libcxx initial import

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@103490 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/tuple b/include/tuple
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+++ b/include/tuple
@@ -0,0 +1,818 @@
+// -*- C++ -*-
+//===--------------------------- tuple ------------------------------------===//
+//
+// ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊThe LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_TUPLE
+#define _LIBCPP_TUPLE
+
+/*
+    tuple synopsis
+
+namespace std
+{
+
+template <class... T>
+class tuple {
+public:
+    constexpr tuple();
+    explicit tuple(const T&...);
+    template <class... U>
+        explicit tuple(U&&...);
+    tuple(const tuple&) = default;
+    tuple(tuple&&);
+    template <class... U>
+        tuple(const tuple<U...>&);
+    template <class... U>
+        tuple(tuple<U...>&&);
+    template <class U1, class U2>
+        tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2
+    template <class U1, class U2>
+        tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2
+
+    // allocator-extended constructors
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a);
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a, const T&...);
+    template <class Alloc, class... U>
+        tuple(allocator_arg_t, const Alloc& a, U&&...);
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a, const tuple&);
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a, tuple&&);
+    template <class Alloc, class... U>
+        tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);
+    template <class Alloc, class... U>
+        tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);
+    template <class Alloc, class U1, class U2>
+        tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);
+    template <class Alloc, class U1, class U2>
+        tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);
+
+    tuple& operator=(const tuple&);
+    tuple& operator=(tuple&&);
+    template <class... U>
+        tuple& operator=(const tuple<U...>&);
+    template <class... U>
+        tuple& operator=(tuple<U...>&&);
+    template <class U1, class U2>
+        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2
+    template <class U1, class U2>
+        tuple& operator=(pair<U1, U2>&&); //iffsizeof...(T) == 2
+
+    void swap(tuple&);
+};
+
+const unspecified ignore;
+
+template <class... T> tuple<V...>  make_tuple(T&&...);
+template <class... T> tuple<T&...> tie(T&...);
+template <class... T, class... U> tuple<T..., U...> tuple_cat(const tuple<T...>&, const tuple<U...>&);
+template <class... T, class... U> tuple<T..., U...> tuple_cat(tuple<T...>&&, const tuple<U...>&);
+template <class... T, class... U> tuple<T..., U...> tuple_cat(const tuple<T...>&, tuple<U...>&&);
+template <class... T, class... U> tuple<T..., U...> tuple_cat(tuple<T...>&&, tuple<U...>&&);
+
+// 20.4.1.4, tuple helper classes:
+template <class T> class tuple_size; // undefined
+template <class... T> class tuple_size<tuple<T...>>;
+template <intsize_t I, class T> class tuple_element; // undefined
+template <intsize_t I, class... T> class tuple_element<I, tuple<T...>>;
+
+// 20.4.1.5, element access:
+template <intsize_t I, class... T> typename tuple_element<I, tuple<T...>>::type& get(tuple<T...>&);
+template <intsize_t I, class... T> typename tuple_element<I, tuple<T...>>::type const& get(const tuple<T...>&);
+
+// 20.4.1.6, relational operators:
+template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&);
+template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);
+template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&);
+template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);
+template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&);
+template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&);
+
+template <class... Types, class Alloc>
+  struct uses_allocator<tuple<Types...>, Alloc>;
+
+template <class... Types>
+  void swap(tuple<Types...>& x, tuple<Types...>& y);
+
+template <class InputIterator>
+  InputIterator begin(const std::tuple<InputIterator, InputIterator>& t);
+
+template <class InputIterator>
+  InputIterator end(const std::tuple<InputIterator, InputIterator>& t);
+
+}  // std
+
+*/
+
+#include <__config>
+#include <__tuple>
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+
+#pragma GCC system_header
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+// tuple_size
+
+template <class ..._Tp>
+class tuple_size<tuple<_Tp...>>
+    : public integral_constant<size_t, sizeof...(_Tp)>
+{
+};
+
+template <class ..._Tp>
+class tuple_size<const tuple<_Tp...>>
+    : public integral_constant<size_t, sizeof...(_Tp)>
+{
+};
+
+// tuple_element
+
+template <size_t _Ip, class ..._Tp>
+class tuple_element<_Ip, tuple<_Tp...>>
+{
+public:
+    typedef typename tuple_element<_Ip, __tuple_types<_Tp...>>::type type;
+};
+
+template <size_t _Ip, class ..._Tp>
+class tuple_element<_Ip, const tuple<_Tp...>>
+{
+public:
+    typedef const typename tuple_element<_Ip, __tuple_types<_Tp...>>::type type;
+};
+
+// __tuple_leaf
+
+template <size_t _Ip, class _Hp, bool=is_empty<_Hp>::value>
+class __tuple_leaf;
+
+template <size_t _Ip, class _Hp, bool _Ep>
+inline
+void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
+{
+    swap(__x.get(), __y.get());
+}
+
+template <size_t _Ip, class _Hp, bool>
+class __tuple_leaf
+{
+    _Hp value;
+
+    __tuple_leaf& operator=(const __tuple_leaf&);
+public:
+    _LIBCPP_INLINE_VISIBILITY __tuple_leaf() : value()
+       {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
+            : value()
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
+            : value(allocator_arg_t(), __a)
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
+            : value(__a)
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(_Tp&& __t)
+            : value(_STD::forward<_Tp>(__t))
+        {static_assert(!is_lvalue_reference<_Hp>::value ||
+                        is_lvalue_reference<_Hp>::value &&
+                        (is_lvalue_reference<_Tp>::value ||
+                         is_same<typename remove_reference<_Tp>::type,
+                                 reference_wrapper<
+                                    typename remove_reference<_Hp>::type
+                                 >
+                                >::value),
+       "Attempted to construct a reference element in a tuple with an rvalue");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
+            : value(_STD::forward<_Tp>(__t))
+        {static_assert(!is_lvalue_reference<_Hp>::value ||
+                        is_lvalue_reference<_Hp>::value &&
+                        (is_lvalue_reference<_Tp>::value ||
+                         is_same<typename remove_reference<_Tp>::type,
+                                 reference_wrapper<
+                                    typename remove_reference<_Hp>::type
+                                 >
+                                >::value),
+       "Attempted to construct a reference element in a tuple with an rvalue");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
+            : value(allocator_arg_t(), __a, _STD::forward<_Tp>(__t))
+        {static_assert(!is_lvalue_reference<_Hp>::value ||
+                        is_lvalue_reference<_Hp>::value &&
+                        (is_lvalue_reference<_Tp>::value ||
+                         is_same<typename remove_reference<_Tp>::type,
+                                 reference_wrapper<
+                                    typename remove_reference<_Hp>::type
+                                 >
+                                >::value),
+       "Attempted to construct a reference element in a tuple with an rvalue");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
+            : value(_STD::forward<_Tp>(__t), __a)
+        {static_assert(!is_lvalue_reference<_Hp>::value ||
+                        is_lvalue_reference<_Hp>::value &&
+                        (is_lvalue_reference<_Tp>::value ||
+                         is_same<typename remove_reference<_Tp>::type,
+                                 reference_wrapper<
+                                    typename remove_reference<_Hp>::type
+                                 >
+                                >::value),
+       "Attempted to construct a reference element in a tuple with an rvalue");}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(const __tuple_leaf<_Ip, _Tp>& __t)
+            : value(__t.get()) {}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf&
+        operator=(_Tp&& __t)
+        {
+            value = _STD::forward<_Tp>(__t);
+            return *this;
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    int swap(__tuple_leaf& __t)
+    {
+        _STD::swap(*this, __t);
+        return 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY       _Hp& get()       {return value;}
+    _LIBCPP_INLINE_VISIBILITY const _Hp& get() const {return value;}
+};
+
+template <size_t _Ip, class _Hp>
+class __tuple_leaf<_Ip, _Hp, true>
+    : private _Hp
+{
+
+    __tuple_leaf& operator=(const __tuple_leaf&);
+public:
+    _LIBCPP_INLINE_VISIBILITY __tuple_leaf() {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
+            : _Hp(allocator_arg_t(), __a) {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
+            : _Hp(__a) {}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(_Tp&& __t)
+            : _Hp(_STD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
+            : _Hp(_STD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
+            : _Hp(allocator_arg_t(), __a, _STD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
+            : _Hp(_STD::forward<_Tp>(__t), __a) {}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        explicit __tuple_leaf(const __tuple_leaf<_Ip, _Tp>& __t)
+            : _Hp(__t.get()) {}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        __tuple_leaf&
+        operator=(_Tp&& __t)
+        {
+            _Hp::operator=(_STD::forward<_Tp>(__t));
+            return *this;
+        }
+
+    _LIBCPP_INLINE_VISIBILITY int swap(__tuple_leaf& __t)
+    {
+        _STD::swap(*this, __t);
+        return 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY       _Hp& get()       {return static_cast<_Hp&>(*this);}
+    _LIBCPP_INLINE_VISIBILITY const _Hp& get() const {return static_cast<const _Hp&>(*this);}
+};
+
+template <class ..._Tp> void __swallow(_Tp&&...) {}
+
+// __tuple_impl
+
+template<class _Indx, class ..._Tp> struct __tuple_impl;
+
+template<size_t ..._Indx, class ..._Tp>
+struct __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
+    : public __tuple_leaf<_Indx, _Tp>...
+{
+    template <size_t ..._Uf, class ..._Tf,
+              size_t ..._Ul, class ..._Tl, class ..._Up>
+        explicit
+        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
+                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
+                     _Up&&... __u) :
+            __tuple_leaf<_Uf, _Tf>(_STD::forward<_Up>(__u))...,
+            __tuple_leaf<_Ul, _Tl>()...
+            {}
+
+    template <class _Alloc, size_t ..._Uf, class ..._Tf,
+              size_t ..._Ul, class ..._Tl, class ..._Up>
+        explicit
+        __tuple_impl(allocator_arg_t, const _Alloc& __a,
+                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
+                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
+                     _Up&&... __u) :
+            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
+            _STD::forward<_Up>(__u))...,
+            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
+            {}
+
+    template <class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_convertible<_Tuple, tuple<_Tp...>>::value
+                      >::type
+             >
+        __tuple_impl(_Tuple&& __t)
+            : __tuple_leaf<_Indx, _Tp>(_STD::forward<typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(_STD::get<_Indx>(__t)))...
+            {}
+
+    template <class _Alloc, class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_convertible<_Tuple, tuple<_Tp...>>::value
+                      >::type
+             >
+        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
+            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a, 
+                                       _STD::forward<typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(_STD::get<_Indx>(__t)))...
+            {}
+
+    template <class _Tuple>
+        typename enable_if
+        <
+            __tuple_assignable<_Tuple, tuple<_Tp...>>::value,
+            __tuple_impl&
+        >::type
+        operator=(_Tuple&& __t)
+        {
+            __swallow(__tuple_leaf<_Indx, _Tp>::operator=(_STD::forward<typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(_STD::get<_Indx>(__t)))...);
+            return *this;
+        }
+
+    void swap(__tuple_impl& __t)
+    {
+        __swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
+    }
+};
+
+template <class ..._Tp>
+class tuple
+{
+    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> base;
+
+    base base_;
+
+    template <size_t _Jp, class ..._Up> friend
+        typename tuple_element<_Jp, tuple<_Up...>>::type& get(tuple<_Up...>&);
+    template <size_t _Jp, class ..._Up> friend
+        const typename tuple_element<_Jp, tuple<_Up...>>::type& get(const tuple<_Up...>&);
+public:
+
+    explicit tuple(const _Tp& ... __t)
+        : base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    template <class _Alloc>
+      tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
+        : base_(allocator_arg_t(), __a,
+                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    template <class ..._Up,
+              class = typename enable_if
+                      <
+                         sizeof...(_Up) <= sizeof...(_Tp) &&
+                         __tuple_convertible
+                         <
+                            tuple<_Up...>,
+                            typename __make_tuple_types<tuple,
+                                     sizeof...(_Up) < sizeof...(_Tp) ?
+                                        sizeof...(_Up) :
+                                        sizeof...(_Tp)>::type
+                         >::value
+                      >::type
+             >
+        explicit
+        tuple(_Up&&... __u)
+            : base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _STD::forward<_Up>(__u)...) {}
+
+    template <class _Alloc, class ..._Up,
+              class = typename enable_if
+                      <
+                         sizeof...(_Up) <= sizeof...(_Tp) &&
+                         __tuple_convertible
+                         <
+                            tuple<_Up...>,
+                            typename __make_tuple_types<tuple,
+                                     sizeof...(_Up) < sizeof...(_Tp) ?
+                                        sizeof...(_Up) :
+                                        sizeof...(_Tp)>::type
+                         >::value
+                      >::type
+             >
+        tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
+            : base_(allocator_arg_t(), __a,
+                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _STD::forward<_Up>(__u)...) {}
+
+    template <class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_convertible<_Tuple, tuple>::value
+                      >::type
+             >
+        tuple(_Tuple&& __t)
+            : base_(_STD::forward<_Tuple>(__t)) {}
+
+    template <class _Alloc, class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_convertible<_Tuple, tuple>::value
+                      >::type
+             >
+        tuple(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
+            : base_(allocator_arg_t(), __a, _STD::forward<_Tuple>(__t)) {}
+
+    template <class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_assignable<_Tuple, tuple>::value
+                      >::type
+             >
+        tuple&
+        operator=(_Tuple&& __t)
+        {
+            base_.operator=(_STD::forward<_Tuple>(__t));
+            return *this;
+        }
+
+    void swap(tuple& __t) {base_.swap(__t.base_);}
+};
+
+template <>
+class tuple<>
+{
+public:
+    tuple() {}
+    template <class _Alloc>
+        tuple(allocator_arg_t, const _Alloc&) {}
+    template <class _Alloc>
+        tuple(allocator_arg_t, const _Alloc&, const tuple&) {}
+    template <class _U>
+        tuple(array<_U, 0>) {}
+    template <class _Alloc, class _U>
+        tuple(allocator_arg_t, const _Alloc&, array<_U, 0>) {}
+    void swap(tuple&) {}
+};
+
+template <class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u) {__t.swap(__u);}
+
+// get
+
+template <size_t _Ip, class ..._Tp>
+inline
+typename tuple_element<_Ip, tuple<_Tp...>>::type&
+get(tuple<_Tp...>& __t)
+{
+    typedef typename tuple_element<_Ip, tuple<_Tp...>>::type type;
+    return static_cast<__tuple_leaf<_Ip, type>&>(__t.base_).get();
+}
+
+template <size_t _Ip, class ..._Tp>
+inline
+const typename tuple_element<_Ip, tuple<_Tp...>>::type&
+get(const tuple<_Tp...>& __t)
+{
+    typedef typename tuple_element<_Ip, tuple<_Tp...>>::type type;
+    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.base_).get();
+}
+
+// tie
+
+template <class ..._Tp>
+inline
+tuple<_Tp&...>
+tie(_Tp&... __t)
+{
+    return tuple<_Tp&...>(__t...);
+}
+
+template <class _Up>
+struct __ignore_t
+{
+    __ignore_t() {}
+    template <class _Tp>
+        __ignore_t(_Tp&&) {}
+    template <class _Tp>
+        const __ignore_t& operator=(_Tp&&) const {return *this;}
+};
+
+namespace { const __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>(); }
+
+template <class _Tp> class reference_wrapper;
+
+template <class _Tp>
+struct ___make_tuple_return
+{
+    typedef _Tp type;
+};
+
+template <class _Tp>
+struct ___make_tuple_return<reference_wrapper<_Tp>>
+{
+    typedef _Tp& type;
+};
+
+template <class _Tp>
+struct __make_tuple_return
+{
+    typedef typename ___make_tuple_return<typename decay<_Tp>::type>::type type;
+};
+
+template <class... _Tp>
+inline
+tuple<typename __make_tuple_return<_Tp>::type...>
+make_tuple(_Tp&&... __t)
+{
+    return tuple<typename __make_tuple_return<_Tp>::type...>(_STD::forward<_Tp>(__t)...);
+}
+
+template <size_t _I>
+struct __tuple_equal
+{
+    template <class _Tp, class _Up>
+    bool operator()(const _Tp& __x, const _Up& __y)
+    {
+        return __tuple_equal<_I - 1>()(__x, __y) && get<_I-1>(__x) == get<_I-1>(__y);
+    }
+};
+
+template <>
+struct __tuple_equal<0>
+{
+    template <class _Tp, class _Up>
+    bool operator()(const _Tp&, const _Up&)
+    {
+        return true;
+    }
+};
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
+}
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__x == __y);
+}
+
+template <size_t _I>
+struct __tuple_less
+{
+    template <class _Tp, class _Up>
+    bool operator()(const _Tp& __x, const _Up& __y)
+    {
+        return __tuple_less<_I-1>()(__x, __y) ||
+             (!__tuple_less<_I-1>()(__y, __x) && get<_I-1>(__x) < get<_I-1>(__y));
+    }
+};
+
+template <>
+struct __tuple_less<0>
+{
+    template <class _Tp, class _Up>
+    bool operator()(const _Tp&, const _Up&)
+    {
+        return false;
+    }
+};
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return __tuple_less<sizeof...(_Tp)>()(__x, __y);
+}
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return __y < __x;
+}
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__x < __y);
+}
+
+template <class ..._Tp, class ..._Up>
+inline
+bool
+operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__y < __x);
+}
+
+// tuple_cat
+
+template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+inline
+tuple<_Tp..., _Up...>
+__tuple_cat(const tuple<_Tp...>& __x, __tuple_indices<_I1...>, const tuple<_Up...>& __y, __tuple_indices<_I2...>)
+{
+    return tuple<_Tp..., _Up...>(get<_I1>(__x)..., get<_I2>(__y)...);
+}
+
+template <class... _Tp, class... _Up>
+inline
+tuple<_Tp..., _Up...>
+tuple_cat(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return __tuple_cat(__x, typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                       __y, typename __make_tuple_indices<sizeof...(_Up)>::type());
+}
+
+template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+inline
+tuple<_Tp..., _Up...>
+__tuple_cat(tuple<_Tp...>&& __x, __tuple_indices<_I1...>, const tuple<_Up...>& __y, __tuple_indices<_I2...>)
+{
+    return tuple<_Tp..., _Up...>(_STD::forward<_Tp>(get<_I1>(__x))..., get<_I2>(__y)...);
+}
+
+template <class... _Tp, class... _Up>
+inline
+tuple<_Tp..., _Up...>
+tuple_cat(tuple<_Tp...>&& __x, const tuple<_Up...>& __y)
+{
+    return __tuple_cat(_STD::move(__x), typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                       __y, typename __make_tuple_indices<sizeof...(_Up)>::type());
+}
+
+template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+inline
+tuple<_Tp..., _Up...>
+__tuple_cat(const tuple<_Tp...>& __x, __tuple_indices<_I1...>, tuple<_Up...>&& __y, __tuple_indices<_I2...>)
+{
+    return tuple<_Tp..., _Up...>(get<_I1>(__x)..., _STD::forward<_Up>(get<_I2>(__y))...);
+}
+
+template <class... _Tp, class... _Up>
+inline
+tuple<_Tp..., _Up...>
+tuple_cat(const tuple<_Tp...>& __x, tuple<_Up...>&& __y)
+{
+    return __tuple_cat(__x, typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                       _STD::move(__y), typename __make_tuple_indices<sizeof...(_Up)>::type());
+}
+
+template <class... _Tp, size_t ..._I1, class... _Up, size_t ..._I2>
+inline
+tuple<_Tp..., _Up...>
+__tuple_cat(tuple<_Tp...>&& __x, __tuple_indices<_I1...>, tuple<_Up...>&& __y, __tuple_indices<_I2...>)
+{
+    return tuple<_Tp..., _Up...>(_STD::forward<_Tp>(get<_I1>(__x))..., _STD::forward<_Up>(get<_I2>(__y))...);
+}
+
+template <class... _Tp, class... _Up>
+inline
+tuple<_Tp..., _Up...>
+tuple_cat(tuple<_Tp...>&& __x, tuple<_Up...>&& __y)
+{
+    return __tuple_cat(_STD::move(__x), typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                       _STD::move(__y), typename __make_tuple_indices<sizeof...(_Up)>::type());
+}
+
+template <class ..._Tp, class _Alloc>
+struct uses_allocator<tuple<_Tp...>, _Alloc>
+    : true_type {};
+
+template <class _InputIterator>
+inline
+_InputIterator
+begin(const std::tuple<_InputIterator, _InputIterator>& __t)
+{
+    return get<0>(__t);
+}
+
+template <class _InputIterator>
+inline
+_InputIterator
+end(const std::tuple<_InputIterator, _InputIterator>& __t)
+{
+    return get<1>(__t);
+}
+
+template <class _T1, class _T2>
+template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
+inline _LIBCPP_INLINE_VISIBILITY
+pair<_T1, _T2>::pair(piecewise_construct_t,
+                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
+                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
+    :  first(_STD::forward<_Args1>(get<_I1>( __first_args))...),
+      second(_STD::forward<_Args2>(get<_I2>(__second_args))...)
+{
+}
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif  // _LIBCPP_TUPLE