xref: /llvm-project-15.0.7/libcxx/include/memory (revision 89bdcd7e)

// -*- 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);

    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 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);
    template<class U> bool owner_before(weak_ptr<U> const& b);
};

// 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>
#if defined(_LIBCPP_NO_EXCEPTIONS)
    #include <cassert>
#endif

#pragma GCC system_header

_LIBCPP_BEGIN_NAMESPACE_STD

// allocator_arg_t

struct _LIBCPP_VISIBLE allocator_arg_t { };

extern const allocator_arg_t allocator_arg;

// addressof

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
_Tp*
addressof(_Tp& __x) _NOEXCEPT
{
    return (_Tp*)&(char&)__x;
}

#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
// Objective-C++ Automatic Reference Counting uses qualified pointers
// that require special addressof() signatures. When
// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
// itself is providing these definitions. Otherwise, we provide them.
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__strong _Tp*
addressof(__strong _Tp& __x) _NOEXCEPT
{
  return &__x;
}

#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__weak _Tp*
addressof(__weak _Tp& __x) _NOEXCEPT
{
  return &__x;
}
#endif

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__autoreleasing _Tp*
addressof(__autoreleasing _Tp& __x) _NOEXCEPT
{
  return &__x;
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__unsafe_unretained _Tp*
addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
{
  return &__x;
}
#endif

template <class _Tp> class allocator;

template <>
class _LIBCPP_VISIBLE allocator<void>
{
public:
    typedef void*             pointer;
    typedef const void*       const_pointer;
    typedef 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 _; char __;};
    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 _; char __;};
    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 _; char __;};
    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_VISIBLE 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_VISIBLE 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 _; char __;};
    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 _; char __;};
    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 _; char __;};
    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 _T>
inline _LIBCPP_INLINE_VISIBILITY
_T*
__to_raw_pointer(_T* __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 _; char __;};
    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 _; char __;};
    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 _; char __;};
    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 _; char __;};
    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 _; char __;};
    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
{
};

#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_VISIBLE 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)
        {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);}

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 __hint, 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;}
};

// uses_allocator

template <class _Tp>
struct __has_allocator_type
{
private:
    struct __two {char _; char __;};
    template <class _Up> static __two __test(...);
    template <class _Up> static char __test(typename _Up::allocator_type* = 0);
public:
    static const bool value = sizeof(__test<_Tp>(0)) == 1;
};

template <class _Tp, class _Alloc, bool = __has_allocator_type<_Tp>::value>
struct __uses_allocator
    : public integral_constant<bool,
        is_convertible<_Alloc, typename _Tp::allocator_type>::value>
{
};

template <class _Tp, class _Alloc>
struct __uses_allocator<_Tp, _Alloc, false>
    : public false_type
{
};

template <class _Tp, class _Alloc>
struct _LIBCPP_VISIBLE uses_allocator
    : public __uses_allocator<_Tp, _Alloc>
{
};

#ifndef _LIBCPP_HAS_NO_VARIADICS

// uses-allocator construction

template <class _Tp, class _Alloc, class ..._Args>
struct __uses_alloc_ctor_imp
{
    static const bool __ua = uses_allocator<_Tp, _Alloc>::value;
    static const bool __ic =
        is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;
    static const int value = __ua ? 2 - __ic : 0;
};

template <class _Tp, class _Alloc, class ..._Args>
struct __uses_alloc_ctor
    : integral_constant<int, __uses_alloc_ctor_imp<_Tp, _Alloc, _Args...>::value>
    {};

#endif  // _LIBCPP_HAS_NO_VARIADICS

// allocator

template <class _Tp>
class _LIBCPP_VISIBLE 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
        typename enable_if
        <
            !is_convertible<_A0, __rv<_A0> >::value,
            void
        >::type
        construct(pointer __p, _A0& __a0)
        {
            ::new((void*)__p) _Tp(__a0);
        }
    template <class _A0>
        _LIBCPP_INLINE_VISIBILITY
        typename enable_if
        <
            !is_convertible<_A0, __rv<_A0> >::value,
            void
        >::type
        construct(pointer __p, const _A0& __a0)
        {
            ::new((void*)__p) _Tp(__a0);
        }
    template <class _A0>
        _LIBCPP_INLINE_VISIBILITY
        typename enable_if
        <
            is_convertible<_A0, __rv<_A0> >::value,
            void
        >::type
        construct(pointer __p, _A0 __a0)
        {
            ::new((void*)__p) _Tp(_VSTD::move(__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_VISIBLE 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_VISIBLE 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_VISIBLE 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,
                                bool = is_empty<_T2>::value>
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, int = 0)
        : __first_(_VSTD::forward<_T1_param>(__t1)) {}
    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2, int* = 0)
        : __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

    _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, int = 0)
        : _T1(_VSTD::forward<_T1_param>(__t1)) {}
    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2, int* = 0)
        : __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

    _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

    _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

    _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& __x)
        _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, int = 0)
        : base(_VSTD::forward<_T1_param>(__t1)) {}
    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T2_param __t2, int* = 0)
        : 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

    _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);}

template <class _Tp>
struct _LIBCPP_VISIBLE default_delete
{
    _LIBCPP_INLINE_VISIBILITY default_delete() _NOEXCEPT {}
    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");
            delete __ptr;
        }
};

template <class _Tp>
struct _LIBCPP_VISIBLE default_delete<_Tp[]>
{
    _LIBCPP_INLINE_VISIBILITY void operator() (_Tp* __ptr) const _NOEXCEPT
        {
            static_assert(sizeof(_Tp) > 0, "default_delete can not delete incomplete type");
            delete [] __ptr;
        }
private:
    template <class _Up> void operator() (_Up*) const;
};

template <class _Tp, class _Dp = default_delete<_Tp> >
class _LIBCPP_VISIBLE 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_;

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    unique_ptr(const unique_ptr&);
    unique_ptr& operator=(const unique_ptr&);
    template <class _Up, class _Ep>
        unique_ptr(const unique_ptr<_Up, _Ep>&);
    template <class _Up, class _Ep>
        unique_ptr& operator=(const unique_ptr<_Up, _Ep>&);
#else  // _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 unique_ptr() _NOEXCEPT
        : __ptr_(pointer())
        {
            static_assert(!is_pointer<deleter_type>::value,
                "unique_ptr constructed with null function pointer deleter");
        }
    _LIBCPP_INLINE_VISIBILITY 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,
                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 operator int __nat::*() const
             _NOEXCEPT
        {return __ptr_.first() ? &__nat::__for_bool_ : 0;}

    _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_VISIBLE 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_;

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    unique_ptr(const unique_ptr&);
    unique_ptr& operator=(const unique_ptr&);
#else  // _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 unique_ptr() _NOEXCEPT
        : __ptr_(pointer())
        {
            static_assert(!is_pointer<deleter_type>::value,
                "unique_ptr constructed with null function pointer deleter");
        }
    _LIBCPP_INLINE_VISIBILITY 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 _P,
              class = typename enable_if<is_same<_P, pointer>::value>::type
             >
    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(_P __p) _NOEXCEPT
        : __ptr_(__p)
        {
            static_assert(!is_pointer<deleter_type>::value,
                "unique_ptr constructed with null function pointer deleter");
        }

    template <class _P,
              class = typename enable_if<is_same<_P, pointer>::value>::type
             >
    _LIBCPP_INLINE_VISIBILITY unique_ptr(_P __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 _P,
              class = typename enable_if<is_same<_P, pointer>::value ||
                                         is_same<_P, nullptr_t>::value>::type
             >
    _LIBCPP_INLINE_VISIBILITY unique_ptr(_P __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;
        }
#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 operator int __nat::*() const _NOEXCEPT
        {return __ptr_.first() ? &__nat::__for_bool_ : 0;}

    _LIBCPP_INLINE_VISIBILITY pointer release() _NOEXCEPT
    {
        pointer __t = __ptr_.first();
        __ptr_.first() = pointer();
        return __t;
    }

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    template <class _P,
              class = typename enable_if<is_same<_P, pointer>::value>::type
             >
    _LIBCPP_INLINE_VISIBILITY void reset(_P __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) {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 __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 _Tp> struct hash;

template<class _Tp>
struct _LIBCPP_VISIBLE hash<_Tp*>
    : public unary_function<_Tp*, size_t>
{
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(_Tp* __v) const _NOEXCEPT
    {
        const size_t* const __p = reinterpret_cast<const size_t*>(&__v);
        return *__p;
    }
};

template <class _Tp, class _Dp>
struct _LIBCPP_VISIBLE 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)
{
    __destruct_n __d(0);
    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
    unique_ptr<value_type, __destruct_n&> __h(&*__r, __d);
    for (; __f != __l; ++__f, ++__r, __d.__incr((value_type*)0))
        ::new(&*__r) value_type(*__f);
    __h.release();
    return __r;
}

template <class _InputIterator, class _Size, class _ForwardIterator>
_ForwardIterator
uninitialized_copy_n(_InputIterator __f, _Size __n, _ForwardIterator __r)
{
    __destruct_n __d(0);
    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
    unique_ptr<value_type, __destruct_n&> __h(&*__r, __d);
    for (; __n > 0; ++__f, ++__r, __d.__incr((value_type*)0), --__n)
        ::new(&*__r) value_type(*__f);
    __h.release();
    return __r;
}

template <class _ForwardIterator, class _Tp>
void
uninitialized_fill(_ForwardIterator __f, _ForwardIterator __l, const _Tp& __x)
{
    __destruct_n __d(0);
    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
    unique_ptr<value_type, __destruct_n&> __h(&*__f, __d);
    for (; __f != __l; ++__f, __d.__incr((value_type*)0))
        ::new(&*__f) value_type(__x);
    __h.release();
}

template <class _ForwardIterator, class _Size, class _Tp>
_ForwardIterator
uninitialized_fill_n(_ForwardIterator __f, _Size __n, const _Tp& __x)
{
    __destruct_n __d(0);
    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
    unique_ptr<value_type, __destruct_n&> __h(&*__f, __d);
    for (; __n > 0; ++__f, --__n, __d.__incr((value_type*)0))
        ::new(&*__f) value_type(__x);
    __h.release();
    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 weak_ptr;

class __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 __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;

#ifndef _LIBCPP_NO_RTTI
    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_(_VSTD::move(__a), _Tp(_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 enable_shared_from_this;

template<class _Tp>
class _LIBCPP_VISIBLE shared_ptr
{
public:
    typedef _Tp element_type;
private:
    element_type*      __ptr_;
    __shared_weak_count* __cntrl_;

    struct __nat {int __for_bool_;};
public:
    shared_ptr() _NOEXCEPT;
    shared_ptr(nullptr_t) _NOEXCEPT;
    template<class _Yp> explicit shared_ptr(_Yp* __p);
    template<class _Yp, class _Dp> shared_ptr(_Yp* __p, _Dp __d);
    template<class _Yp, class _Dp, class _Alloc> 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> shared_ptr(auto_ptr<_Yp>&& __r);
#else
    template<class _Yp> shared_ptr(auto_ptr<_Yp> __r);
#endif
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
private:
    template <class _Yp, class _Dp> shared_ptr(const unique_ptr<_Yp, _Dp>& __r);// = delete;
public:
    template <class _Yp, class _Dp> shared_ptr(unique_ptr<_Yp, _Dp>&&,
       typename enable_if<!is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
    template <class _Yp, class _Dp> 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> shared_ptr(unique_ptr<_Yp, _Dp>,
       typename enable_if<!is_lvalue_reference<_Dp>::value, __nat>::type = __nat());
    template <class _Yp, class _Dp> 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> shared_ptr& operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
    template<class _Yp> shared_ptr& operator=(shared_ptr<_Yp>&& __r);
    template<class _Yp> shared_ptr& operator=(auto_ptr<_Yp>&& __r);
#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    template<class _Yp> shared_ptr& operator=(auto_ptr<_Yp> __r);
#endif
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
private:
    template <class _Yp, class _Dp> shared_ptr& operator=(const unique_ptr<_Yp, _Dp>& __r);// = delete;
public:
    template <class _Yp, class _Dp> shared_ptr& operator=(unique_ptr<_Yp, _Dp>&& __r);
#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    template <class _Yp, class _Dp> shared_ptr& operator=(unique_ptr<_Yp, _Dp> __r);
#endif

    void swap(shared_ptr& __r) _NOEXCEPT;
    void reset() _NOEXCEPT;
    template<class _Yp> void reset(_Yp* __p) _NOEXCEPT;
    template<class _Yp, class _Dp> void reset(_Yp* __p, _Dp __d);
    template<class _Yp, class _Dp, class _Alloc> void 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
    /*explicit*/ operator bool() const _NOEXCEPT {return get() != 0;}
    template <class _U>
        _LIBCPP_INLINE_VISIBILITY
        bool owner_before(shared_ptr<_U> const& __p) const
        {return __cntrl_ < __p.__cntrl_;}
    template <class _U>
        _LIBCPP_INLINE_VISIBILITY
        bool owner_before(weak_ptr<_U> const& __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_VISIBLE shared_ptr;
    template <class _Up> friend class _LIBCPP_VISIBLE weak_ptr;
};

template<class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
    : __ptr_(0),
      __cntrl_(0)
{
}

template<class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
    : __ptr_(0),
      __cntrl_(0)
{
}

template<class _Tp>
template<class _Yp>
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>
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>
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>
#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>
#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>
#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
shared_ptr<_Tp>&
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
shared_ptr<_Tp>&
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
shared_ptr<_Tp>&
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
shared_ptr<_Tp>&
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
shared_ptr<_Tp>&
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
shared_ptr<_Tp>&
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
void
shared_ptr<_Tp>::reset(_Yp* __p)
{
    shared_ptr(__p).swap(*this);
}

template<class _Tp>
template<class _Yp, class _Dp>
inline _LIBCPP_INLINE_VISIBILITY
void
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
void
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
shared_ptr<_Tp>
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
shared_ptr<_Tp>
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
{
    return __x.get() < __y.get();
}

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
shared_ptr<_Tp>
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
shared_ptr<_Tp>
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>
shared_ptr<_Tp>
const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
{
    return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__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_VISIBLE weak_ptr
{
public:
    typedef _Tp element_type;
private:
    element_type*        __ptr_;
    __shared_weak_count* __cntrl_;

public:
    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;

    ~weak_ptr();

    weak_ptr& operator=(weak_ptr const& __r) _NOEXCEPT;
    template<class _Yp> weak_ptr& operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT;
    template<class _Yp> weak_ptr& 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_VISIBLE weak_ptr;
    template <class _Up> friend class _LIBCPP_VISIBLE shared_ptr;
};

template<class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
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();
}

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
weak_ptr<_Tp>&
weak_ptr<_Tp>::operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT
{
    weak_ptr(__r).swap(*this);
    return *this;
}

template<class _Tp>
template<class _Yp>
inline _LIBCPP_INLINE_VISIBILITY
weak_ptr<_Tp>&
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_VISIBLE 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_VISIBLE 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_VISIBLE enable_shared_from_this
{
    mutable weak_ptr<_Tp> __weak_this_;
protected:
    _LIBCPP_INLINE_VISIBILITY
    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_VISIBLE 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 _Y>
inline _LIBCPP_INLINE_VISIBILITY
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Y> const& __p);

//enum class
struct _LIBCPP_VISIBLE pointer_safety
{
    enum _
    {
        relaxed,
        preferred,
        strict
    };

    _ __v_;

    _LIBCPP_INLINE_VISIBILITY
    pointer_safety(_ __v) : __v_(__v) {}
    _LIBCPP_INLINE_VISIBILITY
    operator int() const {return __v_;}
};

void declare_reachable(void* __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* __undeclare_reachable(void* __p);

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
_Tp*
undeclare_reachable(_Tp* __p)
{
    return static_cast<_Tp*>(__undeclare_reachable(__p));
}

void* align(size_t __align, size_t __sz, void*& __ptr, size_t& __space);

_LIBCPP_END_NAMESPACE_STD

#endif  // _LIBCPP_MEMORY