Restoring authorship annotation for Andrey Khalyavin <halyavin@gmail.com>. Commit 1 of 2.

1 files changed, 2992 insertions, 2992 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/deque b/contrib/libs/cxxsupp/libcxx/include/deque
index 67cd6654f1..b55c4bfca1 100644
--- a/contrib/libs/cxxsupp/libcxx/include/deque
+++ b/contrib/libs/cxxsupp/libcxx/include/deque
@@ -1,3030 +1,3030 @@
-// -*- C++ -*-
-//===---------------------------- deque -----------------------------------===//
-//
+// -*- C++ -*- 
+//===---------------------------- deque -----------------------------------===// 
+// 
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#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> reference emplace_front(Args&&... args);  // reference in C++17
-    template <class... Args> reference emplace_back(Args&&... args);   // reference in C++17
-    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 InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-   deque(InputIterator, InputIterator, Allocator = Allocator())
-   -> deque<typename iterator_traits<InputIterator>::value_type, Allocator>;
-
-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)));
-
+// 
+//===----------------------------------------------------------------------===// 
+ 
+#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> reference emplace_front(Args&&... args);  // reference in C++17 
+    template <class... Args> reference emplace_back(Args&&... args);   // reference in C++17 
+    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 InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>> 
+   deque(InputIterator, InputIterator, Allocator = Allocator()) 
+   -> deque<typename iterator_traits<InputIterator>::value_type, Allocator>; 
+ 
+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))); 
+ 
 template <class T, class Allocator, class U>
-    typename deque<T, Allocator>::size_type
-    erase(deque<T, Allocator>& c, const U& value);       // C++20
+    typename deque<T, Allocator>::size_type 
+    erase(deque<T, Allocator>& c, const U& value);       // C++20 
 template <class T, class Allocator, class Predicate>
-    typename deque<T, Allocator>::size_type
-    erase_if(deque<T, Allocator>& c, Predicate pred);    // C++20
-
-}  // std
-
-*/
-
-#include <__config>
-#include <__debug>
-#include <__split_buffer>
-#include <__utility/forward.h>
-#include <algorithm>
-#include <compare>
-#include <initializer_list>
-#include <iterator>
-#include <limits>
-#include <stdexcept>
-#include <type_traits>
+    typename deque<T, Allocator>::size_type 
+    erase_if(deque<T, Allocator>& c, Predicate pred);    // C++20 
+
+}  // std 
+ 
+*/ 
+ 
+#include <__config> 
+#include <__debug> 
+#include <__split_buffer> 
+#include <__utility/forward.h> 
+#include <algorithm> 
+#include <compare> 
+#include <initializer_list> 
+#include <iterator> 
+#include <limits> 
+#include <stdexcept> 
+#include <type_traits> 
 #include <version>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
-#endif
-
-_LIBCPP_PUSH_MACROS
-#include <__undef_macros>
-
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <class _Tp, class _Allocator> class __deque_base;
-template <class _Tp, class _Allocator = allocator<_Tp> > class _LIBCPP_TEMPLATE_VIS deque;
-
-template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
-          class _DiffType, _DiffType _BlockSize>
-class _LIBCPP_TEMPLATE_VIS __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_cpp17_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_cpp17_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_cpp17_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_cpp17_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 {
+ 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 
+#pragma GCC system_header 
+#endif 
+ 
+_LIBCPP_PUSH_MACROS 
+#include <__undef_macros> 
+ 
+ 
+_LIBCPP_BEGIN_NAMESPACE_STD 
+ 
+template <class _Tp, class _Allocator> class __deque_base; 
+template <class _Tp, class _Allocator = allocator<_Tp> > class _LIBCPP_TEMPLATE_VIS deque; 
+ 
+template <class _ValueType, class _Pointer, class _Reference, class _MapPointer, 
+          class _DiffType, _DiffType _BlockSize> 
+class _LIBCPP_TEMPLATE_VIS __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_cpp17_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_cpp17_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_cpp17_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_cpp17_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 __buf_size = 64 * sizeof(void*);
   static const _DiffType value = (__buf_size / sizeof(_ValueType)) > 2 ? (__buf_size / sizeof(_ValueType)) : 2;
   //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_TEMPLATE_VIS __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_TEMPLATE_VIS deque;
-    template <class _Vp, class _Pp, class _Rp, class _MP, class _Dp, _Dp>
-        friend class _LIBCPP_TEMPLATE_VIS __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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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 <class _Tp, class _Allocator>
-class __deque_base
-{
-    __deque_base(const __deque_base& __c);
-    __deque_base& operator=(const __deque_base& __c);
-public:
-    typedef _Allocator                               allocator_type;
-    typedef allocator_traits<allocator_type>         __alloc_traits;
-    typedef typename __alloc_traits::size_type       size_type;
-
-    typedef _Tp                                      value_type;
-    typedef value_type&                              reference;
-    typedef const value_type&                        const_reference;
-    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;
-
-    struct __deque_block_range {
-      explicit __deque_block_range(pointer __b, pointer __e) _NOEXCEPT : __begin_(__b), __end_(__e) {}
-      const pointer __begin_;
-      const pointer __end_;
-    };
-
-    struct __deque_range {
-      iterator __pos_;
-      const iterator __end_;
-
-      __deque_range(iterator __pos, iterator __e) _NOEXCEPT
-        : __pos_(__pos), __end_(__e) {}
-
-      explicit operator bool() const _NOEXCEPT {
-        return __pos_ != __end_;
-      }
-
-      __deque_range begin() const {
-        return *this;
-      }
-
-      __deque_range end() const {
-        return __deque_range(__end_, __end_);
-      }
-      __deque_block_range operator*() const _NOEXCEPT {
-         if (__pos_.__m_iter_ == __end_.__m_iter_) {
-          return __deque_block_range(__pos_.__ptr_, __end_.__ptr_);
-        }
-        return __deque_block_range(__pos_.__ptr_, *__pos_.__m_iter_ + __block_size);
-      }
-
-      __deque_range& operator++() _NOEXCEPT {
-        if (__pos_.__m_iter_ == __end_.__m_iter_) {
-          __pos_ = __end_;
-        } else {
-          ++__pos_.__m_iter_;
-          __pos_.__ptr_ = *__pos_.__m_iter_;
-        }
-        return *this;
-      }
-
-
-      friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) {
-        return __lhs.__pos_ == __rhs.__pos_;
-      }
-      friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) {
-        return !(__lhs == __rhs);
-      }
-    };
-
-
-
-    struct _ConstructTransaction {
-      _ConstructTransaction(__deque_base* __db, __deque_block_range& __r)
-        : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {}
-
-
-      ~_ConstructTransaction() {
-        __base_->size() += (__pos_ - __begin_);
-      }
-
-      pointer __pos_;
-      const pointer __end_;
-    private:
-      const pointer __begin_;
-      __deque_base * const __base_;
-    };
-
-protected:
-    __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_CXX03_LANG
-    __deque_base(__deque_base&& __c)
-        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
-    __deque_base(__deque_base&& __c, const allocator_type& __a);
-#endif // _LIBCPP_CXX03_LANG
-
-    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, __default_init_tag()) {}
-
-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_CXX03_LANG
-
-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_CXX03_LANG
-
-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());
-    _VSTD::__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_TEMPLATE_VIS 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;
-
-    using typename __base::__deque_range;
-    using typename __base::__deque_block_range;
-    using typename __base::_ConstructTransaction;
-
-    // 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_cpp17_input_iterator<_InputIter>::value>::type* = 0);
-    template <class _InputIter>
-        deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
-              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0);
-    deque(const deque& __c);
-    deque(const deque& __c, const __identity_t<allocator_type>& __a);
-
-    deque& operator=(const deque& __c);
-
-#ifndef _LIBCPP_CXX03_LANG
-    deque(initializer_list<value_type> __il);
-    deque(initializer_list<value_type> __il, const allocator_type& __a);
-
-    _LIBCPP_INLINE_VISIBILITY
-    deque& operator=(initializer_list<value_type> __il) {assign(__il); return *this;}
-
-    _LIBCPP_INLINE_VISIBILITY
-    deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__base>::value);
-    _LIBCPP_INLINE_VISIBILITY
-    deque(deque&& __c, const __identity_t<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);
-
-    _LIBCPP_INLINE_VISIBILITY
-    void assign(initializer_list<value_type> __il) {assign(__il.begin(), __il.end());}
-#endif // _LIBCPP_CXX03_LANG
-
-    template <class _InputIter>
-        void assign(_InputIter __f, _InputIter __l,
-                    typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
-                                      !__is_cpp17_random_access_iterator<_InputIter>::value>::type* = 0);
-    template <class _RAIter>
-        void assign(_RAIter __f, _RAIter __l,
-                    typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
-    void assign(size_type __n, const value_type& __v);
-
-    _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 _VSTD::min<size_type>(
+}; 
+ 
+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_TEMPLATE_VIS __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_TEMPLATE_VIS deque; 
+    template <class _Vp, class _Pp, class _Rp, class _MP, class _Dp, _Dp> 
+        friend class _LIBCPP_TEMPLATE_VIS __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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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_cpp17_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 <class _Tp, class _Allocator> 
+class __deque_base 
+{ 
+    __deque_base(const __deque_base& __c); 
+    __deque_base& operator=(const __deque_base& __c); 
+public: 
+    typedef _Allocator                               allocator_type; 
+    typedef allocator_traits<allocator_type>         __alloc_traits; 
+    typedef typename __alloc_traits::size_type       size_type; 
+ 
+    typedef _Tp                                      value_type; 
+    typedef value_type&                              reference; 
+    typedef const value_type&                        const_reference; 
+    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; 
+ 
+    struct __deque_block_range { 
+      explicit __deque_block_range(pointer __b, pointer __e) _NOEXCEPT : __begin_(__b), __end_(__e) {} 
+      const pointer __begin_; 
+      const pointer __end_; 
+    }; 
+ 
+    struct __deque_range { 
+      iterator __pos_; 
+      const iterator __end_; 
+ 
+      __deque_range(iterator __pos, iterator __e) _NOEXCEPT 
+        : __pos_(__pos), __end_(__e) {} 
+ 
+      explicit operator bool() const _NOEXCEPT { 
+        return __pos_ != __end_; 
+      } 
+ 
+      __deque_range begin() const { 
+        return *this; 
+      } 
+ 
+      __deque_range end() const { 
+        return __deque_range(__end_, __end_); 
+      } 
+      __deque_block_range operator*() const _NOEXCEPT { 
+         if (__pos_.__m_iter_ == __end_.__m_iter_) { 
+          return __deque_block_range(__pos_.__ptr_, __end_.__ptr_); 
+        } 
+        return __deque_block_range(__pos_.__ptr_, *__pos_.__m_iter_ + __block_size); 
+      } 
+ 
+      __deque_range& operator++() _NOEXCEPT { 
+        if (__pos_.__m_iter_ == __end_.__m_iter_) { 
+          __pos_ = __end_; 
+        } else { 
+          ++__pos_.__m_iter_; 
+          __pos_.__ptr_ = *__pos_.__m_iter_; 
+        } 
+        return *this; 
+      } 
+ 
+ 
+      friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) { 
+        return __lhs.__pos_ == __rhs.__pos_; 
+      } 
+      friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) { 
+        return !(__lhs == __rhs); 
+      } 
+    }; 
+ 
+ 
+ 
+    struct _ConstructTransaction { 
+      _ConstructTransaction(__deque_base* __db, __deque_block_range& __r) 
+        : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {} 
+ 
+ 
+      ~_ConstructTransaction() { 
+        __base_->size() += (__pos_ - __begin_); 
+      } 
+ 
+      pointer __pos_; 
+      const pointer __end_; 
+    private: 
+      const pointer __begin_; 
+      __deque_base * const __base_; 
+    }; 
+ 
+protected: 
+    __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_CXX03_LANG 
+    __deque_base(__deque_base&& __c) 
+        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value); 
+    __deque_base(__deque_base&& __c, const allocator_type& __a); 
+#endif // _LIBCPP_CXX03_LANG 
+ 
+    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, __default_init_tag()) {} 
+ 
+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_CXX03_LANG 
+ 
+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_CXX03_LANG 
+ 
+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()); 
+    _VSTD::__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_TEMPLATE_VIS 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; 
+ 
+    using typename __base::__deque_range; 
+    using typename __base::__deque_block_range; 
+    using typename __base::_ConstructTransaction; 
+ 
+    // 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_cpp17_input_iterator<_InputIter>::value>::type* = 0); 
+    template <class _InputIter> 
+        deque(_InputIter __f, _InputIter __l, const allocator_type& __a, 
+              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0); 
+    deque(const deque& __c); 
+    deque(const deque& __c, const __identity_t<allocator_type>& __a); 
+ 
+    deque& operator=(const deque& __c); 
+ 
+#ifndef _LIBCPP_CXX03_LANG 
+    deque(initializer_list<value_type> __il); 
+    deque(initializer_list<value_type> __il, const allocator_type& __a); 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    deque& operator=(initializer_list<value_type> __il) {assign(__il); return *this;} 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__base>::value); 
+    _LIBCPP_INLINE_VISIBILITY 
+    deque(deque&& __c, const __identity_t<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); 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    void assign(initializer_list<value_type> __il) {assign(__il.begin(), __il.end());} 
+#endif // _LIBCPP_CXX03_LANG 
+ 
+    template <class _InputIter> 
+        void assign(_InputIter __f, _InputIter __l, 
+                    typename enable_if<__is_cpp17_input_iterator<_InputIter>::value && 
+                                      !__is_cpp17_random_access_iterator<_InputIter>::value>::type* = 0); 
+    template <class _RAIter> 
+        void assign(_RAIter __f, _RAIter __l, 
+                    typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0); 
+    void assign(size_type __n, const value_type& __v); 
+ 
+    _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 _VSTD::min<size_type>( 
             __alloc_traits::max_size(__base::__alloc()),
             numeric_limits<difference_type>::max());}
-    void resize(size_type __n);
-    void resize(size_type __n, const value_type& __v);
-    void shrink_to_fit() _NOEXCEPT;
-    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
-    bool empty() const _NOEXCEPT {return __base::size() == 0;}
-
-    // element access:
-    _LIBCPP_INLINE_VISIBILITY
-    reference operator[](size_type __i) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    const_reference operator[](size_type __i) const _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    reference at(size_type __i);
-    _LIBCPP_INLINE_VISIBILITY
-    const_reference at(size_type __i) const;
-    _LIBCPP_INLINE_VISIBILITY
-    reference front() _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    const_reference front() const _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    reference back() _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    const_reference back() const _NOEXCEPT;
-
-    // 23.2.2.3 modifiers:
-    void push_front(const value_type& __v);
-    void push_back(const value_type& __v);
-#ifndef _LIBCPP_CXX03_LANG
+    void resize(size_type __n); 
+    void resize(size_type __n, const value_type& __v); 
+    void shrink_to_fit() _NOEXCEPT; 
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY 
+    bool empty() const _NOEXCEPT {return __base::size() == 0;} 
+ 
+    // element access: 
+    _LIBCPP_INLINE_VISIBILITY 
+    reference operator[](size_type __i) _NOEXCEPT; 
+    _LIBCPP_INLINE_VISIBILITY 
+    const_reference operator[](size_type __i) const _NOEXCEPT; 
+    _LIBCPP_INLINE_VISIBILITY 
+    reference at(size_type __i); 
+    _LIBCPP_INLINE_VISIBILITY 
+    const_reference at(size_type __i) const; 
+    _LIBCPP_INLINE_VISIBILITY 
+    reference front() _NOEXCEPT; 
+    _LIBCPP_INLINE_VISIBILITY 
+    const_reference front() const _NOEXCEPT; 
+    _LIBCPP_INLINE_VISIBILITY 
+    reference back() _NOEXCEPT; 
+    _LIBCPP_INLINE_VISIBILITY 
+    const_reference back() const _NOEXCEPT; 
+ 
+    // 23.2.2.3 modifiers: 
+    void push_front(const value_type& __v); 
+    void push_back(const value_type& __v); 
+#ifndef _LIBCPP_CXX03_LANG 
 #if _LIBCPP_STD_VER > 14
-    template <class... _Args> reference emplace_front(_Args&&... __args);
-    template <class... _Args> reference emplace_back (_Args&&... __args);
+    template <class... _Args> reference emplace_front(_Args&&... __args); 
+    template <class... _Args> reference emplace_back (_Args&&... __args); 
 #else
     template <class... _Args> void      emplace_front(_Args&&... __args);
     template <class... _Args> void      emplace_back (_Args&&... __args);
 #endif
-    template <class... _Args> iterator emplace(const_iterator __p, _Args&&... __args);
-
-    void push_front(value_type&& __v);
-    void push_back(value_type&& __v);
-    iterator insert(const_iterator __p, value_type&& __v);
-
-    _LIBCPP_INLINE_VISIBILITY
-    iterator insert(const_iterator __p, initializer_list<value_type> __il)
-        {return insert(__p, __il.begin(), __il.end());}
-#endif // _LIBCPP_CXX03_LANG
-    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_cpp17_input_iterator<_InputIter>::value
-                                         &&!__is_cpp17_forward_iterator<_InputIter>::value>::type* = 0);
-    template <class _ForwardIterator>
-        iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
-                               typename enable_if<__is_cpp17_forward_iterator<_ForwardIterator>::value
-                                         &&!__is_cpp17_bidirectional_iterator<_ForwardIterator>::value>::type* = 0);
-    template <class _BiIter>
-        iterator insert(const_iterator __p, _BiIter __f, _BiIter __l,
-                         typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type* = 0);
-
-    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();}
-
-    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 __block_count() const
-    {
-        return __base::__map_.size();
-    }
-
-    _LIBCPP_INLINE_VISIBILITY
-    size_type __front_spare() const
-    {
-        return __base::__start_;
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    size_type __front_spare_blocks() const {
-      return __front_spare() / __base::__block_size;
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    size_type __back_spare() const
-    {
-        return __capacity() - (__base::__start_ + __base::size());
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    size_type __back_spare_blocks() const {
-      return __back_spare() / __base::__block_size;
-    }
-
- private:
-    _LIBCPP_INLINE_VISIBILITY
-    bool __maybe_remove_front_spare(bool __keep_one = true) {
-      if (__front_spare_blocks() >= 2 || (!__keep_one && __front_spare_blocks())) {
-        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.front(),
-                                   __base::__block_size);
-        __base::__map_.pop_front();
-        __base::__start_ -= __base::__block_size;
-        return true;
-      }
-      return false;
-    }
-
-    _LIBCPP_INLINE_VISIBILITY
-    bool __maybe_remove_back_spare(bool __keep_one = true) {
-      if (__back_spare_blocks() >= 2 || (!__keep_one && __back_spare_blocks())) {
-        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.back(),
-                                   __base::__block_size);
-        __base::__map_.pop_back();
-        return true;
-      }
-      return false;
-    }
-
-    template <class _InpIter>
-        void __append(_InpIter __f, _InpIter __l,
-                 typename enable_if<__is_cpp17_input_iterator<_InpIter>::value &&
-                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type* = 0);
-    template <class _ForIter>
-        void __append(_ForIter __f, _ForIter __l,
-                      typename enable_if<__is_cpp17_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);
-};
-
-#if _LIBCPP_STD_VER >= 17
-template<class _InputIterator,
-         class _Alloc = allocator<__iter_value_type<_InputIterator>>,
-         class = enable_if_t<__is_allocator<_Alloc>::value>
-         >
-deque(_InputIterator, _InputIterator)
-  -> deque<__iter_value_type<_InputIterator>, _Alloc>;
-
-template<class _InputIterator,
-         class _Alloc,
-         class = enable_if_t<__is_allocator<_Alloc>::value>
-         >
-deque(_InputIterator, _InputIterator, _Alloc)
-  -> deque<__iter_value_type<_InputIterator>, _Alloc>;
-#endif
-
-
-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_cpp17_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_cpp17_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 __identity_t<allocator_type>& __a)
-    : __base(__a)
-{
-    __append(__c.begin(), __c.end());
-}
-
-template <class _Tp, class _Allocator>
-deque<_Tp, _Allocator>&
-deque<_Tp, _Allocator>::operator=(const deque& __c)
-{
-    if (this != _VSTD::addressof(__c))
-    {
-        __copy_assign_alloc(__c);
-        assign(__c.begin(), __c.end());
-    }
-    return *this;
-}
-
-#ifndef _LIBCPP_CXX03_LANG
-
-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());
-}
-
-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 __identity_t<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_CXX03_LANG
-
-template <class _Tp, class _Allocator>
-template <class _InputIter>
-void
-deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l,
-                               typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
-                                                 !__is_cpp17_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_cpp17_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
-    {
-      __maybe_remove_front_spare(/*__keep_one=*/false);
-      __maybe_remove_back_spare(/*__keep_one=*/false);
-    }
-    __base::__map_.shrink_to_fit();
-}
-
-template <class _Tp, class _Allocator>
-inline
-typename deque<_Tp, _Allocator>::reference
-deque<_Tp, _Allocator>::operator[](size_type __i) _NOEXCEPT
-{
-    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 _NOEXCEPT
-{
-    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())
-        _VSTD::__throw_out_of_range("deque");
-    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())
-        _VSTD::__throw_out_of_range("deque");
-    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() _NOEXCEPT
-{
-    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 _NOEXCEPT
-{
-    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() _NOEXCEPT
-{
-    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 _NOEXCEPT
-{
-    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();
-}
-
-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_CXX03_LANG
-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();
-}
-
-template <class _Tp, class _Allocator>
-template <class... _Args>
+    template <class... _Args> iterator emplace(const_iterator __p, _Args&&... __args); 
+ 
+    void push_front(value_type&& __v); 
+    void push_back(value_type&& __v); 
+    iterator insert(const_iterator __p, value_type&& __v); 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    iterator insert(const_iterator __p, initializer_list<value_type> __il) 
+        {return insert(__p, __il.begin(), __il.end());} 
+#endif // _LIBCPP_CXX03_LANG 
+    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_cpp17_input_iterator<_InputIter>::value 
+                                         &&!__is_cpp17_forward_iterator<_InputIter>::value>::type* = 0); 
+    template <class _ForwardIterator> 
+        iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l, 
+                               typename enable_if<__is_cpp17_forward_iterator<_ForwardIterator>::value 
+                                         &&!__is_cpp17_bidirectional_iterator<_ForwardIterator>::value>::type* = 0); 
+    template <class _BiIter> 
+        iterator insert(const_iterator __p, _BiIter __f, _BiIter __l, 
+                         typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type* = 0); 
+ 
+    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();} 
+ 
+    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 __block_count() const 
+    { 
+        return __base::__map_.size(); 
+    } 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    size_type __front_spare() const 
+    { 
+        return __base::__start_; 
+    } 
+    _LIBCPP_INLINE_VISIBILITY 
+    size_type __front_spare_blocks() const { 
+      return __front_spare() / __base::__block_size; 
+    } 
+    _LIBCPP_INLINE_VISIBILITY 
+    size_type __back_spare() const 
+    { 
+        return __capacity() - (__base::__start_ + __base::size()); 
+    } 
+    _LIBCPP_INLINE_VISIBILITY 
+    size_type __back_spare_blocks() const { 
+      return __back_spare() / __base::__block_size; 
+    } 
+ 
+ private: 
+    _LIBCPP_INLINE_VISIBILITY 
+    bool __maybe_remove_front_spare(bool __keep_one = true) { 
+      if (__front_spare_blocks() >= 2 || (!__keep_one && __front_spare_blocks())) { 
+        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.front(), 
+                                   __base::__block_size); 
+        __base::__map_.pop_front(); 
+        __base::__start_ -= __base::__block_size; 
+        return true; 
+      } 
+      return false; 
+    } 
+ 
+    _LIBCPP_INLINE_VISIBILITY 
+    bool __maybe_remove_back_spare(bool __keep_one = true) { 
+      if (__back_spare_blocks() >= 2 || (!__keep_one && __back_spare_blocks())) { 
+        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.back(), 
+                                   __base::__block_size); 
+        __base::__map_.pop_back(); 
+        return true; 
+      } 
+      return false; 
+    } 
+ 
+    template <class _InpIter> 
+        void __append(_InpIter __f, _InpIter __l, 
+                 typename enable_if<__is_cpp17_input_iterator<_InpIter>::value && 
+                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type* = 0); 
+    template <class _ForIter> 
+        void __append(_ForIter __f, _ForIter __l, 
+                      typename enable_if<__is_cpp17_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); 
+}; 
+ 
+#if _LIBCPP_STD_VER >= 17 
+template<class _InputIterator, 
+         class _Alloc = allocator<__iter_value_type<_InputIterator>>, 
+         class = enable_if_t<__is_allocator<_Alloc>::value> 
+         > 
+deque(_InputIterator, _InputIterator) 
+  -> deque<__iter_value_type<_InputIterator>, _Alloc>; 
+ 
+template<class _InputIterator, 
+         class _Alloc, 
+         class = enable_if_t<__is_allocator<_Alloc>::value> 
+         > 
+deque(_InputIterator, _InputIterator, _Alloc) 
+  -> deque<__iter_value_type<_InputIterator>, _Alloc>; 
+#endif 
+ 
+ 
+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_cpp17_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_cpp17_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 __identity_t<allocator_type>& __a) 
+    : __base(__a) 
+{ 
+    __append(__c.begin(), __c.end()); 
+} 
+ 
+template <class _Tp, class _Allocator> 
+deque<_Tp, _Allocator>& 
+deque<_Tp, _Allocator>::operator=(const deque& __c) 
+{ 
+    if (this != _VSTD::addressof(__c)) 
+    { 
+        __copy_assign_alloc(__c); 
+        assign(__c.begin(), __c.end()); 
+    } 
+    return *this; 
+} 
+ 
+#ifndef _LIBCPP_CXX03_LANG 
+ 
+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()); 
+} 
+ 
+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 __identity_t<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_CXX03_LANG 
+ 
+template <class _Tp, class _Allocator> 
+template <class _InputIter> 
+void 
+deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l, 
+                               typename enable_if<__is_cpp17_input_iterator<_InputIter>::value && 
+                                                 !__is_cpp17_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_cpp17_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 
+    { 
+      __maybe_remove_front_spare(/*__keep_one=*/false); 
+      __maybe_remove_back_spare(/*__keep_one=*/false); 
+    } 
+    __base::__map_.shrink_to_fit(); 
+} 
+ 
+template <class _Tp, class _Allocator> 
+inline 
+typename deque<_Tp, _Allocator>::reference 
+deque<_Tp, _Allocator>::operator[](size_type __i) _NOEXCEPT 
+{ 
+    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 _NOEXCEPT 
+{ 
+    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()) 
+        _VSTD::__throw_out_of_range("deque"); 
+    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()) 
+        _VSTD::__throw_out_of_range("deque"); 
+    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() _NOEXCEPT 
+{ 
+    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 _NOEXCEPT 
+{ 
+    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() _NOEXCEPT 
+{ 
+    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 _NOEXCEPT 
+{ 
+    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(); 
+} 
+ 
+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_CXX03_LANG 
+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(); 
+} 
+ 
+template <class _Tp, class _Allocator> 
+template <class... _Args> 
 #if _LIBCPP_STD_VER > 14
-typename deque<_Tp, _Allocator>::reference
+typename deque<_Tp, _Allocator>::reference 
 #else
 void
 #endif
-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();
+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(); 
 #if _LIBCPP_STD_VER > 14
-    return *--__base::end();
+    return *--__base::end(); 
 #endif
-}
-
-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();
-}
-
-
-template <class _Tp, class _Allocator>
-template <class... _Args>
+} 
+ 
+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(); 
+} 
+ 
+ 
+template <class _Tp, class _Allocator> 
+template <class... _Args> 
 #if _LIBCPP_STD_VER > 14
-typename deque<_Tp, _Allocator>::reference
+typename deque<_Tp, _Allocator>::reference 
 #else
 void
 #endif
-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();
+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(); 
 #if _LIBCPP_STD_VER > 14
-    return *__base::begin();
+    return *__base::begin(); 
 #endif
-}
-
-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;
-}
-
-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
-        {
-            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _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.get());
-        }
-    }
-    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
-        {
-            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _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.get());
-        }
-    }
-    return __base::begin() + __pos;
-}
-
-#endif // _LIBCPP_CXX03_LANG
-
-
-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;
-}
-
-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, (void) ++__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_cpp17_input_iterator<_InputIter>::value
-                                               &&!__is_cpp17_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_cpp17_forward_iterator<_ForwardIterator>::value
-                                               &&!__is_cpp17_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_cpp17_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, (void) ++__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_cpp17_input_iterator<_InpIter>::value &&
-                                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type*)
-{
-    for (; __f != __l; ++__f)
-#ifdef _LIBCPP_CXX03_LANG
-        push_back(*__f);
-#else
-        emplace_back(*__f);
-#endif
-}
-
-template <class _Tp, class _Allocator>
-template <class _ForIter>
-void
-deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l,
-                                 typename enable_if<__is_cpp17_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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
-      _ConstructTransaction __tx(this, __br);
-      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) {
-        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), *__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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
-      _ConstructTransaction __tx(this, __br);
-      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
-        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_));
-      }
-    }
-}
-
-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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
-      _ConstructTransaction __tx(this, __br);
-      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
-        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), __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() >= size_type(__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() >= size_type(__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, _VSTD::__to_address(*(__base::__map_.begin() +
-                                                    __base::__start_ / __base::__block_size) +
-                                                    __base::__start_ % __base::__block_size));
-    --__base::size();
-    ++__base::__start_;
-    __maybe_remove_front_spare();
-}
-
-template <class _Tp, class _Allocator>
-void
-deque<_Tp, _Allocator>::pop_back()
-{
-    _LIBCPP_ASSERT(!empty(), "deque::pop_back called on an empty deque");
-    allocator_type& __a = __base::__alloc();
-    size_type __p = __base::size() + __base::__start_ - 1;
-    __alloc_traits::destroy(__a, _VSTD::__to_address(*(__base::__map_.begin() +
-                                                    __p / __base::__block_size) +
-                                                    __p % __base::__block_size));
-    --__base::size();
-    __maybe_remove_back_spare();
-}
-
-// 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 (static_cast<size_t>(__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_;
-        __maybe_remove_front_spare();
-    }
-    else
-    {   // erase from back
-        iterator __i = _VSTD::move(_VSTD::next(__p), __base::end(), __p);
-        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
-        --__base::size();
-        __maybe_remove_back_spare();
-    }
-    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 (static_cast<size_t>(__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;
+} 
+ 
+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; 
+} 
+ 
+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 
+        { 
+            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _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.get()); 
+        } 
+    } 
+    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 
+        { 
+            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _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.get()); 
+        } 
+    } 
+    return __base::begin() + __pos; 
+} 
+ 
+#endif // _LIBCPP_CXX03_LANG 
+ 
+ 
+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; 
+} 
+ 
+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, (void) ++__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_cpp17_input_iterator<_InputIter>::value 
+                                               &&!__is_cpp17_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_cpp17_forward_iterator<_ForwardIterator>::value 
+                                               &&!__is_cpp17_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_cpp17_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, (void) ++__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_cpp17_input_iterator<_InpIter>::value && 
+                                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type*) 
+{ 
+    for (; __f != __l; ++__f) 
+#ifdef _LIBCPP_CXX03_LANG 
+        push_back(*__f); 
+#else 
+        emplace_back(*__f); 
+#endif 
+} 
+ 
+template <class _Tp, class _Allocator> 
+template <class _ForIter> 
+void 
+deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l, 
+                                 typename enable_if<__is_cpp17_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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) { 
+      _ConstructTransaction __tx(this, __br); 
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) { 
+        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), *__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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) { 
+      _ConstructTransaction __tx(this, __br); 
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) { 
+        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_)); 
+      } 
+    } 
+} 
+ 
+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 (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) { 
+      _ConstructTransaction __tx(this, __br); 
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) { 
+        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), __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() >= size_type(__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() >= size_type(__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, _VSTD::__to_address(*(__base::__map_.begin() + 
+                                                    __base::__start_ / __base::__block_size) + 
+                                                    __base::__start_ % __base::__block_size)); 
+    --__base::size(); 
+    ++__base::__start_; 
+    __maybe_remove_front_spare(); 
+} 
+ 
+template <class _Tp, class _Allocator> 
+void 
+deque<_Tp, _Allocator>::pop_back() 
+{ 
+    _LIBCPP_ASSERT(!empty(), "deque::pop_back called on an empty deque"); 
+    allocator_type& __a = __base::__alloc(); 
+    size_type __p = __base::size() + __base::__start_ - 1; 
+    __alloc_traits::destroy(__a, _VSTD::__to_address(*(__base::__map_.begin() + 
+                                                    __p / __base::__block_size) + 
+                                                    __p % __base::__block_size)); 
+    --__base::size(); 
+    __maybe_remove_back_spare(); 
+} 
+ 
+// 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 (static_cast<size_t>(__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_; 
+        __maybe_remove_front_spare(); 
+    } 
+    else 
+    {   // erase from back 
+        iterator __i = _VSTD::move(_VSTD::next(__p), __base::end(), __p); 
+        __alloc_traits::destroy(__a, _VSTD::addressof(*__i)); 
+        --__base::size(); 
+        __maybe_remove_back_spare(); 
+    } 
+    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 (static_cast<size_t>(__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 (__maybe_remove_front_spare()) {
-            }
-        }
-        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;
+            } 
+        } 
+        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 (__maybe_remove_back_spare()) {
-            }
-        }
-    }
-    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;
+            } 
+        } 
+    } 
+    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 (__maybe_remove_back_spare()) {
-        }
-    }
-}
-
-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);
-}
-
+        } 
+    } 
+} 
+ 
+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); 
+} 
+ 
 #if _LIBCPP_STD_VER > 17
 template <class _Tp, class _Allocator, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type
-erase(deque<_Tp, _Allocator>& __c, const _Up& __v) {
-  auto __old_size = __c.size();
-  __c.erase(_VSTD::remove(__c.begin(), __c.end(), __v), __c.end());
-  return __old_size - __c.size();
-}
+inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type 
+erase(deque<_Tp, _Allocator>& __c, const _Up& __v) { 
+  auto __old_size = __c.size(); 
+  __c.erase(_VSTD::remove(__c.begin(), __c.end(), __v), __c.end()); 
+  return __old_size - __c.size(); 
+} 
 
 template <class _Tp, class _Allocator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type
-erase_if(deque<_Tp, _Allocator>& __c, _Predicate __pred) {
-  auto __old_size = __c.size();
-  __c.erase(_VSTD::remove_if(__c.begin(), __c.end(), __pred), __c.end());
-  return __old_size - __c.size();
-}
+inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type 
+erase_if(deque<_Tp, _Allocator>& __c, _Predicate __pred) { 
+  auto __old_size = __c.size(); 
+  __c.erase(_VSTD::remove_if(__c.begin(), __c.end(), __pred), __c.end()); 
+  return __old_size - __c.size(); 
+} 
 #endif
 
 
-_LIBCPP_END_NAMESPACE_STD
-
-_LIBCPP_POP_MACROS
-
-#endif // _LIBCPP_DEQUE
+_LIBCPP_END_NAMESPACE_STD 
+ 
+_LIBCPP_POP_MACROS 
+ 
+#endif // _LIBCPP_DEQUE