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

third_party/libc++/include/deque

+// -*- C++ -*-
+//===---------------------------- deque -----------------------------------===//
+//
+//                     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_DEQUE
+#define _LIBCPP_DEQUE
+
+/*
+    deque synopsis
+
+namespace std
+{
+
+template <class T, class Allocator = allocator<T> >
+class deque
+{
+public:
+    // types:
+    typedef T value_type;
+    typedef Allocator allocator_type;
+
+    typedef typename allocator_type::reference       reference;
+    typedef typename allocator_type::const_reference const_reference;
+    typedef implementation-defined                   iterator;
+    typedef implementation-defined                   const_iterator;
+    typedef typename allocator_type::size_type       size_type;
+    typedef typename allocator_type::difference_type difference_type;
+
+    typedef typename allocator_type::pointer         pointer;
+    typedef typename allocator_type::const_pointer   const_pointer;
+    typedef std::reverse_iterator<iterator>          reverse_iterator;
+    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
+
+    // construct/copy/destroy:
+    deque() noexcept(is_nothrow_default_constructible<allocator_type>::value);
+    explicit deque(const allocator_type& a);
+    explicit deque(size_type n);
+    explicit deque(size_type n, const allocator_type& a); // C++14
+    deque(size_type n, const value_type& v);
+    deque(size_type n, const value_type& v, const allocator_type& a);
+    template <class InputIterator>
+        deque(InputIterator f, InputIterator l);
+    template <class InputIterator>
+        deque(InputIterator f, InputIterator l, const allocator_type& a);
+    deque(const deque& c);
+    deque(deque&& c)
+        noexcept(is_nothrow_move_constructible<allocator_type>::value);
+    deque(initializer_list<value_type> il, const Allocator& a = allocator_type());
+    deque(const deque& c, const allocator_type& a);
+    deque(deque&& c, const allocator_type& a);
+    ~deque();
+
+    deque& operator=(const deque& c);
+    deque& operator=(deque&& c)
+        noexcept(
+             allocator_type::propagate_on_container_move_assignment::value &&
+             is_nothrow_move_assignable<allocator_type>::value);
+    deque& operator=(initializer_list<value_type> il);
+
+    template <class InputIterator>
+        void assign(InputIterator f, InputIterator l);
+    void assign(size_type n, const value_type& v);
+    void assign(initializer_list<value_type> il);
+
+    allocator_type get_allocator() const noexcept;
+
+    // iterators:
+
+    iterator       begin() noexcept;
+    const_iterator begin() const noexcept;
+    iterator       end() noexcept;
+    const_iterator end() const noexcept;
+
+    reverse_iterator       rbegin() noexcept;
+    const_reverse_iterator rbegin() const noexcept;
+    reverse_iterator       rend() noexcept;
+    const_reverse_iterator rend() const noexcept;
+
+    const_iterator         cbegin() const noexcept;
+    const_iterator         cend() const noexcept;
+    const_reverse_iterator crbegin() const noexcept;
+    const_reverse_iterator crend() const noexcept;
+
+    // capacity:
+    size_type size() const noexcept;
+    size_type max_size() const noexcept;
+    void resize(size_type n);
+    void resize(size_type n, const value_type& v);
+    void shrink_to_fit();
+    bool empty() const noexcept;
+
+    // element access:
+    reference operator[](size_type i);
+    const_reference operator[](size_type i) const;
+    reference at(size_type i);
+    const_reference at(size_type i) const;
+    reference front();
+    const_reference front() const;
+    reference back();
+    const_reference back() const;
+
+    // modifiers:
+    void push_front(const value_type& v);
+    void push_front(value_type&& v);
+    void push_back(const value_type& v);
+    void push_back(value_type&& v);
+    template <class... Args> void emplace_front(Args&&... args);
+    template <class... Args> void emplace_back(Args&&... args);
+    template <class... Args> iterator emplace(const_iterator p, Args&&... args);
+    iterator insert(const_iterator p, const value_type& v);
+    iterator insert(const_iterator p, value_type&& v);
+    iterator insert(const_iterator p, size_type n, const value_type& v);
+    template <class InputIterator>
+        iterator insert (const_iterator p, InputIterator f, InputIterator l);
+    iterator insert(const_iterator p, initializer_list<value_type> il);
+    void pop_front();
+    void pop_back();
+    iterator erase(const_iterator p);
+    iterator erase(const_iterator f, const_iterator l);
+    void swap(deque& c)
+        noexcept(!allocator_type::propagate_on_container_swap::value ||
+                 __is_nothrow_swappable<allocator_type>::value);
+    void clear() noexcept;
+};
+
+template <class T, class Allocator>
+    bool operator==(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+template <class T, class Allocator>
+    bool operator< (const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+template <class T, class Allocator>
+    bool operator!=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+template <class T, class Allocator>
+    bool operator> (const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+template <class T, class Allocator>
+    bool operator>=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+template <class T, class Allocator>
+    bool operator<=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
+
+// specialized algorithms:
+template <class T, class Allocator>
+    void swap(deque<T,Allocator>& x, deque<T,Allocator>& y)
+         noexcept(noexcept(x.swap(y)));
+
+}  // std
+
+*/
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+#include <__config>
+#include <__split_buffer>
+#include <type_traits>
+#include <initializer_list>
+#include <iterator>
+#include <algorithm>
+#include <stdexcept>
+
+#include <__undef_min_max>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Allocator> class __deque_base;
+
+template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
+          class _DiffType, _DiffType _BlockSize>
+class _LIBCPP_TYPE_VIS_ONLY __deque_iterator;
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy(_RAIter __f,
+     _RAIter __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+     typename enable_if<__is_random_access_iterator<_RAIter>::value>::type* = 0);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     _OutputIterator __r);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy_backward(_RAIter __f,
+              _RAIter __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+              typename enable_if<__is_random_access_iterator<_RAIter>::value>::type* = 0);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              _OutputIterator __r);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move(_RAIter __f,
+     _RAIter __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+     typename enable_if<__is_random_access_iterator<_RAIter>::value>::type* = 0);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     _OutputIterator __r);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move_backward(_RAIter __f,
+              _RAIter __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+              typename enable_if<__is_random_access_iterator<_RAIter>::value>::type* = 0);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              _OutputIterator __r);
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
+          class _DiffType, _DiffType _BlockSize>
+class _LIBCPP_TYPE_VIS_ONLY __deque_iterator
+{
+    typedef _MapPointer __map_iterator;
+public:
+    typedef _Pointer  pointer;
+    typedef _DiffType difference_type;
+private:
+    __map_iterator __m_iter_;
+    pointer        __ptr_;
+
+    static const difference_type __block_size = _BlockSize;
+public:
+    typedef _ValueType                  value_type;
+    typedef random_access_iterator_tag  iterator_category;
+    typedef _Reference                  reference;
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator() _NOEXCEPT
+#if _LIBCPP_STD_VER > 11
+     : __m_iter_(nullptr), __ptr_(nullptr)
+#endif
+     {}
+
+    template <class _Pp, class _Rp, class _MP>
+    _LIBCPP_INLINE_VISIBILITY
+    __deque_iterator(const __deque_iterator<value_type, _Pp, _Rp, _MP, difference_type, __block_size>& __it,
+                typename enable_if<is_convertible<_Pp, pointer>::value>::type* = 0) _NOEXCEPT
+        : __m_iter_(__it.__m_iter_), __ptr_(__it.__ptr_) {}
+
+    _LIBCPP_INLINE_VISIBILITY reference operator*() const {return *__ptr_;}
+    _LIBCPP_INLINE_VISIBILITY pointer operator->() const {return __ptr_;}
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator++()
+    {
+        if (++__ptr_ - *__m_iter_ == __block_size)
+        {
+            ++__m_iter_;
+            __ptr_ = *__m_iter_;
+        }
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator++(int)
+    {
+        __deque_iterator __tmp = *this;
+        ++(*this);
+        return __tmp;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator--()
+    {
+        if (__ptr_ == *__m_iter_)
+        {
+            --__m_iter_;
+            __ptr_ = *__m_iter_ + __block_size;
+        }
+        --__ptr_;
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator--(int)
+    {
+        __deque_iterator __tmp = *this;
+        --(*this);
+        return __tmp;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator+=(difference_type __n)
+    {
+        if (__n != 0)
+        {
+            __n += __ptr_ - *__m_iter_;
+            if (__n > 0)
+            {
+                __m_iter_ += __n / __block_size;
+                __ptr_ = *__m_iter_ + __n % __block_size;
+            }
+            else // (__n < 0)
+            {
+                difference_type __z = __block_size - 1 - __n;
+                __m_iter_ -= __z / __block_size;
+                __ptr_ = *__m_iter_ + (__block_size - 1 - __z % __block_size);
+            }
+        }
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator-=(difference_type __n)
+    {
+        return *this += -__n;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator+(difference_type __n) const
+    {
+        __deque_iterator __t(*this);
+        __t += __n;
+        return __t;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator-(difference_type __n) const
+    {
+        __deque_iterator __t(*this);
+        __t -= __n;
+        return __t;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    friend __deque_iterator operator+(difference_type __n, const __deque_iterator& __it)
+        {return __it + __n;}
+
+    _LIBCPP_INLINE_VISIBILITY
+    friend difference_type operator-(const __deque_iterator& __x, const __deque_iterator& __y)
+    {
+        if (__x != __y)
+            return (__x.__m_iter_ - __y.__m_iter_) * __block_size
+                 + (__x.__ptr_ - *__x.__m_iter_)
+                 - (__y.__ptr_ - *__y.__m_iter_);
+        return 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY reference operator[](difference_type __n) const
+        {return *(*this + __n);}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator==(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return __x.__ptr_ == __y.__ptr_;}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator!=(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return !(__x == __y);}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator<(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return __x.__m_iter_ < __y.__m_iter_ ||
+               (__x.__m_iter_ == __y.__m_iter_ && __x.__ptr_ < __y.__ptr_);}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator>(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return __y < __x;}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator<=(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return !(__y < __x);}
+
+    _LIBCPP_INLINE_VISIBILITY friend
+        bool operator>=(const __deque_iterator& __x, const __deque_iterator& __y)
+        {return !(__x < __y);}
+
+private:
+    _LIBCPP_INLINE_VISIBILITY __deque_iterator(__map_iterator __m, pointer __p) _NOEXCEPT
+        : __m_iter_(__m), __ptr_(__p) {}
+
+    template <class _Tp, class _Ap> friend class __deque_base;
+    template <class _Tp, class _Ap> friend class _LIBCPP_TYPE_VIS_ONLY deque;
+    template <class _Vp, class _Pp, class _Rp, class _MP, class _Dp, _Dp>
+        friend class _LIBCPP_TYPE_VIS_ONLY __deque_iterator;
+
+    template <class _RAIter,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    copy(_RAIter __f,
+         _RAIter __l,
+         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+         typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _OutputIterator>
+    friend
+    _OutputIterator
+    copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+         _OutputIterator __r);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+    template <class _RAIter,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    copy_backward(_RAIter __f,
+                  _RAIter __l,
+                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+                  typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _OutputIterator>
+    friend
+    _OutputIterator
+    copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+                  _OutputIterator __r);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+    template <class _RAIter,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    move(_RAIter __f,
+         _RAIter __l,
+         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+         typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _OutputIterator>
+    friend
+    _OutputIterator
+    move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+         _OutputIterator __r);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+
+    template <class _RAIter,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    move_backward(_RAIter __f,
+                  _RAIter __l,
+                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+                  typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _OutputIterator>
+    friend
+    _OutputIterator
+    move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+                  _OutputIterator __r);
+
+    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+    friend
+    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+    move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
+};
+
+// copy
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy(_RAIter __f,
+     _RAIter __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+     typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*)
+{
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
+    while (__f != __l)
+    {
+        pointer __rb = __r.__ptr_;
+        pointer __re = *__r.__m_iter_ + _B2;
+        difference_type __bs = __re - __rb;
+        difference_type __n = __l - __f;
+        _RAIter __m = __l;
+        if (__n > __bs)
+        {
+            __n = __bs;
+            __m = __f + __n;
+        }
+        _VSTD::copy(__f, __m, __rb);
+        __f = __m;
+        __r += __n;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     _OutputIterator __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + _B1;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        __r = _VSTD::copy(__fb, __fe, __r);
+        __n -= __bs;
+        __f += __bs;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + _B1;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        __r = _VSTD::copy(__fb, __fe, __r);
+        __n -= __bs;
+        __f += __bs;
+    }
+    return __r;
+}
+
+// copy_backward
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy_backward(_RAIter __f,
+              _RAIter __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+              typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*)
+{
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
+    while (__f != __l)
+    {
+        __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __rp = _VSTD::prev(__r);
+        pointer __rb = *__rp.__m_iter_;
+        pointer __re = __rp.__ptr_ + 1;
+        difference_type __bs = __re - __rb;
+        difference_type __n = __l - __f;
+        _RAIter __m = __f;
+        if (__n > __bs)
+        {
+            __n = __bs;
+            __m = __l - __n;
+        }
+        _VSTD::copy_backward(__m, __l, __re);
+        __l = __m;
+        __r -= __n;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              _OutputIterator __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        __r = _VSTD::copy_backward(__lb, __le, __r);
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        __r = _VSTD::copy_backward(__lb, __le, __r);
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+    return __r;
+}
+
+// move
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move(_RAIter __f,
+     _RAIter __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+     typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*)
+{
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
+    while (__f != __l)
+    {
+        pointer __rb = __r.__ptr_;
+        pointer __re = *__r.__m_iter_ + _B2;
+        difference_type __bs = __re - __rb;
+        difference_type __n = __l - __f;
+        _RAIter __m = __l;
+        if (__n > __bs)
+        {
+            __n = __bs;
+            __m = __f + __n;
+        }
+        _VSTD::move(__f, __m, __rb);
+        __f = __m;
+        __r += __n;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     _OutputIterator __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + _B1;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        __r = _VSTD::move(__fb, __fe, __r);
+        __n -= __bs;
+        __f += __bs;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + _B1;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        __r = _VSTD::move(__fb, __fe, __r);
+        __n -= __bs;
+        __f += __bs;
+    }
+    return __r;
+}
+
+// move_backward
+
+template <class _RAIter,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move_backward(_RAIter __f,
+              _RAIter __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
+              typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*)
+{
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
+    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
+    while (__f != __l)
+    {
+        __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __rp = _VSTD::prev(__r);
+        pointer __rb = *__rp.__m_iter_;
+        pointer __re = __rp.__ptr_ + 1;
+        difference_type __bs = __re - __rb;
+        difference_type __n = __l - __f;
+        _RAIter __m = __f;
+        if (__n > __bs)
+        {
+            __n = __bs;
+            __m = __l - __n;
+        }
+        _VSTD::move_backward(__m, __l, __re);
+        __l = __m;
+        __r -= __n;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _OutputIterator>
+_OutputIterator
+move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              _OutputIterator __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        __r = _VSTD::move_backward(__lb, __le, __r);
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+    return __r;
+}
+
+template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
+          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
+__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
+move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
+              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
+              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
+{
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
+    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        __r = _VSTD::move_backward(__lb, __le, __r);
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+    return __r;
+}
+
+template <bool>
+class __deque_base_common
+{
+protected:
+    void __throw_length_error() const;
+    void __throw_out_of_range() const;
+};
+
+template <bool __b>
+void
+__deque_base_common<__b>::__throw_length_error() const
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw length_error("deque");
+#endif
+}
+
+template <bool __b>
+void
+__deque_base_common<__b>::__throw_out_of_range() const
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw out_of_range("deque");
+#endif
+}
+
+template <class _Tp, class _Allocator>
+class __deque_base
+    : protected __deque_base_common<true>
+{
+    __deque_base(const __deque_base& __c);
+    __deque_base& operator=(const __deque_base& __c);
+protected:
+    typedef _Tp                                      value_type;
+    typedef _Allocator                               allocator_type;
+    typedef allocator_traits<allocator_type>         __alloc_traits;
+    typedef value_type&                              reference;
+    typedef const value_type&                        const_reference;
+    typedef typename __alloc_traits::size_type       size_type;
+    typedef typename __alloc_traits::difference_type difference_type;
+    typedef typename __alloc_traits::pointer         pointer;
+    typedef typename __alloc_traits::const_pointer   const_pointer;
+
+    static const difference_type __block_size = sizeof(value_type) < 256 ? 4096 / sizeof(value_type) : 16;
+
+    typedef typename __alloc_traits::template
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+                rebind_alloc<pointer>
+#else
+                rebind_alloc<pointer>::other
+#endif
+                                                         __pointer_allocator;
+    typedef allocator_traits<__pointer_allocator>        __map_traits;
+    typedef typename __map_traits::pointer               __map_pointer;
+    typedef typename __alloc_traits::template
+#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
+                rebind_alloc<const_pointer>
+#else
+                rebind_alloc<const_pointer>::other
+#endif
+                                                         __const_pointer_allocator;
+    typedef typename allocator_traits<__const_pointer_allocator>::const_pointer __map_const_pointer;
+    typedef __split_buffer<pointer, __pointer_allocator> __map;
+
+    typedef __deque_iterator<value_type, pointer, reference, __map_pointer,
+                             difference_type, __block_size>    iterator;
+    typedef __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer,
+                             difference_type, __block_size>    const_iterator;
+
+    __map __map_;
+    size_type __start_;
+    __compressed_pair<size_type, allocator_type> __size_;
+
+    iterator       begin() _NOEXCEPT;
+    const_iterator begin() const _NOEXCEPT;
+    iterator       end() _NOEXCEPT;
+    const_iterator end() const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY size_type&            size()          {return __size_.first();}
+    _LIBCPP_INLINE_VISIBILITY
+    const size_type& size() const _NOEXCEPT {return __size_.first();}
+    _LIBCPP_INLINE_VISIBILITY allocator_type&       __alloc()       {return __size_.second();}
+    _LIBCPP_INLINE_VISIBILITY
+    const allocator_type& __alloc() const _NOEXCEPT {return __size_.second();}
+
+    __deque_base()
+        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
+    explicit __deque_base(const allocator_type& __a);
+public:
+    ~__deque_base();
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    __deque_base(__deque_base&& __c)
+        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
+    __deque_base(__deque_base&& __c, const allocator_type& __a);
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    void swap(__deque_base& __c)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
+                   __is_nothrow_swappable<allocator_type>::value);
+protected:
+    void clear() _NOEXCEPT;
+
+    bool __invariants() const;
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign(__deque_base& __c)
+        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
+                   is_nothrow_move_assignable<allocator_type>::value)
+    {
+        __map_ = _VSTD::move(__c.__map_);
+        __start_ = __c.__start_;
+        size() = __c.size();
+        __move_assign_alloc(__c);
+        __c.__start_ = __c.size() = 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign_alloc(__deque_base& __c)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_move_assignment::value ||
+                   is_nothrow_move_assignable<allocator_type>::value)
+        {__move_assign_alloc(__c, integral_constant<bool,
+                      __alloc_traits::propagate_on_container_move_assignment::value>());}
+
+private:
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign_alloc(__deque_base& __c, true_type)
+        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
+        {
+            __alloc() = _VSTD::move(__c.__alloc());
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign_alloc(__deque_base&, false_type) _NOEXCEPT
+        {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static void __swap_alloc(allocator_type& __x, allocator_type& __y)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
+                   __is_nothrow_swappable<allocator_type>::value)
+        {__swap_alloc(__x, __y, integral_constant<bool,
+                      __alloc_traits::propagate_on_container_swap::value>());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    static void __swap_alloc(allocator_type& __x, allocator_type& __y, true_type)
+        _NOEXCEPT_(__is_nothrow_swappable<allocator_type>::value)
+        {
+            using _VSTD::swap;
+            swap(__x, __y);
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    static void __swap_alloc(allocator_type&, allocator_type&, false_type)
+        _NOEXCEPT
+        {}
+};
+
+template <class _Tp, class _Allocator>
+bool
+__deque_base<_Tp, _Allocator>::__invariants() const
+{
+    if (!__map_.__invariants())
+        return false;
+    if (__map_.size() >= size_type(-1) / __block_size)
+        return false;
+    for (typename __map::const_iterator __i = __map_.begin(), __e = __map_.end();
+         __i != __e; ++__i)
+        if (*__i == nullptr)
+            return false;
+    if (__map_.size() != 0)
+    {
+        if (size() >= __map_.size() * __block_size)
+            return false;
+        if (__start_ >= __map_.size() * __block_size - size())
+            return false;
+    }
+    else
+    {
+        if (size() != 0)
+            return false;
+        if (__start_ != 0)
+            return false;
+    }
+    return true;
+}
+
+template <class _Tp, class _Allocator>
+typename __deque_base<_Tp, _Allocator>::iterator
+__deque_base<_Tp, _Allocator>::begin() _NOEXCEPT
+{
+    __map_pointer __mp = __map_.begin() + __start_ / __block_size;
+    return iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
+}
+
+template <class _Tp, class _Allocator>
+typename __deque_base<_Tp, _Allocator>::const_iterator
+__deque_base<_Tp, _Allocator>::begin() const _NOEXCEPT
+{
+    __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __start_ / __block_size);
+    return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
+}
+
+template <class _Tp, class _Allocator>
+typename __deque_base<_Tp, _Allocator>::iterator
+__deque_base<_Tp, _Allocator>::end() _NOEXCEPT
+{
+    size_type __p = size() + __start_;
+    __map_pointer __mp = __map_.begin() + __p / __block_size;
+    return iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
+}
+
+template <class _Tp, class _Allocator>
+typename __deque_base<_Tp, _Allocator>::const_iterator
+__deque_base<_Tp, _Allocator>::end() const _NOEXCEPT
+{
+    size_type __p = size() + __start_;
+    __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __p / __block_size);
+    return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+__deque_base<_Tp, _Allocator>::__deque_base()
+    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
+    : __start_(0), __size_(0) {}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+__deque_base<_Tp, _Allocator>::__deque_base(const allocator_type& __a)
+    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {}
+
+template <class _Tp, class _Allocator>
+__deque_base<_Tp, _Allocator>::~__deque_base()
+{
+    clear();
+    typename __map::iterator __i = __map_.begin();
+    typename __map::iterator __e = __map_.end();
+    for (; __i != __e; ++__i)
+        __alloc_traits::deallocate(__alloc(), *__i, __block_size);
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+__deque_base<_Tp, _Allocator>::__deque_base(__deque_base&& __c)
+    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
+    : __map_(_VSTD::move(__c.__map_)),
+      __start_(_VSTD::move(__c.__start_)),
+      __size_(_VSTD::move(__c.__size_))
+{
+    __c.__start_ = 0;
+    __c.size() = 0;
+}
+
+template <class _Tp, class _Allocator>
+__deque_base<_Tp, _Allocator>::__deque_base(__deque_base&& __c, const allocator_type& __a)
+    : __map_(_VSTD::move(__c.__map_), __pointer_allocator(__a)),
+      __start_(_VSTD::move(__c.__start_)),
+      __size_(_VSTD::move(__c.size()), __a)
+{
+    if (__a == __c.__alloc())
+    {
+        __c.__start_ = 0;
+        __c.size() = 0;
+    }
+    else
+    {
+        __map_.clear();
+        __start_ = 0;
+        size() = 0;
+    }
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+void
+__deque_base<_Tp, _Allocator>::swap(__deque_base& __c)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value||
+                   __is_nothrow_swappable<allocator_type>::value)
+{
+    __map_.swap(__c.__map_);
+    _VSTD::swap(__start_, __c.__start_);
+    _VSTD::swap(size(), __c.size());
+    __swap_alloc(__alloc(), __c.__alloc());
+}
+
+template <class _Tp, class _Allocator>
+void
+__deque_base<_Tp, _Allocator>::clear() _NOEXCEPT
+{
+    allocator_type& __a = __alloc();
+    for (iterator __i = begin(), __e = end(); __i != __e; ++__i)
+        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
+    size() = 0;
+    while (__map_.size() > 2)
+    {
+        __alloc_traits::deallocate(__a, __map_.front(), __block_size);
+        __map_.pop_front();
+    }
+    switch (__map_.size())
+    {
+    case 1:
+        __start_ = __block_size / 2;
+        break;
+    case 2:
+        __start_ = __block_size;
+        break;
+    }
+}
+
+template <class _Tp, class _Allocator = allocator<_Tp> >
+class _LIBCPP_TYPE_VIS_ONLY deque
+    : private __deque_base<_Tp, _Allocator>
+{
+public:
+    // types:
+
+    typedef _Tp value_type;
+    typedef _Allocator allocator_type;
+
+    typedef __deque_base<value_type, allocator_type> __base;
+
+    typedef typename __base::__alloc_traits        __alloc_traits;
+    typedef typename __base::reference             reference;
+    typedef typename __base::const_reference       const_reference;
+    typedef typename __base::iterator              iterator;
+    typedef typename __base::const_iterator        const_iterator;
+    typedef typename __base::size_type             size_type;
+    typedef typename __base::difference_type       difference_type;
+
+    typedef typename __base::pointer               pointer;
+    typedef typename __base::const_pointer         const_pointer;
+    typedef _VSTD::reverse_iterator<iterator>       reverse_iterator;
+    typedef _VSTD::reverse_iterator<const_iterator> const_reverse_iterator;
+
+    // construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY
+    deque()
+        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
+        {}
+    _LIBCPP_INLINE_VISIBILITY deque(const allocator_type& __a) : __base(__a) {}
+    explicit deque(size_type __n);
+#if _LIBCPP_STD_VER > 11
+    explicit deque(size_type __n, const _Allocator& __a);
+#endif
+    deque(size_type __n, const value_type& __v);
+    deque(size_type __n, const value_type& __v, const allocator_type& __a);
+    template <class _InputIter>
+        deque(_InputIter __f, _InputIter __l,
+              typename enable_if<__is_input_iterator<_InputIter>::value>::type* = 0);
+    template <class _InputIter>
+        deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
+              typename enable_if<__is_input_iterator<_InputIter>::value>::type* = 0);
+    deque(const deque& __c);
+    deque(const deque& __c, const allocator_type& __a);
+#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+    deque(initializer_list<value_type> __il);
+    deque(initializer_list<value_type> __il, const allocator_type& __a);
+#endif  // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+
+    deque& operator=(const deque& __c);
+#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+    _LIBCPP_INLINE_VISIBILITY
+    deque& operator=(initializer_list<value_type> __il) {assign(__il); return *this;}
+#endif   // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__base>::value);
+    deque(deque&& __c, const allocator_type& __a);
+    deque& operator=(deque&& __c)
+        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
+                   is_nothrow_move_assignable<allocator_type>::value);
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+    template <class _InputIter>
+        void assign(_InputIter __f, _InputIter __l,
+                    typename enable_if<__is_input_iterator<_InputIter>::value &&
+                                      !__is_random_access_iterator<_InputIter>::value>::type* = 0);
+    template <class _RAIter>
+        void assign(_RAIter __f, _RAIter __l,
+                    typename enable_if<__is_random_access_iterator<_RAIter>::value>::type* = 0);
+    void assign(size_type __n, const value_type& __v);
+#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+    _LIBCPP_INLINE_VISIBILITY
+    void assign(initializer_list<value_type> __il) {assign(__il.begin(), __il.end());}
+#endif  // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+
+    allocator_type get_allocator() const _NOEXCEPT;
+
+    // iterators:
+
+    _LIBCPP_INLINE_VISIBILITY
+    iterator       begin() _NOEXCEPT       {return __base::begin();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator begin() const _NOEXCEPT {return __base::begin();}
+    _LIBCPP_INLINE_VISIBILITY
+    iterator       end() _NOEXCEPT         {return __base::end();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator end()   const _NOEXCEPT {return __base::end();}
+
+    _LIBCPP_INLINE_VISIBILITY
+    reverse_iterator       rbegin() _NOEXCEPT
+        {return       reverse_iterator(__base::end());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator rbegin() const _NOEXCEPT
+        {return const_reverse_iterator(__base::end());}
+    _LIBCPP_INLINE_VISIBILITY
+    reverse_iterator       rend() _NOEXCEPT
+        {return       reverse_iterator(__base::begin());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator rend()   const _NOEXCEPT
+        {return const_reverse_iterator(__base::begin());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator         cbegin()  const _NOEXCEPT
+        {return __base::begin();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator         cend()    const _NOEXCEPT
+        {return __base::end();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator crbegin() const _NOEXCEPT
+        {return const_reverse_iterator(__base::end());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator crend()   const _NOEXCEPT
+        {return const_reverse_iterator(__base::begin());}
+
+    // capacity:
+    _LIBCPP_INLINE_VISIBILITY
+    size_type size() const _NOEXCEPT {return __base::size();}
+    _LIBCPP_INLINE_VISIBILITY
+    size_type max_size() const _NOEXCEPT
+        {return __alloc_traits::max_size(__base::__alloc());}
+    void resize(size_type __n);
+    void resize(size_type __n, const value_type& __v);
+    void shrink_to_fit() _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    bool empty() const _NOEXCEPT {return __base::size() == 0;}
+
+    // element access:
+    reference operator[](size_type __i);
+    const_reference operator[](size_type __i) const;
+    reference at(size_type __i);
+    const_reference at(size_type __i) const;
+    reference front();
+    const_reference front() const;
+    reference back();
+    const_reference back() const;
+
+    // 23.2.2.3 modifiers:
+    void push_front(const value_type& __v);
+    void push_back(const value_type& __v);
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+    template <class... _Args> void emplace_front(_Args&&... __args);
+    template <class... _Args> void emplace_back(_Args&&... __args);
+    template <class... _Args> iterator emplace(const_iterator __p, _Args&&... __args);
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+    void push_front(value_type&& __v);
+    void push_back(value_type&& __v);
+    iterator insert(const_iterator __p, value_type&& __v);
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    iterator insert(const_iterator __p, const value_type& __v);
+    iterator insert(const_iterator __p, size_type __n, const value_type& __v);
+    template <class _InputIter>
+        iterator insert (const_iterator __p, _InputIter __f, _InputIter __l,
+                         typename enable_if<__is_input_iterator<_InputIter>::value
+                                         &&!__is_bidirectional_iterator<_InputIter>::value>::type* = 0);
+    template <class _BiIter>
+        iterator insert (const_iterator __p, _BiIter __f, _BiIter __l,
+                         typename enable_if<__is_bidirectional_iterator<_BiIter>::value>::type* = 0);
+#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+    _LIBCPP_INLINE_VISIBILITY
+    iterator insert(const_iterator __p, initializer_list<value_type> __il)
+        {return insert(__p, __il.begin(), __il.end());}
+#endif  // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+    void pop_front();
+    void pop_back();
+    iterator erase(const_iterator __p);
+    iterator erase(const_iterator __f, const_iterator __l);
+
+    void swap(deque& __c)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
+                   __is_nothrow_swappable<allocator_type>::value);
+    void clear() _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    bool __invariants() const {return __base::__invariants();}
+private:
+    typedef typename __base::__map_const_pointer __map_const_pointer;
+
+    _LIBCPP_INLINE_VISIBILITY
+    static size_type __recommend_blocks(size_type __n)
+    {
+        return __n / __base::__block_size + (__n % __base::__block_size != 0);
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __capacity() const
+    {
+        return __base::__map_.size() == 0 ? 0 : __base::__map_.size() * __base::__block_size - 1;
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __front_spare() const
+    {
+        return __base::__start_;
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __back_spare() const
+    {
+        return __capacity() - (__base::__start_ + __base::size());
+    }
+
+    template <class _InpIter>
+        void __append(_InpIter __f, _InpIter __l,
+                 typename enable_if<__is_input_iterator<_InpIter>::value &&
+                                   !__is_forward_iterator<_InpIter>::value>::type* = 0);
+    template <class _ForIter>
+        void __append(_ForIter __f, _ForIter __l,
+                      typename enable_if<__is_forward_iterator<_ForIter>::value>::type* = 0);
+    void __append(size_type __n);
+    void __append(size_type __n, const value_type& __v);
+    void __erase_to_end(const_iterator __f);
+    void __add_front_capacity();
+    void __add_front_capacity(size_type __n);
+    void __add_back_capacity();
+    void __add_back_capacity(size_type __n);
+    iterator __move_and_check(iterator __f, iterator __l, iterator __r,
+                              const_pointer& __vt);
+    iterator __move_backward_and_check(iterator __f, iterator __l, iterator __r,
+                                       const_pointer& __vt);
+    void __move_construct_and_check(iterator __f, iterator __l,
+                                    iterator __r, const_pointer& __vt);
+    void __move_construct_backward_and_check(iterator __f, iterator __l,
+                                             iterator __r, const_pointer& __vt);
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const deque& __c)
+        {__copy_assign_alloc(__c, integral_constant<bool,
+                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const deque& __c, true_type)
+        {
+            if (__base::__alloc() != __c.__alloc())
+            {
+                clear();
+                shrink_to_fit();
+            }
+            __base::__alloc() = __c.__alloc();
+            __base::__map_.__alloc() = __c.__map_.__alloc();
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const deque&, false_type)
+        {}
+
+    void __move_assign(deque& __c, true_type)
+        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
+    void __move_assign(deque& __c, false_type);
+};
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(size_type __n)
+{
+    if (__n > 0)
+        __append(__n);
+}
+
+#if _LIBCPP_STD_VER > 11
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(size_type __n, const _Allocator& __a)
+    : __base(__a)
+{
+    if (__n > 0)
+        __append(__n);
+}
+#endif
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v)
+{
+    if (__n > 0)
+        __append(__n, __v);
+}
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v, const allocator_type& __a)
+    : __base(__a)
+{
+    if (__n > 0)
+        __append(__n, __v);
+}
+
+template <class _Tp, class _Allocator>
+template <class _InputIter>
+deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l,
+              typename enable_if<__is_input_iterator<_InputIter>::value>::type*)
+{
+    __append(__f, __l);
+}
+
+template <class _Tp, class _Allocator>
+template <class _InputIter>
+deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
+              typename enable_if<__is_input_iterator<_InputIter>::value>::type*)
+    : __base(__a)
+{
+    __append(__f, __l);
+}
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(const deque& __c)
+    : __base(__alloc_traits::select_on_container_copy_construction(__c.__alloc()))
+{
+    __append(__c.begin(), __c.end());
+}
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(const deque& __c, const allocator_type& __a)
+    : __base(__a)
+{
+    __append(__c.begin(), __c.end());
+}
+
+#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il)
+{
+    __append(__il.begin(), __il.end());
+}
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il, const allocator_type& __a)
+    : __base(__a)
+{
+    __append(__il.begin(), __il.end());
+}
+
+#endif  // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
+
+template <class _Tp, class _Allocator>
+deque<_Tp, _Allocator>&
+deque<_Tp, _Allocator>::operator=(const deque& __c)
+{
+    if (this != &__c)
+    {
+        __copy_assign_alloc(__c);
+        assign(__c.begin(), __c.end());
+    }
+    return *this;
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+deque<_Tp, _Allocator>::deque(deque&& __c)
+    _NOEXCEPT_(is_nothrow_move_constructible<__base>::value)
+    : __base(_VSTD::move(__c))
+{
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+deque<_Tp, _Allocator>::deque(deque&& __c, const allocator_type& __a)
+    : __base(_VSTD::move(__c), __a)
+{
+    if (__a != __c.__alloc())
+    {
+        typedef move_iterator<iterator> _Ip;
+        assign(_Ip(__c.begin()), _Ip(__c.end()));
+    }
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+deque<_Tp, _Allocator>&
+deque<_Tp, _Allocator>::operator=(deque&& __c)
+        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
+                   is_nothrow_move_assignable<allocator_type>::value)
+{
+    __move_assign(__c, integral_constant<bool,
+          __alloc_traits::propagate_on_container_move_assignment::value>());
+    return *this;
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__move_assign(deque& __c, false_type)
+{
+    if (__base::__alloc() != __c.__alloc())
+    {
+        typedef move_iterator<iterator> _Ip;
+        assign(_Ip(__c.begin()), _Ip(__c.end()));
+    }
+    else
+        __move_assign(__c, true_type());
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__move_assign(deque& __c, true_type)
+    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
+{
+    clear();
+    shrink_to_fit();
+    __base::__move_assign(__c);
+}
+
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+template <class _InputIter>
+void
+deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l,
+                               typename enable_if<__is_input_iterator<_InputIter>::value &&
+                                                 !__is_random_access_iterator<_InputIter>::value>::type*)
+{
+    iterator __i = __base::begin();
+    iterator __e = __base::end();
+    for (; __f != __l && __i != __e; ++__f, ++__i)
+        *__i = *__f;
+    if (__f != __l)
+        __append(__f, __l);
+    else
+        __erase_to_end(__i);
+}
+
+template <class _Tp, class _Allocator>
+template <class _RAIter>
+void
+deque<_Tp, _Allocator>::assign(_RAIter __f, _RAIter __l,
+                               typename enable_if<__is_random_access_iterator<_RAIter>::value>::type*)
+{
+    if (static_cast<size_type>(__l - __f) > __base::size())
+    {
+        _RAIter __m = __f + __base::size();
+        _VSTD::copy(__f, __m, __base::begin());
+        __append(__m, __l);
+    }
+    else
+        __erase_to_end(_VSTD::copy(__f, __l, __base::begin()));
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::assign(size_type __n, const value_type& __v)
+{
+    if (__n > __base::size())
+    {
+        _VSTD::fill_n(__base::begin(), __base::size(), __v);
+        __n -= __base::size();
+        __append(__n, __v);
+    }
+    else
+        __erase_to_end(_VSTD::fill_n(__base::begin(), __n, __v));
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+_Allocator
+deque<_Tp, _Allocator>::get_allocator() const _NOEXCEPT
+{
+    return __base::__alloc();
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::resize(size_type __n)
+{
+    if (__n > __base::size())
+        __append(__n - __base::size());
+    else if (__n < __base::size())
+        __erase_to_end(__base::begin() + __n);
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::resize(size_type __n, const value_type& __v)
+{
+    if (__n > __base::size())
+        __append(__n - __base::size(), __v);
+    else if (__n < __base::size())
+        __erase_to_end(__base::begin() + __n);
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
+{
+    allocator_type& __a = __base::__alloc();
+    if (empty())
+    {
+        while (__base::__map_.size() > 0)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+            __base::__map_.pop_back();
+        }
+        __base::__start_ = 0;
+    }
+    else
+    {
+        if (__front_spare() >= __base::__block_size)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.front(), __base::__block_size);
+            __base::__map_.pop_front();
+            __base::__start_ -= __base::__block_size;
+        }
+        if (__back_spare() >= __base::__block_size)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+            __base::__map_.pop_back();
+        }
+    }
+    __base::__map_.shrink_to_fit();
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::reference
+deque<_Tp, _Allocator>::operator[](size_type __i)
+{
+    size_type __p = __base::__start_ + __i;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::const_reference
+deque<_Tp, _Allocator>::operator[](size_type __i) const
+{
+    size_type __p = __base::__start_ + __i;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::reference
+deque<_Tp, _Allocator>::at(size_type __i)
+{
+    if (__i >= __base::size())
+        __base::__throw_out_of_range();
+    size_type __p = __base::__start_ + __i;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::const_reference
+deque<_Tp, _Allocator>::at(size_type __i) const
+{
+    if (__i >= __base::size())
+        __base::__throw_out_of_range();
+    size_type __p = __base::__start_ + __i;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::reference
+deque<_Tp, _Allocator>::front()
+{
+    return *(*(__base::__map_.begin() + __base::__start_ / __base::__block_size)
+                                      + __base::__start_ % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::const_reference
+deque<_Tp, _Allocator>::front() const
+{
+    return *(*(__base::__map_.begin() + __base::__start_ / __base::__block_size)
+                                      + __base::__start_ % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::reference
+deque<_Tp, _Allocator>::back()
+{
+    size_type __p = __base::size() + __base::__start_ - 1;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename deque<_Tp, _Allocator>::const_reference
+deque<_Tp, _Allocator>::back() const
+{
+    size_type __p = __base::size() + __base::__start_ - 1;
+    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::push_back(const value_type& __v)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__back_spare() == 0)
+        __add_back_capacity();
+    // __back_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), __v);
+    ++__base::size();
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::push_back(value_type&& __v)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__back_spare() == 0)
+        __add_back_capacity();
+    // __back_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::move(__v));
+    ++__base::size();
+}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Tp, class _Allocator>
+template <class... _Args>
+void
+deque<_Tp, _Allocator>::emplace_back(_Args&&... __args)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__back_spare() == 0)
+        __add_back_capacity();
+    // __back_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::forward<_Args>(__args)...);
+    ++__base::size();
+}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::push_front(const value_type& __v)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__front_spare() == 0)
+        __add_front_capacity();
+    // __front_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), __v);
+    --__base::__start_;
+    ++__base::size();
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::push_front(value_type&& __v)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__front_spare() == 0)
+        __add_front_capacity();
+    // __front_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::move(__v));
+    --__base::__start_;
+    ++__base::size();
+}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Tp, class _Allocator>
+template <class... _Args>
+void
+deque<_Tp, _Allocator>::emplace_front(_Args&&... __args)
+{
+    allocator_type& __a = __base::__alloc();
+    if (__front_spare() == 0)
+        __add_front_capacity();
+    // __front_spare() >= 1
+    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::forward<_Args>(__args)...);
+    --__base::__start_;
+    ++__base::size();
+}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::insert(const_iterator __p, const value_type& __v)
+{
+    size_type __pos = __p - __base::begin();
+    size_type __to_end = __base::size() - __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < __to_end)
+    {   // insert by shifting things backward
+        if (__front_spare() == 0)
+            __add_front_capacity();
+        // __front_spare() >= 1
+        if (__pos == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), __v);
+            --__base::__start_;
+            ++__base::size();
+        }
+        else
+        {
+            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
+            iterator __b = __base::begin();
+            iterator __bm1 = _VSTD::prev(__b);
+            if (__vt == pointer_traits<const_pointer>::pointer_to(*__b))
+                __vt = pointer_traits<const_pointer>::pointer_to(*__bm1);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
+            --__base::__start_;
+            ++__base::size();
+            if (__pos > 1)
+                __b = __move_and_check(_VSTD::next(__b), __b + __pos, __b, __vt);
+            *__b = *__vt;
+        }
+    }
+    else
+    {   // insert by shifting things forward
+        if (__back_spare() == 0)
+            __add_back_capacity();
+        // __back_capacity >= 1
+        size_type __de = __base::size() - __pos;
+        if (__de == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), __v);
+            ++__base::size();
+        }
+        else
+        {
+            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
+            iterator __e = __base::end();
+            iterator __em1 = _VSTD::prev(__e);
+            if (__vt == pointer_traits<const_pointer>::pointer_to(*__em1))
+                __vt = pointer_traits<const_pointer>::pointer_to(*__e);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
+            ++__base::size();
+            if (__de > 1)
+                __e = __move_backward_and_check(__e - __de, __em1, __e, __vt);
+            *--__e = *__vt;
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::insert(const_iterator __p, value_type&& __v)
+{
+    size_type __pos = __p - __base::begin();
+    size_type __to_end = __base::size() - __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < __to_end)
+    {   // insert by shifting things backward
+        if (__front_spare() == 0)
+            __add_front_capacity();
+        // __front_spare() >= 1
+        if (__pos == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::move(__v));
+            --__base::__start_;
+            ++__base::size();
+        }
+        else
+        {
+            iterator __b = __base::begin();
+            iterator __bm1 = _VSTD::prev(__b);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
+            --__base::__start_;
+            ++__base::size();
+            if (__pos > 1)
+                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
+            *__b = _VSTD::move(__v);
+        }
+    }
+    else
+    {   // insert by shifting things forward
+        if (__back_spare() == 0)
+            __add_back_capacity();
+        // __back_capacity >= 1
+        size_type __de = __base::size() - __pos;
+        if (__de == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::move(__v));
+            ++__base::size();
+        }
+        else
+        {
+            iterator __e = __base::end();
+            iterator __em1 = _VSTD::prev(__e);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
+            ++__base::size();
+            if (__de > 1)
+                __e = _VSTD::move_backward(__e - __de, __em1, __e);
+            *--__e = _VSTD::move(__v);
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+template <class _Tp, class _Allocator>
+template <class... _Args>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::emplace(const_iterator __p, _Args&&... __args)
+{
+    size_type __pos = __p - __base::begin();
+    size_type __to_end = __base::size() - __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < __to_end)
+    {   // insert by shifting things backward
+        if (__front_spare() == 0)
+            __add_front_capacity();
+        // __front_spare() >= 1
+        if (__pos == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::forward<_Args>(__args)...);
+            --__base::__start_;
+            ++__base::size();
+        }
+        else
+        {
+            value_type __tmp(_VSTD::forward<_Args>(__args)...);
+            iterator __b = __base::begin();
+            iterator __bm1 = _VSTD::prev(__b);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
+            --__base::__start_;
+            ++__base::size();
+            if (__pos > 1)
+                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
+            *__b = _VSTD::move(__tmp);
+        }
+    }
+    else
+    {   // insert by shifting things forward
+        if (__back_spare() == 0)
+            __add_back_capacity();
+        // __back_capacity >= 1
+        size_type __de = __base::size() - __pos;
+        if (__de == 0)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::forward<_Args>(__args)...);
+            ++__base::size();
+        }
+        else
+        {
+            value_type __tmp(_VSTD::forward<_Args>(__args)...);
+            iterator __e = __base::end();
+            iterator __em1 = _VSTD::prev(__e);
+            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
+            ++__base::size();
+            if (__de > 1)
+                __e = _VSTD::move_backward(__e - __de, __em1, __e);
+            *--__e = _VSTD::move(__tmp);
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+#endif  // _LIBCPP_HAS_NO_VARIADICS
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::insert(const_iterator __p, size_type __n, const value_type& __v)
+{
+    size_type __pos = __p - __base::begin();
+    size_type __to_end = __base::size() - __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < __to_end)
+    {   // insert by shifting things backward
+        if (__n > __front_spare())
+            __add_front_capacity(__n - __front_spare());
+        // __n <= __front_spare()
+        size_type __old_n = __n;
+        iterator __old_begin = __base::begin();
+        iterator __i = __old_begin;
+        if (__n > __pos)
+        {
+            for (size_type __m = __n - __pos; __m; --__m, --__base::__start_, ++__base::size())
+                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), __v);
+            __n = __pos;
+        }
+        if (__n > 0)
+        {
+            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
+            iterator __obn = __old_begin + __n;
+            __move_construct_backward_and_check(__old_begin, __obn, __i, __vt);
+            if (__n < __pos)
+                __old_begin = __move_and_check(__obn, __old_begin + __pos, __old_begin, __vt);
+            _VSTD::fill_n(__old_begin, __n, *__vt);
+        }
+    }
+    else
+    {   // insert by shifting things forward
+        size_type __back_capacity = __back_spare();
+        if (__n > __back_capacity)
+            __add_back_capacity(__n - __back_capacity);
+        // __n <= __back_capacity
+        size_type __old_n = __n;
+        iterator __old_end = __base::end();
+        iterator __i = __old_end;
+        size_type __de = __base::size() - __pos;
+        if (__n > __de)
+        {
+            for (size_type __m = __n - __de; __m; --__m, ++__i, ++__base::size())
+                __alloc_traits::construct(__a, _VSTD::addressof(*__i), __v);
+            __n = __de;
+        }
+        if (__n > 0)
+        {
+            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
+            iterator __oen = __old_end - __n;
+            __move_construct_and_check(__oen, __old_end, __i, __vt);
+            if (__n < __de)
+                __old_end = __move_backward_and_check(__old_end - __de, __oen, __old_end, __vt);
+            _VSTD::fill_n(__old_end - __n, __n, *__vt);
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+template <class _Tp, class _Allocator>
+template <class _InputIter>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::insert(const_iterator __p, _InputIter __f, _InputIter __l,
+                               typename enable_if<__is_input_iterator<_InputIter>::value
+                                               &&!__is_bidirectional_iterator<_InputIter>::value>::type*)
+{
+    __split_buffer<value_type, allocator_type&> __buf(__base::__alloc());
+    __buf.__construct_at_end(__f, __l);
+    typedef typename __split_buffer<value_type, allocator_type&>::iterator __bi;
+    return insert(__p, move_iterator<__bi>(__buf.begin()), move_iterator<__bi>(__buf.end()));
+}
+
+template <class _Tp, class _Allocator>
+template <class _BiIter>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::insert(const_iterator __p, _BiIter __f, _BiIter __l,
+                               typename enable_if<__is_bidirectional_iterator<_BiIter>::value>::type*)
+{
+    size_type __n = _VSTD::distance(__f, __l);
+    size_type __pos = __p - __base::begin();
+    size_type __to_end = __base::size() - __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < __to_end)
+    {   // insert by shifting things backward
+        if (__n > __front_spare())
+            __add_front_capacity(__n - __front_spare());
+        // __n <= __front_spare()
+        size_type __old_n = __n;
+        iterator __old_begin = __base::begin();
+        iterator __i = __old_begin;
+        _BiIter __m = __f;
+        if (__n > __pos)
+        {
+            __m = __pos < __n / 2 ? _VSTD::prev(__l, __pos) : _VSTD::next(__f, __n - __pos);
+            for (_BiIter __j = __m; __j != __f; --__base::__start_, ++__base::size())
+                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), *--__j);
+            __n = __pos;
+        }
+        if (__n > 0)
+        {
+            iterator __obn = __old_begin + __n;
+            for (iterator __j = __obn; __j != __old_begin;)
+            {
+                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), _VSTD::move(*--__j));
+                --__base::__start_;
+                ++__base::size();
+            }
+            if (__n < __pos)
+                __old_begin = _VSTD::move(__obn, __old_begin + __pos, __old_begin);
+            _VSTD::copy(__m, __l, __old_begin);
+        }
+    }
+    else
+    {   // insert by shifting things forward
+        size_type __back_capacity = __back_spare();
+        if (__n > __back_capacity)
+            __add_back_capacity(__n - __back_capacity);
+        // __n <= __back_capacity
+        size_type __old_n = __n;
+        iterator __old_end = __base::end();
+        iterator __i = __old_end;
+        _BiIter __m = __l;
+        size_type __de = __base::size() - __pos;
+        if (__n > __de)
+        {
+            __m = __de < __n / 2 ? _VSTD::next(__f, __de) : _VSTD::prev(__l, __n - __de);
+            for (_BiIter __j = __m; __j != __l; ++__i, ++__j, ++__base::size())
+                __alloc_traits::construct(__a, _VSTD::addressof(*__i), *__j);
+            __n = __de;
+        }
+        if (__n > 0)
+        {
+            iterator __oen = __old_end - __n;
+            for (iterator __j = __oen; __j != __old_end; ++__i, ++__j, ++__base::size())
+                __alloc_traits::construct(__a, _VSTD::addressof(*__i), _VSTD::move(*__j));
+            if (__n < __de)
+                __old_end = _VSTD::move_backward(__old_end - __de, __oen, __old_end);
+            _VSTD::copy_backward(__f, __m, __old_end);
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+template <class _Tp, class _Allocator>
+template <class _InpIter>
+void
+deque<_Tp, _Allocator>::__append(_InpIter __f, _InpIter __l,
+                                 typename enable_if<__is_input_iterator<_InpIter>::value &&
+                                                   !__is_forward_iterator<_InpIter>::value>::type*)
+{
+    for (; __f != __l; ++__f)
+        push_back(*__f);
+}
+
+template <class _Tp, class _Allocator>
+template <class _ForIter>
+void
+deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l,
+                                 typename enable_if<__is_forward_iterator<_ForIter>::value>::type*)
+{
+    size_type __n = _VSTD::distance(__f, __l);
+    allocator_type& __a = __base::__alloc();
+    size_type __back_capacity = __back_spare();
+    if (__n > __back_capacity)
+        __add_back_capacity(__n - __back_capacity);
+    // __n <= __back_capacity
+    for (iterator __i = __base::end(); __f != __l; ++__i, ++__f, ++__base::size())
+        __alloc_traits::construct(__a, _VSTD::addressof(*__i), *__f);
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__append(size_type __n)
+{
+    allocator_type& __a = __base::__alloc();
+    size_type __back_capacity = __back_spare();
+    if (__n > __back_capacity)
+        __add_back_capacity(__n - __back_capacity);
+    // __n <= __back_capacity
+    for (iterator __i = __base::end(); __n; --__n, ++__i, ++__base::size())
+        __alloc_traits::construct(__a, _VSTD::addressof(*__i));
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__append(size_type __n, const value_type& __v)
+{
+    allocator_type& __a = __base::__alloc();
+    size_type __back_capacity = __back_spare();
+    if (__n > __back_capacity)
+        __add_back_capacity(__n - __back_capacity);
+    // __n <= __back_capacity
+    for (iterator __i = __base::end(); __n; --__n, ++__i, ++__base::size())
+        __alloc_traits::construct(__a, _VSTD::addressof(*__i), __v);
+}
+
+// Create front capacity for one block of elements.
+// Strong guarantee.  Either do it or don't touch anything.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__add_front_capacity()
+{
+    allocator_type& __a = __base::__alloc();
+    if (__back_spare() >= __base::__block_size)
+    {
+        __base::__start_ += __base::__block_size;
+        pointer __pt = __base::__map_.back();
+        __base::__map_.pop_back();
+        __base::__map_.push_front(__pt);
+    }
+    // Else if __base::__map_.size() < __base::__map_.capacity() then we need to allocate 1 buffer
+    else if (__base::__map_.size() < __base::__map_.capacity())
+    {   // we can put the new buffer into the map, but don't shift things around
+        // until all buffers are allocated.  If we throw, we don't need to fix
+        // anything up (any added buffers are undetectible)
+        if (__base::__map_.__front_spare() > 0)
+            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
+        else
+        {
+            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+            // Done allocating, reorder capacity
+            pointer __pt = __base::__map_.back();
+            __base::__map_.pop_back();
+            __base::__map_.push_front(__pt);
+        }
+        __base::__start_ = __base::__map_.size() == 1 ?
+                               __base::__block_size / 2 :
+                               __base::__start_ + __base::__block_size;
+    }
+    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
+    else
+    {
+        __split_buffer<pointer, typename __base::__pointer_allocator&>
+            __buf(max<size_type>(2 * __base::__map_.capacity(), 1),
+                  0, __base::__map_.__alloc());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __alloc_traits::deallocate(__a, __buf.front(), __base::__block_size);
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        for (typename __base::__map_pointer __i = __base::__map_.begin();
+                __i != __base::__map_.end(); ++__i)
+            __buf.push_back(*__i);
+        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
+        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
+        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
+        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
+        __base::__start_ = __base::__map_.size() == 1 ?
+                               __base::__block_size / 2 :
+                               __base::__start_ + __base::__block_size;
+    }
+}
+
+// Create front capacity for __n elements.
+// Strong guarantee.  Either do it or don't touch anything.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__add_front_capacity(size_type __n)
+{
+    allocator_type& __a = __base::__alloc();
+    size_type __nb = __recommend_blocks(__n + __base::__map_.empty());
+    // Number of unused blocks at back:
+    size_type __back_capacity = __back_spare() / __base::__block_size;
+    __back_capacity = _VSTD::min(__back_capacity, __nb);  // don't take more than you need
+    __nb -= __back_capacity;  // number of blocks need to allocate
+    // If __nb == 0, then we have sufficient capacity.
+    if (__nb == 0)
+    {
+        __base::__start_ += __base::__block_size * __back_capacity;
+        for (; __back_capacity > 0; --__back_capacity)
+        {
+            pointer __pt = __base::__map_.back();
+            __base::__map_.pop_back();
+            __base::__map_.push_front(__pt);
+        }
+    }
+    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
+    else if (__nb <= __base::__map_.capacity() - __base::__map_.size())
+    {   // we can put the new buffers into the map, but don't shift things around
+        // until all buffers are allocated.  If we throw, we don't need to fix
+        // anything up (any added buffers are undetectible)
+        for (; __nb > 0; --__nb, __base::__start_ += __base::__block_size - (__base::__map_.size() == 1))
+        {
+            if (__base::__map_.__front_spare() == 0)
+                break;
+            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
+        }
+        for (; __nb > 0; --__nb, ++__back_capacity)
+            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+        // Done allocating, reorder capacity
+        __base::__start_ += __back_capacity * __base::__block_size;
+        for (; __back_capacity > 0; --__back_capacity)
+        {
+            pointer __pt = __base::__map_.back();
+            __base::__map_.pop_back();
+            __base::__map_.push_front(__pt);
+        }
+    }
+    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
+    else
+    {
+        size_type __ds = (__nb + __back_capacity) * __base::__block_size - __base::__map_.empty();
+        __split_buffer<pointer, typename __base::__pointer_allocator&>
+            __buf(max<size_type>(2* __base::__map_.capacity(),
+                                 __nb + __base::__map_.size()),
+                  0, __base::__map_.__alloc());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            for (; __nb > 0; --__nb)
+                __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            for (typename __base::__map_pointer __i = __buf.begin();
+                    __i != __buf.end(); ++__i)
+                __alloc_traits::deallocate(__a, *__i, __base::__block_size);
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        for (; __back_capacity > 0; --__back_capacity)
+        {
+            __buf.push_back(__base::__map_.back());
+            __base::__map_.pop_back();
+        }
+        for (typename __base::__map_pointer __i = __base::__map_.begin();
+                __i != __base::__map_.end(); ++__i)
+            __buf.push_back(*__i);
+        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
+        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
+        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
+        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
+        __base::__start_ += __ds;
+    }
+}
+
+// Create back capacity for one block of elements.
+// Strong guarantee.  Either do it or don't touch anything.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__add_back_capacity()
+{
+    allocator_type& __a = __base::__alloc();
+    if (__front_spare() >= __base::__block_size)
+    {
+        __base::__start_ -= __base::__block_size;
+        pointer __pt = __base::__map_.front();
+        __base::__map_.pop_front();
+        __base::__map_.push_back(__pt);
+    }
+    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
+    else if (__base::__map_.size() < __base::__map_.capacity())
+    {   // we can put the new buffer into the map, but don't shift things around
+        // until it is allocated.  If we throw, we don't need to fix
+        // anything up (any added buffers are undetectible)
+        if (__base::__map_.__back_spare() != 0)
+            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+        else
+        {
+            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
+            // Done allocating, reorder capacity
+            pointer __pt = __base::__map_.front();
+            __base::__map_.pop_front();
+            __base::__map_.push_back(__pt);
+        }
+    }
+    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
+    else
+    {
+        __split_buffer<pointer, typename __base::__pointer_allocator&>
+            __buf(max<size_type>(2* __base::__map_.capacity(), 1),
+                  __base::__map_.size(),
+                  __base::__map_.__alloc());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __alloc_traits::deallocate(__a, __buf.back(), __base::__block_size);
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        for (typename __base::__map_pointer __i = __base::__map_.end();
+                __i != __base::__map_.begin();)
+            __buf.push_front(*--__i);
+        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
+        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
+        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
+        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
+    }
+}
+
+// Create back capacity for __n elements.
+// Strong guarantee.  Either do it or don't touch anything.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__add_back_capacity(size_type __n)
+{
+    allocator_type& __a = __base::__alloc();
+    size_type __nb = __recommend_blocks(__n + __base::__map_.empty());
+    // Number of unused blocks at front:
+    size_type __front_capacity = __front_spare() / __base::__block_size;
+    __front_capacity = _VSTD::min(__front_capacity, __nb);  // don't take more than you need
+    __nb -= __front_capacity;  // number of blocks need to allocate
+    // If __nb == 0, then we have sufficient capacity.
+    if (__nb == 0)
+    {
+        __base::__start_ -= __base::__block_size * __front_capacity;
+        for (; __front_capacity > 0; --__front_capacity)
+        {
+            pointer __pt = __base::__map_.front();
+            __base::__map_.pop_front();
+            __base::__map_.push_back(__pt);
+        }
+    }
+    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
+    else if (__nb <= __base::__map_.capacity() - __base::__map_.size())
+    {   // we can put the new buffers into the map, but don't shift things around
+        // until all buffers are allocated.  If we throw, we don't need to fix
+        // anything up (any added buffers are undetectible)
+        for (; __nb > 0; --__nb)
+        {
+            if (__base::__map_.__back_spare() == 0)
+                break;
+            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+        }
+        for (; __nb > 0; --__nb, ++__front_capacity, __base::__start_ +=
+                                 __base::__block_size - (__base::__map_.size() == 1))
+            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
+        // Done allocating, reorder capacity
+        __base::__start_ -= __base::__block_size * __front_capacity;
+        for (; __front_capacity > 0; --__front_capacity)
+        {
+            pointer __pt = __base::__map_.front();
+            __base::__map_.pop_front();
+            __base::__map_.push_back(__pt);
+        }
+    }
+    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
+    else
+    {
+        size_type __ds = __front_capacity * __base::__block_size;
+        __split_buffer<pointer, typename __base::__pointer_allocator&>
+            __buf(max<size_type>(2* __base::__map_.capacity(),
+                                 __nb + __base::__map_.size()),
+                  __base::__map_.size() - __front_capacity,
+                  __base::__map_.__alloc());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        try
+        {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+            for (; __nb > 0; --__nb)
+                __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            for (typename __base::__map_pointer __i = __buf.begin();
+                    __i != __buf.end(); ++__i)
+                __alloc_traits::deallocate(__a, *__i, __base::__block_size);
+            throw;
+        }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        for (; __front_capacity > 0; --__front_capacity)
+        {
+            __buf.push_back(__base::__map_.front());
+            __base::__map_.pop_front();
+        }
+        for (typename __base::__map_pointer __i = __base::__map_.end();
+                __i != __base::__map_.begin();)
+            __buf.push_front(*--__i);
+        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
+        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
+        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
+        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
+        __base::__start_ -= __ds;
+    }
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::pop_front()
+{
+    allocator_type& __a = __base::__alloc();
+    __alloc_traits::destroy(__a, __to_raw_pointer(*(__base::__map_.begin() +
+                                                    __base::__start_ / __base::__block_size) +
+                                                    __base::__start_ % __base::__block_size));
+    --__base::size();
+    if (++__base::__start_ >= 2 * __base::__block_size)
+    {
+        __alloc_traits::deallocate(__a, __base::__map_.front(), __base::__block_size);
+        __base::__map_.pop_front();
+        __base::__start_ -= __base::__block_size;
+    }
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::pop_back()
+{
+    allocator_type& __a = __base::__alloc();
+    size_type __p = __base::size() + __base::__start_ - 1;
+    __alloc_traits::destroy(__a, __to_raw_pointer(*(__base::__map_.begin() +
+                                                    __p / __base::__block_size) +
+                                                    __p % __base::__block_size));
+    --__base::size();
+    if (__back_spare() >= 2 * __base::__block_size)
+    {
+        __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+        __base::__map_.pop_back();
+    }
+}
+
+// move assign [__f, __l) to [__r, __r + (__l-__f)).
+// If __vt points into [__f, __l), then subtract (__f - __r) from __vt.
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::__move_and_check(iterator __f, iterator __l, iterator __r,
+                                         const_pointer& __vt)
+{
+    // as if
+    //   for (; __f != __l; ++__f, ++__r)
+    //       *__r = _VSTD::move(*__f);
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + __base::__block_size;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        if (__fb <= __vt && __vt < __fe)
+            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) -= __f - __r).__ptr_;
+        __r = _VSTD::move(__fb, __fe, __r);
+        __n -= __bs;
+        __f += __bs;
+    }
+    return __r;
+}
+
+// move assign [__f, __l) to [__r - (__l-__f), __r) backwards.
+// If __vt points into [__f, __l), then add (__r - __l) to __vt.
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::__move_backward_and_check(iterator __f, iterator __l, iterator __r,
+                                                  const_pointer& __vt)
+{
+    // as if
+    //   while (__f != __l)
+    //       *--__r = _VSTD::move(*--__l);
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        if (__lb <= __vt && __vt < __le)
+            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) += __r - __l - 1).__ptr_;
+        __r = _VSTD::move_backward(__lb, __le, __r);
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+    return __r;
+}
+
+// move construct [__f, __l) to [__r, __r + (__l-__f)).
+// If __vt points into [__f, __l), then add (__r - __f) to __vt.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__move_construct_and_check(iterator __f, iterator __l,
+                                                   iterator __r, const_pointer& __vt)
+{
+    allocator_type& __a = __base::__alloc();
+    // as if
+    //   for (; __f != __l; ++__r, ++__f, ++__base::size())
+    //       __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__f));
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        pointer __fb = __f.__ptr_;
+        pointer __fe = *__f.__m_iter_ + __base::__block_size;
+        difference_type __bs = __fe - __fb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __fe = __fb + __bs;
+        }
+        if (__fb <= __vt && __vt < __fe)
+            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) += __r - __f).__ptr_;
+        for (; __fb != __fe; ++__fb, ++__r, ++__base::size())
+            __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__fb));
+        __n -= __bs;
+        __f += __bs;
+    }
+}
+
+// move construct [__f, __l) to [__r - (__l-__f), __r) backwards.
+// If __vt points into [__f, __l), then subtract (__l - __r) from __vt.
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__move_construct_backward_and_check(iterator __f, iterator __l,
+                                                            iterator __r, const_pointer& __vt)
+{
+    allocator_type& __a = __base::__alloc();
+    // as if
+    //   for (iterator __j = __l; __j != __f;)
+    //   {
+    //       __alloc_traitsconstruct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__j));
+    //       --__base::__start_;
+    //       ++__base::size();
+    //   }
+    difference_type __n = __l - __f;
+    while (__n > 0)
+    {
+        --__l;
+        pointer __lb = *__l.__m_iter_;
+        pointer __le = __l.__ptr_ + 1;
+        difference_type __bs = __le - __lb;
+        if (__bs > __n)
+        {
+            __bs = __n;
+            __lb = __le - __bs;
+        }
+        if (__lb <= __vt && __vt < __le)
+            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) -= __l - __r + 1).__ptr_;
+        while (__le != __lb)
+        {
+            __alloc_traits::construct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__le));
+            --__base::__start_;
+            ++__base::size();
+        }
+        __n -= __bs;
+        __l -= __bs - 1;
+    }
+}
+
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::erase(const_iterator __f)
+{
+    difference_type __n = 1;
+    iterator __b = __base::begin();
+    difference_type __pos = __f - __b;
+    iterator __p = __b + __pos;
+    allocator_type& __a = __base::__alloc();
+    if (__pos < (__base::size() - 1) / 2)
+    {   // erase from front
+        _VSTD::move_backward(__b, __p, _VSTD::next(__p));
+        __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
+        --__base::size();
+        ++__base::__start_;
+        if (__front_spare() >= 2 * __base::__block_size)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.front(), __base::__block_size);
+            __base::__map_.pop_front();
+            __base::__start_ -= __base::__block_size;
+        }
+    }
+    else
+    {   // erase from back
+        iterator __i = _VSTD::move(_VSTD::next(__p), __base::end(), __p);
+        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
+        --__base::size();
+        if (__back_spare() >= 2 * __base::__block_size)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+            __base::__map_.pop_back();
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+template <class _Tp, class _Allocator>
+typename deque<_Tp, _Allocator>::iterator
+deque<_Tp, _Allocator>::erase(const_iterator __f, const_iterator __l)
+{
+    difference_type __n = __l - __f;
+    iterator __b = __base::begin();
+    difference_type __pos = __f - __b;
+    iterator __p = __b + __pos;
+    if (__n > 0)
+    {
+        allocator_type& __a = __base::__alloc();
+        if (__pos < (__base::size() - __n) / 2)
+        {   // erase from front
+            iterator __i = _VSTD::move_backward(__b, __p, __p + __n);
+            for (; __b != __i; ++__b)
+                __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
+            __base::size() -= __n;
+            __base::__start_ += __n;
+            while (__front_spare() >= 2 * __base::__block_size)
+            {
+                __alloc_traits::deallocate(__a, __base::__map_.front(), __base::__block_size);
+                __base::__map_.pop_front();
+                __base::__start_ -= __base::__block_size;
+            }
+        }
+        else
+        {   // erase from back
+            iterator __i = _VSTD::move(__p + __n, __base::end(), __p);
+            for (iterator __e = __base::end(); __i != __e; ++__i)
+                __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
+            __base::size() -= __n;
+            while (__back_spare() >= 2 * __base::__block_size)
+            {
+                __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+                __base::__map_.pop_back();
+            }
+        }
+    }
+    return __base::begin() + __pos;
+}
+
+template <class _Tp, class _Allocator>
+void
+deque<_Tp, _Allocator>::__erase_to_end(const_iterator __f)
+{
+    iterator __e = __base::end();
+    difference_type __n = __e - __f;
+    if (__n > 0)
+    {
+        allocator_type& __a = __base::__alloc();
+        iterator __b = __base::begin();
+        difference_type __pos = __f - __b;
+        for (iterator __p = __b + __pos; __p != __e; ++__p)
+            __alloc_traits::destroy(__a, _VSTD::addressof(*__p));
+        __base::size() -= __n;
+        while (__back_spare() >= 2 * __base::__block_size)
+        {
+            __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
+            __base::__map_.pop_back();
+        }
+    }
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+deque<_Tp, _Allocator>::swap(deque& __c)
+        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
+                   __is_nothrow_swappable<allocator_type>::value)
+{
+    __base::swap(__c);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+deque<_Tp, _Allocator>::clear() _NOEXCEPT
+{
+    __base::clear();
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    const typename deque<_Tp, _Allocator>::size_type __sz = __x.size();
+    return __sz == __y.size() && _VSTD::equal(__x.begin(), __x.end(), __y.begin());
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    return !(__x == __y);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator< (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    return _VSTD::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator> (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    return __y < __x;
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    return !(__x < __y);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
+{
+    return !(__y < __x);
+}
+
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(deque<_Tp, _Allocator>& __x, deque<_Tp, _Allocator>& __y)
+    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
+{
+    __x.swap(__y);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif  // _LIBCPP_DEQUE