src/third_party/libc++/trunk/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; // constexpr in C++14
  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 template <size_t _Ip, class ..._Tp>
  86   using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type; // C++14
  87
  88 // 20.4.1.5, element access:
  89 template <intsize_t I, class... T>
  90     typename tuple_element<I, tuple<T...>>::type&
  91     get(tuple<T...>&) noexcept; // constexpr in C++14
  92 template <intsize_t I, class... T>
  93     typename const tuple_element<I, tuple<T...>>::type &
  94     get(const tuple<T...>&) noexcept; // constexpr in C++14
  95 template <intsize_t I, class... T>
  96     typename tuple_element<I, tuple<T...>>::type&&
  97     get(tuple<T...>&&) noexcept; // constexpr in C++14
  98
  99 template <class T1, class... T>
 100     constexpr T1& get(tuple<T...>&) noexcept;  // C++14
 101 template <class T1, class... T>
 102     constexpr T1 const& get(const tuple<T...>&) noexcept;   // C++14
 103 template <class T1, class... T>
 104     constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
 105
 106 // 20.4.1.6, relational operators:
 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 template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 112 template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
 113
 114 template <class... Types, class Alloc>
 115   struct uses_allocator<tuple<Types...>, Alloc>;
 116
 117 template <class... Types>
 118   void
 119   swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
 120
 121 }  // std
 122
 123 */
 124
 125 #include <__config>
 126 #include <__tuple>
 127 #include <cstddef>
 128 #include <type_traits>
 129 #include <__functional_base>
 130 #include <utility>
 131
 132 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 133 #pragma GCC system_header
 134 #endif
 135
 136 _LIBCPP_BEGIN_NAMESPACE_STD
 137
 138 #ifndef _LIBCPP_HAS_NO_VARIADICS
 139
 140 // tuple_size
 141
 142 template <class ..._Tp>
 143 class _LIBCPP_TYPE_VIS_ONLY tuple_size<tuple<_Tp...> >
 144     : public integral_constant<size_t, sizeof...(_Tp)>
 145 {
 146 };
 147
 148 // tuple_element
 149
 150 template <size_t _Ip, class ..._Tp>
 151 class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, tuple<_Tp...> >
 152 {
 153 public:
 154     typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
 155 };
 156
 157 #if _LIBCPP_STD_VER > 11
 158 template <size_t _Ip, class ..._Tp>
 159 using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type;
 160 #endif
 161
 162 // __tuple_leaf
 163
 164 template <size_t _Ip, class _Hp, bool=is_empty<_Hp>::value
 165 #if __has_feature(is_final)
 166                                  && !__is_final(_Hp)
 167 #endif
 168          >
 169 class __tuple_leaf;
 170
 171 template <size_t _Ip, class _Hp, bool _Ep>
 172 inline _LIBCPP_INLINE_VISIBILITY
 173 void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
 174     _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
 175 {
 176     swap(__x.get(), __y.get());
 177 }
 178
 179 template <size_t _Ip, class _Hp, bool>
 180 class __tuple_leaf
 181 {
 182     _Hp value;
 183
 184     __tuple_leaf& operator=(const __tuple_leaf&);
 185 public:
 186     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
 187              _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : 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, 0>, const _Alloc&)
 194             : value()
 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, 1>, const _Alloc& __a)
 201             : value(allocator_arg_t(), __a)
 202         {static_assert(!is_reference<_Hp>::value,
 203               "Attempted to default construct a reference element in a tuple");}
 204
 205     template <class _Alloc>
 206         _LIBCPP_INLINE_VISIBILITY
 207         __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
 208             : value(__a)
 209         {static_assert(!is_reference<_Hp>::value,
 210               "Attempted to default construct a reference element in a tuple");}
 211
 212     template <class _Tp,
 213               class = typename enable_if<
 214                   __lazy_and<
 215                       __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
 216                     , is_constructible<_Hp, _Tp>
 217                     >::value
 218                 >::type
 219             >
 220         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 221         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
 222             : value(_VSTD::forward<_Tp>(__t))
 223         {static_assert(!is_reference<_Hp>::value ||
 224                        (is_lvalue_reference<_Hp>::value &&
 225                         (is_lvalue_reference<_Tp>::value ||
 226                          is_same<typename remove_reference<_Tp>::type,
 227                                  reference_wrapper<
 228                                     typename remove_reference<_Hp>::type
 229                                  >
 230                                 >::value)) ||
 231                         (is_rvalue_reference<_Hp>::value &&
 232                          !is_lvalue_reference<_Tp>::value),
 233        "Attempted to construct a reference element in a tuple with an rvalue");}
 234
 235     template <class _Tp, class _Alloc>
 236         _LIBCPP_INLINE_VISIBILITY
 237         explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
 238             : value(_VSTD::forward<_Tp>(__t))
 239         {static_assert(!is_lvalue_reference<_Hp>::value ||
 240                        (is_lvalue_reference<_Hp>::value &&
 241                         (is_lvalue_reference<_Tp>::value ||
 242                          is_same<typename remove_reference<_Tp>::type,
 243                                  reference_wrapper<
 244                                     typename remove_reference<_Hp>::type
 245                                  >
 246                                 >::value)),
 247        "Attempted to construct a reference element in a tuple with an rvalue");}
 248
 249     template <class _Tp, class _Alloc>
 250         _LIBCPP_INLINE_VISIBILITY
 251         explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
 252             : value(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
 253         {static_assert(!is_lvalue_reference<_Hp>::value ||
 254                        (is_lvalue_reference<_Hp>::value &&
 255                         (is_lvalue_reference<_Tp>::value ||
 256                          is_same<typename remove_reference<_Tp>::type,
 257                                  reference_wrapper<
 258                                     typename remove_reference<_Hp>::type
 259                                  >
 260                                 >::value)),
 261        "Attempted to construct a reference element in a tuple with an rvalue");}
 262
 263     template <class _Tp, class _Alloc>
 264         _LIBCPP_INLINE_VISIBILITY
 265         explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
 266             : value(_VSTD::forward<_Tp>(__t), __a)
 267         {static_assert(!is_lvalue_reference<_Hp>::value ||
 268                        (is_lvalue_reference<_Hp>::value &&
 269                         (is_lvalue_reference<_Tp>::value ||
 270                          is_same<typename remove_reference<_Tp>::type,
 271                                  reference_wrapper<
 272                                     typename remove_reference<_Hp>::type
 273                                  >
 274                                 >::value)),
 275        "Attempted to construct a reference element in a tuple with an rvalue");}
 276
 277     __tuple_leaf(const __tuple_leaf& __t) = default;
 278     __tuple_leaf(__tuple_leaf&& __t) = default;
 279
 280     template <class _Tp>
 281         _LIBCPP_INLINE_VISIBILITY
 282         __tuple_leaf&
 283         operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
 284         {
 285             value = _VSTD::forward<_Tp>(__t);
 286             return *this;
 287         }
 288
 289     _LIBCPP_INLINE_VISIBILITY
 290     int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
 291     {
 292         _VSTD::swap(*this, __t);
 293         return 0;
 294     }
 295
 296     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return value;}
 297     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return value;}
 298 };
 299
 300 template <size_t _Ip, class _Hp>
 301 class __tuple_leaf<_Ip, _Hp, true>
 302     : private _Hp
 303 {
 304
 305     __tuple_leaf& operator=(const __tuple_leaf&);
 306 public:
 307     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __tuple_leaf()
 308              _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
 309
 310     template <class _Alloc>
 311         _LIBCPP_INLINE_VISIBILITY
 312         __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
 313
 314     template <class _Alloc>
 315         _LIBCPP_INLINE_VISIBILITY
 316         __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
 317             : _Hp(allocator_arg_t(), __a) {}
 318
 319     template <class _Alloc>
 320         _LIBCPP_INLINE_VISIBILITY
 321         __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
 322             : _Hp(__a) {}
 323
 324     template <class _Tp,
 325               class = typename enable_if<
 326                   __lazy_and<
 327                         __lazy_not<is_same<typename decay<_Tp>::type, __tuple_leaf>>
 328                       , is_constructible<_Hp, _Tp>
 329                     >::value
 330                 >::type
 331             >
 332         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 333         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
 334             : _Hp(_VSTD::forward<_Tp>(__t)) {}
 335
 336     template <class _Tp, class _Alloc>
 337         _LIBCPP_INLINE_VISIBILITY
 338         explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
 339             : _Hp(_VSTD::forward<_Tp>(__t)) {}
 340
 341     template <class _Tp, class _Alloc>
 342         _LIBCPP_INLINE_VISIBILITY
 343         explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
 344             : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
 345
 346     template <class _Tp, class _Alloc>
 347         _LIBCPP_INLINE_VISIBILITY
 348         explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
 349             : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
 350
 351     __tuple_leaf(__tuple_leaf const &) = default;
 352     __tuple_leaf(__tuple_leaf &&) = default;
 353
 354     template <class _Tp>
 355         _LIBCPP_INLINE_VISIBILITY
 356         __tuple_leaf&
 357         operator=(_Tp&& __t) _NOEXCEPT_((is_nothrow_assignable<_Hp&, _Tp>::value))
 358         {
 359             _Hp::operator=(_VSTD::forward<_Tp>(__t));
 360             return *this;
 361         }
 362
 363     _LIBCPP_INLINE_VISIBILITY
 364     int
 365     swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
 366     {
 367         _VSTD::swap(*this, __t);
 368         return 0;
 369     }
 370
 371     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
 372     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
 373 };
 374
 375 template <class ..._Tp>
 376 _LIBCPP_INLINE_VISIBILITY
 377 void __swallow(_Tp&&...) _NOEXCEPT {}
 378
 379 template <bool ...> struct __all;
 380
 381 template <>
 382 struct __all<>
 383 {
 384     static const bool value = true;
 385 };
 386
 387 template <bool _B0, bool ... _Bp>
 388 struct __all<_B0, _Bp...>
 389 {
 390     static const bool value = _B0 && __all<_Bp...>::value;
 391 };
 392
 393 // __tuple_impl
 394
 395 template<class _Indx, class ..._Tp> struct __tuple_impl;
 396
 397 template<size_t ..._Indx, class ..._Tp>
 398 struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
 399     : public __tuple_leaf<_Indx, _Tp>...
 400 {
 401     _LIBCPP_INLINE_VISIBILITY
 402     _LIBCPP_CONSTEXPR __tuple_impl()
 403         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 404
 405     template <size_t ..._Uf, class ..._Tf,
 406               size_t ..._Ul, class ..._Tl, class ..._Up>
 407         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 408         explicit
 409         __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 410                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 411                      _Up&&... __u)
 412                      _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
 413                                  __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
 414             __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
 415             __tuple_leaf<_Ul, _Tl>()...
 416             {}
 417
 418     template <class _Alloc, size_t ..._Uf, class ..._Tf,
 419               size_t ..._Ul, class ..._Tl, class ..._Up>
 420         _LIBCPP_INLINE_VISIBILITY
 421         explicit
 422         __tuple_impl(allocator_arg_t, const _Alloc& __a,
 423                      __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 424                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 425                      _Up&&... __u) :
 426             __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
 427             _VSTD::forward<_Up>(__u))...,
 428             __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
 429             {}
 430
 431     template <class _Tuple,
 432               class = typename enable_if
 433                       <
 434                          __tuple_constructible<_Tuple, tuple<_Tp...> >::value
 435                       >::type
 436              >
 437         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 438         __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
 439                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 440             : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
 441                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 442             {}
 443
 444     template <class _Alloc, class _Tuple,
 445               class = typename enable_if
 446                       <
 447                          __tuple_convertible<_Tuple, tuple<_Tp...> >::value
 448                       >::type
 449              >
 450         _LIBCPP_INLINE_VISIBILITY
 451         __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 452             : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
 453                                        typename __make_tuple_types<_Tuple>::type>::type>(), __a,
 454                                        _VSTD::forward<typename tuple_element<_Indx,
 455                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 456             {}
 457
 458     template <class _Tuple>
 459         _LIBCPP_INLINE_VISIBILITY
 460         typename enable_if
 461         <
 462             __tuple_assignable<_Tuple, tuple<_Tp...> >::value,
 463             __tuple_impl&
 464         >::type
 465         operator=(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_assignable<_Tp&, typename tuple_element<_Indx,
 466                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 467         {
 468             __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<typename tuple_element<_Indx,
 469                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...);
 470             return *this;
 471         }
 472
 473     __tuple_impl(const __tuple_impl&) = default;
 474     __tuple_impl(__tuple_impl&&) = default;
 475
 476     _LIBCPP_INLINE_VISIBILITY
 477     __tuple_impl&
 478     operator=(const __tuple_impl& __t) _NOEXCEPT_((__all<is_nothrow_copy_assignable<_Tp>::value...>::value))
 479     {
 480         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t).get())...);
 481         return *this;
 482     }
 483
 484     _LIBCPP_INLINE_VISIBILITY
 485     __tuple_impl&
 486     operator=(__tuple_impl&& __t) _NOEXCEPT_((__all<is_nothrow_move_assignable<_Tp>::value...>::value))
 487     {
 488         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<_Tp>(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t).get()))...);
 489         return *this;
 490     }
 491
 492     _LIBCPP_INLINE_VISIBILITY
 493     void swap(__tuple_impl& __t)
 494         _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 495     {
 496         __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
 497     }
 498 };
 499
 500 template <class ..._Tp>
 501 class _LIBCPP_TYPE_VIS_ONLY tuple
 502 {
 503     typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
 504
 505     base base_;
 506
 507     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 508         typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
 509     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 510         const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
 511     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 512         typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
 513 public:
 514
 515     _LIBCPP_INLINE_VISIBILITY
 516     _LIBCPP_CONSTEXPR tuple()
 517         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 518
 519     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 520     explicit tuple(const _Tp& ... __t) _NOEXCEPT_((__all<is_nothrow_copy_constructible<_Tp>::value...>::value))
 521         : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 522                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 523                 typename __make_tuple_indices<0>::type(),
 524                 typename __make_tuple_types<tuple, 0>::type(),
 525                 __t...
 526                ) {}
 527
 528     template <class _Alloc>
 529       _LIBCPP_INLINE_VISIBILITY
 530       tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
 531         : base_(allocator_arg_t(), __a,
 532                 typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 533                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 534                 typename __make_tuple_indices<0>::type(),
 535                 typename __make_tuple_types<tuple, 0>::type(),
 536                 __t...
 537                ) {}
 538
 539     template <class ..._Up,
 540               typename enable_if
 541                       <
 542                          sizeof...(_Up) <= sizeof...(_Tp) &&
 543                          __tuple_convertible
 544                          <
 545                             tuple<_Up...>,
 546                             typename __make_tuple_types<tuple,
 547                                      sizeof...(_Up) < sizeof...(_Tp) ?
 548                                         sizeof...(_Up) :
 549                                         sizeof...(_Tp)>::type
 550                          >::value,
 551                          bool
 552                       >::type = false
 553              >
 554         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 555         tuple(_Up&&... __u)
 556             _NOEXCEPT_((
 557                 is_nothrow_constructible<
 558                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 559                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 560                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 561                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 562                     _Up...
 563                 >::value
 564             ))
 565             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 566                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 567                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 568                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 569                     _VSTD::forward<_Up>(__u)...) {}
 570
 571     template <class ..._Up,
 572               typename enable_if
 573                       <
 574                          sizeof...(_Up) <= sizeof...(_Tp) &&
 575                          __tuple_constructible
 576                          <
 577                             tuple<_Up...>,
 578                             typename __make_tuple_types<tuple,
 579                                      sizeof...(_Up) < sizeof...(_Tp) ?
 580                                         sizeof...(_Up) :
 581                                         sizeof...(_Tp)>::type
 582                          >::value &&
 583                          !__tuple_convertible
 584                          <
 585                             tuple<_Up...>,
 586                             typename __make_tuple_types<tuple,
 587                                      sizeof...(_Up) < sizeof...(_Tp) ?
 588                                         sizeof...(_Up) :
 589                                         sizeof...(_Tp)>::type
 590                          >::value,
 591                          bool
 592                       >::type =false
 593              >
 594         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 595         explicit
 596         tuple(_Up&&... __u)
 597             _NOEXCEPT_((
 598                 is_nothrow_constructible<
 599                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 600                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 601                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 602                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 603                     _Up...
 604                 >::value
 605             ))
 606             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 607                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 608                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 609                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 610                     _VSTD::forward<_Up>(__u)...) {}
 611
 612     template <class _Alloc, class ..._Up,
 613               class = typename enable_if
 614                       <
 615                          sizeof...(_Up) <= sizeof...(_Tp) &&
 616                          __tuple_convertible
 617                          <
 618                             tuple<_Up...>,
 619                             typename __make_tuple_types<tuple,
 620                                      sizeof...(_Up) < sizeof...(_Tp) ?
 621                                         sizeof...(_Up) :
 622                                         sizeof...(_Tp)>::type
 623                          >::value
 624                       >::type
 625              >
 626         _LIBCPP_INLINE_VISIBILITY
 627         tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
 628             : base_(allocator_arg_t(), __a,
 629                     typename __make_tuple_indices<sizeof...(_Up)>::type(),
 630                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 631                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 632                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 633                     _VSTD::forward<_Up>(__u)...) {}
 634
 635     template <class _Tuple,
 636               typename enable_if
 637                       <
 638                          __tuple_convertible<_Tuple, tuple>::value,
 639                          bool
 640                       >::type = false
 641              >
 642         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 643         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 644             : base_(_VSTD::forward<_Tuple>(__t)) {}
 645
 646     template <class _Tuple,
 647               typename enable_if
 648                       <
 649                          __tuple_constructible<_Tuple, tuple>::value &&
 650                          !__tuple_convertible<_Tuple, tuple>::value,
 651                          bool
 652                       >::type = false
 653              >
 654         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 655         explicit
 656         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 657             : base_(_VSTD::forward<_Tuple>(__t)) {}
 658
 659     template <class _Alloc, class _Tuple,
 660               class = typename enable_if
 661                       <
 662                          __tuple_convertible<_Tuple, tuple>::value
 663                       >::type
 664              >
 665         _LIBCPP_INLINE_VISIBILITY
 666         tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 667             : base_(allocator_arg_t(), __a, _VSTD::forward<_Tuple>(__t)) {}
 668
 669     template <class _Tuple,
 670               class = typename enable_if
 671                       <
 672                          __tuple_assignable<_Tuple, tuple>::value
 673                       >::type
 674              >
 675         _LIBCPP_INLINE_VISIBILITY
 676         tuple&
 677         operator=(_Tuple&& __t) _NOEXCEPT_((is_nothrow_assignable<base&, _Tuple>::value))
 678         {
 679             base_.operator=(_VSTD::forward<_Tuple>(__t));
 680             return *this;
 681         }
 682
 683     _LIBCPP_INLINE_VISIBILITY
 684     void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 685         {base_.swap(__t.base_);}
 686 };
 687
 688 template <>
 689 class _LIBCPP_TYPE_VIS_ONLY tuple<>
 690 {
 691 public:
 692     _LIBCPP_INLINE_VISIBILITY
 693     _LIBCPP_CONSTEXPR tuple() _NOEXCEPT {}
 694     template <class _Alloc>
 695     _LIBCPP_INLINE_VISIBILITY
 696         tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
 697     template <class _Alloc>
 698     _LIBCPP_INLINE_VISIBILITY
 699         tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
 700     template <class _Up>
 701     _LIBCPP_INLINE_VISIBILITY
 702         tuple(array<_Up, 0>) _NOEXCEPT {}
 703     template <class _Alloc, class _Up>
 704     _LIBCPP_INLINE_VISIBILITY
 705         tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
 706     _LIBCPP_INLINE_VISIBILITY
 707     void swap(tuple&) _NOEXCEPT {}
 708 };
 709
 710 template <class ..._Tp>
 711 inline _LIBCPP_INLINE_VISIBILITY
 712 typename enable_if
 713 <
 714     __all<__is_swappable<_Tp>::value...>::value,
 715     void
 716 >::type
 717 swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
 718                  _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 719     {__t.swap(__u);}
 720
 721 // get
 722
 723 template <size_t _Ip, class ..._Tp>
 724 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 725 typename tuple_element<_Ip, tuple<_Tp...> >::type&
 726 get(tuple<_Tp...>& __t) _NOEXCEPT
 727 {
 728     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 729     return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
 730 }
 731
 732 template <size_t _Ip, class ..._Tp>
 733 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 734 const typename tuple_element<_Ip, tuple<_Tp...> >::type&
 735 get(const tuple<_Tp...>& __t) _NOEXCEPT
 736 {
 737     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 738     return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
 739 }
 740
 741 template <size_t _Ip, class ..._Tp>
 742 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 743 typename tuple_element<_Ip, tuple<_Tp...> >::type&&
 744 get(tuple<_Tp...>&& __t) _NOEXCEPT
 745 {
 746     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 747     return static_cast<type&&>(
 748              static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
 749 }
 750
 751 #if _LIBCPP_STD_VER > 11
 752 // get by type
 753 template <typename _T1, size_t _Idx, typename... _Args>
 754 struct __find_exactly_one_t_helper;
 755
 756 // -- find exactly one
 757 template <typename _T1, size_t _Idx, typename... _Args>
 758 struct __find_exactly_one_t_checker {
 759     static constexpr size_t value = _Idx;
 760 //  Check the rest of the list to make sure there's only one
 761     static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
 762     };
 763
 764
 765 template <typename _T1, size_t _Idx>
 766 struct __find_exactly_one_t_helper <_T1, _Idx> {
 767     static constexpr size_t value = -1;
 768     };
 769
 770 template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
 771 struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
 772     static constexpr size_t value =
 773         std::conditional<
 774             std::is_same<_T1, _Head>::value,
 775             __find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
 776             __find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
 777         >::type::value;
 778     };
 779
 780 template <typename _T1, typename... _Args>
 781 struct __find_exactly_one_t {
 782     static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
 783     static_assert ( value != -1, "type not found in type list" );
 784     };
 785
 786 template <class _T1, class... _Args>
 787 inline _LIBCPP_INLINE_VISIBILITY
 788 constexpr _T1& get(tuple<_Args...>& __tup) noexcept
 789 {
 790     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 791 }
 792
 793 template <class _T1, class... _Args>
 794 inline _LIBCPP_INLINE_VISIBILITY
 795 constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
 796 {
 797     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 798 }
 799
 800 template <class _T1, class... _Args>
 801 inline _LIBCPP_INLINE_VISIBILITY
 802 constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
 803 {
 804     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
 805 }
 806
 807 #endif
 808
 809 // tie
 810
 811 template <class ..._Tp>
 812 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 813 tuple<_Tp&...>
 814 tie(_Tp&... __t) _NOEXCEPT
 815 {
 816     return tuple<_Tp&...>(__t...);
 817 }
 818
 819 template <class _Up>
 820 struct __ignore_t
 821 {
 822     template <class _Tp>
 823         _LIBCPP_INLINE_VISIBILITY
 824         const __ignore_t& operator=(_Tp&&) const {return *this;}
 825 };
 826
 827 namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
 828
 829 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
 830
 831 template <class _Tp>
 832 struct __make_tuple_return_impl
 833 {
 834     typedef _Tp type;
 835 };
 836
 837 template <class _Tp>
 838 struct __make_tuple_return_impl<reference_wrapper<_Tp> >
 839 {
 840     typedef _Tp& type;
 841 };
 842
 843 template <class _Tp>
 844 struct __make_tuple_return
 845 {
 846     typedef typename __make_tuple_return_impl<typename decay<_Tp>::type>::type type;
 847 };
 848
 849 template <class... _Tp>
 850 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 851 tuple<typename __make_tuple_return<_Tp>::type...>
 852 make_tuple(_Tp&&... __t)
 853 {
 854     return tuple<typename __make_tuple_return<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
 855 }
 856
 857 template <class... _Tp>
 858 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 859 tuple<_Tp&&...>
 860 forward_as_tuple(_Tp&&... __t) _NOEXCEPT
 861 {
 862     return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
 863 }
 864
 865 template <size_t _Ip>
 866 struct __tuple_equal
 867 {
 868     template <class _Tp, class _Up>
 869     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 870     bool operator()(const _Tp& __x, const _Up& __y)
 871     {
 872         return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
 873     }
 874 };
 875
 876 template <>
 877 struct __tuple_equal<0>
 878 {
 879     template <class _Tp, class _Up>
 880     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 881     bool operator()(const _Tp&, const _Up&)
 882     {
 883         return true;
 884     }
 885 };
 886
 887 template <class ..._Tp, class ..._Up>
 888 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 889 bool
 890 operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 891 {
 892     return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
 893 }
 894
 895 template <class ..._Tp, class ..._Up>
 896 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 897 bool
 898 operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 899 {
 900     return !(__x == __y);
 901 }
 902
 903 template <size_t _Ip>
 904 struct __tuple_less
 905 {
 906     template <class _Tp, class _Up>
 907     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 908     bool operator()(const _Tp& __x, const _Up& __y)
 909     {
 910         return __tuple_less<_Ip-1>()(__x, __y) ||
 911              (!__tuple_less<_Ip-1>()(__y, __x) && _VSTD::get<_Ip-1>(__x) < _VSTD::get<_Ip-1>(__y));
 912     }
 913 };
 914
 915 template <>
 916 struct __tuple_less<0>
 917 {
 918     template <class _Tp, class _Up>
 919     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 920     bool operator()(const _Tp&, const _Up&)
 921     {
 922         return false;
 923     }
 924 };
 925
 926 template <class ..._Tp, class ..._Up>
 927 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 928 bool
 929 operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 930 {
 931     return __tuple_less<sizeof...(_Tp)>()(__x, __y);
 932 }
 933
 934 template <class ..._Tp, class ..._Up>
 935 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 936 bool
 937 operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 938 {
 939     return __y < __x;
 940 }
 941
 942 template <class ..._Tp, class ..._Up>
 943 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 944 bool
 945 operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 946 {
 947     return !(__x < __y);
 948 }
 949
 950 template <class ..._Tp, class ..._Up>
 951 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 952 bool
 953 operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 954 {
 955     return !(__y < __x);
 956 }
 957
 958 // tuple_cat
 959
 960 template <class _Tp, class _Up> struct __tuple_cat_type;
 961
 962 template <class ..._Ttypes, class ..._Utypes>
 963 struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
 964 {
 965     typedef tuple<_Ttypes..., _Utypes...> type;
 966 };
 967
 968 template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
 969 struct __tuple_cat_return_1
 970 {
 971 };
 972
 973 template <class ..._Types, class _Tuple0>
 974 struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
 975 {
 976     typedef typename __tuple_cat_type<tuple<_Types...>,
 977             typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type>::type
 978                                                                            type;
 979 };
 980
 981 template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
 982 struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
 983     : public __tuple_cat_return_1<
 984                  typename __tuple_cat_type<
 985                      tuple<_Types...>,
 986                      typename __make_tuple_types<typename remove_reference<_Tuple0>::type>::type
 987                  >::type,
 988                  __tuple_like<typename remove_reference<_Tuple1>::type>::value,
 989                  _Tuple1, _Tuples...>
 990 {
 991 };
 992
 993 template <class ..._Tuples> struct __tuple_cat_return;
 994
 995 template <class _Tuple0, class ..._Tuples>
 996 struct __tuple_cat_return<_Tuple0, _Tuples...>
 997     : public __tuple_cat_return_1<tuple<>,
 998          __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
 999                                                                      _Tuples...>
1000 {
1001 };
1002
1003 template <>
1004 struct __tuple_cat_return<>
1005 {
1006     typedef tuple<> type;
1007 };
1008
1009 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1010 tuple<>
1011 tuple_cat()
1012 {
1013     return tuple<>();
1014 }
1015
1016 template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1017 struct __tuple_cat_return_ref_imp;
1018
1019 template <class ..._Types, size_t ..._I0, class _Tuple0>
1020 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1021 {
1022     typedef typename remove_reference<_Tuple0>::type _T0;
1023     typedef tuple<_Types..., typename __apply_cv<_Tuple0,
1024                           typename tuple_element<_I0, _T0>::type>::type&&...> type;
1025 };
1026
1027 template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1028 struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1029                                   _Tuple0, _Tuple1, _Tuples...>
1030     : public __tuple_cat_return_ref_imp<
1031          tuple<_Types..., typename __apply_cv<_Tuple0,
1032                typename tuple_element<_I0,
1033                   typename remove_reference<_Tuple0>::type>::type>::type&&...>,
1034          typename __make_tuple_indices<tuple_size<typename
1035                                  remove_reference<_Tuple1>::type>::value>::type,
1036          _Tuple1, _Tuples...>
1037 {
1038 };
1039
1040 template <class _Tuple0, class ..._Tuples>
1041 struct __tuple_cat_return_ref
1042     : public __tuple_cat_return_ref_imp<tuple<>,
1043                typename __make_tuple_indices<
1044                         tuple_size<typename remove_reference<_Tuple0>::type>::value
1045                >::type, _Tuple0, _Tuples...>
1046 {
1047 };
1048
1049 template <class _Types, class _I0, class _J0>
1050 struct __tuple_cat;
1051
1052 template <class ..._Types, size_t ..._I0, size_t ..._J0>
1053 struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1054 {
1055     template <class _Tuple0>
1056     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1057     typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1058     operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1059     {
1060         return forward_as_tuple(_VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1061                                       _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1062     }
1063
1064     template <class _Tuple0, class _Tuple1, class ..._Tuples>
1065     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1066     typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1067     operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1068     {
1069         typedef typename remove_reference<_Tuple0>::type _T0;
1070         typedef typename remove_reference<_Tuple1>::type _T1;
1071         return __tuple_cat<
1072            tuple<_Types..., typename __apply_cv<_Tuple0, typename tuple_element<_J0, _T0>::type>::type&&...>,
1073            typename __make_tuple_indices<sizeof ...(_Types) + tuple_size<_T0>::value>::type,
1074            typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
1075                            (forward_as_tuple(
1076                               _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1077                               _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
1078                             ),
1079                             _VSTD::forward<_Tuple1>(__t1),
1080                             _VSTD::forward<_Tuples>(__tpls)...);
1081     }
1082 };
1083
1084 template <class _Tuple0, class... _Tuples>
1085 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1086 typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1087 tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1088 {
1089     typedef typename remove_reference<_Tuple0>::type _T0;
1090     return __tuple_cat<tuple<>, __tuple_indices<>,
1091                   typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1092                   (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1093                                             _VSTD::forward<_Tuples>(__tpls)...);
1094 }
1095
1096 template <class ..._Tp, class _Alloc>
1097 struct _LIBCPP_TYPE_VIS_ONLY uses_allocator<tuple<_Tp...>, _Alloc>
1098     : true_type {};
1099
1100 template <class _T1, class _T2>
1101 template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1102 inline _LIBCPP_INLINE_VISIBILITY
1103 pair<_T1, _T2>::pair(piecewise_construct_t,
1104                      tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1105                      __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1106     :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
1107       second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
1108 {
1109 }
1110
1111 #endif  // _LIBCPP_HAS_NO_VARIADICS
1112
1113 _LIBCPP_END_NAMESPACE_STD
1114
1115 #endif  // _LIBCPP_TUPLE