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