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, 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 ..._Pred>
 380 struct __all
 381     : is_same<__all<_Pred...>, __all<(_Pred, true)...>>
 382 { };
 383
 384 template <class _Tp>
 385 struct __all_default_constructible;
 386
 387 template <class ..._Tp>
 388 struct __all_default_constructible<__tuple_types<_Tp...>>
 389     : __all<is_default_constructible<_Tp>::value...>
 390 { };
 391
 392 // __tuple_impl
 393
 394 template<class _Indx, class ..._Tp> struct __tuple_impl;
 395
 396 template<size_t ..._Indx, class ..._Tp>
 397 struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
 398     : public __tuple_leaf<_Indx, _Tp>...
 399 {
 400     _LIBCPP_INLINE_VISIBILITY
 401     _LIBCPP_CONSTEXPR __tuple_impl()
 402         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 403
 404     template <size_t ..._Uf, class ..._Tf,
 405               size_t ..._Ul, class ..._Tl, class ..._Up>
 406         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 407         explicit
 408         __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 409                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 410                      _Up&&... __u)
 411                      _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
 412                                  __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
 413             __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
 414             __tuple_leaf<_Ul, _Tl>()...
 415             {}
 416
 417     template <class _Alloc, size_t ..._Uf, class ..._Tf,
 418               size_t ..._Ul, class ..._Tl, class ..._Up>
 419         _LIBCPP_INLINE_VISIBILITY
 420         explicit
 421         __tuple_impl(allocator_arg_t, const _Alloc& __a,
 422                      __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
 423                      __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
 424                      _Up&&... __u) :
 425             __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
 426             _VSTD::forward<_Up>(__u))...,
 427             __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
 428             {}
 429
 430     template <class _Tuple,
 431               class = typename enable_if
 432                       <
 433                          __tuple_constructible<_Tuple, tuple<_Tp...> >::value
 434                       >::type
 435              >
 436         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 437         __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
 438                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 439             : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
 440                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 441             {}
 442
 443     template <class _Alloc, class _Tuple,
 444               class = typename enable_if
 445                       <
 446                          __tuple_convertible<_Tuple, tuple<_Tp...> >::value
 447                       >::type
 448              >
 449         _LIBCPP_INLINE_VISIBILITY
 450         __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 451             : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
 452                                        typename __make_tuple_types<_Tuple>::type>::type>(), __a,
 453                                        _VSTD::forward<typename tuple_element<_Indx,
 454                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
 455             {}
 456
 457     template <class _Tuple>
 458         _LIBCPP_INLINE_VISIBILITY
 459         typename enable_if
 460         <
 461             __tuple_assignable<_Tuple, tuple<_Tp...> >::value,
 462             __tuple_impl&
 463         >::type
 464         operator=(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_assignable<_Tp&, typename tuple_element<_Indx,
 465                                        typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
 466         {
 467             __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<typename tuple_element<_Indx,
 468                                        typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...);
 469             return *this;
 470         }
 471
 472     __tuple_impl(const __tuple_impl&) = default;
 473     __tuple_impl(__tuple_impl&&) = default;
 474
 475     _LIBCPP_INLINE_VISIBILITY
 476     __tuple_impl&
 477     operator=(const __tuple_impl& __t) _NOEXCEPT_((__all<is_nothrow_copy_assignable<_Tp>::value...>::value))
 478     {
 479         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t).get())...);
 480         return *this;
 481     }
 482
 483     _LIBCPP_INLINE_VISIBILITY
 484     __tuple_impl&
 485     operator=(__tuple_impl&& __t) _NOEXCEPT_((__all<is_nothrow_move_assignable<_Tp>::value...>::value))
 486     {
 487         __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_VSTD::forward<_Tp>(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t).get()))...);
 488         return *this;
 489     }
 490
 491     _LIBCPP_INLINE_VISIBILITY
 492     void swap(__tuple_impl& __t)
 493         _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 494     {
 495         __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
 496     }
 497 };
 498
 499 template <class ..._Tp>
 500 class _LIBCPP_TYPE_VIS_ONLY tuple
 501 {
 502     typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
 503
 504     base base_;
 505
 506     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 507         typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
 508     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 509         const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
 510     template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
 511         typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
 512 public:
 513
 514     template <bool _Dummy = true, class _Up = typename enable_if<
 515         __all<(_Dummy && is_default_constructible<_Tp>::value)...>::value
 516     >::type>
 517     _LIBCPP_INLINE_VISIBILITY
 518     _LIBCPP_CONSTEXPR tuple()
 519         _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 520
 521     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 522     explicit tuple(const _Tp& ... __t) _NOEXCEPT_((__all<is_nothrow_copy_constructible<_Tp>::value...>::value))
 523         : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 524                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 525                 typename __make_tuple_indices<0>::type(),
 526                 typename __make_tuple_types<tuple, 0>::type(),
 527                 __t...
 528                ) {}
 529
 530     template <class _Alloc>
 531       _LIBCPP_INLINE_VISIBILITY
 532       tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
 533         : base_(allocator_arg_t(), __a,
 534                 typename __make_tuple_indices<sizeof...(_Tp)>::type(),
 535                 typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
 536                 typename __make_tuple_indices<0>::type(),
 537                 typename __make_tuple_types<tuple, 0>::type(),
 538                 __t...
 539                ) {}
 540
 541     template <class ..._Up,
 542               typename enable_if
 543                       <
 544                          sizeof...(_Up) <= sizeof...(_Tp) &&
 545                          __tuple_convertible
 546                          <
 547                             tuple<_Up...>,
 548                             typename __make_tuple_types<tuple,
 549                                      sizeof...(_Up) < sizeof...(_Tp) ?
 550                                         sizeof...(_Up) :
 551                                         sizeof...(_Tp)>::type
 552                          >::value &&
 553                          __all_default_constructible<
 554                             typename __make_tuple_types<tuple, sizeof...(_Tp),
 555                                 sizeof...(_Up) < sizeof...(_Tp) ?
 556                                     sizeof...(_Up) :
 557                                     sizeof...(_Tp)>::type
 558                          >::value,
 559                          bool
 560                       >::type = false
 561              >
 562         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 563         tuple(_Up&&... __u)
 564             _NOEXCEPT_((
 565                 is_nothrow_constructible<base,
 566                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 567                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 568                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 569                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 570                     _Up...
 571                 >::value
 572             ))
 573             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 574                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 575                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 576                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 577                     _VSTD::forward<_Up>(__u)...) {}
 578
 579     template <class ..._Up,
 580               typename enable_if
 581                       <
 582                          sizeof...(_Up) <= sizeof...(_Tp) &&
 583                          __tuple_constructible
 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                          !__tuple_convertible
 592                          <
 593                             tuple<_Up...>,
 594                             typename __make_tuple_types<tuple,
 595                                      sizeof...(_Up) < sizeof...(_Tp) ?
 596                                         sizeof...(_Up) :
 597                                         sizeof...(_Tp)>::type
 598                          >::value &&
 599                          __all_default_constructible<
 600                             typename __make_tuple_types<tuple, sizeof...(_Tp),
 601                                 sizeof...(_Up) < sizeof...(_Tp) ?
 602                                     sizeof...(_Up) :
 603                                     sizeof...(_Tp)>::type
 604                          >::value,
 605                          bool
 606                       >::type =false
 607              >
 608         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 609         explicit
 610         tuple(_Up&&... __u)
 611             _NOEXCEPT_((
 612                 is_nothrow_constructible<base,
 613                     typename __make_tuple_indices<sizeof...(_Up)>::type,
 614                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type,
 615                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type,
 616                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type,
 617                     _Up...
 618                 >::value
 619             ))
 620             : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
 621                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 622                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 623                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 624                     _VSTD::forward<_Up>(__u)...) {}
 625
 626     template <class _Alloc, class ..._Up,
 627               class = typename enable_if
 628                       <
 629                          sizeof...(_Up) <= sizeof...(_Tp) &&
 630                          __tuple_convertible
 631                          <
 632                             tuple<_Up...>,
 633                             typename __make_tuple_types<tuple,
 634                                      sizeof...(_Up) < sizeof...(_Tp) ?
 635                                         sizeof...(_Up) :
 636                                         sizeof...(_Tp)>::type
 637                          >::value &&
 638                          __all_default_constructible<
 639                             typename __make_tuple_types<tuple, sizeof...(_Tp),
 640                                 sizeof...(_Up) < sizeof...(_Tp) ?
 641                                     sizeof...(_Up) :
 642                                     sizeof...(_Tp)>::type
 643                          >::value
 644                       >::type
 645              >
 646         _LIBCPP_INLINE_VISIBILITY
 647         tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
 648             : base_(allocator_arg_t(), __a,
 649                     typename __make_tuple_indices<sizeof...(_Up)>::type(),
 650                     typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
 651                     typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
 652                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
 653                     _VSTD::forward<_Up>(__u)...) {}
 654
 655     template <class _Tuple,
 656               typename enable_if
 657                       <
 658                          __tuple_convertible<_Tuple, tuple>::value,
 659                          bool
 660                       >::type = false
 661              >
 662         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 663         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 664             : base_(_VSTD::forward<_Tuple>(__t)) {}
 665
 666     template <class _Tuple,
 667               typename enable_if
 668                       <
 669                          __tuple_constructible<_Tuple, tuple>::value &&
 670                          !__tuple_convertible<_Tuple, tuple>::value,
 671                          bool
 672                       >::type = false
 673              >
 674         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 675         explicit
 676         tuple(_Tuple&& __t) _NOEXCEPT_((is_nothrow_constructible<base, _Tuple>::value))
 677             : base_(_VSTD::forward<_Tuple>(__t)) {}
 678
 679     template <class _Alloc, class _Tuple,
 680               class = typename enable_if
 681                       <
 682                          __tuple_convertible<_Tuple, tuple>::value
 683                       >::type
 684              >
 685         _LIBCPP_INLINE_VISIBILITY
 686         tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
 687             : base_(allocator_arg_t(), __a, _VSTD::forward<_Tuple>(__t)) {}
 688
 689     template <class _Tuple,
 690               class = typename enable_if
 691                       <
 692                          __tuple_assignable<_Tuple, tuple>::value
 693                       >::type
 694              >
 695         _LIBCPP_INLINE_VISIBILITY
 696         tuple&
 697         operator=(_Tuple&& __t) _NOEXCEPT_((is_nothrow_assignable<base&, _Tuple>::value))
 698         {
 699             base_.operator=(_VSTD::forward<_Tuple>(__t));
 700             return *this;
 701         }
 702
 703     _LIBCPP_INLINE_VISIBILITY
 704     void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 705         {base_.swap(__t.base_);}
 706 };
 707
 708 template <>
 709 class _LIBCPP_TYPE_VIS_ONLY tuple<>
 710 {
 711 public:
 712     _LIBCPP_INLINE_VISIBILITY
 713     _LIBCPP_CONSTEXPR tuple() _NOEXCEPT {}
 714     template <class _Alloc>
 715     _LIBCPP_INLINE_VISIBILITY
 716         tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
 717     template <class _Alloc>
 718     _LIBCPP_INLINE_VISIBILITY
 719         tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
 720     template <class _Up>
 721     _LIBCPP_INLINE_VISIBILITY
 722         tuple(array<_Up, 0>) _NOEXCEPT {}
 723     template <class _Alloc, class _Up>
 724     _LIBCPP_INLINE_VISIBILITY
 725         tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
 726     _LIBCPP_INLINE_VISIBILITY
 727     void swap(tuple&) _NOEXCEPT {}
 728 };
 729
 730 template <class ..._Tp>
 731 inline _LIBCPP_INLINE_VISIBILITY
 732 typename enable_if
 733 <
 734     __all<__is_swappable<_Tp>::value...>::value,
 735     void
 736 >::type
 737 swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
 738                  _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
 739     {__t.swap(__u);}
 740
 741 // get
 742
 743 template <size_t _Ip, class ..._Tp>
 744 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 745 typename tuple_element<_Ip, tuple<_Tp...> >::type&
 746 get(tuple<_Tp...>& __t) _NOEXCEPT
 747 {
 748     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 749     return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
 750 }
 751
 752 template <size_t _Ip, class ..._Tp>
 753 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 754 const typename tuple_element<_Ip, tuple<_Tp...> >::type&
 755 get(const tuple<_Tp...>& __t) _NOEXCEPT
 756 {
 757     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 758     return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
 759 }
 760
 761 template <size_t _Ip, class ..._Tp>
 762 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 763 typename tuple_element<_Ip, tuple<_Tp...> >::type&&
 764 get(tuple<_Tp...>&& __t) _NOEXCEPT
 765 {
 766     typedef typename tuple_element<_Ip, tuple<_Tp...> >::type type;
 767     return static_cast<type&&>(
 768              static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
 769 }
 770
 771 #if _LIBCPP_STD_VER > 11
 772 // get by type
 773 template <typename _T1, size_t _Idx, typename... _Args>
 774 struct __find_exactly_one_t_helper;
 775
 776 // -- find exactly one
 777 template <typename _T1, size_t _Idx, typename... _Args>
 778 struct __find_exactly_one_t_checker {
 779     static constexpr size_t value = _Idx;
 780 //  Check the rest of the list to make sure there's only one
 781     static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
 782     };
 783
 784
 785 template <typename _T1, size_t _Idx>
 786 struct __find_exactly_one_t_helper <_T1, _Idx> {
 787     static constexpr size_t value = -1;
 788     };
 789
 790 template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
 791 struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
 792     static constexpr size_t value =
 793         std::conditional<
 794             std::is_same<_T1, _Head>::value,
 795             __find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
 796             __find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
 797         >::type::value;
 798     };
 799
 800 template <typename _T1, typename... _Args>
 801 struct __find_exactly_one_t {
 802     static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
 803     static_assert ( value != -1, "type not found in type list" );
 804     };
 805
 806 template <class _T1, class... _Args>
 807 inline _LIBCPP_INLINE_VISIBILITY
 808 constexpr _T1& get(tuple<_Args...>& __tup) noexcept
 809 {
 810     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 811 }
 812
 813 template <class _T1, class... _Args>
 814 inline _LIBCPP_INLINE_VISIBILITY
 815 constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
 816 {
 817     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
 818 }
 819
 820 template <class _T1, class... _Args>
 821 inline _LIBCPP_INLINE_VISIBILITY
 822 constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
 823 {
 824     return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
 825 }
 826
 827 #endif
 828
 829 // tie
 830
 831 template <class ..._Tp>
 832 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 833 tuple<_Tp&...>
 834 tie(_Tp&... __t) _NOEXCEPT
 835 {
 836     return tuple<_Tp&...>(__t...);
 837 }
 838
 839 template <class _Up>
 840 struct __ignore_t
 841 {
 842     template <class _Tp>
 843         _LIBCPP_INLINE_VISIBILITY
 844         const __ignore_t& operator=(_Tp&&) const {return *this;}
 845 };
 846
 847 namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
 848
 849 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
 850
 851 template <class _Tp>
 852 struct __make_tuple_return_impl
 853 {
 854     typedef _Tp type;
 855 };
 856
 857 template <class _Tp>
 858 struct __make_tuple_return_impl<reference_wrapper<_Tp> >
 859 {
 860     typedef _Tp& type;
 861 };
 862
 863 template <class _Tp>
 864 struct __make_tuple_return
 865 {
 866     typedef typename __make_tuple_return_impl<typename decay<_Tp>::type>::type type;
 867 };
 868
 869 template <class... _Tp>
 870 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 871 tuple<typename __make_tuple_return<_Tp>::type...>
 872 make_tuple(_Tp&&... __t)
 873 {
 874     return tuple<typename __make_tuple_return<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
 875 }
 876
 877 template <class... _Tp>
 878 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 879 tuple<_Tp&&...>
 880 forward_as_tuple(_Tp&&... __t) _NOEXCEPT
 881 {
 882     return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
 883 }
 884
 885 template <size_t _Ip>
 886 struct __tuple_equal
 887 {
 888     template <class _Tp, class _Up>
 889     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 890     bool operator()(const _Tp& __x, const _Up& __y)
 891     {
 892         return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
 893     }
 894 };
 895
 896 template <>
 897 struct __tuple_equal<0>
 898 {
 899     template <class _Tp, class _Up>
 900     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 901     bool operator()(const _Tp&, const _Up&)
 902     {
 903         return true;
 904     }
 905 };
 906
 907 template <class ..._Tp, class ..._Up>
 908 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 909 bool
 910 operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 911 {
 912     return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
 913 }
 914
 915 template <class ..._Tp, class ..._Up>
 916 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 917 bool
 918 operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
 919 {
 920     return !(__x == __y);
 921 }
 922
 923 template <size_t _Ip>
 924 struct __tuple_less
 925 {
 926     template <class _Tp, class _Up>
 927     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 928     bool operator()(const _Tp& __x, const _Up& __y)
 929     {
 930         return __tuple_less<_Ip-1>()(__x, __y) ||
 931              (!__tuple_less<_Ip-1>()(__y, __x) && _VSTD::get<_Ip-1>(__x) < _VSTD::get<_Ip-1>(__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