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_traits<allocator_type>::is_always_equal::value); // C++17
 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 _Tp, class _Allocator = allocator<_Tp> > class _LIBCPP_TYPE_VIS_ONLY deque;

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 _DiffType>
struct __deque_block_size {
 static const _DiffType value = sizeof(_ValueType) < 256 ? 4096 / sizeof(_ValueType) : 16;
};

template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
 class _DiffType, _DiffType _BS =
#ifdef _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
// Keep template parameter to avoid changing all template declarations thoughout
// this file.
 0
#else
 __deque_block_size<_ValueType, _DiffType>::value
#endif
 >
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;
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, _BS>& __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);
};

template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
 class _DiffType, _DiffType _BlockSize>
const _DiffType __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer,
 _DiffType, _BlockSize>::__block_size =
 __deque_block_size<_ValueType, _DiffType>::value;

// 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;
 const difference_type __block_size = __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::__block_size;
 while (__f != __l)
 {
 pointer __rb = __r.__ptr_;
 pointer __re = *__r.__m_iter_ + __block_size;
 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;
 const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
 difference_type __n = __l - __f;
 while (__n > 0)
 {
 pointer __fb = __f.__ptr_;
 pointer __fe = *__f.__m_iter_ + __block_size;
 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;
 const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
 difference_type __n = __l - __f;
 while (__n > 0)
 {
 pointer __fb = __f.__ptr_;
 pointer __fe = *__f.__m_iter_ + __block_size;
 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;
 const difference_type __block_size = __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::__block_size;
 while (__f != __l)
 {
 pointer __rb = __r.__ptr_;
 pointer __re = *__r.__m_iter_ + __block_size;
 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;
 const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
 difference_type __n = __l - __f;
 while (__n > 0)
 {
 pointer __fb = __f.__ptr_;
 pointer __fe = *__f.__m_iter_ + __block_size;
 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;
 const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
 difference_type __n = __l - __f;
 while (__n > 0)
 {
 pointer __fb = __f.__ptr_;
 pointer __fe = *__f.__m_iter_ + __block_size;
 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;

 typedef typename __rebind_alloc_helper<__alloc_traits, pointer>::type __pointer_allocator;
 typedef allocator_traits<__pointer_allocator> __map_traits;
 typedef typename __map_traits::pointer __map_pointer;
 typedef typename __rebind_alloc_helper<__alloc_traits, const_pointer>::type __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> iterator;
 typedef __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer,
 difference_type> 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();}

 _LIBCPP_INLINE_VISIBILITY
 __deque_base()
 _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
 _LIBCPP_INLINE_VISIBILITY
 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)
#if _LIBCPP_STD_VER >= 14
 _NOEXCEPT;
#else
 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || 
 __is_nothrow_swappable<allocator_type>::value);
#endif
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
 {}
};

template <class _Tp, class _Allocator>
const typename __deque_base<_Tp, _Allocator>::difference_type
 __deque_base<_Tp, _Allocator>::__block_size =
 __deque_block_size<value_type, difference_type>::value;

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
__deque_base<_Tp, _Allocator>::__deque_base()
 _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
 : __start_(0), __size_(0) {}

template <class _Tp, class _Allocator>
inline
__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)
#if _LIBCPP_STD_VER >= 14
 _NOEXCEPT
#else
 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || 
 __is_nothrow_swappable<allocator_type>::value)
#endif
{
 __map_.swap(__c.__map_);
 _VSTD::swap(__start_, __c.__start_);
 _VSTD::swap(size(), __c.size());
 __swap_allocator(__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;

 static_assert((is_same<typename allocator_type::value_type, value_type>::value),
 "Allocator::value_type must be same type as value_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 explicit 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
 _LIBCPP_INLINE_VISIBILITY
 deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__base>::value);
 _LIBCPP_INLINE_VISIBILITY
 deque(deque&& __c, const allocator_type& __a);
 _LIBCPP_INLINE_VISIBILITY
 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

 _LIBCPP_INLINE_VISIBILITY
 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:
 _LIBCPP_INLINE_VISIBILITY
 reference operator[](size_type __i);
 _LIBCPP_INLINE_VISIBILITY
 const_reference operator[](size_type __i) const;
 _LIBCPP_INLINE_VISIBILITY
 reference at(size_type __i);
 _LIBCPP_INLINE_VISIBILITY
 const_reference at(size_type __i) const;
 _LIBCPP_INLINE_VISIBILITY
 reference front();
 _LIBCPP_INLINE_VISIBILITY
 const_reference front() const;
 _LIBCPP_INLINE_VISIBILITY
 reference back();
 _LIBCPP_INLINE_VISIBILITY
 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_forward_iterator<_InputIter>::value>::type* = 0);
 template <class _ForwardIterator>
 iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
 typename enable_if<__is_forward_iterator<_ForwardIterator>::value
 &&!__is_bidirectional_iterator<_ForwardIterator>::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);

 _LIBCPP_INLINE_VISIBILITY
 void swap(deque& __c)
#if _LIBCPP_STD_VER >= 14
 _NOEXCEPT;
#else
 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
 __is_nothrow_swappable<allocator_type>::value);
#endif
 _LIBCPP_INLINE_VISIBILITY
 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
deque<_Tp, _Allocator>::deque(deque&& __c)
 _NOEXCEPT_(is_nothrow_move_constructible<__base>::value)
 : __base(_VSTD::move(__c))
{
}

template <class _Tp, class _Allocator>
inline
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
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, (void) ++__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
_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
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
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
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
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
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
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
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
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()
 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
 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_forward_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 _ForwardIterator>
typename deque<_Tp, _Allocator>::iterator
deque<_Tp, _Allocator>::insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
 typename enable_if<__is_forward_iterator<_ForwardIterator>::value
 &&!__is_bidirectional_iterator<_ForwardIterator>::value>::type*)
{
 size_type __n = _VSTD::distance(__f, __l);
 __split_buffer<value_type, allocator_type&> __buf(__n, 0, __base::__alloc());
 __buf.__construct_at_end(__f, __l);
 typedef typename __split_buffer<value_type, allocator_type&>::iterator __fwd;
 return insert(__p, move_iterator<__fwd>(__buf.begin()), move_iterator<__fwd>(__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()
 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
 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, (void) ++__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, (void) ++__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());

 typedef __allocator_destructor<_Allocator> _Dp;
 unique_ptr<pointer, _Dp> __hold(
 __alloc_traits::allocate(__a, __base::__block_size),
 _Dp(__a, __base::__block_size));
 __buf.push_back(__hold.get());
 __hold.release();
 
 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());

 typedef __allocator_destructor<_Allocator> _Dp;
 unique_ptr<pointer, _Dp> __hold(
 __alloc_traits::allocate(__a, __base::__block_size),
 _Dp(__a, __base::__block_size));
 __buf.push_back(__hold.get());
 __hold.release();

 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)
{
 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
void
deque<_Tp, _Allocator>::swap(deque& __c)
#if _LIBCPP_STD_VER >= 14
 _NOEXCEPT
#else
 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || 
 __is_nothrow_swappable<allocator_type>::value)
#endif
{
 __base::swap(__c);
}

template <class _Tp, class _Allocator>
inline
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