type, _Tuple0, _Tuples...>
1033 {
1034 };
1035
1036 template <class _Types, class _I0, class _J0>
1037 struct __tuple_cat;
1038
1039 template <class ..._Types, size_t ..._I0, size_t ..._J0>
1040 struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1041 {
1042     template <class _Tuple0>
1043     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1044     typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1045     operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1046     {
1047         return forward_as_tuple(_VSTD::forward<_Types>(get<_I0>(__t))...,
1048                                       get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1049     }
1050
1051     template <class _Tuple0, class _Tuple1, class ..._Tuples>
1052     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1053     typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1054     operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1055     {
1056         typedef typename remove_reference<_Tuple0>::type _T0;
1057         typedef typename remove_reference<_Tuple1>::type _T1;
1058         return __tuple_cat<
1059            tuple<_Types..., typename __apply_cv<_Tuple0, typename tuple_element<_J0, _T0>::type>::type&&...>,
1060            typename __make_tuple_indices<sizeof ...(_Types) + tuple_size<_T0>::value>::type,
1061            typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
1062                            (forward_as_tuple(
1063                               _VSTD::forward<_Types>(get<_I0>(__t))...,
1064                               get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
1065                             ),
1066                             _VSTD::forward<_Tuple1>(__t1),
1067                             _VSTD::forward<_Tuples>(__tpls)...);
1068     }
1069 };
1070
1071 template <class _Tuple0, class... _Tuples>
1072 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1073 typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1074 tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1075 {
1076     typedef typename remove_reference<_Tuple0>::type _T0;
1077     return __tuple_cat<tuple<>, __tuple_indices<>,
1078                   typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1079                   (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1080                                             _VSTD::forward<_Tuples>(__tpls)...);
1081 }
1082
1083 template <class ..._Tp, class _Alloc>
1084 struct _LIBCPP_TYPE_VIS_ONLY uses_allocator<tuple<_Tp...>, _Alloc>
1085     : true_type {};
1086
1087 template <class _T1, class _T2>
1088 template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1089 inline _LIBCPP_INLINE_VISIBILITY
1090 pair<_T1, _T2>::pair(piecewise_construct_t,
1091                      tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1092                      __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1093     :  first(_VSTD::forward<_Args1>(get<_I1>( __first_args))...),
1094       second(_VSTD::forward<_Args2>(get<_I2>(__second_args))...)
1095 {
1096 }
1097
1098 #endif  // _LIBCPP_HAS_NO_VARIADICS
1099
1100 _LIBCPP_END_NAMESPACE_STD
1101
1102 #endif  // _LIBCPP_TUPLE