Add libc++ and libc++abi to third-party.

third_party/libcxx/include/memory

+// -*- C++ -*-
+//===-------------------------- memory ------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_MEMORY
+#define _LIBCPP_MEMORY
+
+/*
+    memory synopsis
+
+namespace std
+{
+
+struct allocator_arg_t { };
+constexpr allocator_arg_t allocator_arg = allocator_arg_t();
+
+template <class T, class Alloc> struct uses_allocator;
+
+template <class Ptr>
+struct pointer_traits
+{
+    typedef Ptr pointer;
+    typedef <details> element_type;
+    typedef <details> difference_type;
+
+    template <class U> using rebind = <details>;
+
+    static pointer pointer_to(<details>);
+};
+
+template <class T>
+struct pointer_traits<T*>
+{
+    typedef T* pointer;
+    typedef T element_type;
+    typedef ptrdiff_t difference_type;
+
+    template <class U> using rebind = U*;
+
+    static pointer pointer_to(<details>) noexcept;
+};
+
+template <class Alloc>
+struct allocator_traits
+{
+    typedef Alloc                        allocator_type;
+    typedef typename allocator_type::value_type
+                                         value_type;
+
+    typedef Alloc::pointer | value_type* pointer;
+    typedef Alloc::const_pointer
+          | pointer_traits<pointer>::rebind<const value_type>
+                                         const_pointer;
+    typedef Alloc::void_pointer
+          | pointer_traits<pointer>::rebind<void>
+                                         void_pointer;
+    typedef Alloc::const_void_pointer
+          | pointer_traits<pointer>::rebind<const void>
+                                         const_void_pointer;
+    typedef Alloc::difference_type
+          | pointer_traits<pointer>::difference_type
+                                         difference_type;
+    typedef Alloc::size_type
+          | make_unsigned<difference_type>::type
+                                         size_type;
+    typedef Alloc::propagate_on_container_copy_assignment
+          | false_type                   propagate_on_container_copy_assignment;
+    typedef Alloc::propagate_on_container_move_assignment
+          | false_type                   propagate_on_container_move_assignment;
+    typedef Alloc::propagate_on_container_swap
+          | false_type                   propagate_on_container_swap;
+
+    template <class T> using rebind_alloc  = Alloc::rebind<U>::other | Alloc<T, Args...>;
+    template <class T> using rebind_traits = allocator_traits<rebind_alloc<T>>;
+
+    static pointer allocate(allocator_type& a, size_type n);
+    static pointer allocate(allocator_type& a, size_type n, const_void_pointer hint);
+
+    static void deallocate(allocator_type& a, pointer p, size_type n) noexcept;
+
+    template <class T, class... Args>
+        static void construct(allocator_type& a, T* p, Args&&... args);
+
+    template <class T>
+        static void destroy(allocator_type& a, T* p);
+
+    static size_type max_size(const allocator_type& a); // noexcept in C++14
+
+    static allocator_type
+        select_on_container_copy_construction(const allocator_type& a);
+};
+
+template <>
+class allocator<void>
+{
+public:
+    typedef void*                                 pointer;
+    typedef const void*                           const_pointer;
+    typedef void                                  value_type;
+
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
+};
+
+template <class T>
+class allocator
+{
+public:
+    typedef size_t                                size_type;
+    typedef ptrdiff_t                             difference_type;
+    typedef T*                                    pointer;
+    typedef const T*                              const_pointer;
+    typedef typename add_lvalue_reference<T>::type       reference;
+    typedef typename add_lvalue_reference<const T>::type const_reference;
+    typedef T                                     value_type;
+
+    template <class U> struct rebind {typedef allocator<U> other;};
+
+    allocator() noexcept;
+    allocator(const allocator&) noexcept;
+    template <class U> allocator(const allocator<U>&) noexcept;
+    ~allocator();
+    pointer address(reference x) const noexcept;
+    const_pointer address(const_reference x) const noexcept;
+    pointer allocate(size_type, allocator<void>::const_pointer hint = 0);
+    void deallocate(pointer p, size_type n) noexcept;
+    size_type max_size() const noexcept;
+    template<class U, class... Args>
+        void construct(U* p, Args&&... args);
+    template <class U>
+        void destroy(U* p);
+};
+
+template <class T, class U>
+bool operator==(const allocator<T>&, const allocator<U>&) noexcept;
+
+template <class T, class U>
+bool operator!=(const allocator<T>&, const allocator<U>&) noexcept;
+
+template <class OutputIterator, class T>
+class raw_storage_iterator
+    : public iterator<output_iterator_tag,
+                      T,                               // purposefully not C++03
+                      ptrdiff_t,                       // purposefully not C++03
+                      T*,                              // purposefully not C++03
+                      raw_storage_iterator&>           // purposefully not C++03
+{
+public:
+    explicit raw_storage_iterator(OutputIterator x);
+    raw_storage_iterator& operator*();
+    raw_storage_iterator& operator=(const T& element);
+    raw_storage_iterator& operator++();
+    raw_storage_iterator  operator++(int);
+};
+
+template <class T> pair<T*,ptrdiff_t> get_temporary_buffer(ptrdiff_t n) noexcept;
+template <class T> void               return_temporary_buffer(T* p) noexcept;
+
+template <class T> T* addressof(T& r) noexcept;
+
+template <class InputIterator, class ForwardIterator>
+ForwardIterator
+uninitialized_copy(InputIterator first, InputIterator last, ForwardIterator result);
+
+template <class InputIterator, class Size, class ForwardIterator>
+ForwardIterator
+uninitialized_copy_n(InputIterator first, Size n, ForwardIterator result);
+
+template <class ForwardIterator, class T>
+void uninitialized_fill(ForwardIterator first, ForwardIterator last, const T& x);
+
+template <class ForwardIterator, class Size, class T>
+ForwardIterator
+uninitialized_fill_n(ForwardIterator first, Size n, const T& x);
+
+template <class Y> struct auto_ptr_ref {};
+
+template<class X>
+class auto_ptr
+{
+public:
+    typedef X element_type;
+
+    explicit auto_ptr(X* p =0) throw();
+    auto_ptr(auto_ptr&) throw();
+    template<class Y> auto_ptr(auto_ptr<Y>&) throw();
+    auto_ptr& operator=(auto_ptr&) throw();
+    template<class Y> auto_ptr& operator=(auto_ptr<Y>&) throw();
+    auto_ptr& operator=(auto_ptr_ref<X> r) throw();
+    ~auto_ptr() throw();
+
+    typename add_lvalue_reference<X>::type operator*() const throw();
+    X* operator->() const throw();
+    X* get() const throw();
+    X* release() throw();
+    void reset(X* p =0) throw();
+
+    auto_ptr(auto_ptr_ref<X>) throw();
+    template<class Y> operator auto_ptr_ref<Y>() throw();
+    template<class Y> operator auto_ptr<Y>() throw();
+};
+
+template <class T>
+struct default_delete
+{
+    constexpr default_delete() noexcept = default;
+    template <class U> default_delete(const default_delete<U>&) noexcept;
+
+    void operator()(T*) const noexcept;
+};
+
+template <class T>
+struct default_delete<T[]>
+{
+    constexpr default_delete() noexcept = default;
+    void operator()(T*) const noexcept;
+    template <class U> void operator()(U*) const = delete;
+};
+
+template <class T, class D = default_delete<T>>
+class unique_ptr
+{
+public:
+    typedef see below pointer;
+    typedef T element_type;
+    typedef D deleter_type;
+
+    // constructors
+    constexpr unique_ptr() noexcept;
+    explicit unique_ptr(pointer p) noexcept;
+    unique_ptr(pointer p, see below d1) noexcept;
+    unique_ptr(pointer p, see below d2) noexcept;
+    unique_ptr(unique_ptr&& u) noexcept;
+    unique_ptr(nullptr_t) noexcept : unique_ptr() { }
+    template <class U, class E>
+        unique_ptr(unique_ptr<U, E>&& u) noexcept;
+    template <class U>
+        unique_ptr(auto_ptr<U>&& u) noexcept;
+
+    // destructor
+    ~unique_ptr();
+
+    // assignment
+    unique_ptr& operator=(unique_ptr&& u) noexcept;
+    template <class U, class E> unique_ptr& operator=(unique_ptr<U, E>&& u) noexcept;
+    unique_ptr& operator=(nullptr_t) noexcept;
+
+    // observers
+    typename add_lvalue_reference<T>::type operator*() const;
+    pointer operator->() const noexcept;
+    pointer get() const noexcept;
+    deleter_type& get_deleter() noexcept;
+    const deleter_type& get_deleter() const noexcept;
+    explicit operator bool() const noexcept;
+
+    // modifiers
+    pointer release() noexcept;
+    void reset(pointer p = pointer()) noexcept;
+    void swap(unique_ptr& u) noexcept;
+};
+
+template <class T, class D>
+class unique_ptr<T[], D>
+{
+public:
+    typedef implementation-defined pointer;
+    typedef T element_type;
+    typedef D deleter_type;
+
+    // constructors
+    constexpr unique_ptr() noexcept;
+    explicit unique_ptr(pointer p) noexcept;
+    unique_ptr(pointer p, see below d) noexcept;
+    unique_ptr(pointer p, see below d) noexcept;
+    unique_ptr(unique_ptr&& u) noexcept;
+    unique_ptr(nullptr_t) noexcept : unique_ptr() { }
+
+    // destructor
+    ~unique_ptr();
+
+    // assignment
+    unique_ptr& operator=(unique_ptr&& u) noexcept;
+    unique_ptr& operator=(nullptr_t) noexcept;
+
+    // observers
+    T& operator[](size_t i) const;
+    pointer get() const noexcept;
+    deleter_type& get_deleter() noexcept;
+    const deleter_type& get_deleter() const noexcept;
+    explicit operator bool() const noexcept;
+
+    // modifiers
+    pointer release() noexcept;
+    void reset(pointer p = pointer()) noexcept;
+    void reset(nullptr_t) noexcept;
+    template <class U> void reset(U) = delete;
+    void swap(unique_ptr& u) noexcept;
+};
+
+template <class T, class D>
+    void swap(unique_ptr<T, D>& x, unique_ptr<T, D>& y) noexcept;
+
+template <class T1, class D1, class T2, class D2>
+    bool operator==(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+template <class T1, class D1, class T2, class D2>
+    bool operator!=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+template <class T1, class D1, class T2, class D2>
+    bool operator<(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+template <class T1, class D1, class T2, class D2>
+    bool operator<=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+template <class T1, class D1, class T2, class D2>
+    bool operator>(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+template <class T1, class D1, class T2, class D2>
+    bool operator>=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
+
+template <class T, class D>
+    bool operator==(const unique_ptr<T, D>& x, nullptr_t) noexcept;
+template <class T, class D>
+    bool operator==(nullptr_t, const unique_ptr<T, D>& y) noexcept;
+template <class T, class D>
+    bool operator!=(const unique_ptr<T, D>& x, nullptr_t) noexcept;
+template <class T, class D>
+    bool operator!=(nullptr_t, const unique_ptr<T, D>& y) noexcept;
+
+template <class T, class D>
+    bool operator<(const unique_ptr<T, D>& x, nullptr_t);
+template <class T, class D>
+    bool operator<(nullptr_t, const unique_ptr<T, D>& y);
+template <class T, class D>
+    bool operator<=(const unique_ptr<T, D>& x, nullptr_t);
+template <class T, class D>
+    bool operator<=(nullptr_t, const unique_ptr<T, D>& y);
+template <class T, class D>
+    bool operator>(const unique_ptr<T, D>& x, nullptr_t);
+template <class T, class D>
+    bool operator>(nullptr_t, const unique_ptr<T, D>& y);
+template <class T, class D>
+    bool operator>=(const unique_ptr<T, D>& x, nullptr_t);
+template <class T, class D>
+    bool operator>=(nullptr_t, const unique_ptr<T, D>& y);
+
+class bad_weak_ptr
+    : public std::exception
+{
+    bad_weak_ptr() noexcept;
+};
+
+template<class T, class... Args> unique_ptr<T> make_unique(Args&&... args);     // C++14
+template<class T>                unique_ptr<T> make_unique(size_t n);           // C++14
+template<class T, class... Args> unspecified   make_unique(Args&&...) = delete; // C++14, T == U[N]
+
+template<class T>
+class shared_ptr
+{
+public:
+    typedef T element_type;
+
+    // constructors:
+    constexpr shared_ptr() noexcept;
+    template<class Y> explicit shared_ptr(Y* p);
+    template<class Y, class D> shared_ptr(Y* p, D d);
+    template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
+    template <class D> shared_ptr(nullptr_t p, D d);
+    template <class D, class A> shared_ptr(nullptr_t p, D d, A a);
+    template<class Y> shared_ptr(const shared_ptr<Y>& r, T *p) noexcept;
+    shared_ptr(const shared_ptr& r) noexcept;
+    template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
+    shared_ptr(shared_ptr&& r) noexcept;
+    template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
+    template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
+    template<class Y> shared_ptr(auto_ptr<Y>&& r);
+    template <class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
+    shared_ptr(nullptr_t) : shared_ptr() { }
+
+    // destructor:
+    ~shared_ptr();
+
+    // assignment:
+    shared_ptr& operator=(const shared_ptr& r) noexcept;
+    template<class Y> shared_ptr& operator=(const shared_ptr<Y>& r) noexcept;
+    shared_ptr& operator=(shared_ptr&& r) noexcept;
+    template<class Y> shared_ptr& operator=(shared_ptr<Y>&& r);
+    template<class Y> shared_ptr& operator=(auto_ptr<Y>&& r);
+    template <class Y, class D> shared_ptr& operator=(unique_ptr<Y, D>&& r);
+
+    // modifiers:
+    void swap(shared_ptr& r) noexcept;
+    void reset() noexcept;
+    template<class Y> void reset(Y* p);
+    template<class Y, class D> void reset(Y* p, D d);
+    template<class Y, class D, class A> void reset(Y* p, D d, A a);
+
+    // observers:
+    T* get() const noexcept;
+    T& operator*() const noexcept;
+    T* operator->() const noexcept;
+    long use_count() const noexcept;
+    bool unique() const noexcept;
+    explicit operator bool() const noexcept;
+    template<class U> bool owner_before(shared_ptr<U> const& b) const;
+    template<class U> bool owner_before(weak_ptr<U> const& b) const;
+};
+
+// shared_ptr comparisons:
+template<class T, class U>
+    bool operator==(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+template<class T, class U>
+    bool operator!=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+template<class T, class U>
+    bool operator<(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+template<class T, class U>
+    bool operator>(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+template<class T, class U>
+    bool operator<=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+template<class T, class U>
+    bool operator>=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
+
+template <class T>
+    bool operator==(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+    bool operator==(nullptr_t, const shared_ptr<T>& y) noexcept;
+template <class T>
+    bool operator!=(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+    bool operator!=(nullptr_t, const shared_ptr<T>& y) noexcept;
+template <class T>
+    bool operator<(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+bool operator<(nullptr_t, const shared_ptr<T>& y) noexcept;
+template <class T>
+    bool operator<=(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+    bool operator<=(nullptr_t, const shared_ptr<T>& y) noexcept;
+template <class T>
+    bool operator>(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+    bool operator>(nullptr_t, const shared_ptr<T>& y) noexcept;
+template <class T>
+    bool operator>=(const shared_ptr<T>& x, nullptr_t) noexcept;
+template <class T>
+    bool operator>=(nullptr_t, const shared_ptr<T>& y) noexcept;
+
+// shared_ptr specialized algorithms:
+template<class T> void swap(shared_ptr<T>& a, shared_ptr<T>& b) noexcept;
+
+// shared_ptr casts:
+template<class T, class U>
+    shared_ptr<T> static_pointer_cast(shared_ptr<U> const& r) noexcept;
+template<class T, class U>
+    shared_ptr<T> dynamic_pointer_cast(shared_ptr<U> const& r) noexcept;
+template<class T, class U>
+    shared_ptr<T> const_pointer_cast(shared_ptr<U> const& r) noexcept;
+
+// shared_ptr I/O:
+template<class E, class T, class Y>
+    basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, shared_ptr<Y> const& p);
+
+// shared_ptr get_deleter:
+template<class D, class T> D* get_deleter(shared_ptr<T> const& p) noexcept;
+
+template<class T, class... Args>
+    shared_ptr<T> make_shared(Args&&... args);
+template<class T, class A, class... Args>
+    shared_ptr<T> allocate_shared(const A& a, Args&&... args);
+
+template<class T>
+class weak_ptr
+{
+public:
+    typedef T element_type;
+
+    // constructors
+    constexpr weak_ptr() noexcept;
+    template<class Y> weak_ptr(shared_ptr<Y> const& r) noexcept;
+    weak_ptr(weak_ptr const& r) noexcept;
+    template<class Y> weak_ptr(weak_ptr<Y> const& r) noexcept;
+
+    // destructor
+    ~weak_ptr();
+
+    // assignment
+    weak_ptr& operator=(weak_ptr const& r) noexcept;
+    template<class Y> weak_ptr& operator=(weak_ptr<Y> const& r) noexcept;
+    template<class Y> weak_ptr& operator=(shared_ptr<Y> const& r) noexcept;
+
+    // modifiers
+    void swap(weak_ptr& r) noexcept;
+    void reset() noexcept;
+
+    // observers
+    long use_count() const noexcept;
+    bool expired() const noexcept;
+    shared_ptr<T> lock() const noexcept;
+    template<class U> bool owner_before(shared_ptr<U> const& b) const;
+    template<class U> bool owner_before(weak_ptr<U> const& b) const;
+};
+
+// weak_ptr specialized algorithms:
+template<class T> void swap(weak_ptr<T>& a, weak_ptr<T>& b) noexcept;
+
+// class owner_less:
+template<class T> struct owner_less;
+
+template<class T>
+struct owner_less<shared_ptr<T>>
+    : binary_function<shared_ptr<T>, shared_ptr<T>, bool>
+{
+    typedef bool result_type;
+    bool operator()(shared_ptr<T> const&, shared_ptr<T> const&) const;
+    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const;
+    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const;
+};
+
+template<class T>
+struct owner_less<weak_ptr<T>>
+    : binary_function<weak_ptr<T>, weak_ptr<T>, bool>
+{
+    typedef bool result_type;
+    bool operator()(weak_ptr<T> const&, weak_ptr<T> const&) const;
+    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const;
+    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const;
+};
+
+template<class T>
+class enable_shared_from_this
+{
+protected:
+    constexpr enable_shared_from_this() noexcept;
+    enable_shared_from_this(enable_shared_from_this const&) noexcept;
+    enable_shared_from_this& operator=(enable_shared_from_this const&) noexcept;
+    ~enable_shared_from_this();
+public:
+    shared_ptr<T> shared_from_this();
+    shared_ptr<T const> shared_from_this() const;
+};
+
+template<class T>
+    bool atomic_is_lock_free(const shared_ptr<T>* p);
+template<class T>
+    shared_ptr<T> atomic_load(const shared_ptr<T>* p);
+template<class T>
+    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);
+template<class T>
+    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);
+template<class T>
+    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+template<class T>
+    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);
+template<class T>
+    shared_ptr<T>
+    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+template<class T>
+    bool
+    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+template<class T>
+    bool
+    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+template<class T>
+    bool
+    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
+                                          shared_ptr<T> w, memory_order success,
+                                          memory_order failure);
+template<class T>
+    bool
+    atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
+                                            shared_ptr<T> w, memory_order success,
+                                            memory_order failure);
+// Hash support
+template <class T> struct hash;
+template <class T, class D> struct hash<unique_ptr<T, D> >;
+template <class T> struct hash<shared_ptr<T> >;
+
+// Pointer safety
+enum class pointer_safety { relaxed, preferred, strict };
+void declare_reachable(void *p);
+template <class T> T *undeclare_reachable(T *p);
+void declare_no_pointers(char *p, size_t n);
+void undeclare_no_pointers(char *p, size_t n);
+pointer_safety get_pointer_safety() noexcept;
+
+void* align(size_t alignment, size_t size, void*& ptr, size_t& space);
+
+}  // std
+
+*/
+
+#include <__config>
+#include <type_traits>
+#include <typeinfo>
+#include <cstddef>
+#include <cstdint>
+#include <new>
+#include <utility>
+#include <limits>
+#include <iterator>
+#include <__functional_base>
+#include <iosfwd>
+#include <tuple>
+#include <cstring>
+#if defined(_LIBCPP_NO_EXCEPTIONS)
+    #include <cassert>
+#endif
+
+#if __has_feature(cxx_atomic)
+#  include <atomic>
+#endif
+
+#include <__undef_min_max>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// addressof moved to <__functional_base>
+
+template <class _Tp> class allocator;
+
+template <>
+class _LIBCPP_TYPE_VIS_ONLY allocator<void>
+{
+public:
+    typedef void*             pointer;
+    typedef const void*       const_pointer;
+    typedef void              value_type;
+
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
+};
+
+template <>
+class _LIBCPP_TYPE_VIS_ONLY allocator<const void>
+{
+public:
+    typedef const void*       pointer;
+    typedef const void*       const_pointer;
+    typedef const void        value_type;
+
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
+};
+
+// pointer_traits
+
+template <class _Tp>
+struct __has_element_type
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::element_type* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Ptr, bool = __has_element_type<_Ptr>::value>
+struct __pointer_traits_element_type;
+
+template <class _Ptr>
+struct __pointer_traits_element_type<_Ptr, true>
+{
+    typedef typename _Ptr::element_type type;
+};
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args>
+struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, true>
+{
+    typedef typename _Sp<_Tp, _Args...>::element_type type;
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args>
+struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, false>
+{
+    typedef _Tp type;
+};
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class> class _Sp, class _Tp>
+struct __pointer_traits_element_type<_Sp<_Tp>, true>
+{
+    typedef typename _Sp<_Tp>::element_type type;
+};
+
+template <template <class> class _Sp, class _Tp>
+struct __pointer_traits_element_type<_Sp<_Tp>, false>
+{
+    typedef _Tp type;
+};
+
+template <template <class, class> class _Sp, class _Tp, class _A0>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0>, true>
+{
+    typedef typename _Sp<_Tp, _A0>::element_type type;
+};
+
+template <template <class, class> class _Sp, class _Tp, class _A0>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0>, false>
+{
+    typedef _Tp type;
+};
+
+template <template <class, class, class> class _Sp, class _Tp, class _A0, class _A1>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0, _A1>, true>
+{
+    typedef typename _Sp<_Tp, _A0, _A1>::element_type type;
+};
+
+template <template <class, class, class> class _Sp, class _Tp, class _A0, class _A1>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0, _A1>, false>
+{
+    typedef _Tp type;
+};
+
+template <template <class, class, class, class> class _Sp, class _Tp, class _A0,
+                                                           class _A1, class _A2>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0, _A1, _A2>, true>
+{
+    typedef typename _Sp<_Tp, _A0, _A1, _A2>::element_type type;
+};
+
+template <template <class, class, class, class> class _Sp, class _Tp, class _A0,
+                                                           class _A1, class _A2>
+struct __pointer_traits_element_type<_Sp<_Tp, _A0, _A1, _A2>, false>
+{
+    typedef _Tp type;
+};
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Tp>
+struct __has_difference_type
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::difference_type* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Ptr, bool = __has_difference_type<_Ptr>::value>
+struct __pointer_traits_difference_type
+{
+    typedef ptrdiff_t type;
+};
+
+template <class _Ptr>
+struct __pointer_traits_difference_type<_Ptr, true>
+{
+    typedef typename _Ptr::difference_type type;
+};
+
+template <class _Tp, class _Up>
+struct __has_rebind
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Xp> static __two __test(...);
+    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
+struct __pointer_traits_rebind
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Tp::template rebind<_Up> type;
+#else
+    typedef typename _Tp::template rebind<_Up>::other type;
+#endif
+};
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, true>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Sp<_Tp, _Args...>::template rebind<_Up> type;
+#else
+    typedef typename _Sp<_Tp, _Args...>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, false>
+{
+    typedef _Sp<_Up, _Args...> type;
+};
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class> class _Sp, class _Tp, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp>, _Up, true>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Sp<_Tp>::template rebind<_Up> type;
+#else
+    typedef typename _Sp<_Tp>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class> class _Sp, class _Tp, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp>, _Up, false>
+{
+    typedef _Sp<_Up> type;
+};
+
+template <template <class, class> class _Sp, class _Tp, class _A0, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0>, _Up, true>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Sp<_Tp, _A0>::template rebind<_Up> type;
+#else
+    typedef typename _Sp<_Tp, _A0>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class> class _Sp, class _Tp, class _A0, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0>, _Up, false>
+{
+    typedef _Sp<_Up, _A0> type;
+};
+
+template <template <class, class, class> class _Sp, class _Tp, class _A0,
+                                         class _A1, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0, _A1>, _Up, true>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Sp<_Tp, _A0, _A1>::template rebind<_Up> type;
+#else
+    typedef typename _Sp<_Tp, _A0, _A1>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class, class> class _Sp, class _Tp, class _A0,
+                                         class _A1, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0, _A1>, _Up, false>
+{
+    typedef _Sp<_Up, _A0, _A1> type;
+};
+
+template <template <class, class, class, class> class _Sp, class _Tp, class _A0,
+                                                class _A1, class _A2, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0, _A1, _A2>, _Up, true>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename _Sp<_Tp, _A0, _A1, _A2>::template rebind<_Up> type;
+#else
+    typedef typename _Sp<_Tp, _A0, _A1, _A2>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class, class, class> class _Sp, class _Tp, class _A0,
+                                                class _A1, class _A2, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _A0, _A1, _A2>, _Up, false>
+{
+    typedef _Sp<_Up, _A0, _A1, _A2> type;
+};
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Ptr>
+struct _LIBCPP_TYPE_VIS_ONLY pointer_traits
+{
+    typedef _Ptr                                                     pointer;
+    typedef typename __pointer_traits_element_type<pointer>::type    element_type;
+    typedef typename __pointer_traits_difference_type<pointer>::type difference_type;
+
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    template <class _Up> using rebind = typename __pointer_traits_rebind<pointer, _Up>::type;
+#else
+    template <class _Up> struct rebind
+        {typedef typename __pointer_traits_rebind<pointer, _Up>::type other;};
+#endif  // _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+
+private:
+    struct __nat {};
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer pointer_to(typename conditional<is_void<element_type>::value,
+                                           __nat, element_type>::type& __r)
+        {return pointer::pointer_to(__r);}
+};
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY pointer_traits<_Tp*>
+{
+    typedef _Tp*      pointer;
+    typedef _Tp       element_type;
+    typedef ptrdiff_t difference_type;
+
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    template <class _Up> using rebind = _Up*;
+#else
+    template <class _Up> struct rebind {typedef _Up* other;};
+#endif
+
+private:
+    struct __nat {};
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer pointer_to(typename conditional<is_void<element_type>::value,
+                                      __nat, element_type>::type& __r) _NOEXCEPT
+        {return _VSTD::addressof(__r);}
+};
+
+// allocator_traits
+
+namespace __has_pointer_type_imp
+{
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::pointer* = 0);
+}
+
+template <class _Tp>
+struct __has_pointer_type
+    : public integral_constant<bool, sizeof(__has_pointer_type_imp::__test<_Tp>(0)) == 1>
+{
+};
+
+namespace __pointer_type_imp
+{
+
+template <class _Tp, class _Dp, bool = __has_pointer_type<_Dp>::value>
+struct __pointer_type
+{
+    typedef typename _Dp::pointer type;
+};
+
+template <class _Tp, class _Dp>
+struct __pointer_type<_Tp, _Dp, false>
+{
+    typedef _Tp* type;
+};
+
+}  // __pointer_type_imp
+
+template <class _Tp, class _Dp>
+struct __pointer_type
+{
+    typedef typename __pointer_type_imp::__pointer_type<_Tp, typename remove_reference<_Dp>::type>::type type;
+};
+
+template <class _Tp>
+struct __has_const_pointer
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::const_pointer* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Tp, class _Ptr, class _Alloc, bool = __has_const_pointer<_Alloc>::value>
+struct __const_pointer
+{
+    typedef typename _Alloc::const_pointer type;
+};
+
+template <class _Tp, class _Ptr, class _Alloc>
+struct __const_pointer<_Tp, _Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename pointer_traits<_Ptr>::template rebind<const _Tp> type;
+#else
+    typedef typename pointer_traits<_Ptr>::template rebind<const _Tp>::other type;
+#endif
+};
+
+template <class _Tp>
+struct __has_void_pointer
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::void_pointer* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Ptr, class _Alloc, bool = __has_void_pointer<_Alloc>::value>
+struct __void_pointer
+{
+    typedef typename _Alloc::void_pointer type;
+};
+
+template <class _Ptr, class _Alloc>
+struct __void_pointer<_Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename pointer_traits<_Ptr>::template rebind<void> type;
+#else
+    typedef typename pointer_traits<_Ptr>::template rebind<void>::other type;
+#endif
+};
+
+template <class _Tp>
+struct __has_const_void_pointer
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::const_void_pointer* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Ptr, class _Alloc, bool = __has_const_void_pointer<_Alloc>::value>
+struct __const_void_pointer
+{
+    typedef typename _Alloc::const_void_pointer type;
+};
+
+template <class _Ptr, class _Alloc>
+struct __const_void_pointer<_Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    typedef typename pointer_traits<_Ptr>::template rebind<const void> type;
+#else
+    typedef typename pointer_traits<_Ptr>::template rebind<const void>::other type;
+#endif
+};
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Tp*
+__to_raw_pointer(_Tp* __p) _NOEXCEPT
+{
+    return __p;
+}
+
+template <class _Pointer>
+inline _LIBCPP_INLINE_VISIBILITY
+typename pointer_traits<_Pointer>::element_type*
+__to_raw_pointer(_Pointer __p) _NOEXCEPT
+{
+    return _VSTD::__to_raw_pointer(__p.operator->());
+}
+
+template <class _Tp>
+struct __has_size_type
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::size_type* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Alloc, class _DiffType, bool = __has_size_type<_Alloc>::value>
+struct __size_type
+{
+    typedef typename make_unsigned<_DiffType>::type type;
+};
+
+template <class _Alloc, class _DiffType>
+struct __size_type<_Alloc, _DiffType, true>
+{
+    typedef typename _Alloc::size_type type;
+};
+
+template <class _Tp>
+struct __has_propagate_on_container_copy_assignment
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::propagate_on_container_copy_assignment* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Alloc, bool = __has_propagate_on_container_copy_assignment<_Alloc>::value>
+struct __propagate_on_container_copy_assignment
+{
+    typedef false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_copy_assignment<_Alloc, true>
+{
+    typedef typename _Alloc::propagate_on_container_copy_assignment type;
+};
+
+template <class _Tp>
+struct __has_propagate_on_container_move_assignment
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::propagate_on_container_move_assignment* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Alloc, bool = __has_propagate_on_container_move_assignment<_Alloc>::value>
+struct __propagate_on_container_move_assignment
+{
+    typedef false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_move_assignment<_Alloc, true>
+{
+    typedef typename _Alloc::propagate_on_container_move_assignment type;
+};
+
+template <class _Tp>
+struct __has_propagate_on_container_swap
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Up> static __two __test(...);
+    template <class _Up> static char __test(typename _Up::propagate_on_container_swap* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Alloc, bool = __has_propagate_on_container_swap<_Alloc>::value>
+struct __propagate_on_container_swap
+{
+    typedef false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_swap<_Alloc, true>
+{
+    typedef typename _Alloc::propagate_on_container_swap type;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
+struct __has_rebind_other
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Xp> static __two __test(...);
+    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>::other* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Tp, class _Up>
+struct __has_rebind_other<_Tp, _Up, false>
+{
+    static const bool value = false;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind_other<_Tp, _Up>::value>
+struct __allocator_traits_rebind
+{
+    typedef typename _Tp::template rebind<_Up>::other type;
+};
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, true>
+{
+    typedef typename _Alloc<_Tp, _Args...>::template rebind<_Up>::other type;
+};
+
+template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, false>
+{
+    typedef _Alloc<_Up, _Args...> type;
+};
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template <template <class> class _Alloc, class _Tp, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp>, _Up, true>
+{
+    typedef typename _Alloc<_Tp>::template rebind<_Up>::other type;
+};
+
+template <template <class> class _Alloc, class _Tp, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp>, _Up, false>
+{
+    typedef _Alloc<_Up> type;
+};
+
+template <template <class, class> class _Alloc, class _Tp, class _A0, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0>, _Up, true>
+{
+    typedef typename _Alloc<_Tp, _A0>::template rebind<_Up>::other type;
+};
+
+template <template <class, class> class _Alloc, class _Tp, class _A0, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0>, _Up, false>
+{
+    typedef _Alloc<_Up, _A0> type;
+};
+
+template <template <class, class, class> class _Alloc, class _Tp, class _A0,
+                                         class _A1, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0, _A1>, _Up, true>
+{
+    typedef typename _Alloc<_Tp, _A0, _A1>::template rebind<_Up>::other type;
+};
+
+template <template <class, class, class> class _Alloc, class _Tp, class _A0,
+                                         class _A1, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0, _A1>, _Up, false>
+{
+    typedef _Alloc<_Up, _A0, _A1> type;
+};
+
+template <template <class, class, class, class> class _Alloc, class _Tp, class _A0,
+                                                class _A1, class _A2, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0, _A1, _A2>, _Up, true>
+{
+    typedef typename _Alloc<_Tp, _A0, _A1, _A2>::template rebind<_Up>::other type;
+};
+
+template <template <class, class, class, class> class _Alloc, class _Tp, class _A0,
+                                                class _A1, class _A2, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _A0, _A1, _A2>, _Up, false>
+{
+    typedef _Alloc<_Up, _A0, _A1, _A2> type;
+};
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+#ifndef _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+auto
+__has_allocate_hint_test(_Alloc&& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
+    -> decltype(__a.allocate(__sz, __p), true_type());
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+auto
+__has_allocate_hint_test(const _Alloc& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
+    -> false_type;
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+struct __has_allocate_hint
+    : integral_constant<bool,
+        is_same<
+            decltype(__has_allocate_hint_test(declval<_Alloc>(),
+                                          declval<_SizeType>(),
+                                          declval<_ConstVoidPtr>())),
+            true_type>::value>
+{
+};
+
+#else  // _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+struct __has_allocate_hint
+    : true_type
+{
+};
+
+#endif  // _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+#if !defined(_LIBCPP_HAS_NO_ADVANCED_SFINAE) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+
+template <class _Alloc, class _Tp, class ..._Args>
+decltype(_VSTD::declval<_Alloc>().construct(_VSTD::declval<_Tp*>(),
+                                           _VSTD::declval<_Args>()...),
+                                           true_type())
+__has_construct_test(_Alloc&& __a, _Tp* __p, _Args&& ...__args);
+
+template <class _Alloc, class _Pointer, class ..._Args>
+false_type
+__has_construct_test(const _Alloc& __a, _Pointer&& __p, _Args&& ...__args);
+
+template <class _Alloc, class _Pointer, class ..._Args>
+struct __has_construct
+    : integral_constant<bool,
+        is_same<
+            decltype(__has_construct_test(declval<_Alloc>(),
+                                          declval<_Pointer>(),
+                                          declval<_Args>()...)),
+            true_type>::value>
+{
+};
+
+template <class _Alloc, class _Pointer>
+auto
+__has_destroy_test(_Alloc&& __a, _Pointer&& __p)
+    -> decltype(__a.destroy(__p), true_type());
+
+template <class _Alloc, class _Pointer>
+auto
+__has_destroy_test(const _Alloc& __a, _Pointer&& __p)
+    -> false_type;
+
+template <class _Alloc, class _Pointer>
+struct __has_destroy
+    : integral_constant<bool,
+        is_same<
+            decltype(__has_destroy_test(declval<_Alloc>(),
+                                        declval<_Pointer>())),
+            true_type>::value>
+{
+};
+
+template <class _Alloc>
+auto
+__has_max_size_test(_Alloc&& __a)
+    -> decltype(__a.max_size(), true_type());
+
+template <class _Alloc>
+auto
+__has_max_size_test(const volatile _Alloc& __a)
+    -> false_type;
+
+template <class _Alloc>
+struct __has_max_size
+    : integral_constant<bool,
+        is_same<
+            decltype(__has_max_size_test(declval<_Alloc&>())),
+            true_type>::value>
+{
+};
+
+template <class _Alloc>
+auto
+__has_select_on_container_copy_construction_test(_Alloc&& __a)
+    -> decltype(__a.select_on_container_copy_construction(), true_type());
+
+template <class _Alloc>
+auto
+__has_select_on_container_copy_construction_test(const volatile _Alloc& __a)
+    -> false_type;
+
+template <class _Alloc>
+struct __has_select_on_container_copy_construction
+    : integral_constant<bool,
+        is_same<
+            decltype(__has_select_on_container_copy_construction_test(declval<_Alloc&>())),
+            true_type>::value>
+{
+};
+
+#else  // _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Alloc, class _Pointer, class ..._Args>
+struct __has_construct
+    : false_type
+{
+};
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Alloc, class _Pointer, class _Args>
+struct __has_construct
+    : false_type
+{
+};
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Alloc, class _Pointer>
+struct __has_destroy
+    : false_type
+{
+};
+
+template <class _Alloc>
+struct __has_max_size
+    : true_type
+{
+};
+
+template <class _Alloc>
+struct __has_select_on_container_copy_construction
+    : false_type
+{
+};
+
+#endif  // _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+template <class _Alloc, class _Ptr, bool = __has_difference_type<_Alloc>::value>
+struct __alloc_traits_difference_type
+{
+    typedef typename pointer_traits<_Ptr>::difference_type type;
+};
+
+template <class _Alloc, class _Ptr>
+struct __alloc_traits_difference_type<_Alloc, _Ptr, true>
+{
+    typedef typename _Alloc::difference_type type;
+};
+
+template <class _Alloc>
+struct _LIBCPP_TYPE_VIS_ONLY allocator_traits
+{
+    typedef _Alloc                              allocator_type;
+    typedef typename allocator_type::value_type value_type;
+
+    typedef typename __pointer_type<value_type, allocator_type>::type pointer;
+    typedef typename __const_pointer<value_type, pointer, allocator_type>::type const_pointer;
+    typedef typename __void_pointer<pointer, allocator_type>::type void_pointer;
+    typedef typename __const_void_pointer<pointer, allocator_type>::type const_void_pointer;
+
+    typedef typename __alloc_traits_difference_type<allocator_type, pointer>::type difference_type;
+    typedef typename __size_type<allocator_type, difference_type>::type size_type;
+
+    typedef typename __propagate_on_container_copy_assignment<allocator_type>::type
+                     propagate_on_container_copy_assignment;
+    typedef typename __propagate_on_container_move_assignment<allocator_type>::type
+                     propagate_on_container_move_assignment;
+    typedef typename __propagate_on_container_swap<allocator_type>::type
+                     propagate_on_container_swap;
+
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    template <class _Tp> using rebind_alloc =
+                  typename __allocator_traits_rebind<allocator_type, _Tp>::type;
+    template <class _Tp> using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
+#else  // _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+    template <class _Tp> struct rebind_alloc
+        {typedef typename __allocator_traits_rebind<allocator_type, _Tp>::type other;};
+    template <class _Tp> struct rebind_traits
+        {typedef allocator_traits<typename rebind_alloc<_Tp>::other> other;};
+#endif  // _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer allocate(allocator_type& __a, size_type __n)
+        {return __a.allocate(__n);}
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
+        {return allocate(__a, __n, __hint,
+            __has_allocate_hint<allocator_type, size_type, const_void_pointer>());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static void deallocate(allocator_type& __a, pointer __p, size_type __n) _NOEXCEPT
+        {__a.deallocate(__p, __n);}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY
+        static void construct(allocator_type& __a, _Tp* __p, _Args&&... __args)
+            {__construct(__has_construct<allocator_type, pointer, _Args...>(),
+                         __a, __p, _VSTD::forward<_Args>(__args)...);}
+#else  // _LIBCPP_HAS_NO_VARIADICS
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static void construct(allocator_type& __a, _Tp* __p)
+            {
+                ::new ((void*)__p) _Tp();
+            }
+    template <class _Tp, class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0)
+            {
+                ::new ((void*)__p) _Tp(__a0);
+            }
+    template <class _Tp, class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0,
+                              const _A1& __a1)
+            {
+                ::new ((void*)__p) _Tp(__a0, __a1);
+            }
+    template <class _Tp, class _A0, class _A1, class _A2>
+        _LIBCPP_INLINE_VISIBILITY
+        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0,
+                              const _A1& __a1, const _A2& __a2)
+            {
+                ::new ((void*)__p) _Tp(__a0, __a1, __a2);
+            }
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static void destroy(allocator_type& __a, _Tp* __p)
+            {__destroy(__has_destroy<allocator_type, _Tp*>(), __a, __p);}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static size_type max_size(const allocator_type& __a) _NOEXCEPT
+        {return __max_size(__has_max_size<const allocator_type>(), __a);}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static allocator_type
+        select_on_container_copy_construction(const allocator_type& __a)
+            {return select_on_container_copy_construction(
+                __has_select_on_container_copy_construction<const allocator_type>(),
+                __a);}
+
+    template <class _Ptr>
+        _LIBCPP_INLINE_VISIBILITY
+        static
+        void
+        __construct_forward(allocator_type& __a, _Ptr __begin1, _Ptr __end1, _Ptr& __begin2)
+        {
+            for (; __begin1 != __end1; ++__begin1, ++__begin2)
+                construct(__a, _VSTD::__to_raw_pointer(__begin2), _VSTD::move_if_noexcept(*__begin1));
+        }
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static
+        typename enable_if
+        <
+            (is_same<allocator_type, allocator<_Tp> >::value
+                || !__has_construct<allocator_type, _Tp*, _Tp>::value) &&
+             is_trivially_move_constructible<_Tp>::value,
+            void
+        >::type
+        __construct_forward(allocator_type& __a, _Tp* __begin1, _Tp* __end1, _Tp*& __begin2)
+        {
+            ptrdiff_t _Np = __end1 - __begin1;
+            _VSTD::memcpy(__begin2, __begin1, _Np * sizeof(_Tp));
+            __begin2 += _Np;
+        }
+
+    template <class _Ptr>
+        _LIBCPP_INLINE_VISIBILITY
+        static
+        void
+        __construct_backward(allocator_type& __a, _Ptr __begin1, _Ptr __end1, _Ptr& __end2)
+        {
+            while (__end1 != __begin1)
+            {
+                construct(__a, _VSTD::__to_raw_pointer(__end2-1), _VSTD::move_if_noexcept(*--__end1));
+                --__end2;
+            }
+        }
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static
+        typename enable_if
+        <
+            (is_same<allocator_type, allocator<_Tp> >::value
+                || !__has_construct<allocator_type, _Tp*, _Tp>::value) &&
+             is_trivially_move_constructible<_Tp>::value,
+            void
+        >::type
+        __construct_backward(allocator_type& __a, _Tp* __begin1, _Tp* __end1, _Tp*& __end2)
+        {
+            ptrdiff_t _Np = __end1 - __begin1;
+            __end2 -= _Np;
+            _VSTD::memcpy(__end2, __begin1, _Np * sizeof(_Tp));
+        }
+
+private:
+
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer allocate(allocator_type& __a, size_type __n,
+        const_void_pointer __hint, true_type)
+        {return __a.allocate(__n, __hint);}
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer allocate(allocator_type& __a, size_type __n,
+        const_void_pointer, false_type)
+        {return __a.allocate(__n);}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY
+        static void __construct(true_type, allocator_type& __a, _Tp* __p, _Args&&... __args)
+            {__a.construct(__p, _VSTD::forward<_Args>(__args)...);}
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY
+        static void __construct(false_type, allocator_type&, _Tp* __p, _Args&&... __args)
+            {
+                ::new ((void*)__p) _Tp(_VSTD::forward<_Args>(__args)...);
+            }
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static void __destroy(true_type, allocator_type& __a, _Tp* __p)
+            {__a.destroy(__p);}
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY
+        static void __destroy(false_type, allocator_type&, _Tp* __p)
+            {
+                __p->~_Tp();
+            }
+
+    _LIBCPP_INLINE_VISIBILITY
+    static size_type __max_size(true_type, const allocator_type& __a)
+            {return __a.max_size();}
+    _LIBCPP_INLINE_VISIBILITY
+    static size_type __max_size(false_type, const allocator_type&)
+            {return numeric_limits<size_type>::max();}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static allocator_type
+        select_on_container_copy_construction(true_type, const allocator_type& __a)
+            {return __a.select_on_container_copy_construction();}
+    _LIBCPP_INLINE_VISIBILITY
+    static allocator_type
+        select_on_container_copy_construction(false_type, const allocator_type& __a)
+            {return __a;}
+};
+
+// allocator
+
+template <class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY allocator
+{
+public:
+    typedef size_t            size_type;
+    typedef ptrdiff_t         difference_type;
+    typedef _Tp*              pointer;
+    typedef const _Tp*        const_pointer;
+    typedef _Tp&              reference;
+    typedef const _Tp&        const_reference;
+    typedef _Tp               value_type;
+
+    typedef true_type propagate_on_container_move_assignment;
+
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
+
+    _LIBCPP_INLINE_VISIBILITY allocator() _NOEXCEPT {}
+    template <class _Up> _LIBCPP_INLINE_VISIBILITY allocator(const allocator<_Up>&) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY pointer address(reference __x) const _NOEXCEPT
+        {return _VSTD::addressof(__x);}
+    _LIBCPP_INLINE_VISIBILITY const_pointer address(const_reference __x) const _NOEXCEPT
+        {return _VSTD::addressof(__x);}
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
+        {return static_cast<pointer>(::operator new(__n * sizeof(_Tp)));}
+    _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
+        {::operator delete((void*)__p);}
+    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
+        {return size_type(~0) / sizeof(_Tp);}
+#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+    template <class _Up, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(_Up* __p, _Args&&... __args)
+        {
+            ::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
+        }
+#else  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p)
+        {
+            ::new((void*)__p) _Tp();
+        }
+# if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
+
+    template <class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0)
+        {
+            ::new((void*)__p) _Tp(__a0);
+        }
+    template <class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0)
+        {
+            ::new((void*)__p) _Tp(__a0);
+        }
+# endif  // defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0, _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0, _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0, const _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0, const _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+#endif  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+    _LIBCPP_INLINE_VISIBILITY void destroy(pointer __p) {__p->~_Tp();}
+};
+
+template <class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY allocator<const _Tp>
+{
+public:
+    typedef size_t            size_type;
+    typedef ptrdiff_t         difference_type;
+    typedef const _Tp*        pointer;
+    typedef const _Tp*        const_pointer;
+    typedef const _Tp&        reference;
+    typedef const _Tp&        const_reference;
+    typedef const _Tp         value_type;
+
+    typedef true_type propagate_on_container_move_assignment;
+
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
+
+    _LIBCPP_INLINE_VISIBILITY allocator() _NOEXCEPT {}
+    template <class _Up> _LIBCPP_INLINE_VISIBILITY allocator(const allocator<_Up>&) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY const_pointer address(const_reference __x) const _NOEXCEPT
+        {return _VSTD::addressof(__x);}
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, allocator<void>::const_pointer = 0)
+        {return static_cast<pointer>(::operator new(__n * sizeof(_Tp)));}
+    _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
+        {::operator delete((void*)__p);}
+    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
+        {return size_type(~0) / sizeof(_Tp);}
+#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+    template <class _Up, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(_Up* __p, _Args&&... __args)
+        {
+            ::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
+        }
+#else  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p)
+        {
+            ::new((void*)__p) _Tp();
+        }
+# if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
+
+    template <class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0)
+        {
+            ::new((void*)__p) _Tp(__a0);
+        }
+    template <class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0)
+        {
+            ::new((void*)__p) _Tp(__a0);
+        }
+# endif  // defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0, _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0, _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, _A0& __a0, const _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        construct(pointer __p, const _A0& __a0, const _A1& __a1)
+        {
+            ::new((void*)__p) _Tp(__a0, __a1);
+        }
+#endif  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
+    _LIBCPP_INLINE_VISIBILITY void destroy(pointer __p) {__p->~_Tp();}
+};
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return true;}
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return false;}
+
+template <class _OutputIterator, class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY raw_storage_iterator
+    : public iterator<output_iterator_tag,
+                      _Tp,                                         // purposefully not C++03
+                      ptrdiff_t,                                   // purposefully not C++03
+                      _Tp*,                                        // purposefully not C++03
+                      raw_storage_iterator<_OutputIterator, _Tp>&> // purposefully not C++03
+{
+private:
+    _OutputIterator __x_;
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit raw_storage_iterator(_OutputIterator __x) : __x_(__x) {}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator*() {return *this;}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator=(const _Tp& __element)
+        {::new(&*__x_) _Tp(__element); return *this;}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator++() {++__x_; return *this;}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator  operator++(int)
+        {raw_storage_iterator __t(*this); ++__x_; return __t;}
+};
+
+template <class _Tp>
+pair<_Tp*, ptrdiff_t>
+get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
+{
+    pair<_Tp*, ptrdiff_t> __r(0, 0);
+    const ptrdiff_t __m = (~ptrdiff_t(0) ^
+                           ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1)))
+                           / sizeof(_Tp);
+    if (__n > __m)
+        __n = __m;
+    while (__n > 0)
+    {
+        __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow));
+        if (__r.first)
+        {
+            __r.second = __n;
+            break;
+        }
+        __n /= 2;
+    }
+    return __r;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void return_temporary_buffer(_Tp* __p) _NOEXCEPT {::operator delete(__p);}
+
+template <class _Tp>
+struct auto_ptr_ref
+{
+    _Tp* __ptr_;
+};
+
+template<class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY auto_ptr
+{
+private:
+    _Tp* __ptr_;
+public:
+    typedef _Tp element_type;
+
+    _LIBCPP_INLINE_VISIBILITY explicit auto_ptr(_Tp* __p = 0) throw() : __ptr_(__p) {}
+    _LIBCPP_INLINE_VISIBILITY auto_ptr(auto_ptr& __p) throw() : __ptr_(__p.release()) {}
+    template<class _Up> _LIBCPP_INLINE_VISIBILITY auto_ptr(auto_ptr<_Up>& __p) throw()
+        : __ptr_(__p.release()) {}
+    _LIBCPP_INLINE_VISIBILITY auto_ptr& operator=(auto_ptr& __p) throw()
+        {reset(__p.release()); return *this;}
+    template<class _Up> _LIBCPP_INLINE_VISIBILITY auto_ptr& operator=(auto_ptr<_Up>& __p) throw()
+        {reset(__p.release()); return *this;}
+    _LIBCPP_INLINE_VISIBILITY auto_ptr& operator=(auto_ptr_ref<_Tp> __p) throw()
+        {reset(__p.__ptr_); return *this;}
+    _LIBCPP_INLINE_VISIBILITY ~auto_ptr() throw() {delete __ptr_;}
+
+    _LIBCPP_INLINE_VISIBILITY _Tp& operator*() const throw()
+        {return *__ptr_;}
+    _LIBCPP_INLINE_VISIBILITY _Tp* operator->() const throw() {return __ptr_;}
+    _LIBCPP_INLINE_VISIBILITY _Tp* get() const throw() {return __ptr_;}
+    _LIBCPP_INLINE_VISIBILITY _Tp* release() throw()
+    {
+        _Tp* __t = __ptr_;
+        __ptr_ = 0;
+        return __t;
+    }
+    _LIBCPP_INLINE_VISIBILITY void reset(_Tp* __p = 0) throw()
+    {
+        if (__ptr_ != __p)
+            delete __ptr_;
+        __ptr_ = __p;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY auto_ptr(auto_ptr_ref<_Tp> __p) throw() : __ptr_(__p.__ptr_) {}
+    template<class _Up> _LIBCPP_INLINE_VISIBILITY operator auto_ptr_ref<_Up>() throw()
+        {auto_ptr_ref<_Up> __t; __t.__ptr_ = release(); return __t;}
+    template<class _Up> _LIBCPP_INLINE_VISIBILITY operator auto_ptr<_Up>() throw()
+        {return auto_ptr<_Up>(release());}
+};
+
+template <>
+class _LIBCPP_TYPE_VIS_ONLY auto_ptr<void>
+{
+public:
+    typedef void element_type;
+};
+
+template <class _T1, class _T2, bool = is_same<typename remove_cv<_T1>::type,
+                                                     typename remove_cv<_T2>::type>::value,
+                                bool = is_empty<_T1>::value
+#if __has_feature(is_final)
+                                       && !__is_final(_T1)
+#endif
+                                ,
+                                bool = is_empty<_T2>::value
+#if __has_feature(is_final)
+                                       && !__is_final(_T2)
+#endif
+         >
+struct __libcpp_compressed_pair_switch;
+
+template <class _T1, class _T2, bool IsSame>
+struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, false, false> {enum {value = 0};};
+
+template <class _T1, class _T2, bool IsSame>
+struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, true, false>  {enum {value = 1};};
+
+template <class _T1, class _T2, bool IsSame>
+struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, false, true>  {enum {value = 2};};
+
+template <class _T1, class _T2>
+struct __libcpp_compressed_pair_switch<_T1, _T2, false, true, true>    {enum {value = 3};};
+
+template <class _T1, class _T2>
+struct __libcpp_compressed_pair_switch<_T1, _T2, true, true, true>     {enum {value = 1};};
+
+template <class _T1, class _T2, unsigned = __libcpp_compressed_pair_switch<_T1, _T2>::value>
+class __libcpp_compressed_pair_imp;
+
+template <class _T1, class _T2>
+class __libcpp_compressed_pair_imp<_T1, _T2, 0>
+{
+private:
+    _T1 __first_;
+    _T2 __second_;
+public:
+    typedef _T1 _T1_param;
+    typedef _T2 _T2_param;
+
+    typedef typename remove_reference<_T1>::type& _T1_reference;
+    typedef typename remove_reference<_T2>::type& _T2_reference;
+
+    typedef const typename remove_reference<_T1>::type& _T1_const_reference;
+    typedef const typename remove_reference<_T2>::type& _T2_const_reference;
+
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+        : __first_(_VSTD::forward<_T1_param>(__t1)) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+        : __second_(_VSTD::forward<_T2_param>(__t2)) {}
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+        : __first_(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
+                   is_nothrow_copy_constructible<_T2>::value)
+        : __first_(__p.first()),
+          __second_(__p.second()) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
+                   is_nothrow_copy_assignable<_T2>::value)
+        {
+            __first_ = __p.first();
+            __second_ = __p.second();
+            return *this;
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : __first_(_VSTD::forward<_T1>(__p.first())),
+          __second_(_VSTD::forward<_T2>(__p.second())) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
+                   is_nothrow_move_assignable<_T2>::value)
+        {
+            __first_ = _VSTD::forward<_T1>(__p.first());
+            __second_ = _VSTD::forward<_T2>(__p.second());
+            return *this;
+        }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+#endif  // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
+        _LIBCPP_INLINE_VISIBILITY
+        __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
+                                     tuple<_Args1...> __first_args,
+                                     tuple<_Args2...> __second_args,
+                                     __tuple_indices<_I1...>,
+                                     __tuple_indices<_I2...>)
+            : __first_(_VSTD::forward<_Args1>(get<_I1>(__first_args))...),
+              __second_(_VSTD::forward<_Args2>(get<_I2>(__second_args))...)
+            {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return __first_;}
+    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return __first_;}
+
+    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return __second_;}
+    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return __second_;}
+
+    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+    {
+        using _VSTD::swap;
+        swap(__first_, __x.__first_);
+        swap(__second_, __x.__second_);
+    }
+};
+
+template <class _T1, class _T2>
+class __libcpp_compressed_pair_imp<_T1, _T2, 1>
+    : private _T1
+{
+private:
+    _T2 __second_;
+public:
+    typedef _T1 _T1_param;
+    typedef _T2 _T2_param;
+
+    typedef _T1&                                        _T1_reference;
+    typedef typename remove_reference<_T2>::type& _T2_reference;
+
+    typedef const _T1&                                        _T1_const_reference;
+    typedef const typename remove_reference<_T2>::type& _T2_const_reference;
+
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+        : _T1(_VSTD::forward<_T1_param>(__t1)) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+        : __second_(_VSTD::forward<_T2_param>(__t2)) {}
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+        : _T1(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
+                   is_nothrow_copy_constructible<_T2>::value)
+        : _T1(__p.first()), __second_(__p.second()) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
+                   is_nothrow_copy_assignable<_T2>::value)
+        {
+            _T1::operator=(__p.first());
+            __second_ = __p.second();
+            return *this;
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : _T1(_VSTD::move(__p.first())), __second_(_VSTD::forward<_T2>(__p.second())) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
+                   is_nothrow_move_assignable<_T2>::value)
+        {
+            _T1::operator=(_VSTD::move(__p.first()));
+            __second_ = _VSTD::forward<_T2>(__p.second());
+            return *this;
+        }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+#endif  // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
+        _LIBCPP_INLINE_VISIBILITY
+        __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
+                                     tuple<_Args1...> __first_args,
+                                     tuple<_Args2...> __second_args,
+                                     __tuple_indices<_I1...>,
+                                     __tuple_indices<_I2...>)
+            : _T1(_VSTD::forward<_Args1>(get<_I1>(__first_args))...),
+              __second_(_VSTD::forward<_Args2>(get<_I2>(__second_args))...)
+            {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return *this;}
+    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return *this;}
+
+    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return __second_;}
+    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return __second_;}
+
+    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+    {
+        using _VSTD::swap;
+        swap(__second_, __x.__second_);
+    }
+};
+
+template <class _T1, class _T2>
+class __libcpp_compressed_pair_imp<_T1, _T2, 2>
+    : private _T2
+{
+private:
+    _T1 __first_;
+public:
+    typedef _T1 _T1_param;
+    typedef _T2 _T2_param;
+
+    typedef typename remove_reference<_T1>::type& _T1_reference;
+    typedef _T2&                                        _T2_reference;
+
+    typedef const typename remove_reference<_T1>::type& _T1_const_reference;
+    typedef const _T2&                                        _T2_const_reference;
+
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+        : __first_(_VSTD::forward<_T1_param>(__t1)) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+        : _T2(_VSTD::forward<_T2_param>(__t2)) {}
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : _T2(_VSTD::forward<_T2_param>(__t2)), __first_(_VSTD::forward<_T1_param>(__t1)) {}
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
+                   is_nothrow_copy_constructible<_T2>::value)
+        : _T2(__p.second()), __first_(__p.first()) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
+                   is_nothrow_copy_assignable<_T2>::value)
+        {
+            _T2::operator=(__p.second());
+            __first_ = __p.first();
+            return *this;
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : _T2(_VSTD::forward<_T2>(__p.second())), __first_(_VSTD::move(__p.first())) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
+                   is_nothrow_move_assignable<_T2>::value)
+        {
+            _T2::operator=(_VSTD::forward<_T2>(__p.second()));
+            __first_ = _VSTD::move(__p.first());
+            return *this;
+        }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+#endif  // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
+        _LIBCPP_INLINE_VISIBILITY
+        __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
+                                     tuple<_Args1...> __first_args,
+                                     tuple<_Args2...> __second_args,
+                                     __tuple_indices<_I1...>,
+                                     __tuple_indices<_I2...>)
+            : _T2(_VSTD::forward<_Args2>(get<_I2>(__second_args))...),
+              __first_(_VSTD::forward<_Args1>(get<_I1>(__first_args))...)
+              
+            {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return __first_;}
+    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return __first_;}
+
+    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return *this;}
+    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return *this;}
+
+    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+    {
+        using _VSTD::swap;
+        swap(__first_, __x.__first_);
+    }
+};
+
+template <class _T1, class _T2>
+class __libcpp_compressed_pair_imp<_T1, _T2, 3>
+    : private _T1,
+      private _T2
+{
+public:
+    typedef _T1 _T1_param;
+    typedef _T2 _T2_param;
+
+    typedef _T1& _T1_reference;
+    typedef _T2& _T2_reference;
+
+    typedef const _T1& _T1_const_reference;
+    typedef const _T2& _T2_const_reference;
+
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
+        : _T1(_VSTD::forward<_T1_param>(__t1)) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
+        : _T2(_VSTD::forward<_T2_param>(__t2)) {}
+    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
+        : _T1(_VSTD::forward<_T1_param>(__t1)), _T2(_VSTD::forward<_T2_param>(__t2)) {}
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
+                   is_nothrow_copy_constructible<_T2>::value)
+        : _T1(__p.first()), _T2(__p.second()) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(const __libcpp_compressed_pair_imp& __p)
+        _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
+                   is_nothrow_copy_assignable<_T2>::value)
+        {
+            _T1::operator=(__p.first());
+            _T2::operator=(__p.second());
+            return *this;
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : _T1(_VSTD::move(__p.first())), _T2(_VSTD::move(__p.second())) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&& __p)
+        _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
+                   is_nothrow_move_assignable<_T2>::value)
+        {
+            _T1::operator=(_VSTD::move(__p.first()));
+            _T2::operator=(_VSTD::move(__p.second()));
+            return *this;
+        }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+#endif  // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
+        _LIBCPP_INLINE_VISIBILITY
+        __libcpp_compressed_pair_imp(piecewise_construct_t __pc,
+                                     tuple<_Args1...> __first_args,
+                                     tuple<_Args2...> __second_args,
+                                     __tuple_indices<_I1...>,
+                                     __tuple_indices<_I2...>)
+            : _T1(_VSTD::forward<_Args1>(get<_I1>(__first_args))...),
+              _T2(_VSTD::forward<_Args2>(get<_I2>(__second_args))...)
+            {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return *this;}
+    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return *this;}
+
+    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return *this;}
+    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return *this;}
+
+    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp&)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+    {
+    }
+};
+
+template <class _T1, class _T2>
+class __compressed_pair
+    : private __libcpp_compressed_pair_imp<_T1, _T2>
+{
+    typedef __libcpp_compressed_pair_imp<_T1, _T2> base;
+public:
+    typedef typename base::_T1_param _T1_param;
+    typedef typename base::_T2_param _T2_param;
+
+    typedef typename base::_T1_reference _T1_reference;
+    typedef typename base::_T2_reference _T2_reference;
+
+    typedef typename base::_T1_const_reference _T1_const_reference;
+    typedef typename base::_T2_const_reference _T2_const_reference;
+
+    _LIBCPP_INLINE_VISIBILITY __compressed_pair() {}
+    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T1_param __t1)
+        : base(_VSTD::forward<_T1_param>(__t1)) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T2_param __t2)
+        : base(_VSTD::forward<_T2_param>(__t2)) {}
+    _LIBCPP_INLINE_VISIBILITY __compressed_pair(_T1_param __t1, _T2_param __t2)
+        : base(_VSTD::forward<_T1_param>(__t1), _VSTD::forward<_T2_param>(__t2)) {}
+
+#ifdef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __compressed_pair(const __compressed_pair& __p)
+        _NOEXCEPT_(is_nothrow_copy_constructible<_T1>::value &&
+                   is_nothrow_copy_constructible<_T2>::value)
+        : base(__p) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __compressed_pair& operator=(const __compressed_pair& __p)
+        _NOEXCEPT_(is_nothrow_copy_assignable<_T1>::value &&
+                   is_nothrow_copy_assignable<_T2>::value)
+        {
+            base::operator=(__p);
+            return *this;
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    _LIBCPP_INLINE_VISIBILITY
+    __compressed_pair(__compressed_pair&& __p)
+        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
+                   is_nothrow_move_constructible<_T2>::value)
+        : base(_VSTD::move(__p)) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __compressed_pair& operator=(__compressed_pair&& __p)
+        _NOEXCEPT_(is_nothrow_move_assignable<_T1>::value &&
+                   is_nothrow_move_assignable<_T2>::value)
+        {
+            base::operator=(_VSTD::move(__p));
+            return *this;
+        }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+#endif  // _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template <class... _Args1, class... _Args2>
+        _LIBCPP_INLINE_VISIBILITY
+        __compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
+                                                      tuple<_Args2...> __second_args)
+            : base(__pc, _VSTD::move(__first_args), _VSTD::move(__second_args),
+                   typename __make_tuple_indices<sizeof...(_Args1)>::type(),
+                   typename __make_tuple_indices<sizeof...(_Args2) >::type())
+            {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return base::first();}
+    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return base::first();}
+
+    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return base::second();}
+    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return base::second();}
+
+    _LIBCPP_INLINE_VISIBILITY void swap(__compressed_pair& __x)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+        {base::swap(__x);}
+};
+
+template <class _T1, class _T2>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(__compressed_pair<_T1, _T2>& __x, __compressed_pair<_T1, _T2>& __y)
+        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+                   __is_nothrow_swappable<_T1>::value)
+    {__x.swap(__y);}
+
+// __same_or_less_cv_qualified
+
+template <class _Ptr1, class _Ptr2,
+          bool = is_same<typename remove_cv<typename pointer_traits<_Ptr1>::element_type>::type,
+                         typename remove_cv<typename pointer_traits<_Ptr2>::element_type>::type
+                        >::value
+         >
+struct __same_or_less_cv_qualified_imp
+    : is_convertible<_Ptr1, _Ptr2> {};
+
+template <class _Ptr1, class _Ptr2>
+struct __same_or_less_cv_qualified_imp<_Ptr1, _Ptr2, false>
+    : false_type {};
+
+template <class _Ptr1, class _Ptr2, bool = is_scalar<_Ptr1>::value &&
+                                         !is_pointer<_Ptr1>::value>
+struct __same_or_less_cv_qualified
+    : __same_or_less_cv_qualified_imp<_Ptr1, _Ptr2> {};
+
+template <class _Ptr1, class _Ptr2>
+struct __same_or_less_cv_qualified<_Ptr1, _Ptr2, true>
+    : false_type {};
+
+// default_delete
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY default_delete
+{
+#ifndef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;
+#else
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT {}
+#endif
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY default_delete(const default_delete<_Up>&,
+             typename enable_if<is_convertible<_Up*, _Tp*>::value>::type* = 0) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY void operator() (_Tp* __ptr) const _NOEXCEPT
+        {
+            static_assert(sizeof(_Tp) > 0, "default_delete can not delete incomplete type");
+            static_assert(!is_void<_Tp>::value, "default_delete can not delete incomplete type");
+            delete __ptr;
+        }
+};
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY default_delete<_Tp[]>
+{
+public:
+#ifndef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;
+#else
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT {}
+#endif
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY default_delete(const default_delete<_Up[]>&,
+             typename enable_if<__same_or_less_cv_qualified<_Up*, _Tp*>::value>::type* = 0) _NOEXCEPT {}
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        void operator() (_Up* __ptr,
+                         typename enable_if<__same_or_less_cv_qualified<_Up*, _Tp*>::value>::type* = 0) const _NOEXCEPT
+        {
+            static_assert(sizeof(_Tp) > 0, "default_delete can not delete incomplete type");
+            static_assert(!is_void<_Tp>::value, "default_delete can not delete incomplete type");
+            delete [] __ptr;
+        }
+};
+
+template <class _Tp, class _Dp = default_delete<_Tp> >
+class _LIBCPP_TYPE_VIS_ONLY unique_ptr
+{
+public:
+    typedef _Tp element_type;
+    typedef _Dp deleter_type;
+    typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
+private:
+    __compressed_pair<pointer, deleter_type> __ptr_;
+
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    unique_ptr(unique_ptr&);
+    template <class _Up, class _Ep>
+        unique_ptr(unique_ptr<_Up, _Ep>&);
+    unique_ptr& operator=(unique_ptr&);
+    template <class _Up, class _Ep>
+        unique_ptr& operator=(unique_ptr<_Up, _Ep>&);
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    struct __nat {int __for_bool_;};
+
+    typedef       typename remove_reference<deleter_type>::type& _Dp_reference;
+    typedef const typename remove_reference<deleter_type>::type& _Dp_const_reference;
+public:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT
+        : __ptr_(pointer())
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT
+        : __ptr_(pointer())
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(pointer __p) _NOEXCEPT
+        : __ptr_(_VSTD::move(__p))
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename conditional<
+                                        is_reference<deleter_type>::value,
+                                        deleter_type,
+                                        typename add_lvalue_reference<const deleter_type>::type>::type __d)
+             _NOEXCEPT
+        : __ptr_(__p, __d) {}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename remove_reference<deleter_type>::type&& __d)
+             _NOEXCEPT
+        : __ptr_(__p, _VSTD::move(__d))
+        {
+            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
+        }
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(unique_ptr&& __u) _NOEXCEPT
+        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
+    template <class _Up, class _Ep>
+        _LIBCPP_INLINE_VISIBILITY
+        unique_ptr(unique_ptr<_Up, _Ep>&& __u,
+                   typename enable_if
+                      <
+                        !is_array<_Up>::value &&
+                         is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
+                         is_convertible<_Ep, deleter_type>::value &&
+                         (
+                            !is_reference<deleter_type>::value ||
+                            is_same<deleter_type, _Ep>::value
+                         ),
+                         __nat
+                      >::type = __nat()) _NOEXCEPT
+            : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {}
+
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY unique_ptr(auto_ptr<_Up>&& __p,
+                typename enable_if<
+                                      is_convertible<_Up*, _Tp*>::value &&
+                                      is_same<_Dp, default_delete<_Tp> >::value,
+                                      __nat
+                                  >::type = __nat()) _NOEXCEPT
+            : __ptr_(__p.release())
+            {
+            }
+
+        _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT
+            {
+                reset(__u.release());
+                __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+                return *this;
+            }
+
+        template <class _Up, class _Ep>
+            _LIBCPP_INLINE_VISIBILITY
+            typename enable_if
+            <
+                !is_array<_Up>::value &&
+                is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
+                is_assignable<deleter_type&, _Ep&&>::value,
+                unique_ptr&
+            >::type
+            operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
+            {
+                reset(__u.release());
+                __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
+                return *this;
+            }
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY operator __rv<unique_ptr>()
+    {
+        return __rv<unique_ptr>(*this);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(__rv<unique_ptr> __u)
+        : __ptr_(__u->release(), _VSTD::forward<deleter_type>(__u->get_deleter())) {}
+
+    template <class _Up, class _Ep>
+    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(unique_ptr<_Up, _Ep> __u)
+    {
+        reset(__u.release());
+        __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, deleter_type __d)
+        : __ptr_(_VSTD::move(__p), _VSTD::move(__d)) {}
+
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+                typename enable_if<
+                                      is_convertible<_Up*, _Tp*>::value &&
+                                      is_same<_Dp, default_delete<_Tp> >::value,
+                                      unique_ptr&
+                                  >::type
+        operator=(auto_ptr<_Up> __p)
+            {reset(__p.release()); return *this;}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    _LIBCPP_INLINE_VISIBILITY ~unique_ptr() {reset();}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(nullptr_t) _NOEXCEPT
+    {
+        reset();
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY typename add_lvalue_reference<_Tp>::type operator*() const
+        {return *__ptr_.first();}
+    _LIBCPP_INLINE_VISIBILITY pointer operator->() const _NOEXCEPT {return __ptr_.first();}
+    _LIBCPP_INLINE_VISIBILITY pointer get() const _NOEXCEPT {return __ptr_.first();}
+    _LIBCPP_INLINE_VISIBILITY       _Dp_reference get_deleter() _NOEXCEPT
+        {return __ptr_.second();}
+    _LIBCPP_INLINE_VISIBILITY _Dp_const_reference get_deleter() const _NOEXCEPT
+        {return __ptr_.second();}
+    _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT
+        {return __ptr_.first() != nullptr;}
+
+    _LIBCPP_INLINE_VISIBILITY pointer release() _NOEXCEPT
+    {
+        pointer __t = __ptr_.first();
+        __ptr_.first() = pointer();
+        return __t;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY void reset(pointer __p = pointer()) _NOEXCEPT
+    {
+        pointer __tmp = __ptr_.first();
+        __ptr_.first() = __p;
+        if (__tmp)
+            __ptr_.second()(__tmp);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY void swap(unique_ptr& __u) _NOEXCEPT
+        {__ptr_.swap(__u.__ptr_);}
+};
+
+template <class _Tp, class _Dp>
+class _LIBCPP_TYPE_VIS_ONLY unique_ptr<_Tp[], _Dp>
+{
+public:
+    typedef _Tp element_type;
+    typedef _Dp deleter_type;
+    typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
+private:
+    __compressed_pair<pointer, deleter_type> __ptr_;
+
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    unique_ptr(unique_ptr&);
+    template <class _Up>
+        unique_ptr(unique_ptr<_Up>&);
+    unique_ptr& operator=(unique_ptr&);
+    template <class _Up>
+        unique_ptr& operator=(unique_ptr<_Up>&);
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    struct __nat {int __for_bool_;};
+
+    typedef       typename remove_reference<deleter_type>::type& _Dp_reference;
+    typedef const typename remove_reference<deleter_type>::type& _Dp_const_reference;
+public:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT
+        : __ptr_(pointer())
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT
+        : __ptr_(pointer())
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template <class _Pp,
+              class = typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value>::type
+             >
+    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(_Pp __p) _NOEXCEPT
+        : __ptr_(__p)
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+
+    template <class _Pp,
+              class = typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value>::type
+             >
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(_Pp __p, typename conditional<
+                                       is_reference<deleter_type>::value,
+                                       deleter_type,
+                                       typename add_lvalue_reference<const deleter_type>::type>::type __d)
+             _NOEXCEPT
+        : __ptr_(__p, __d) {}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, typename conditional<
+                                       is_reference<deleter_type>::value,
+                                       deleter_type,
+                                       typename add_lvalue_reference<const deleter_type>::type>::type __d)
+             _NOEXCEPT
+        : __ptr_(pointer(), __d) {}
+
+    template <class _Pp,
+              class = typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value>::type
+             >
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(_Pp __p, typename remove_reference<deleter_type>::type&& __d)
+             _NOEXCEPT
+        : __ptr_(__p, _VSTD::move(__d))
+        {
+            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
+        }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, typename remove_reference<deleter_type>::type&& __d)
+             _NOEXCEPT
+        : __ptr_(pointer(), _VSTD::move(__d))
+        {
+            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
+        }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(unique_ptr&& __u) _NOEXCEPT
+        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT
+        {
+            reset(__u.release());
+            __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+            return *this;
+        }
+
+    template <class _Up, class _Ep>
+        _LIBCPP_INLINE_VISIBILITY
+        unique_ptr(unique_ptr<_Up, _Ep>&& __u,
+                   typename enable_if
+                            <
+                                is_array<_Up>::value &&
+                                __same_or_less_cv_qualified<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value
+                                && is_convertible<_Ep, deleter_type>::value &&
+                                (
+                                    !is_reference<deleter_type>::value ||
+                                    is_same<deleter_type, _Ep>::value
+                                ),
+                                __nat
+                            >::type = __nat()
+                  ) _NOEXCEPT
+        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
+
+
+        template <class _Up, class _Ep>
+            _LIBCPP_INLINE_VISIBILITY
+            typename enable_if
+            <
+                is_array<_Up>::value &&
+                __same_or_less_cv_qualified<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
+                is_assignable<deleter_type&, _Ep&&>::value,
+                unique_ptr&
+            >::type
+            operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
+            {
+                reset(__u.release());
+                __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
+                return *this;
+            }
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(pointer __p)
+        : __ptr_(__p)
+        {
+            static_assert(!is_pointer<deleter_type>::value,
+                "unique_ptr constructed with null function pointer deleter");
+        }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, deleter_type __d)
+        : __ptr_(__p, _VSTD::forward<deleter_type>(__d)) {}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, deleter_type __d)
+        : __ptr_(pointer(), _VSTD::forward<deleter_type>(__d)) {}
+
+    _LIBCPP_INLINE_VISIBILITY operator __rv<unique_ptr>()
+    {
+        return __rv<unique_ptr>(*this);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr(__rv<unique_ptr> __u)
+        : __ptr_(__u->release(), _VSTD::forward<deleter_type>(__u->get_deleter())) {}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(__rv<unique_ptr> __u)
+    {
+        reset(__u->release());
+        __ptr_.second() = _VSTD::forward<deleter_type>(__u->get_deleter());
+        return *this;
+    }
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    _LIBCPP_INLINE_VISIBILITY ~unique_ptr() {reset();}
+
+    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(nullptr_t) _NOEXCEPT
+    {
+        reset();
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY typename add_lvalue_reference<_Tp>::type operator[](size_t __i) const
+        {return __ptr_.first()[__i];}
+    _LIBCPP_INLINE_VISIBILITY pointer get() const _NOEXCEPT {return __ptr_.first();}
+    _LIBCPP_INLINE_VISIBILITY       _Dp_reference get_deleter() _NOEXCEPT
+        {return __ptr_.second();}
+    _LIBCPP_INLINE_VISIBILITY _Dp_const_reference get_deleter() const _NOEXCEPT
+        {return __ptr_.second();}
+    _LIBCPP_INLINE_VISIBILITY
+        _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT
+        {return __ptr_.first() != nullptr;}
+
+    _LIBCPP_INLINE_VISIBILITY pointer release() _NOEXCEPT
+    {
+        pointer __t = __ptr_.first();
+        __ptr_.first() = pointer();
+        return __t;
+    }
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template <class _Pp,
+              class = typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value>::type
+             >
+    _LIBCPP_INLINE_VISIBILITY void reset(_Pp __p) _NOEXCEPT
+    {
+        pointer __tmp = __ptr_.first();
+        __ptr_.first() = __p;
+        if (__tmp)
+            __ptr_.second()(__tmp);
+    }
+    _LIBCPP_INLINE_VISIBILITY void reset(nullptr_t) _NOEXCEPT
+    {
+        pointer __tmp = __ptr_.first();
+        __ptr_.first() = nullptr;
+        if (__tmp)
+            __ptr_.second()(__tmp);
+    }
+    _LIBCPP_INLINE_VISIBILITY void reset() _NOEXCEPT
+    {
+        pointer __tmp = __ptr_.first();
+        __ptr_.first() = nullptr;
+        if (__tmp)
+            __ptr_.second()(__tmp);
+    }
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    _LIBCPP_INLINE_VISIBILITY void reset(pointer __p = pointer())
+    {
+        pointer __tmp = __ptr_.first();
+        __ptr_.first() = __p;
+        if (__tmp)
+            __ptr_.second()(__tmp);
+    }
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    _LIBCPP_INLINE_VISIBILITY void swap(unique_ptr& __u) {__ptr_.swap(__u.__ptr_);}
+private:
+
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template <class _Up>
+        explicit unique_ptr(_Up);
+    template <class _Up>
+        unique_ptr(_Up __u,
+                   typename conditional<
+                                       is_reference<deleter_type>::value,
+                                       deleter_type,
+                                       typename add_lvalue_reference<const deleter_type>::type>::type,
+                   typename enable_if
+                      <
+                         is_convertible<_Up, pointer>::value,
+                         __nat
+                      >::type = __nat());
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+};
+
+template <class _Tp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(unique_ptr<_Tp, _Dp>& __x, unique_ptr<_Tp, _Dp>& __y) _NOEXCEPT {__x.swap(__y);}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __x.get() == __y.get();}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x == __y);}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator< (const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y)
+{
+    typedef typename unique_ptr<_T1, _D1>::pointer _P1;
+    typedef typename unique_ptr<_T2, _D2>::pointer _P2;
+    typedef typename common_type<_P1, _P2>::type _V;
+    return less<_V>()(__x.get(), __y.get());
+}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator> (const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __y < __x;}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__y < __x);}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x < __y);}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
+{
+    return !__x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
+{
+    return !__x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    typedef typename unique_ptr<_T1, _D1>::pointer _P1;
+    return less<_P1>()(__x.get(), nullptr);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    typedef typename unique_ptr<_T1, _D1>::pointer _P1;
+    return less<_P1>()(nullptr, __x.get());
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return nullptr < __x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return __x < nullptr;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return !(nullptr < __x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return !(__x < nullptr);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return !(__x < nullptr);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return !(nullptr < __x);
+}
+
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+unique_ptr<_Tp, _Dp>
+move(unique_ptr<_Tp, _Dp>& __t)
+{
+    return unique_ptr<_Tp, _Dp>(__rv<unique_ptr<_Tp, _Dp> >(__t));
+}
+
+#endif
+
+#if _LIBCPP_STD_VER > 11
+
+template<class _Tp>
+struct __unique_if
+{
+    typedef unique_ptr<_Tp> __unique_single;
+};
+
+template<class _Tp>
+struct __unique_if<_Tp[]>
+{
+    typedef unique_ptr<_Tp[]> __unique_array_unknown_bound;
+};
+
+template<class _Tp, size_t _Np>
+struct __unique_if<_Tp[_Np]>
+{
+    typedef void __unique_array_known_bound;
+};
+
+template<class _Tp, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+typename __unique_if<_Tp>::__unique_single
+make_unique(_Args&&... __args)
+{
+    return unique_ptr<_Tp>(new _Tp(_VSTD::forward<_Args>(__args)...));
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename __unique_if<_Tp>::__unique_array_unknown_bound
+make_unique(size_t __n)
+{
+    typedef typename remove_extent<_Tp>::type _Up;
+    return unique_ptr<_Tp>(new _Up[__n]());
+}
+
+template<class _Tp, class... _Args>
+    typename __unique_if<_Tp>::__unique_array_known_bound
+    make_unique(_Args&&...) = delete;
+
+#endif  // _LIBCPP_STD_VER > 11
+
+template <class _Tp> struct hash;
+
+template <class _Size>
+inline _LIBCPP_INLINE_VISIBILITY
+_Size
+__loadword(const void* __p)
+{
+    _Size __r;
+    std::memcpy(&__r, __p, sizeof(__r));
+    return __r;
+}
+
+// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
+// is 64 bits.  This is because cityhash64 uses 64bit x 64bit
+// multiplication, which can be very slow on 32-bit systems.
+template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
+struct __murmur2_or_cityhash;
+
+template <class _Size>
+struct __murmur2_or_cityhash<_Size, 32>
+{
+    _Size operator()(const void* __key, _Size __len);
+};
+
+// murmur2
+template <class _Size>
+_Size
+__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
+{
+    const _Size __m = 0x5bd1e995;
+    const _Size __r = 24;
+    _Size __h = __len;
+    const unsigned char* __data = static_cast<const unsigned char*>(__key);
+    for (; __len >= 4; __data += 4, __len -= 4)
+    {
+        _Size __k = __loadword<_Size>(__data);
+        __k *= __m;
+        __k ^= __k >> __r;
+        __k *= __m;
+        __h *= __m;
+        __h ^= __k;
+    }
+    switch (__len)
+    {
+    case 3:
+        __h ^= __data[2] << 16;
+    case 2:
+        __h ^= __data[1] << 8;
+    case 1:
+        __h ^= __data[0];
+        __h *= __m;
+    }
+    __h ^= __h >> 13;
+    __h *= __m;
+    __h ^= __h >> 15;
+    return __h;
+}
+
+template <class _Size>
+struct __murmur2_or_cityhash<_Size, 64>
+{
+    _Size operator()(const void* __key, _Size __len);
+
+ private:
+  // Some primes between 2^63 and 2^64.
+  static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
+  static const _Size __k1 = 0xb492b66fbe98f273ULL;
+  static const _Size __k2 = 0x9ae16a3b2f90404fULL;
+  static const _Size __k3 = 0xc949d7c7509e6557ULL;
+
+  static _Size __rotate(_Size __val, int __shift) {
+    return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
+  }
+
+  static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
+    return (__val >> __shift) | (__val << (64 - __shift));
+  }
+
+  static _Size __shift_mix(_Size __val) {
+    return __val ^ (__val >> 47);
+  }
+
+  static _Size __hash_len_16(_Size __u, _Size __v) {
+    const _Size __mul = 0x9ddfea08eb382d69ULL;
+    _Size __a = (__u ^ __v) * __mul;
+    __a ^= (__a >> 47);
+    _Size __b = (__v ^ __a) * __mul;
+    __b ^= (__b >> 47);
+    __b *= __mul;
+    return __b;
+  }
+
+  static _Size __hash_len_0_to_16(const char* __s, _Size __len) {
+    if (__len > 8) {
+      const _Size __a = __loadword<_Size>(__s);
+      const _Size __b = __loadword<_Size>(__s + __len - 8);
+      return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
+    }
+    if (__len >= 4) {
+      const uint32_t __a = __loadword<uint32_t>(__s);
+      const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
+      return __hash_len_16(__len + (__a << 3), __b);
+    }
+    if (__len > 0) {
+      const unsigned char __a = __s[0];
+      const unsigned char __b = __s[__len >> 1];
+      const unsigned char __c = __s[__len - 1];
+      const uint32_t __y = static_cast<uint32_t>(__a) +
+                           (static_cast<uint32_t>(__b) << 8);
+      const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
+      return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
+    }
+    return __k2;
+  }
+
+  static _Size __hash_len_17_to_32(const char *__s, _Size __len) {
+    const _Size __a = __loadword<_Size>(__s) * __k1;
+    const _Size __b = __loadword<_Size>(__s + 8);
+    const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
+    const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
+    return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
+                         __a + __rotate(__b ^ __k3, 20) - __c + __len);
+  }
+
+  // Return a 16-byte hash for 48 bytes.  Quick and dirty.
+  // Callers do best to use "random-looking" values for a and b.
+  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
+      _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) {
+    __a += __w;
+    __b = __rotate(__b + __a + __z, 21);
+    const _Size __c = __a;
+    __a += __x;
+    __a += __y;
+    __b += __rotate(__a, 44);
+    return pair<_Size, _Size>(__a + __z, __b + __c);
+  }
+
+  // Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.
+  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
+      const char* __s, _Size __a, _Size __b) {
+    return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
+                                         __loadword<_Size>(__s + 8),
+                                         __loadword<_Size>(__s + 16),
+                                         __loadword<_Size>(__s + 24),
+                                         __a,
+                                         __b);
+  }
+
+  // Return an 8-byte hash for 33 to 64 bytes.
+  static _Size __hash_len_33_to_64(const char *__s, size_t __len) {
+    _Size __z = __loadword<_Size>(__s + 24);
+    _Size __a = __loadword<_Size>(__s) +
+                (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
+    _Size __b = __rotate(__a + __z, 52);
+    _Size __c = __rotate(__a, 37);
+    __a += __loadword<_Size>(__s + 8);
+    __c += __rotate(__a, 7);
+    __a += __loadword<_Size>(__s + 16);
+    _Size __vf = __a + __z;
+    _Size __vs = __b + __rotate(__a, 31) + __c;
+    __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
+    __z += __loadword<_Size>(__s + __len - 8);
+    __b = __rotate(__a + __z, 52);
+    __c = __rotate(__a, 37);
+    __a += __loadword<_Size>(__s + __len - 24);
+    __c += __rotate(__a, 7);
+    __a += __loadword<_Size>(__s + __len - 16);
+    _Size __wf = __a + __z;
+    _Size __ws = __b + __rotate(__a, 31) + __c;
+    _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
+    return __shift_mix(__r * __k0 + __vs) * __k2;
+  }
+};
+
+// cityhash64
+template <class _Size>
+_Size
+__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
+{
+  const char* __s = static_cast<const char*>(__key);
+  if (__len <= 32) {
+    if (__len <= 16) {
+      return __hash_len_0_to_16(__s, __len);
+    } else {
+      return __hash_len_17_to_32(__s, __len);
+    }
+  } else if (__len <= 64) {
+    return __hash_len_33_to_64(__s, __len);
+  }
+
+  // For strings over 64 bytes we hash the end first, and then as we
+  // loop we keep 56 bytes of state: v, w, x, y, and z.
+  _Size __x = __loadword<_Size>(__s + __len - 40);
+  _Size __y = __loadword<_Size>(__s + __len - 16) +
+              __loadword<_Size>(__s + __len - 56);
+  _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
+                          __loadword<_Size>(__s + __len - 24));
+  pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
+  pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
+  __x = __x * __k1 + __loadword<_Size>(__s);
+
+  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
+  __len = (__len - 1) & ~static_cast<_Size>(63);
+  do {
+    __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
+    __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
+    __x ^= __w.second;
+    __y += __v.first + __loadword<_Size>(__s + 40);
+    __z = __rotate(__z + __w.first, 33) * __k1;
+    __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
+    __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
+                                        __y + __loadword<_Size>(__s + 16));
+    std::swap(__z, __x);
+    __s += 64;
+    __len -= 64;
+  } while (__len != 0);
+  return __hash_len_16(
+      __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
+      __hash_len_16(__v.second, __w.second) + __x);
+}
+
+template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
+struct __scalar_hash;
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 0>
+    : public unary_function<_Tp, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp    __t;
+            size_t __a;
+        } __u;
+        __u.__a = 0;
+        __u.__t = __v;
+        return __u.__a;
+    }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 1>
+    : public unary_function<_Tp, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp    __t;
+            size_t __a;
+        } __u;
+        __u.__t = __v;
+        return __u.__a;
+    }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 2>
+    : public unary_function<_Tp, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp __t;
+            struct
+            {
+                size_t __a;
+                size_t __b;
+            };
+        } __u;
+        __u.__t = __v;
+        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+    }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 3>
+    : public unary_function<_Tp, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp __t;
+            struct
+            {
+                size_t __a;
+                size_t __b;
+                size_t __c;
+            };
+        } __u;
+        __u.__t = __v;
+        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+    }
+};
+
+template <class _Tp>
+struct __scalar_hash<_Tp, 4>
+    : public unary_function<_Tp, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp __t;
+            struct
+            {
+                size_t __a;
+                size_t __b;
+                size_t __c;
+                size_t __d;
+            };
+        } __u;
+        __u.__t = __v;
+        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+    }
+};
+
+template<class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY hash<_Tp*>
+    : public unary_function<_Tp*, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(_Tp* __v) const _NOEXCEPT
+    {
+        union
+        {
+            _Tp* __t;
+            size_t __a;
+        } __u;
+        __u.__t = __v;
+        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
+    }
+};
+
+template <class _Tp, class _Dp>
+struct _LIBCPP_TYPE_VIS_ONLY hash<unique_ptr<_Tp, _Dp> >
+{
+    typedef unique_ptr<_Tp, _Dp> argument_type;
+    typedef size_t               result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    result_type operator()(const argument_type& __ptr) const _NOEXCEPT
+    {
+        typedef typename argument_type::pointer pointer;
+        return hash<pointer>()(__ptr.get());
+    }
+};
+
+struct __destruct_n
+{
+private:
+    size_t size;
+
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void __process(_Tp* __p, false_type) _NOEXCEPT
+        {for (size_t __i = 0; __i < size; ++__i, ++__p) __p->~_Tp();}
+
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void __process(_Tp*, true_type) _NOEXCEPT
+        {}
+
+    _LIBCPP_INLINE_VISIBILITY void __incr(false_type) _NOEXCEPT
+        {++size;}
+    _LIBCPP_INLINE_VISIBILITY void __incr(true_type) _NOEXCEPT
+        {}
+
+    _LIBCPP_INLINE_VISIBILITY void __set(size_t __s, false_type) _NOEXCEPT
+        {size = __s;}
+    _LIBCPP_INLINE_VISIBILITY void __set(size_t, true_type) _NOEXCEPT
+        {}
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit __destruct_n(size_t __s) _NOEXCEPT
+        : size(__s) {}
+
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void __incr(_Tp*) _NOEXCEPT
+        {__incr(integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
+
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void __set(size_t __s, _Tp*) _NOEXCEPT
+        {__set(__s, integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
+
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) _NOEXCEPT
+        {__process(__p, integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
+};
+
+template <class _Alloc>
+class __allocator_destructor
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+public:
+    typedef typename __alloc_traits::pointer pointer;
+    typedef typename __alloc_traits::size_type size_type;
+private:
+    _Alloc& __alloc_;
+    size_type __s_;
+public:
+    _LIBCPP_INLINE_VISIBILITY __allocator_destructor(_Alloc& __a, size_type __s)
+             _NOEXCEPT
+        : __alloc_(__a), __s_(__s) {}
+    _LIBCPP_INLINE_VISIBILITY
+    void operator()(pointer __p) _NOEXCEPT
+        {__alloc_traits::deallocate(__alloc_, __p, __s_);}
+};
+
+template <class _InputIterator, class _ForwardIterator>
+_ForwardIterator
+uninitialized_copy(_InputIterator __f, _InputIterator __l, _ForwardIterator __r)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __r;
+    try
+    {
+#endif
+        for (; __f != __l; ++__f, ++__r)
+            ::new(&*__r) value_type(*__f);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __r; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __r;
+}
+
+template <class _InputIterator, class _Size, class _ForwardIterator>
+_ForwardIterator
+uninitialized_copy_n(_InputIterator __f, _Size __n, _ForwardIterator __r)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __r;
+    try
+    {
+#endif
+        for (; __n > 0; ++__f, ++__r, --__n)
+            ::new(&*__r) value_type(*__f);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __r; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __r;
+}
+
+template <class _ForwardIterator, class _Tp>
+void
+uninitialized_fill(_ForwardIterator __f, _ForwardIterator __l, const _Tp& __x)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __f;
+    try
+    {
+#endif
+        for (; __f != __l; ++__f)
+            ::new(&*__f) value_type(__x);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __f; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+}
+
+template <class _ForwardIterator, class _Size, class _Tp>
+_ForwardIterator
+uninitialized_fill_n(_ForwardIterator __f, _Size __n, const _Tp& __x)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __f;
+    try
+    {
+#endif
+        for (; __n > 0; ++__f, --__n)
+            ::new(&*__f) value_type(__x);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __f; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __f;
+}
+
+class _LIBCPP_EXCEPTION_ABI bad_weak_ptr
+    : public std::exception
+{
+public:
+    virtual ~bad_weak_ptr() _NOEXCEPT;
+    virtual const char* what() const  _NOEXCEPT;
+};
+
+template<class _Tp> class _LIBCPP_TYPE_VIS_ONLY weak_ptr;
+
+class _LIBCPP_TYPE_VIS __shared_count
+{
+    __shared_count(const __shared_count&);
+    __shared_count& operator=(const __shared_count&);
+
+protected:
+    long __shared_owners_;
+    virtual ~__shared_count();
+private:
+    virtual void __on_zero_shared() _NOEXCEPT = 0;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __shared_count(long __refs = 0) _NOEXCEPT
+        : __shared_owners_(__refs) {}
+
+    void __add_shared() _NOEXCEPT;
+    bool __release_shared() _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {return __shared_owners_ + 1;}
+};
+
+class _LIBCPP_TYPE_VIS __shared_weak_count
+    : private __shared_count
+{
+    long __shared_weak_owners_;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
+        : __shared_count(__refs),
+          __shared_weak_owners_(__refs) {}
+protected:
+    virtual ~__shared_weak_count();
+
+public:
+    void __add_shared() _NOEXCEPT;
+    void __add_weak() _NOEXCEPT;
+    void __release_shared() _NOEXCEPT;
+    void __release_weak() _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {return __shared_count::use_count();}
+    __shared_weak_count* lock() _NOEXCEPT;
+
+    // Define the function out only if we build static libc++ without RTTI.
+    // Otherwise we may break clients who need to compile their projects with
+    // -fno-rtti and yet link against a libc++.dylib compiled
+    // without -fno-rtti.
+#if !defined(_LIBCPP_NO_RTTI) || !defined(_LIBCPP_BUILD_STATIC)
+    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
+#endif
+private:
+    virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
+};
+
+template <class _Tp, class _Dp, class _Alloc>
+class __shared_ptr_pointer
+    : public __shared_weak_count
+{
+    __compressed_pair<__compressed_pair<_Tp, _Dp>, _Alloc> __data_;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    __shared_ptr_pointer(_Tp __p, _Dp __d, _Alloc __a)
+        :  __data_(__compressed_pair<_Tp, _Dp>(__p, _VSTD::move(__d)), _VSTD::move(__a)) {}
+
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
+#endif
+
+private:
+    virtual void __on_zero_shared() _NOEXCEPT;
+    virtual void __on_zero_shared_weak() _NOEXCEPT;
+};
+
+#ifndef _LIBCPP_NO_RTTI
+
+template <class _Tp, class _Dp, class _Alloc>
+const void*
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__get_deleter(const type_info& __t) const _NOEXCEPT
+{
+    return __t == typeid(_Dp) ? &__data_.first().second() : 0;
+}
+
+#endif  // _LIBCPP_NO_RTTI
+
+template <class _Tp, class _Dp, class _Alloc>
+void
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared() _NOEXCEPT
+{
+    __data_.first().second()(__data_.first().first());
+    __data_.first().second().~_Dp();
+}
+
+template <class _Tp, class _Dp, class _Alloc>
+void
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
+{
+    typename _Alloc::template rebind<__shared_ptr_pointer>::other __a(__data_.second());
+    __data_.second().~_Alloc();
+    __a.deallocate(this, 1);
+}
+
+template <class _Tp, class _Alloc>
+class __shared_ptr_emplace
+    : public __shared_weak_count
+{
+    __compressed_pair<_Alloc, _Tp> __data_;
+public:
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __shared_ptr_emplace(_Alloc __a)
+        :  __data_(_VSTD::move(__a)) {}
+
+    template <class ..._Args>
+        _LIBCPP_INLINE_VISIBILITY
+        __shared_ptr_emplace(_Alloc __a, _Args&& ...__args)
+            :  __data_(piecewise_construct, _VSTD::forward_as_tuple(__a),
+                   _VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...)) {}
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+    _LIBCPP_INLINE_VISIBILITY
+    __shared_ptr_emplace(_Alloc __a)
+        :  __data_(__a) {}
+
+    template <class _A0>
+        _LIBCPP_INLINE_VISIBILITY
+        __shared_ptr_emplace(_Alloc __a, _A0& __a0)
+            :  __data_(__a, _Tp(__a0)) {}
+
+    template <class _A0, class _A1>
+        _LIBCPP_INLINE_VISIBILITY
+        __shared_ptr_emplace(_Alloc __a, _A0& __a0, _A1& __a1)
+            :  __data_(__a, _Tp(__a0, __a1)) {}
+
+    template <class _A0, class _A1, class _A2>
+        _LIBCPP_INLINE_VISIBILITY
+        __shared_ptr_emplace(_Alloc __a, _A0& __a0, _A1& __a1, _A2& __a2)
+            :  __data_(__a, _Tp(__a0, __a1, __a2)) {}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+private:
+    virtual void __on_zero_shared() _NOEXCEPT;
+    virtual void __on_zero_shared_weak() _NOEXCEPT;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    _Tp* get() _NOEXCEPT {return &__data_.second();}
+};
+
+template <class _Tp, class _Alloc>
+void
+__shared_ptr_emplace<_Tp, _Alloc>::__on_zero_shared() _NOEXCEPT
+{
+    __data_.second().~_Tp();
+}
+
+template <class _Tp, class _Alloc>
+void
+__shared_ptr_emplace<_Tp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
+{
+    typename _Alloc::template rebind<__shared_ptr_emplace>::other __a(__data_.first());
+    __data_.first().~_Alloc();
+    __a.deallocate(this, 1);
+}
+
+template<class _Tp> class _LIBCPP_TYPE_VIS_ONLY enable_shared_from_this;
+
+template<class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY shared_ptr
+{
+public:
+    typedef _Tp element_type;
+private:
+    element_type*      __ptr_;
+    __shared_weak_count* __cntrl_;
+
+    struct __nat {int __for_bool_;};
+public:
+    _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT;
+    _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
+    template<class _Yp,
+             class = typename enable_if
+                     <
+                        is_convertible<_Yp*, element_type*>::value
+                     >::type
+            >
+        explicit shared_ptr(_Yp* __p);
+    template<class _Yp, class _Dp,
+             class = typename enable_if
+                     <
+                        is_convertible<_Yp*, element_type*>::value
+                     >::type
+            >
+        shared_ptr(_Yp* __p, _Dp __d);
+    template<class _Yp, class _Dp, class _Alloc,
+             class = typename enable_if
+                     <
+                        is_convertible<_Yp*, element_type*>::value
+                     >::type
+            >
+        shared_ptr(_Yp* __p, _Dp __d, _Alloc __a);
+    template <class _Dp> shared_ptr(nullptr_t __p, _Dp __d);
+    template <class _Dp, class _Alloc> shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a);
+    template<class _Yp> shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) _NOEXCEPT;
+    shared_ptr(const shared_ptr& __r) _NOEXCEPT;
+    template<class _Yp>
+        shared_ptr(const shared_ptr<_Yp>& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type = __nat())
+                       _NOEXCEPT;
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    shared_ptr(shared_ptr&& __r) _NOEXCEPT;
+    template<class _Yp> shared_ptr(shared_ptr<_Yp>&& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type = __nat())
+                       _NOEXCEPT;
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template<class _Yp> explicit shared_ptr(const weak_ptr<_Yp>& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type= __nat());
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template<class _Yp,
+             class = typename enable_if
+                     <
+                        is_convertible<_Yp*, element_type*>::value
+                     >::type
+            >
+        shared_ptr(auto_ptr<_Yp>&& __r);
+#else
+    template<class _Yp,
+             class = typename enable_if
+                     <
+                        is_convertible<_Yp*, element_type*>::value
+                     >::type
+            >
+        shared_ptr(auto_ptr<_Yp> __r);
+#endif
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template <class _Yp, class _Dp,
+                 class = typename enable_if
+                 <
+                    !is_array<_Yp>::value &&
+                    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+                 >::type
+             >
+       shared_ptr(unique_ptr<_Yp, _Dp>&&,
+       typename enable_if<!is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
+    template <class _Yp, class _Dp,
+                 class = typename enable_if
+                 <
+                    !is_array<_Yp>::value &&
+                    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+                 >::type
+             >
+       shared_ptr(unique_ptr<_Yp, _Dp>&&,
+       typename enable_if<is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template <class _Yp, class _Dp,
+                 class = typename enable_if
+                 <
+                    !is_array<_Yp>::value &&
+                    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+                 >::type
+             > shared_ptr(unique_ptr<_Yp, _Dp>,
+       typename enable_if<!is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
+    template <class _Yp, class _Dp,
+                 class = typename enable_if
+                 <
+                    !is_array<_Yp>::value &&
+                    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
+                 >::type
+             >
+       shared_ptr(unique_ptr<_Yp, _Dp>,
+       typename enable_if<is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    ~shared_ptr();
+
+    shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            shared_ptr&
+        >::type
+        operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            shared_ptr<_Tp>&
+        >::type
+        operator=(shared_ptr<_Yp>&& __r);
+    template<class _Yp>
+        typename enable_if
+        <
+            !is_array<_Yp>::value &&
+            is_convertible<_Yp*, element_type*>::value,
+            shared_ptr
+        >::type&
+        operator=(auto_ptr<_Yp>&& __r);
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    template<class _Yp>
+        typename enable_if
+        <
+            !is_array<_Yp>::value &&
+            is_convertible<_Yp*, element_type*>::value,
+            shared_ptr&
+        >::type
+        operator=(auto_ptr<_Yp> __r);
+#endif
+    template <class _Yp, class _Dp>
+        typename enable_if
+        <
+            !is_array<_Yp>::value &&
+            is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+            shared_ptr&
+        >::type
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+        operator=(unique_ptr<_Yp, _Dp>&& __r);
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+        operator=(unique_ptr<_Yp, _Dp> __r);
+#endif
+
+    void swap(shared_ptr& __r) _NOEXCEPT;
+    void reset() _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            void
+        >::type
+        reset(_Yp* __p);
+    template<class _Yp, class _Dp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            void
+        >::type
+        reset(_Yp* __p, _Dp __d);
+    template<class _Yp, class _Dp, class _Alloc>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            void
+        >::type
+        reset(_Yp* __p, _Dp __d, _Alloc __a);
+
+    _LIBCPP_INLINE_VISIBILITY
+    element_type* get() const _NOEXCEPT {return __ptr_;}
+    _LIBCPP_INLINE_VISIBILITY
+    typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
+        {return *__ptr_;}
+    _LIBCPP_INLINE_VISIBILITY
+    element_type* operator->() const _NOEXCEPT {return __ptr_;}
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {return __cntrl_ ? __cntrl_->use_count() : 0;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool unique() const _NOEXCEPT {return use_count() == 1;}
+    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != 0;}
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(shared_ptr<_Up> const& __p) const
+        {return __cntrl_ < __p.__cntrl_;}
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(weak_ptr<_Up> const& __p) const
+        {return __cntrl_ < __p.__cntrl_;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool
+    __owner_equivalent(const shared_ptr& __p) const
+        {return __cntrl_ == __p.__cntrl_;}
+
+#ifndef _LIBCPP_NO_RTTI
+    template <class _Dp>
+        _LIBCPP_INLINE_VISIBILITY
+        _Dp* __get_deleter() const _NOEXCEPT
+            {return (_Dp*)(__cntrl_ ? __cntrl_->__get_deleter(typeid(_Dp)) : 0);}
+#endif  // _LIBCPP_NO_RTTI
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+    template<class ..._Args>
+        static
+        shared_ptr<_Tp>
+        make_shared(_Args&& ...__args);
+
+    template<class _Alloc, class ..._Args>
+        static
+        shared_ptr<_Tp>
+        allocate_shared(const _Alloc& __a, _Args&& ...__args);
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+    static shared_ptr<_Tp> make_shared();
+
+    template<class _A0>
+        static shared_ptr<_Tp> make_shared(_A0&);
+
+    template<class _A0, class _A1>
+        static shared_ptr<_Tp> make_shared(_A0&, _A1&);
+
+    template<class _A0, class _A1, class _A2>
+        static shared_ptr<_Tp> make_shared(_A0&, _A1&, _A2&);
+
+    template<class _Alloc>
+        static shared_ptr<_Tp>
+        allocate_shared(const _Alloc& __a);
+
+    template<class _Alloc, class _A0>
+        static shared_ptr<_Tp>
+        allocate_shared(const _Alloc& __a, _A0& __a0);
+
+    template<class _Alloc, class _A0, class _A1>
+        static shared_ptr<_Tp>
+        allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1);
+
+    template<class _Alloc, class _A0, class _A1, class _A2>
+        static shared_ptr<_Tp>
+        allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1, _A2& __a2);
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+private:
+
+    template <class _Yp>
+        _LIBCPP_INLINE_VISIBILITY
+        void
+        __enable_weak_this(const enable_shared_from_this<_Yp>* __e) _NOEXCEPT
+        {
+            if (__e)
+                __e->__weak_this_ = *this;
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __enable_weak_this(const void*) _NOEXCEPT {}
+
+    template <class _Up> friend class _LIBCPP_TYPE_VIS_ONLY shared_ptr;
+    template <class _Up> friend class _LIBCPP_TYPE_VIS_ONLY weak_ptr;
+};
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR
+shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
+    : __ptr_(0),
+      __cntrl_(0)
+{
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR
+shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
+    : __ptr_(0),
+      __cntrl_(0)
+{
+}
+
+template<class _Tp>
+template<class _Yp, class>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p)
+    : __ptr_(__p)
+{
+    unique_ptr<_Yp> __hold(__p);
+    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__p, default_delete<_Yp>(), allocator<_Yp>());
+    __hold.release();
+    __enable_weak_this(__p);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp, class>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d)
+    : __ptr_(__p)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<_Yp*, _Dp, allocator<_Yp> > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__p, __d, allocator<_Yp>());
+        __enable_weak_this(__p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Dp>
+shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
+    : __ptr_(0)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<nullptr_t, _Dp, allocator<_Tp> > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__p, __d, allocator<_Tp>());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp, class _Alloc, class>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a)
+    : __ptr_(__p)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
+        typedef typename _Alloc::template rebind<_CntrlBlk>::other _A2;
+        typedef __allocator_destructor<_A2> _D2;
+        _A2 __a2(__a);
+        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+        ::new(__hold2.get()) _CntrlBlk(__p, __d, __a);
+        __cntrl_ = __hold2.release();
+        __enable_weak_this(__p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Dp, class _Alloc>
+shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
+    : __ptr_(0)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
+        typedef typename _Alloc::template rebind<_CntrlBlk>::other _A2;
+        typedef __allocator_destructor<_A2> _D2;
+        _A2 __a2(__a);
+        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+        ::new(__hold2.get()) _CntrlBlk(__p, __d, __a);
+        __cntrl_ = __hold2.release();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
+    : __ptr_(__p),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>::shared_ptr(const shared_ptr& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r,
+                            typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = 0;
+    __r.__cntrl_ = 0;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
+                            typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = 0;
+    __r.__cntrl_ = 0;
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+template<class _Yp, class>
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp>&& __r)
+#else
+shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp> __r)
+#endif
+    : __ptr_(__r.get())
+{
+    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
+    __enable_weak_this(__r.get());
+    __r.release();
+}
+
+template<class _Tp>
+template <class _Yp, class _Dp, class>
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
+#else
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp> __r,
+#endif
+           typename enable_if<!is_lvalue_reference<_Dp>::value, __nat>::type)
+    : __ptr_(__r.get())
+{
+    typedef __shared_ptr_pointer<_Yp*, _Dp, allocator<_Yp> > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), allocator<_Yp>());
+    __enable_weak_this(__r.get());
+    __r.release();
+}
+
+template<class _Tp>
+template <class _Yp, class _Dp, class>
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
+#else
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp> __r,
+#endif
+           typename enable_if<is_lvalue_reference<_Dp>::value, __nat>::type)
+    : __ptr_(__r.get())
+{
+    typedef __shared_ptr_pointer<_Yp*,
+                                 reference_wrapper<typename remove_reference<_Dp>::type>,
+                                 allocator<_Yp> > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__r.get(), ref(__r.get_deleter()), allocator<_Yp>());
+    __enable_weak_this(__r.get());
+    __r.release();
+}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp>
+template<class ..._Args>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::make_shared(_Args&& ...__args)
+{
+    typedef __shared_ptr_emplace<_Tp, allocator<_Tp> > _CntrlBlk;
+    typedef allocator<_CntrlBlk> _A2;
+    typedef __allocator_destructor<_A2> _D2;
+    _A2 __a2;
+    unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a2, _VSTD::forward<_Args>(__args)...);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _Alloc, class ..._Args>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::allocate_shared(const _Alloc& __a, _Args&& ...__args)
+{
+    typedef __shared_ptr_emplace<_Tp, _Alloc> _CntrlBlk;
+    typedef typename _Alloc::template rebind<_CntrlBlk>::other _A2;
+    typedef __allocator_destructor<_A2> _D2;
+    _A2 __a2(__a);
+    unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a, _VSTD::forward<_Args>(__args)...);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::make_shared()
+{
+    typedef __shared_ptr_emplace<_Tp, allocator<_Tp> > _CntrlBlk;
+    typedef allocator<_CntrlBlk> _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2;
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__alloc2);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _A0>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::make_shared(_A0& __a0)
+{
+    typedef __shared_ptr_emplace<_Tp, allocator<_Tp> > _CntrlBlk;
+    typedef allocator<_CntrlBlk> _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2;
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__alloc2, __a0);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _A0, class _A1>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::make_shared(_A0& __a0, _A1& __a1)
+{
+    typedef __shared_ptr_emplace<_Tp, allocator<_Tp> > _CntrlBlk;
+    typedef allocator<_CntrlBlk> _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2;
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__alloc2, __a0, __a1);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _A0, class _A1, class _A2>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::make_shared(_A0& __a0, _A1& __a1, _A2& __a2)
+{
+    typedef __shared_ptr_emplace<_Tp, allocator<_Tp> > _CntrlBlk;
+    typedef allocator<_CntrlBlk> _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2;
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__alloc2, __a0, __a1, __a2);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _Alloc>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::allocate_shared(const _Alloc& __a)
+{
+    typedef __shared_ptr_emplace<_Tp, _Alloc> _CntrlBlk;
+    typedef typename _Alloc::template rebind<_CntrlBlk>::other _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2(__a);
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _Alloc, class _A0>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::allocate_shared(const _Alloc& __a, _A0& __a0)
+{
+    typedef __shared_ptr_emplace<_Tp, _Alloc> _CntrlBlk;
+    typedef typename _Alloc::template rebind<_CntrlBlk>::other _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2(__a);
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a, __a0);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _Alloc, class _A0, class _A1>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1)
+{
+    typedef __shared_ptr_emplace<_Tp, _Alloc> _CntrlBlk;
+    typedef typename _Alloc::template rebind<_CntrlBlk>::other _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2(__a);
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a, __a0, __a1);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+template<class _Tp>
+template<class _Alloc, class _A0, class _A1, class _A2>
+shared_ptr<_Tp>
+shared_ptr<_Tp>::allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1, _A2& __a2)
+{
+    typedef __shared_ptr_emplace<_Tp, _Alloc> _CntrlBlk;
+    typedef typename _Alloc::template rebind<_CntrlBlk>::other _Alloc2;
+    typedef __allocator_destructor<_Alloc2> _D2;
+    _Alloc2 __alloc2(__a);
+    unique_ptr<_CntrlBlk, _D2> __hold2(__alloc2.allocate(1), _D2(__alloc2, 1));
+    ::new(__hold2.get()) _CntrlBlk(__a, __a0, __a1, __a2);
+    shared_ptr<_Tp> __r;
+    __r.__ptr_ = __hold2.get()->get();
+    __r.__cntrl_ = __hold2.release();
+    __r.__enable_weak_this(__r.__ptr_);
+    return __r;
+}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp>
+shared_ptr<_Tp>::~shared_ptr()
+{
+    if (__cntrl_)
+        __cntrl_->__release_shared();
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>&
+shared_ptr<_Tp>::operator=(const shared_ptr& __r) _NOEXCEPT
+{
+    shared_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
+{
+    shared_ptr(__r).swap(*this);
+    return *this;
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>&
+shared_ptr<_Tp>::operator=(shared_ptr&& __r) _NOEXCEPT
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Yp>::value &&
+    is_convertible<_Yp*, _Tp*>::value,
+    shared_ptr<_Tp>
+>::type&
+shared_ptr<_Tp>::operator=(auto_ptr<_Yp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template <class _Yp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Yp>::value &&
+    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, _Tp*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Yp>::value &&
+    is_convertible<_Yp*, _Tp*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(auto_ptr<_Yp> __r)
+{
+    shared_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template <class _Yp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Yp>::value &&
+    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, _Tp*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp> __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+shared_ptr<_Tp>::swap(shared_ptr& __r) _NOEXCEPT
+{
+    _VSTD::swap(__ptr_, __r.__ptr_);
+    _VSTD::swap(__cntrl_, __r.__cntrl_);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+shared_ptr<_Tp>::reset() _NOEXCEPT
+{
+    shared_ptr().swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p)
+{
+    shared_ptr(__p).swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d)
+{
+    shared_ptr(__p, __d).swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp, class _Alloc>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d, _Alloc __a)
+{
+    shared_ptr(__p, __d, __a).swap(*this);
+}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp, class ..._Args>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Tp>::value,
+    shared_ptr<_Tp>
+>::type
+make_shared(_Args&& ...__args)
+{
+    return shared_ptr<_Tp>::make_shared(_VSTD::forward<_Args>(__args)...);
+}
+
+template<class _Tp, class _Alloc, class ..._Args>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Tp>::value,
+    shared_ptr<_Tp>
+>::type
+allocate_shared(const _Alloc& __a, _Args&& ...__args)
+{
+    return shared_ptr<_Tp>::allocate_shared(__a, _VSTD::forward<_Args>(__args)...);
+}
+
+#else  // _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+make_shared()
+{
+    return shared_ptr<_Tp>::make_shared();
+}
+
+template<class _Tp, class _A0>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+make_shared(_A0& __a0)
+{
+    return shared_ptr<_Tp>::make_shared(__a0);
+}
+
+template<class _Tp, class _A0, class _A1>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+make_shared(_A0& __a0, _A1& __a1)
+{
+    return shared_ptr<_Tp>::make_shared(__a0, __a1);
+}
+
+template<class _Tp, class _A0, class _A1, class _A2>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+make_shared(_A0& __a0, _A1& __a1, _A2& __a2)
+{
+    return shared_ptr<_Tp>::make_shared(__a0, __a1, __a2);
+}
+
+template<class _Tp, class _Alloc>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+allocate_shared(const _Alloc& __a)
+{
+    return shared_ptr<_Tp>::allocate_shared(__a);
+}
+
+template<class _Tp, class _Alloc, class _A0>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+allocate_shared(const _Alloc& __a, _A0& __a0)
+{
+    return shared_ptr<_Tp>::allocate_shared(__a, __a0);
+}
+
+template<class _Tp, class _Alloc, class _A0, class _A1>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1)
+{
+    return shared_ptr<_Tp>::allocate_shared(__a, __a0, __a1);
+}
+
+template<class _Tp, class _Alloc, class _A0, class _A1, class _A2>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+allocate_shared(const _Alloc& __a, _A0& __a0, _A1& __a1, _A2& __a2)
+{
+    return shared_ptr<_Tp>::allocate_shared(__a, __a0, __a1, __a2);
+}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return __x.get() == __y.get();
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__x == __y);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    typedef typename common_type<_Tp*, _Up*>::type _V;
+    return less<_V>()(__x.get(), __y.get());
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return __y < __x;
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__y < __x);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__x < __y);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !__x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !__x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return less<_Tp*>()(__x.get(), nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return less<_Tp*>()(nullptr, __x.get());
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return nullptr < __x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return __x < nullptr;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !(nullptr < __x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !(__x < nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !(__x < nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !(nullptr < __x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(shared_ptr<_Tp>& __x, shared_ptr<_Tp>& __y) _NOEXCEPT
+{
+    __x.swap(__y);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Tp>::value && !is_array<_Up>::value,
+    shared_ptr<_Tp>
+>::type
+static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get()));
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_array<_Tp>::value && !is_array<_Up>::value,
+    shared_ptr<_Tp>
+>::type
+dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    _Tp* __p = dynamic_cast<_Tp*>(__r.get());
+    return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>();
+}
+
+template<class _Tp, class _Up>
+typename enable_if
+<
+    is_array<_Tp>::value == is_array<_Up>::value,
+    shared_ptr<_Tp>
+>::type
+const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    typedef typename remove_extent<_Tp>::type _RTp;
+    return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get()));
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Dp, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Dp*
+get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT
+{
+    return __p.template __get_deleter<_Dp>();
+}
+
+#endif  // _LIBCPP_NO_RTTI
+
+template<class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY weak_ptr
+{
+public:
+    typedef _Tp element_type;
+private:
+    element_type*        __ptr_;
+    __shared_weak_count* __cntrl_;
+
+public:
+    _LIBCPP_CONSTEXPR weak_ptr() _NOEXCEPT;
+    template<class _Yp> weak_ptr(shared_ptr<_Yp> const& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                        _NOEXCEPT;
+    weak_ptr(weak_ptr const& __r) _NOEXCEPT;
+    template<class _Yp> weak_ptr(weak_ptr<_Yp> const& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                         _NOEXCEPT;
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    weak_ptr(weak_ptr&& __r) _NOEXCEPT;
+    template<class _Yp> weak_ptr(weak_ptr<_Yp>&& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                         _NOEXCEPT;
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    ~weak_ptr();
+
+    weak_ptr& operator=(weak_ptr const& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT;
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    weak_ptr& operator=(weak_ptr&& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT;
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT;
+
+    void swap(weak_ptr& __r) _NOEXCEPT;
+    void reset() _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT
+        {return __cntrl_ ? __cntrl_->use_count() : 0;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool expired() const _NOEXCEPT
+        {return __cntrl_ == 0 || __cntrl_->use_count() == 0;}
+    shared_ptr<_Tp> lock() const _NOEXCEPT;
+    template<class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(const shared_ptr<_Up>& __r) const
+        {return __cntrl_ < __r.__cntrl_;}
+    template<class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(const weak_ptr<_Up>& __r) const
+        {return __cntrl_ < __r.__cntrl_;}
+
+    template <class _Up> friend class _LIBCPP_TYPE_VIS_ONLY weak_ptr;
+    template <class _Up> friend class _LIBCPP_TYPE_VIS_ONLY shared_ptr;
+};
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR
+weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
+    : __ptr_(0),
+      __cntrl_(0)
+{
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>::weak_ptr(weak_ptr const& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>::weak_ptr(shared_ptr<_Yp> const& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+                         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp> const& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>::weak_ptr(weak_ptr&& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = 0;
+    __r.__cntrl_ = 0;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp>&& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = 0;
+    __r.__cntrl_ = 0;
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+weak_ptr<_Tp>::~weak_ptr()
+{
+    if (__cntrl_)
+        __cntrl_->__release_weak();
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>&
+weak_ptr<_Tp>::operator=(weak_ptr const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+weak_ptr<_Tp>&
+weak_ptr<_Tp>::operator=(weak_ptr&& __r) _NOEXCEPT
+{
+    weak_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT
+{
+    weak_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template<class _Tp>
+template<class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+weak_ptr<_Tp>::swap(weak_ptr& __r) _NOEXCEPT
+{
+    _VSTD::swap(__ptr_, __r.__ptr_);
+    _VSTD::swap(__cntrl_, __r.__cntrl_);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(weak_ptr<_Tp>& __x, weak_ptr<_Tp>& __y) _NOEXCEPT
+{
+    __x.swap(__y);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+weak_ptr<_Tp>::reset() _NOEXCEPT
+{
+    weak_ptr().swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp>
+shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
+                            typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat>::type)
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
+{
+    if (__cntrl_ == 0)
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        throw bad_weak_ptr();
+#else
+        assert(!"bad_weak_ptr");
+#endif
+}
+
+template<class _Tp>
+shared_ptr<_Tp>
+weak_ptr<_Tp>::lock() const _NOEXCEPT
+{
+    shared_ptr<_Tp> __r;
+    __r.__cntrl_ = __cntrl_ ? __cntrl_->lock() : __cntrl_;
+    if (__r.__cntrl_)
+        __r.__ptr_ = __ptr_;
+    return __r;
+}
+
+template <class _Tp> struct owner_less;
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY owner_less<shared_ptr<_Tp> >
+    : binary_function<shared_ptr<_Tp>, shared_ptr<_Tp>, bool>
+{
+    typedef bool result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+};
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY owner_less<weak_ptr<_Tp> >
+    : binary_function<weak_ptr<_Tp>, weak_ptr<_Tp>, bool>
+{
+    typedef bool result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const
+        {return __x.owner_before(__y);}
+};
+
+template<class _Tp>
+class _LIBCPP_TYPE_VIS_ONLY enable_shared_from_this
+{
+    mutable weak_ptr<_Tp> __weak_this_;
+protected:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    enable_shared_from_this() _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY
+    enable_shared_from_this(enable_shared_from_this const&) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY
+    enable_shared_from_this& operator=(enable_shared_from_this const&) _NOEXCEPT
+        {return *this;}
+    _LIBCPP_INLINE_VISIBILITY
+    ~enable_shared_from_this() {}
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr<_Tp> shared_from_this()
+        {return shared_ptr<_Tp>(__weak_this_);}
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr<_Tp const> shared_from_this() const
+        {return shared_ptr<const _Tp>(__weak_this_);}
+
+    template <class _Up> friend class shared_ptr;
+};
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY hash<shared_ptr<_Tp> >
+{
+    typedef shared_ptr<_Tp>      argument_type;
+    typedef size_t               result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    result_type operator()(const argument_type& __ptr) const _NOEXCEPT
+    {
+        return hash<_Tp*>()(__ptr.get());
+    }
+};
+
+template<class _CharT, class _Traits, class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_ostream<_CharT, _Traits>&
+operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
+
+#if __has_feature(cxx_atomic)
+
+class _LIBCPP_TYPE_VIS __sp_mut
+{
+    void* __lx;
+public:
+    void lock() _NOEXCEPT;
+    void unlock() _NOEXCEPT;
+
+private:
+    _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
+    __sp_mut(const __sp_mut&);
+    __sp_mut& operator=(const __sp_mut&);
+
+    friend _LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
+};
+
+_LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+atomic_is_lock_free(const shared_ptr<_Tp>*)
+{
+    return false;
+}
+
+template <class _Tp>
+shared_ptr<_Tp>
+atomic_load(const shared_ptr<_Tp>* __p)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    shared_ptr<_Tp> __q = *__p;
+    __m.unlock();
+    return __q;
+}
+  
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
+{
+    return atomic_load(__p);
+}
+
+template <class _Tp>
+void
+atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    __p->swap(__r);
+    __m.unlock();
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
+{
+    atomic_store(__p, __r);
+}
+
+template <class _Tp>
+shared_ptr<_Tp>
+atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    __p->swap(__r);
+    __m.unlock();
+    return __r;
+}
+  
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
+{
+    return atomic_exchange(__p, __r);
+}
+
+template <class _Tp>
+bool
+atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    if (__p->__owner_equivalent(*__v))
+    {
+        *__p = __w;
+        __m.unlock();
+        return true;
+    }
+    *__v = *__p;
+    __m.unlock();
+    return false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
+{
+    return atomic_compare_exchange_strong(__p, __v, __w);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
+                                        shared_ptr<_Tp> __w, memory_order, memory_order)
+{
+    return atomic_compare_exchange_strong(__p, __v, __w);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
+                                      shared_ptr<_Tp> __w, memory_order, memory_order)
+{
+    return atomic_compare_exchange_weak(__p, __v, __w);
+}
+
+#endif  // __has_feature(cxx_atomic)
+
+//enum class
+struct _LIBCPP_TYPE_VIS pointer_safety
+{
+    enum __lx
+    {
+        relaxed,
+        preferred,
+        strict
+    };
+
+    __lx __v_;
+
+    _LIBCPP_INLINE_VISIBILITY
+    pointer_safety(__lx __v) : __v_(__v) {}
+    _LIBCPP_INLINE_VISIBILITY
+    operator int() const {return __v_;}
+};
+
+_LIBCPP_FUNC_VIS void declare_reachable(void* __p);
+_LIBCPP_FUNC_VIS void declare_no_pointers(char* __p, size_t __n);
+_LIBCPP_FUNC_VIS void undeclare_no_pointers(char* __p, size_t __n);
+_LIBCPP_FUNC_VIS pointer_safety get_pointer_safety() _NOEXCEPT;
+_LIBCPP_FUNC_VIS void* __undeclare_reachable(void* __p);
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Tp*
+undeclare_reachable(_Tp* __p)
+{
+    return static_cast<_Tp*>(__undeclare_reachable(__p));
+}
+
+_LIBCPP_FUNC_VIS void* align(size_t __align, size_t __sz, void*& __ptr, size_t& __space);
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif  // _LIBCPP_MEMORY