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 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // 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___CXX03_DEQUE
 #define _LIBCPP___CXX03_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);
     template<container-compatible-range<T> R>
         deque(from_range_t, R&& rg, const Allocator& = Allocator()); // C++23
     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);
     template<container-compatible-range<T> R>
       void assign_range(R&& rg); // C++23
     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);
     template<container-compatible-range<T> R>
       void prepend_range(R&& rg); // C++23
     void push_back(const value_type& v);
     void push_back(value_type&& v);
     template<container-compatible-range<T> R>
       void append_range(R&& rg); // C++23
     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);
     template<container-compatible-range<T> R>
       iterator insert_range(const_iterator position, R&& rg); // C++23
     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>; // C++17
 
 template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
   deque(from_range_t, R&&, Allocator = Allocator())
     -> deque<ranges::range_value_t<R>, Allocator>; // C++23
 
 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); // removed in C++20
 template <class T, class Allocator>
     bool operator!=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
 template <class T, class Allocator>
     bool operator> (const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
 template <class T, class Allocator>
     bool operator>=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
 template <class T, class Allocator>
     bool operator<=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
 template<class T, class Allocator>
     synth-three-way-result<T> operator<=>(const deque<T, Allocator>& x,
                                           const deque<T, Allocator>& y);       // since C++20
 
 // 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
 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 <__cxx03/__algorithm/copy.h>
 #include <__cxx03/__algorithm/copy_backward.h>
 #include <__cxx03/__algorithm/copy_n.h>
 #include <__cxx03/__algorithm/equal.h>
 #include <__cxx03/__algorithm/fill_n.h>
 #include <__cxx03/__algorithm/lexicographical_compare.h>
 #include <__cxx03/__algorithm/lexicographical_compare_three_way.h>
 #include <__cxx03/__algorithm/min.h>
 #include <__cxx03/__algorithm/remove.h>
 #include <__cxx03/__algorithm/remove_if.h>
 #include <__cxx03/__algorithm/unwrap_iter.h>
 #include <__cxx03/__assert>
 #include <__cxx03/__config>
 #include <__cxx03/__debug_utils/sanitizers.h>
 #include <__cxx03/__format/enable_insertable.h>
 #include <__cxx03/__fwd/deque.h>
 #include <__cxx03/__iterator/distance.h>
 #include <__cxx03/__iterator/iterator_traits.h>
 #include <__cxx03/__iterator/next.h>
 #include <__cxx03/__iterator/prev.h>
 #include <__cxx03/__iterator/reverse_iterator.h>
 #include <__cxx03/__iterator/segmented_iterator.h>
 #include <__cxx03/__memory/addressof.h>
 #include <__cxx03/__memory/allocator_destructor.h>
 #include <__cxx03/__memory/pointer_traits.h>
 #include <__cxx03/__memory/temp_value.h>
 #include <__cxx03/__memory/unique_ptr.h>
 #include <__cxx03/__memory_resource/polymorphic_allocator.h>
 #include <__cxx03/__ranges/access.h>
 #include <__cxx03/__ranges/concepts.h>
 #include <__cxx03/__ranges/container_compatible_range.h>
 #include <__cxx03/__ranges/from_range.h>
 #include <__cxx03/__ranges/size.h>
 #include <__cxx03/__split_buffer>
 #include <__cxx03/__type_traits/is_allocator.h>
 #include <__cxx03/__type_traits/is_convertible.h>
 #include <__cxx03/__type_traits/is_same.h>
 #include <__cxx03/__type_traits/is_swappable.h>
 #include <__cxx03/__type_traits/type_identity.h>
 #include <__cxx03/__utility/forward.h>
 #include <__cxx03/__utility/move.h>
 #include <__cxx03/__utility/pair.h>
 #include <__cxx03/__utility/swap.h>
 #include <__cxx03/limits>
 #include <__cxx03/stdexcept>
 #include <__cxx03/version>
 
 // standard-mandated includes
 
 // [iterator.range]
 #include <__cxx03/__iterator/access.h>
 #include <__cxx03/__iterator/data.h>
 #include <__cxx03/__iterator/empty.h>
 #include <__cxx03/__iterator/reverse_access.h>
 #include <__cxx03/__iterator/size.h>
 
 // [deque.syn]
 #include <__cxx03/compare>
 #include <__cxx03/initializer_list>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__cxx03/__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _ValueType, class _DiffType>
 struct __deque_block_size {
   static const _DiffType value = sizeof(_ValueType) < 256 ? 4096 / sizeof(_ValueType) : 16;
 };
 
 template <class _ValueType,
           class _Pointer,
           class _Reference,
           class _MapPointer,
           class _DiffType,
           _DiffType _BS =
 #ifdef _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
               // Keep template parameter to avoid changing all template declarations thoughout
               // this file.
           0
 #else
               __deque_block_size<_ValueType, _DiffType>::value
 #endif
           >
 class _LIBCPP_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_HIDE_FROM_ABI __deque_iterator() _NOEXCEPT
 #if _LIBCPP_STD_VER >= 14
       : __m_iter_(nullptr),
         __ptr_(nullptr)
 #endif
   {
   }
 
   template <class _Pp, class _Rp, class _MP, __enable_if_t<is_convertible<_Pp, pointer>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI
   __deque_iterator(const __deque_iterator<value_type, _Pp, _Rp, _MP, difference_type, _BS>& __it) _NOEXCEPT
       : __m_iter_(__it.__m_iter_),
         __ptr_(__it.__ptr_) {}
 
   _LIBCPP_HIDE_FROM_ABI reference operator*() const { return *__ptr_; }
   _LIBCPP_HIDE_FROM_ABI pointer operator->() const { return __ptr_; }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator++() {
     if (++__ptr_ - *__m_iter_ == __block_size) {
       ++__m_iter_;
       __ptr_ = *__m_iter_;
     }
     return *this;
   }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator operator++(int) {
     __deque_iterator __tmp = *this;
     ++(*this);
     return __tmp;
   }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator--() {
     if (__ptr_ == *__m_iter_) {
       --__m_iter_;
       __ptr_ = *__m_iter_ + __block_size;
     }
     --__ptr_;
     return *this;
   }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator operator--(int) {
     __deque_iterator __tmp = *this;
     --(*this);
     return __tmp;
   }
 
   _LIBCPP_HIDE_FROM_ABI __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_HIDE_FROM_ABI __deque_iterator& operator-=(difference_type __n) { return *this += -__n; }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator operator+(difference_type __n) const {
     __deque_iterator __t(*this);
     __t += __n;
     return __t;
   }
 
   _LIBCPP_HIDE_FROM_ABI __deque_iterator operator-(difference_type __n) const {
     __deque_iterator __t(*this);
     __t -= __n;
     return __t;
   }
 
   _LIBCPP_HIDE_FROM_ABI friend __deque_iterator operator+(difference_type __n, const __deque_iterator& __it) {
     return __it + __n;
   }
 
   _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI reference operator[](difference_type __n) const { return *(*this + __n); }
 
   _LIBCPP_HIDE_FROM_ABI friend bool operator==(const __deque_iterator& __x, const __deque_iterator& __y) {
     return __x.__ptr_ == __y.__ptr_;
   }
 
 #if _LIBCPP_STD_VER <= 17
   _LIBCPP_HIDE_FROM_ABI friend bool operator!=(const __deque_iterator& __x, const __deque_iterator& __y) {
     return !(__x == __y);
   }
 #endif
 
   // TODO(mordante) disable these overloads in the LLVM 20 release.
   _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI friend bool operator>(const __deque_iterator& __x, const __deque_iterator& __y) {
     return __y < __x;
   }
 
   _LIBCPP_HIDE_FROM_ABI friend bool operator<=(const __deque_iterator& __x, const __deque_iterator& __y) {
     return !(__y < __x);
   }
 
   _LIBCPP_HIDE_FROM_ABI friend bool operator>=(const __deque_iterator& __x, const __deque_iterator& __y) {
     return !(__x < __y);
   }
 
 #if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI friend strong_ordering operator<=>(const __deque_iterator& __x, const __deque_iterator& __y) {
     if (__x.__m_iter_ < __y.__m_iter_)
       return strong_ordering::less;
 
     if (__x.__m_iter_ == __y.__m_iter_) {
       if constexpr (three_way_comparable<pointer, strong_ordering>) {
         return __x.__ptr_ <=> __y.__ptr_;
       } else {
         if (__x.__ptr_ < __y.__ptr_)
           return strong_ordering::less;
 
         if (__x.__ptr_ == __y.__ptr_)
           return strong_ordering::equal;
 
         return strong_ordering::greater;
       }
     }
 
     return strong_ordering::greater;
   }
 #endif // _LIBCPP_STD_VER >= 20
 
 private:
   _LIBCPP_HIDE_FROM_ABI explicit __deque_iterator(__map_iterator __m, pointer __p) _NOEXCEPT
       : __m_iter_(__m),
         __ptr_(__p) {}
 
   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>
   friend struct __segmented_iterator_traits;
 };
 
 template <class _ValueType, class _Pointer, class _Reference, class _MapPointer, class _DiffType, _DiffType _BlockSize>
 struct __segmented_iterator_traits<
     __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer, _DiffType, _BlockSize> > {
 private:
   using _Iterator = __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer, _DiffType, _BlockSize>;
 
 public:
   using __is_segmented_iterator = true_type;
   using __segment_iterator      = _MapPointer;
   using __local_iterator        = _Pointer;
 
   static _LIBCPP_HIDE_FROM_ABI __segment_iterator __segment(_Iterator __iter) { return __iter.__m_iter_; }
   static _LIBCPP_HIDE_FROM_ABI __local_iterator __local(_Iterator __iter) { return __iter.__ptr_; }
   static _LIBCPP_HIDE_FROM_ABI __local_iterator __begin(__segment_iterator __iter) { return *__iter; }
 
   static _LIBCPP_HIDE_FROM_ABI __local_iterator __end(__segment_iterator __iter) {
     return *__iter + _Iterator::__block_size;
   }
 
   static _LIBCPP_HIDE_FROM_ABI _Iterator __compose(__segment_iterator __segment, __local_iterator __local) {
     if (__segment && __local == __end(__segment)) {
       ++__segment;
       return _Iterator(__segment, *__segment);
     }
     return _Iterator(__segment, __local);
   }
 };
 
 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;
 
 template <class _Tp, class _Allocator /*= allocator<_Tp>*/>
 class _LIBCPP_TEMPLATE_VIS deque {
 public:
   // types:
 
   using value_type = _Tp;
 
   using allocator_type = _Allocator;
   using __alloc_traits = allocator_traits<allocator_type>;
   static_assert(__check_valid_allocator<allocator_type>::value, "");
   static_assert(is_same<typename allocator_type::value_type, value_type>::value,
                 "Allocator::value_type must be same type as value_type");
 
   using size_type       = typename __alloc_traits::size_type;
   using difference_type = typename __alloc_traits::difference_type;
 
   using pointer       = typename __alloc_traits::pointer;
   using const_pointer = typename __alloc_traits::const_pointer;
 
   using __pointer_allocator       = __rebind_alloc<__alloc_traits, pointer>;
   using __const_pointer_allocator = __rebind_alloc<__alloc_traits, const_pointer>;
   using __map                     = __split_buffer<pointer, __pointer_allocator>;
   using __map_alloc_traits        = allocator_traits<__pointer_allocator>;
   using __map_pointer             = typename __map_alloc_traits::pointer;
   using __map_const_pointer       = typename allocator_traits<__const_pointer_allocator>::const_pointer;
   using __map_const_iterator      = typename __map::const_iterator;
 
   using reference       = value_type&;
   using const_reference = const value_type&;
 
   using iterator = __deque_iterator<value_type, pointer, reference, __map_pointer, difference_type>;
   using const_iterator =
       __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer, difference_type>;
   using reverse_iterator       = std::reverse_iterator<iterator>;
   using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
   // A deque contains the following members which may be trivially relocatable:
   // - __map: is a `__split_buffer`, see `__split_buffer` for more information on when it is trivially relocatable
   // - size_type: is always trivially relocatable, since it is required to be an integral type
   // - allocator_type: may not be trivially relocatable, so it's checked
   // None of these are referencing the `deque` itself, so if all of them are trivially relocatable, `deque` is too.
   using __trivially_relocatable = __conditional_t<
       __libcpp_is_trivially_relocatable<__map>::value && __libcpp_is_trivially_relocatable<allocator_type>::value,
       deque,
       void>;
 
   static_assert(is_nothrow_default_constructible<allocator_type>::value ==
                     is_nothrow_default_constructible<__pointer_allocator>::value,
                 "rebinding an allocator should not change exception guarantees");
   static_assert(is_nothrow_move_constructible<allocator_type>::value ==
                     is_nothrow_move_constructible<typename __map::allocator_type>::value,
                 "rebinding an allocator should not change exception guarantees");
 
 private:
   struct __deque_block_range {
     explicit _LIBCPP_HIDE_FROM_ABI __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_;
 
     _LIBCPP_HIDE_FROM_ABI __deque_range(iterator __pos, iterator __e) _NOEXCEPT : __pos_(__pos), __end_(__e) {}
 
     explicit _LIBCPP_HIDE_FROM_ABI operator bool() const _NOEXCEPT { return __pos_ != __end_; }
 
     _LIBCPP_HIDE_FROM_ABI __deque_range begin() const { return *this; }
 
     _LIBCPP_HIDE_FROM_ABI __deque_range end() const { return __deque_range(__end_, __end_); }
     _LIBCPP_HIDE_FROM_ABI __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);
     }
 
     _LIBCPP_HIDE_FROM_ABI __deque_range& operator++() _NOEXCEPT {
       if (__pos_.__m_iter_ == __end_.__m_iter_) {
         __pos_ = __end_;
       } else {
         ++__pos_.__m_iter_;
         __pos_.__ptr_ = *__pos_.__m_iter_;
       }
       return *this;
     }
 
     _LIBCPP_HIDE_FROM_ABI friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) {
       return __lhs.__pos_ == __rhs.__pos_;
     }
     _LIBCPP_HIDE_FROM_ABI friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) {
       return !(__lhs == __rhs);
     }
   };
 
   struct _ConstructTransaction {
     _LIBCPP_HIDE_FROM_ABI _ConstructTransaction(deque* __db, __deque_block_range& __r)
         : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {}
 
     _LIBCPP_HIDE_FROM_ABI ~_ConstructTransaction() { __base_->__size() += (__pos_ - __begin_); }
 
     pointer __pos_;
     const pointer __end_;
 
   private:
     const pointer __begin_;
     deque* const __base_;
   };
 
   static const difference_type __block_size;
 
   __map __map_;
   size_type __start_;
   __compressed_pair<size_type, allocator_type> __size_;
 
 public:
   // construct/copy/destroy:
   _LIBCPP_HIDE_FROM_ABI deque() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
       : __start_(0), __size_(0, __default_init_tag()) {
     __annotate_new(0);
   }
 
   _LIBCPP_HIDE_FROM_ABI ~deque() {
     clear();
     __annotate_delete();
     typename __map::iterator __i = __map_.begin();
     typename __map::iterator __e = __map_.end();
     for (; __i != __e; ++__i)
       __alloc_traits::deallocate(__alloc(), *__i, __block_size);
   }
 
   _LIBCPP_HIDE_FROM_ABI explicit deque(const allocator_type& __a)
       : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
     __annotate_new(0);
   }
 
   explicit _LIBCPP_HIDE_FROM_ABI deque(size_type __n);
 #if _LIBCPP_STD_VER >= 14
   explicit _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const _Allocator& __a);
 #endif
   _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const value_type& __v);
 
   template <__enable_if_t<__is_allocator<_Allocator>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const value_type& __v, const allocator_type& __a)
       : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
     __annotate_new(0);
     if (__n > 0)
       __append(__n, __v);
   }
 
   template <class _InputIter, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI deque(_InputIter __f, _InputIter __l);
   template <class _InputIter, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI deque(_InputIter __f, _InputIter __l, const allocator_type& __a);
 
 #if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<_Tp> _Range>
   _LIBCPP_HIDE_FROM_ABI deque(from_range_t, _Range&& __range, const allocator_type& __a = allocator_type())
       : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
     if constexpr (ranges::forward_range<_Range> || ranges::sized_range<_Range>) {
       __append_with_size(ranges::begin(__range), ranges::distance(__range));
 
     } else {
       for (auto&& __e : __range) {
         emplace_back(std::forward<decltype(__e)>(__e));
       }
     }
   }
 #endif
 
   _LIBCPP_HIDE_FROM_ABI deque(const deque& __c);
   _LIBCPP_HIDE_FROM_ABI deque(const deque& __c, const __type_identity_t<allocator_type>& __a);
 
   _LIBCPP_HIDE_FROM_ABI deque& operator=(const deque& __c);
 
 #ifndef _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI deque(initializer_list<value_type> __il);
   _LIBCPP_HIDE_FROM_ABI deque(initializer_list<value_type> __il, const allocator_type& __a);
 
   _LIBCPP_HIDE_FROM_ABI deque& operator=(initializer_list<value_type> __il) {
     assign(__il);
     return *this;
   }
 
   _LIBCPP_HIDE_FROM_ABI deque(deque&& __c) noexcept(is_nothrow_move_constructible<allocator_type>::value);
   _LIBCPP_HIDE_FROM_ABI deque(deque&& __c, const __type_identity_t<allocator_type>& __a);
   _LIBCPP_HIDE_FROM_ABI deque&
   operator=(deque&& __c) noexcept(__alloc_traits::propagate_on_container_move_assignment::value &&
                                   is_nothrow_move_assignable<allocator_type>::value);
 
   _LIBCPP_HIDE_FROM_ABI void assign(initializer_list<value_type> __il) { assign(__il.begin(), __il.end()); }
 #endif // _LIBCPP_CXX03_LANG
 
   template <class _InputIter,
             __enable_if_t<__has_input_iterator_category<_InputIter>::value &&
                               !__has_random_access_iterator_category<_InputIter>::value,
                           int> = 0>
   _LIBCPP_HIDE_FROM_ABI void assign(_InputIter __f, _InputIter __l);
   template <class _RAIter, __enable_if_t<__has_random_access_iterator_category<_RAIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void assign(_RAIter __f, _RAIter __l);
 
 #if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<_Tp> _Range>
   _LIBCPP_HIDE_FROM_ABI void assign_range(_Range&& __range) {
     if constexpr (ranges::random_access_range<_Range>) {
       auto __n = static_cast<size_type>(ranges::distance(__range));
       __assign_with_size_random_access(ranges::begin(__range), __n);
 
     } else if constexpr (ranges::forward_range<_Range> || ranges::sized_range<_Range>) {
       auto __n = static_cast<size_type>(ranges::distance(__range));
       __assign_with_size(ranges::begin(__range), __n);
 
     } else {
       __assign_with_sentinel(ranges::begin(__range), ranges::end(__range));
     }
   }
 #endif
 
   _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __v);
 
   _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI allocator_type& __alloc() _NOEXCEPT { return __size_.second(); }
   _LIBCPP_HIDE_FROM_ABI const allocator_type& __alloc() const _NOEXCEPT { return __size_.second(); }
 
   // iterators:
 
   _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT {
     __map_pointer __mp = __map_.begin() + __start_ / __block_size;
     return iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
   }
 
   _LIBCPP_HIDE_FROM_ABI const_iterator 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);
   }
 
   _LIBCPP_HIDE_FROM_ABI iterator 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);
   }
 
   _LIBCPP_HIDE_FROM_ABI const_iterator 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);
   }
 
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); }
   _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); }
   _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { return const_reverse_iterator(begin()); }
 
   _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return begin(); }
   _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return end(); }
   _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
   _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return const_reverse_iterator(begin()); }
 
   // capacity:
   _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size(); }
 
   _LIBCPP_HIDE_FROM_ABI size_type& __size() _NOEXCEPT { return __size_.first(); }
   _LIBCPP_HIDE_FROM_ABI const size_type& __size() const _NOEXCEPT { return __size_.first(); }
 
   _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
     return std::min<size_type>(__alloc_traits::max_size(__alloc()), numeric_limits<difference_type>::max());
   }
   _LIBCPP_HIDE_FROM_ABI void resize(size_type __n);
   _LIBCPP_HIDE_FROM_ABI void resize(size_type __n, const value_type& __v);
   _LIBCPP_HIDE_FROM_ABI void shrink_to_fit() _NOEXCEPT;
   _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return size() == 0; }
 
   // element access:
   _LIBCPP_HIDE_FROM_ABI reference operator[](size_type __i) _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI const_reference operator[](size_type __i) const _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI reference at(size_type __i);
   _LIBCPP_HIDE_FROM_ABI const_reference at(size_type __i) const;
   _LIBCPP_HIDE_FROM_ABI reference front() _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI const_reference front() const _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI reference back() _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI const_reference back() const _NOEXCEPT;
 
   // 23.2.2.3 modifiers:
   _LIBCPP_HIDE_FROM_ABI void push_front(const value_type& __v);
   _LIBCPP_HIDE_FROM_ABI void push_back(const value_type& __v);
 #ifndef _LIBCPP_CXX03_LANG
 #  if _LIBCPP_STD_VER >= 17
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI reference emplace_front(_Args&&... __args);
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI reference emplace_back(_Args&&... __args);
 #  else
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI void emplace_front(_Args&&... __args);
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI void emplace_back(_Args&&... __args);
 #  endif
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI iterator emplace(const_iterator __p, _Args&&... __args);
 
   _LIBCPP_HIDE_FROM_ABI void push_front(value_type&& __v);
   _LIBCPP_HIDE_FROM_ABI void push_back(value_type&& __v);
 
 #  if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<_Tp> _Range>
   _LIBCPP_HIDE_FROM_ABI void prepend_range(_Range&& __range) {
     insert_range(begin(), std::forward<_Range>(__range));
   }
 
   template <_ContainerCompatibleRange<_Tp> _Range>
   _LIBCPP_HIDE_FROM_ABI void append_range(_Range&& __range) {
     insert_range(end(), std::forward<_Range>(__range));
   }
 #  endif
 
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __v);
 
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, initializer_list<value_type> __il) {
     return insert(__p, __il.begin(), __il.end());
   }
 #endif // _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __v);
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, size_type __n, const value_type& __v);
   template <class _InputIter, __enable_if_t<__has_exactly_input_iterator_category<_InputIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _InputIter __f, _InputIter __l);
   template <class _ForwardIterator,
             __enable_if_t<__has_exactly_forward_iterator_category<_ForwardIterator>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l);
   template <class _BiIter, __enable_if_t<__has_bidirectional_iterator_category<_BiIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _BiIter __f, _BiIter __l);
 
 #if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<_Tp> _Range>
   _LIBCPP_HIDE_FROM_ABI iterator insert_range(const_iterator __position, _Range&& __range) {
     if constexpr (ranges::bidirectional_range<_Range>) {
       auto __n = static_cast<size_type>(ranges::distance(__range));
       return __insert_bidirectional(__position, ranges::begin(__range), ranges::end(__range), __n);
 
     } else if constexpr (ranges::forward_range<_Range> || ranges::sized_range<_Range>) {
       auto __n = static_cast<size_type>(ranges::distance(__range));
       return __insert_with_size(__position, ranges::begin(__range), __n);
 
     } else {
       return __insert_with_sentinel(__position, ranges::begin(__range), ranges::end(__range));
     }
   }
 #endif
 
   _LIBCPP_HIDE_FROM_ABI void pop_front();
   _LIBCPP_HIDE_FROM_ABI void pop_back();
   _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p);
   _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l);
 
   _LIBCPP_HIDE_FROM_ABI void swap(deque& __c)
 #if _LIBCPP_STD_VER >= 14
       _NOEXCEPT;
 #else
       _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<allocator_type>);
 #endif
   _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT;
 
   _LIBCPP_HIDE_FROM_ABI bool __invariants() const {
     if (!__map_.__invariants())
       return false;
     if (__map_.size() >= size_type(-1) / __block_size)
       return false;
     for (__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;
   }
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(deque& __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>());
   }
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(deque& __c, true_type)
       _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value) {
     __alloc() = std::move(__c.__alloc());
   }
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(deque&, false_type) _NOEXCEPT {}
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign(deque& __c)
       _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value&&
                      is_nothrow_move_assignable<allocator_type>::value) {
     __map_   = std::move(__c.__map_);
     __start_ = __c.__start_;
     __size() = __c.size();
     __move_assign_alloc(__c);
     __c.__start_ = __c.__size() = 0;
   }
 
   _LIBCPP_HIDE_FROM_ABI static size_type __recommend_blocks(size_type __n) {
     return __n / __block_size + (__n % __block_size != 0);
   }
   _LIBCPP_HIDE_FROM_ABI size_type __capacity() const {
     return __map_.size() == 0 ? 0 : __map_.size() * __block_size - 1;
   }
   _LIBCPP_HIDE_FROM_ABI size_type __block_count() const { return __map_.size(); }
 
   _LIBCPP_HIDE_FROM_ABI size_type __front_spare() const { return __start_; }
   _LIBCPP_HIDE_FROM_ABI size_type __front_spare_blocks() const { return __front_spare() / __block_size; }
   _LIBCPP_HIDE_FROM_ABI size_type __back_spare() const { return __capacity() - (__start_ + size()); }
   _LIBCPP_HIDE_FROM_ABI size_type __back_spare_blocks() const { return __back_spare() / __block_size; }
 
 private:
   enum __asan_annotation_type { __asan_unposion, __asan_poison };
 
   enum __asan_annotation_place {
     __asan_front_moved,
     __asan_back_moved,
   };
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_from_to(
       size_type __beg,
       size_type __end,
       __asan_annotation_type __annotation_type,
       __asan_annotation_place __place) const _NOEXCEPT {
     (void)__beg;
     (void)__end;
     (void)__annotation_type;
     (void)__place;
 #ifndef _LIBCPP_HAS_NO_ASAN
     // __beg - index of the first item to annotate
     // __end - index behind the last item to annotate (so last item + 1)
     // __annotation_type - __asan_unposion or __asan_poison
     // __place - __asan_front_moved or __asan_back_moved
     // Note: All indexes in __map_
     if (__beg == __end)
       return;
     // __annotations_beg_map - first chunk which annotations we want to modify
     // __annotations_end_map - last chunk which annotations we want to modify
     // NOTE: if __end % __block_size == 0, __annotations_end_map points at the next block, which may not exist
     __map_const_iterator __annotations_beg_map = __map_.begin() + __beg / __block_size;
     __map_const_iterator __annotations_end_map = __map_.begin() + __end / __block_size;
 
     bool const __poisoning = __annotation_type == __asan_poison;
     // __old_c_beg_index - index of the first element in old container
     // __old_c_end_index - index of the end of old container (last + 1)
     // Note: may be outside the area we are annotating
     size_t __old_c_beg_index = (__poisoning && __place == __asan_front_moved) ? __beg : __start_;
     size_t __old_c_end_index = (__poisoning && __place == __asan_back_moved) ? __end : __start_ + size();
     bool const __front       = __place == __asan_front_moved;
 
     if (__poisoning && empty()) {
       // Special case: we shouldn't trust __start_
       __old_c_beg_index = __beg;
       __old_c_end_index = __end;
     }
     // __old_c_beg_map - memory block (chunk) with first element
     // __old_c_end_map - memory block (chunk) with end of old container
     // Note: if __old_c_end_index % __block_size == 0, __old_c_end_map points at the next block,
     // which may not exist
     __map_const_iterator __old_c_beg_map = __map_.begin() + __old_c_beg_index / __block_size;
     __map_const_iterator __old_c_end_map = __map_.begin() + __old_c_end_index / __block_size;
 
     // One edge (front/end) of the container was moved and one was not modified.
     // __new_edge_index - index of new edge
     // __new_edge_map    - memory block (chunk) with new edge, it always equals to
     //                    __annotations_beg_map or __annotations_end_map
     // __old_edge_map    - memory block (chunk) with old edge, it always equals to
     //                    __old_c_beg_map or __old_c_end_map
     size_t __new_edge_index             = (__poisoning ^ __front) ? __beg : __end;
     __map_const_iterator __new_edge_map = __map_.begin() + __new_edge_index / __block_size;
     __map_const_iterator __old_edge_map = __front ? __old_c_end_map : __old_c_beg_map;
 
     // We iterate over map pointers (chunks) and fully poison all memory blocks between the first and the last.
     // First and last chunk may be partially poisoned.
     // __annotate_end_map may point at not existing chunk, therefore we have to have a check for it.
     for (__map_const_iterator __map_it = __annotations_beg_map; __map_it <= __annotations_end_map; ++__map_it) {
       if (__map_it == __annotations_end_map && __end % __block_size == 0)
         // Chunk may not exist, but nothing to do here anyway
         break;
 
       // The beginning and the end of the current memory block
       const void* __mem_beg = std::__to_address(*__map_it);
       const void* __mem_end = std::__to_address(*__map_it + __block_size);
 
       // The beginning of memory-in-use in the memory block before container modification
       const void* __old_beg =
           (__map_it == __old_c_beg_map) ? std::__to_address(*__map_it + (__old_c_beg_index % __block_size)) : __mem_beg;
 
       // The end of memory-in-use in the memory block before container modification
       const void* __old_end;
       if (__map_it < __old_c_beg_map || __map_it > __old_c_end_map || (!__poisoning && empty()))
         __old_end = __old_beg;
       else
         __old_end = (__map_it == __old_c_end_map)
                       ? std::__to_address(*__map_it + (__old_c_end_index % __block_size))
                       : __mem_end;
 
       // New edge of the container in current memory block
       // If the edge is in a different chunk it points on corresponding end of the memory block
       const void* __new_edge;
       if (__map_it == __new_edge_map)
         __new_edge = std::__to_address(*__map_it + (__new_edge_index % __block_size));
       else
         __new_edge = (__poisoning ^ __front) ? __mem_beg : __mem_end;
 
       // Not modified edge of the container
       // If the edge is in a different chunk it points on corresponding end of the memory block
       const void* __old_edge;
       if (__map_it == __old_edge_map)
         __old_edge = __front ? __old_end : __old_beg;
       else
         __old_edge = __front ? __mem_end : __mem_beg;
 
       // __new_beg - the beginning of memory-in-use in the memory block after container modification
       // __new_end - the end of memory-in-use in the memory block after container modification
       const void* __new_beg = __front ? __new_edge : __old_edge;
       const void* __new_end = __front ? __old_edge : __new_edge;
 
       std::__annotate_double_ended_contiguous_container<_Allocator>(
           __mem_beg, __mem_end, __old_beg, __old_end, __new_beg, __new_end);
     }
 #endif // !_LIBCPP_HAS_NO_ASAN
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_new(size_type __current_size) const _NOEXCEPT {
     (void)__current_size;
 #ifndef _LIBCPP_HAS_NO_ASAN
     if (__current_size == 0)
       __annotate_from_to(0, __map_.size() * __block_size, __asan_poison, __asan_back_moved);
     else {
       __annotate_from_to(0, __start_, __asan_poison, __asan_front_moved);
       __annotate_from_to(__start_ + __current_size, __map_.size() * __block_size, __asan_poison, __asan_back_moved);
     }
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_delete() const _NOEXCEPT {
 #ifndef _LIBCPP_HAS_NO_ASAN
     if (empty()) {
       for (size_t __i = 0; __i < __map_.size(); ++__i) {
         __annotate_whole_block(__i, __asan_unposion);
       }
     } else {
       __annotate_from_to(0, __start_, __asan_unposion, __asan_front_moved);
       __annotate_from_to(__start_ + size(), __map_.size() * __block_size, __asan_unposion, __asan_back_moved);
     }
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_increase_front(size_type __n) const _NOEXCEPT {
     (void)__n;
 #ifndef _LIBCPP_HAS_NO_ASAN
     __annotate_from_to(__start_ - __n, __start_, __asan_unposion, __asan_front_moved);
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_increase_back(size_type __n) const _NOEXCEPT {
     (void)__n;
 #ifndef _LIBCPP_HAS_NO_ASAN
     __annotate_from_to(__start_ + size(), __start_ + size() + __n, __asan_unposion, __asan_back_moved);
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_shrink_front(size_type __old_size, size_type __old_start) const _NOEXCEPT {
     (void)__old_size;
     (void)__old_start;
 #ifndef _LIBCPP_HAS_NO_ASAN
     __annotate_from_to(__old_start, __old_start + (__old_size - size()), __asan_poison, __asan_front_moved);
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_shrink_back(size_type __old_size, size_type __old_start) const _NOEXCEPT {
     (void)__old_size;
     (void)__old_start;
 #ifndef _LIBCPP_HAS_NO_ASAN
     __annotate_from_to(__old_start + size(), __old_start + __old_size, __asan_poison, __asan_back_moved);
 #endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __annotate_poison_block(const void* __beginning, const void* __end) const _NOEXCEPT {
     std::__annotate_double_ended_contiguous_container<_Allocator>(__beginning, __end, __beginning, __end, __end, __end);
   }
 
   _LIBCPP_HIDE_FROM_ABI void
   __annotate_whole_block(size_t __block_index, __asan_annotation_type __annotation_type) const _NOEXCEPT {
     (void)__block_index;
     (void)__annotation_type;
 #ifndef _LIBCPP_HAS_NO_ASAN
     __map_const_iterator __block_it = __map_.begin() + __block_index;
     const void* __block_start       = std::__to_address(*__block_it);
     const void* __block_end         = std::__to_address(*__block_it + __block_size);
 
     if (__annotation_type == __asan_poison)
       __annotate_poison_block(__block_start, __block_end);
     else {
       std::__annotate_double_ended_contiguous_container<_Allocator>(
           __block_start, __block_end, __block_start, __block_start, __block_start, __block_end);
     }
 #endif
   }
 #if !defined(_LIBCPP_HAS_NO_ASAN)
 
 public:
   _LIBCPP_HIDE_FROM_ABI bool __verify_asan_annotations() const _NOEXCEPT {
     // This function tests deque object annotations.
     if (empty()) {
       for (__map_const_iterator __it = __map_.begin(); __it != __map_.end(); ++__it) {
         if (!__sanitizer_verify_double_ended_contiguous_container(
                 std::__to_address(*__it),
                 std::__to_address(*__it),
                 std::__to_address(*__it),
                 std::__to_address(*__it + __block_size)))
           return false;
       }
 
       return true;
     }
 
     size_type __end                 = __start_ + size();
     __map_const_iterator __first_mp = __map_.begin() + __start_ / __block_size;
     __map_const_iterator __last_mp  = __map_.begin() + (__end - 1) / __block_size;
 
     // Pointers to first and after last elements
     // Those can be in different deque blocks
     const void* __p_beg = std::__to_address(*__first_mp + (__start_ % __block_size));
     const void* __p_end =
         std::__to_address(*__last_mp + ((__end % __block_size == 0) ? __block_size : __end % __block_size));
 
     for (__map_const_iterator __it = __map_.begin(); __it != __map_.end(); ++__it) {
       // Go over all blocks, find the place we are in and verify its annotations
       // Note that __p_end points *behind* the last item.
 
       // - blocks before the first block with container elements
       // - first block with items
       // - last block with items
       // - blocks after last block with ciontainer elements
 
       // Is the block before or after deque blocks that contain elements?
       if (__it < __first_mp || __it > __last_mp) {
         if (!__sanitizer_verify_double_ended_contiguous_container(
                 std::__to_address(*__it),
                 std::__to_address(*__it),
                 std::__to_address(*__it),
                 std::__to_address(*__it + __block_size)))
           return false;
       } else {
         const void* __containers_buffer_beg = (__it == __first_mp) ? __p_beg : (const void*)std::__to_address(*__it);
         const void* __containers_buffer_end =
             (__it == __last_mp) ? __p_end : (const void*)std::__to_address(*__it + __block_size);
         if (!__sanitizer_verify_double_ended_contiguous_container(
                 std::__to_address(*__it),
                 __containers_buffer_beg,
                 __containers_buffer_end,
                 std::__to_address(*__it + __block_size))) {
           return false;
         }
       }
     }
     return true;
   }
 
 private:
 #endif // _LIBCPP_VERIFY_ASAN_DEQUE_ANNOTATIONS
   _LIBCPP_HIDE_FROM_ABI bool __maybe_remove_front_spare(bool __keep_one = true) {
     if (__front_spare_blocks() >= 2 || (!__keep_one && __front_spare_blocks())) {
       __annotate_whole_block(0, __asan_unposion);
       __alloc_traits::deallocate(__alloc(), __map_.front(), __block_size);
       __map_.pop_front();
       __start_ -= __block_size;
       return true;
     }
     return false;
   }
 
   _LIBCPP_HIDE_FROM_ABI bool __maybe_remove_back_spare(bool __keep_one = true) {
     if (__back_spare_blocks() >= 2 || (!__keep_one && __back_spare_blocks())) {
       __annotate_whole_block(__map_.size() - 1, __asan_unposion);
       __alloc_traits::deallocate(__alloc(), __map_.back(), __block_size);
       __map_.pop_back();
       return true;
     }
     return false;
   }
 
   template <class _Iterator, class _Sentinel>
   _LIBCPP_HIDE_FROM_ABI void __assign_with_sentinel(_Iterator __f, _Sentinel __l);
 
   template <class _RandomAccessIterator>
   _LIBCPP_HIDE_FROM_ABI void __assign_with_size_random_access(_RandomAccessIterator __f, difference_type __n);
   template <class _Iterator>
   _LIBCPP_HIDE_FROM_ABI void __assign_with_size(_Iterator __f, difference_type __n);
 
   template <class _Iterator, class _Sentinel>
   _LIBCPP_HIDE_FROM_ABI iterator __insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l);
 
   template <class _Iterator>
   _LIBCPP_HIDE_FROM_ABI iterator __insert_with_size(const_iterator __p, _Iterator __f, size_type __n);
 
   template <class _BiIter, class _Sentinel>
   _LIBCPP_HIDE_FROM_ABI iterator
   __insert_bidirectional(const_iterator __p, _BiIter __f, _Sentinel __sent, size_type __n);
   template <class _BiIter>
   _LIBCPP_HIDE_FROM_ABI iterator __insert_bidirectional(const_iterator __p, _BiIter __f, _BiIter __l, size_type __n);
 
   template <class _InpIter, __enable_if_t<__has_exactly_input_iterator_category<_InpIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __append(_InpIter __f, _InpIter __l);
   template <class _ForIter, __enable_if_t<__has_forward_iterator_category<_ForIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __append(_ForIter __f, _ForIter __l);
 
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void __append_with_size(_InputIterator __from, size_type __n);
   template <class _InputIterator, class _Sentinel>
   _LIBCPP_HIDE_FROM_ABI void __append_with_sentinel(_InputIterator __f, _Sentinel __l);
 
   _LIBCPP_HIDE_FROM_ABI void __append(size_type __n);
   _LIBCPP_HIDE_FROM_ABI void __append(size_type __n, const value_type& __v);
   _LIBCPP_HIDE_FROM_ABI void __erase_to_end(const_iterator __f);
   _LIBCPP_HIDE_FROM_ABI void __add_front_capacity();
   _LIBCPP_HIDE_FROM_ABI void __add_front_capacity(size_type __n);
   _LIBCPP_HIDE_FROM_ABI void __add_back_capacity();
   _LIBCPP_HIDE_FROM_ABI void __add_back_capacity(size_type __n);
   _LIBCPP_HIDE_FROM_ABI iterator __move_and_check(iterator __f, iterator __l, iterator __r, const_pointer& __vt);
   _LIBCPP_HIDE_FROM_ABI iterator
   __move_backward_and_check(iterator __f, iterator __l, iterator __r, const_pointer& __vt);
   _LIBCPP_HIDE_FROM_ABI void __move_construct_and_check(iterator __f, iterator __l, iterator __r, const_pointer& __vt);
   _LIBCPP_HIDE_FROM_ABI void
   __move_construct_backward_and_check(iterator __f, iterator __l, iterator __r, const_pointer& __vt);
 
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const deque& __c) {
     __copy_assign_alloc(__c, integral_constant<bool, __alloc_traits::propagate_on_container_copy_assignment::value>());
   }
 
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const deque& __c, true_type) {
     if (__alloc() != __c.__alloc()) {
       clear();
       shrink_to_fit();
     }
     __alloc()        = __c.__alloc();
     __map_.__alloc() = __c.__map_.__alloc();
   }
 
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const deque&, false_type) {}
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign(deque& __c, true_type)
       _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
   _LIBCPP_HIDE_FROM_ABI void __move_assign(deque& __c, false_type);
 };
 
 template <class _Tp, class _Alloc>
 _LIBCPP_CONSTEXPR const typename allocator_traits<_Alloc>::difference_type deque<_Tp, _Alloc>::__block_size =
     __deque_block_size<value_type, difference_type>::value;
 
 #if _LIBCPP_STD_VER >= 17
 template <class _InputIterator,
           class _Alloc = allocator<__iter_value_type<_InputIterator>>,
           class        = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
           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<__has_input_iterator_category<_InputIterator>::value>,
           class = enable_if_t<__is_allocator<_Alloc>::value> >
 deque(_InputIterator, _InputIterator, _Alloc) -> deque<__iter_value_type<_InputIterator>, _Alloc>;
 #endif
 
 #if _LIBCPP_STD_VER >= 23
 template <ranges::input_range _Range,
           class _Alloc = allocator<ranges::range_value_t<_Range>>,
           class        = enable_if_t<__is_allocator<_Alloc>::value> >
 deque(from_range_t, _Range&&, _Alloc = _Alloc()) -> deque<ranges::range_value_t<_Range>, _Alloc>;
 #endif
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(size_type __n) : __start_(0), __size_(0, __default_init_tag()) {
   __annotate_new(0);
   if (__n > 0)
     __append(__n);
 }
 
 #if _LIBCPP_STD_VER >= 14
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(size_type __n, const _Allocator& __a)
     : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
   __annotate_new(0);
   if (__n > 0)
     __append(__n);
 }
 #endif
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v) : __start_(0), __size_(0, __default_init_tag()) {
   __annotate_new(0);
   if (__n > 0)
     __append(__n, __v);
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIter, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> >
 deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l) : __start_(0), __size_(0, __default_init_tag()) {
   __annotate_new(0);
   __append(__f, __l);
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIter, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> >
 deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l, const allocator_type& __a)
     : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
   __annotate_new(0);
   __append(__f, __l);
 }
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(const deque& __c)
     : __map_(__pointer_allocator(__alloc_traits::select_on_container_copy_construction(__c.__alloc()))),
       __start_(0),
       __size_(0, __map_.__alloc()) {
   __annotate_new(0);
   __append(__c.begin(), __c.end());
 }
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(const deque& __c, const __type_identity_t<allocator_type>& __a)
     : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
   __annotate_new(0);
   __append(__c.begin(), __c.end());
 }
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>& deque<_Tp, _Allocator>::operator=(const deque& __c) {
   if (this != std::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) : __start_(0), __size_(0, __default_init_tag()) {
   __annotate_new(0);
   __append(__il.begin(), __il.end());
 }
 
 template <class _Tp, class _Allocator>
 deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il, const allocator_type& __a)
     : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {
   __annotate_new(0);
   __append(__il.begin(), __il.end());
 }
 
 template <class _Tp, class _Allocator>
 inline deque<_Tp, _Allocator>::deque(deque&& __c) noexcept(is_nothrow_move_constructible<allocator_type>::value)
     : __map_(std::move(__c.__map_)), __start_(std::move(__c.__start_)), __size_(std::move(__c.__size_)) {
   __c.__start_ = 0;
   __c.__size() = 0;
 }
 
 template <class _Tp, class _Allocator>
 inline deque<_Tp, _Allocator>::deque(deque&& __c, const __type_identity_t<allocator_type>& __a)
     : __map_(std::move(__c.__map_), __pointer_allocator(__a)),
       __start_(std::move(__c.__start_)),
       __size_(std::move(__c.__size()), __a) {
   if (__a == __c.__alloc()) {
     __c.__start_ = 0;
     __c.__size() = 0;
   } else {
     __map_.clear();
     __start_ = 0;
     __size() = 0;
     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 (__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();
   __move_assign(__c);
 }
 
 #endif // _LIBCPP_CXX03_LANG
 
 template <class _Tp, class _Allocator>
 template <class _InputIter,
           __enable_if_t<__has_input_iterator_category<_InputIter>::value &&
                             !__has_random_access_iterator_category<_InputIter>::value,
                         int> >
 void deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l) {
   __assign_with_sentinel(__f, __l);
 }
 
 template <class _Tp, class _Allocator>
 template <class _Iterator, class _Sentinel>
 _LIBCPP_HIDE_FROM_ABI void deque<_Tp, _Allocator>::__assign_with_sentinel(_Iterator __f, _Sentinel __l) {
   iterator __i = begin();
   iterator __e = end();
   for (; __f != __l && __i != __e; ++__f, (void)++__i)
     *__i = *__f;
   if (__f != __l)
     __append_with_sentinel(std::move(__f), std::move(__l));
   else
     __erase_to_end(__i);
 }
 
 template <class _Tp, class _Allocator>
 template <class _RAIter, __enable_if_t<__has_random_access_iterator_category<_RAIter>::value, int> >
 void deque<_Tp, _Allocator>::assign(_RAIter __f, _RAIter __l) {
   __assign_with_size_random_access(__f, __l - __f);
 }
 
 template <class _Tp, class _Allocator>
 template <class _RandomAccessIterator>
 _LIBCPP_HIDE_FROM_ABI void
 deque<_Tp, _Allocator>::__assign_with_size_random_access(_RandomAccessIterator __f, difference_type __n) {
   if (static_cast<size_type>(__n) > size()) {
     auto __l = __f + size();
     std::copy(__f, __l, begin());
     __append_with_size(__l, __n - size());
   } else
     __erase_to_end(std::copy_n(__f, __n, begin()));
 }
 
 template <class _Tp, class _Allocator>
 template <class _Iterator>
 _LIBCPP_HIDE_FROM_ABI void deque<_Tp, _Allocator>::__assign_with_size(_Iterator __f, difference_type __n) {
   if (static_cast<size_type>(__n) > size()) {
     auto __added_size = __n - size();
 
     auto __i = begin();
     for (auto __count = size(); __count != 0; --__count) {
       *__i++ = *__f++;
     }
 
     __append_with_size(__f, __added_size);
 
   } else {
     __erase_to_end(std::copy_n(__f, __n, begin()));
   }
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::assign(size_type __n, const value_type& __v) {
   if (__n > size()) {
     std::fill_n(begin(), size(), __v);
     __n -= size();
     __append(__n, __v);
   } else
     __erase_to_end(std::fill_n(begin(), __n, __v));
 }
 
 template <class _Tp, class _Allocator>
 inline _Allocator deque<_Tp, _Allocator>::get_allocator() const _NOEXCEPT {
   return __alloc();
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::resize(size_type __n) {
   if (__n > size())
     __append(__n - size());
   else if (__n < size())
     __erase_to_end(begin() + __n);
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::resize(size_type __n, const value_type& __v) {
   if (__n > size())
     __append(__n - size(), __v);
   else if (__n < size())
     __erase_to_end(begin() + __n);
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT {
   allocator_type& __a = __alloc();
   if (empty()) {
     __annotate_delete();
     while (__map_.size() > 0) {
       __alloc_traits::deallocate(__a, __map_.back(), __block_size);
       __map_.pop_back();
     }
     __start_ = 0;
   } else {
     __maybe_remove_front_spare(/*__keep_one=*/false);
     __maybe_remove_back_spare(/*__keep_one=*/false);
   }
   __map_.shrink_to_fit();
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::reference deque<_Tp, _Allocator>::operator[](size_type __i) _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i < size(), "deque::operator[] index out of bounds");
   size_type __p = __start_ + __i;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::const_reference
 deque<_Tp, _Allocator>::operator[](size_type __i) const _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i < size(), "deque::operator[] index out of bounds");
   size_type __p = __start_ + __i;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::reference deque<_Tp, _Allocator>::at(size_type __i) {
   if (__i >= size())
     std::__throw_out_of_range("deque");
   size_type __p = __start_ + __i;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::const_reference deque<_Tp, _Allocator>::at(size_type __i) const {
   if (__i >= size())
     std::__throw_out_of_range("deque");
   size_type __p = __start_ + __i;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::reference deque<_Tp, _Allocator>::front() _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::front called on an empty deque");
   return *(*(__map_.begin() + __start_ / __block_size) + __start_ % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::const_reference deque<_Tp, _Allocator>::front() const _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::front called on an empty deque");
   return *(*(__map_.begin() + __start_ / __block_size) + __start_ % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::reference deque<_Tp, _Allocator>::back() _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::back called on an empty deque");
   size_type __p = size() + __start_ - 1;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 inline typename deque<_Tp, _Allocator>::const_reference deque<_Tp, _Allocator>::back() const _NOEXCEPT {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::back called on an empty deque");
   size_type __p = size() + __start_ - 1;
   return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::push_back(const value_type& __v) {
   allocator_type& __a = __alloc();
   if (__back_spare() == 0)
     __add_back_capacity();
   // __back_spare() >= 1
   __annotate_increase_back(1);
   __alloc_traits::construct(__a, std::addressof(*end()), __v);
   ++__size();
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::push_front(const value_type& __v) {
   allocator_type& __a = __alloc();
   if (__front_spare() == 0)
     __add_front_capacity();
   // __front_spare() >= 1
   __annotate_increase_front(1);
   __alloc_traits::construct(__a, std::addressof(*--begin()), __v);
   --__start_;
   ++__size();
 }
 
 #ifndef _LIBCPP_CXX03_LANG
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::push_back(value_type&& __v) {
   allocator_type& __a = __alloc();
   if (__back_spare() == 0)
     __add_back_capacity();
   // __back_spare() >= 1
   __annotate_increase_back(1);
   __alloc_traits::construct(__a, std::addressof(*end()), std::move(__v));
   ++__size();
 }
 
 template <class _Tp, class _Allocator>
 template <class... _Args>
 #  if _LIBCPP_STD_VER >= 17
 typename deque<_Tp, _Allocator>::reference
 #  else
 void
 #  endif
 deque<_Tp, _Allocator>::emplace_back(_Args&&... __args) {
   allocator_type& __a = __alloc();
   if (__back_spare() == 0)
     __add_back_capacity();
   // __back_spare() >= 1
   __annotate_increase_back(1);
   __alloc_traits::construct(__a, std::addressof(*end()), std::forward<_Args>(__args)...);
   ++__size();
 #  if _LIBCPP_STD_VER >= 17
   return *--end();
 #  endif
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::push_front(value_type&& __v) {
   allocator_type& __a = __alloc();
   if (__front_spare() == 0)
     __add_front_capacity();
   // __front_spare() >= 1
   __annotate_increase_front(1);
   __alloc_traits::construct(__a, std::addressof(*--begin()), std::move(__v));
   --__start_;
   ++__size();
 }
 
 template <class _Tp, class _Allocator>
 template <class... _Args>
 #  if _LIBCPP_STD_VER >= 17
 typename deque<_Tp, _Allocator>::reference
 #  else
 void
 #  endif
 deque<_Tp, _Allocator>::emplace_front(_Args&&... __args) {
   allocator_type& __a = __alloc();
   if (__front_spare() == 0)
     __add_front_capacity();
   // __front_spare() >= 1
   __annotate_increase_front(1);
   __alloc_traits::construct(__a, std::addressof(*--begin()), std::forward<_Args>(__args)...);
   --__start_;
   ++__size();
 #  if _LIBCPP_STD_VER >= 17
   return *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 - begin();
   size_type __to_end  = size() - __pos;
   allocator_type& __a = __alloc();
   if (__pos < __to_end) { // insert by shifting things backward
     if (__front_spare() == 0)
       __add_front_capacity();
     // __front_spare() >= 1
     __annotate_increase_front(1);
     if (__pos == 0) {
       __alloc_traits::construct(__a, std::addressof(*--begin()), std::move(__v));
       --__start_;
       ++__size();
     } else {
       iterator __b   = begin();
       iterator __bm1 = std::prev(__b);
       __alloc_traits::construct(__a, std::addressof(*__bm1), std::move(*__b));
       --__start_;
       ++__size();
       if (__pos > 1)
         __b = std::move(std::next(__b), __b + __pos, __b);
       *__b = std::move(__v);
     }
   } else { // insert by shifting things forward
     if (__back_spare() == 0)
       __add_back_capacity();
     // __back_capacity >= 1
     __annotate_increase_back(1);
     size_type __de = size() - __pos;
     if (__de == 0) {
       __alloc_traits::construct(__a, std::addressof(*end()), std::move(__v));
       ++__size();
     } else {
       iterator __e   = end();
       iterator __em1 = std::prev(__e);
       __alloc_traits::construct(__a, std::addressof(*__e), std::move(*__em1));
       ++__size();
       if (__de > 1)
         __e = std::move_backward(__e - __de, __em1, __e);
       *--__e = std::move(__v);
     }
   }
   return 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 - begin();
   size_type __to_end  = size() - __pos;
   allocator_type& __a = __alloc();
   if (__pos < __to_end) { // insert by shifting things backward
     if (__front_spare() == 0)
       __add_front_capacity();
     // __front_spare() >= 1
     __annotate_increase_front(1);
     if (__pos == 0) {
       __alloc_traits::construct(__a, std::addressof(*--begin()), std::forward<_Args>(__args)...);
       --__start_;
       ++__size();
     } else {
       __temp_value<value_type, _Allocator> __tmp(__alloc(), std::forward<_Args>(__args)...);
       iterator __b   = begin();
       iterator __bm1 = std::prev(__b);
       __alloc_traits::construct(__a, std::addressof(*__bm1), std::move(*__b));
       --__start_;
       ++__size();
       if (__pos > 1)
         __b = std::move(std::next(__b), __b + __pos, __b);
       *__b = std::move(__tmp.get());
     }
   } else { // insert by shifting things forward
     if (__back_spare() == 0)
       __add_back_capacity();
     // __back_capacity >= 1
     __annotate_increase_back(1);
     size_type __de = size() - __pos;
     if (__de == 0) {
       __alloc_traits::construct(__a, std::addressof(*end()), std::forward<_Args>(__args)...);
       ++__size();
     } else {
       __temp_value<value_type, _Allocator> __tmp(__alloc(), std::forward<_Args>(__args)...);
       iterator __e   = end();
       iterator __em1 = std::prev(__e);
       __alloc_traits::construct(__a, std::addressof(*__e), std::move(*__em1));
       ++__size();
       if (__de > 1)
         __e = std::move_backward(__e - __de, __em1, __e);
       *--__e = std::move(__tmp.get());
     }
   }
   return 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 - begin();
   size_type __to_end  = size() - __pos;
   allocator_type& __a = __alloc();
   if (__pos < __to_end) { // insert by shifting things backward
     if (__front_spare() == 0)
       __add_front_capacity();
     // __front_spare() >= 1
     __annotate_increase_front(1);
     if (__pos == 0) {
       __alloc_traits::construct(__a, std::addressof(*--begin()), __v);
       --__start_;
       ++__size();
     } else {
       const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
       iterator __b       = begin();
       iterator __bm1     = std::prev(__b);
       if (__vt == pointer_traits<const_pointer>::pointer_to(*__b))
         __vt = pointer_traits<const_pointer>::pointer_to(*__bm1);
       __alloc_traits::construct(__a, std::addressof(*__bm1), std::move(*__b));
       --__start_;
       ++__size();
       if (__pos > 1)
         __b = __move_and_check(std::next(__b), __b + __pos, __b, __vt);
       *__b = *__vt;
     }
   } else { // insert by shifting things forward
     if (__back_spare() == 0)
       __add_back_capacity();
     // __back_capacity >= 1
     __annotate_increase_back(1);
     size_type __de = size() - __pos;
     if (__de == 0) {
       __alloc_traits::construct(__a, std::addressof(*end()), __v);
       ++__size();
     } else {
       const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
       iterator __e       = end();
       iterator __em1     = std::prev(__e);
       if (__vt == pointer_traits<const_pointer>::pointer_to(*__em1))
         __vt = pointer_traits<const_pointer>::pointer_to(*__e);
       __alloc_traits::construct(__a, std::addressof(*__e), std::move(*__em1));
       ++__size();
       if (__de > 1)
         __e = __move_backward_and_check(__e - __de, __em1, __e, __vt);
       *--__e = *__vt;
     }
   }
   return 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 - begin();
   size_type __to_end  = __size() - __pos;
   allocator_type& __a = __alloc();
   if (__pos < __to_end) { // insert by shifting things backward
     if (__n > __front_spare())
       __add_front_capacity(__n - __front_spare());
     // __n <= __front_spare()
     __annotate_increase_front(__n);
     iterator __old_begin = begin();
     iterator __i         = __old_begin;
     if (__n > __pos) {
       for (size_type __m = __n - __pos; __m; --__m, --__start_, ++__size())
         __alloc_traits::construct(__a, std::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);
       std::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
     __annotate_increase_back(__n);
     iterator __old_end = end();
     iterator __i       = __old_end;
     size_type __de     = size() - __pos;
     if (__n > __de) {
       for (size_type __m = __n - __de; __m; --__m, (void)++__i, ++__size())
         __alloc_traits::construct(__a, std::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);
       std::fill_n(__old_end - __n, __n, *__vt);
     }
   }
   return begin() + __pos;
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIter, __enable_if_t<__has_exactly_input_iterator_category<_InputIter>::value, int> >
 typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::insert(const_iterator __p, _InputIter __f, _InputIter __l) {
   return __insert_with_sentinel(__p, __f, __l);
 }
 
 template <class _Tp, class _Allocator>
 template <class _Iterator, class _Sentinel>
 _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::__insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l) {
   __split_buffer<value_type, allocator_type&> __buf(__alloc());
   __buf.__construct_at_end_with_sentinel(std::move(__f), std::move(__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, __enable_if_t<__has_exactly_forward_iterator_category<_ForwardIterator>::value, int> >
 typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l) {
   return __insert_with_size(__p, __f, std::distance(__f, __l));
 }
 
 template <class _Tp, class _Allocator>
 template <class _Iterator>
 _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::__insert_with_size(const_iterator __p, _Iterator __f, size_type __n) {
   __split_buffer<value_type, allocator_type&> __buf(__n, 0, __alloc());
   __buf.__construct_at_end_with_size(__f, __n);
   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, __enable_if_t<__has_bidirectional_iterator_category<_BiIter>::value, int> >
 typename deque<_Tp, _Allocator>::iterator deque<_Tp, _Allocator>::insert(const_iterator __p, _BiIter __f, _BiIter __l) {
   return __insert_bidirectional(__p, __f, __l, std::distance(__f, __l));
 }
 
 template <class _Tp, class _Allocator>
 template <class _BiIter, class _Sentinel>
 _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::__insert_bidirectional(const_iterator __p, _BiIter __f, _Sentinel, size_type __n) {
   return __insert_bidirectional(__p, __f, std::next(__f, __n), __n);
 }
 
 template <class _Tp, class _Allocator>
 template <class _BiIter>
 _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::iterator
 deque<_Tp, _Allocator>::__insert_bidirectional(const_iterator __p, _BiIter __f, _BiIter __l, size_type __n) {
   size_type __pos     = __p - begin();
   size_type __to_end  = size() - __pos;
   allocator_type& __a = __alloc();
   if (__pos < __to_end) { // insert by shifting things backward
     if (__n > __front_spare())
       __add_front_capacity(__n - __front_spare());
     // __n <= __front_spare()
     __annotate_increase_front(__n);
     iterator __old_begin = begin();
     iterator __i         = __old_begin;
     _BiIter __m          = __f;
     if (__n > __pos) {
       __m = __pos < __n / 2 ? std::prev(__l, __pos) : std::next(__f, __n - __pos);
       for (_BiIter __j = __m; __j != __f; --__start_, ++__size())
         __alloc_traits::construct(__a, std::addressof(*--__i), *--__j);
       __n = __pos;
     }
     if (__n > 0) {
       iterator __obn = __old_begin + __n;
       for (iterator __j = __obn; __j != __old_begin;) {
         __alloc_traits::construct(__a, std::addressof(*--__i), std::move(*--__j));
         --__start_;
         ++__size();
       }
       if (__n < __pos)
         __old_begin = std::move(__obn, __old_begin + __pos, __old_begin);
       std::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
     __annotate_increase_back(__n);
     iterator __old_end = end();
     iterator __i       = __old_end;
     _BiIter __m        = __l;
     size_type __de     = size() - __pos;
     if (__n > __de) {
       __m = __de < __n / 2 ? std::next(__f, __de) : std::prev(__l, __n - __de);
       for (_BiIter __j = __m; __j != __l; ++__i, (void)++__j, ++__size())
         __alloc_traits::construct(__a, std::addressof(*__i), *__j);
       __n = __de;
     }
     if (__n > 0) {
       iterator __oen = __old_end - __n;
       for (iterator __j = __oen; __j != __old_end; ++__i, (void)++__j, ++__size())
         __alloc_traits::construct(__a, std::addressof(*__i), std::move(*__j));
       if (__n < __de)
         __old_end = std::move_backward(__old_end - __de, __oen, __old_end);
       std::copy_backward(__f, __m, __old_end);
     }
   }
   return begin() + __pos;
 }
 
 template <class _Tp, class _Allocator>
 template <class _InpIter, __enable_if_t<__has_exactly_input_iterator_category<_InpIter>::value, int> >
 void deque<_Tp, _Allocator>::__append(_InpIter __f, _InpIter __l) {
   __append_with_sentinel(__f, __l);
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIterator, class _Sentinel>
 _LIBCPP_HIDE_FROM_ABI void deque<_Tp, _Allocator>::__append_with_sentinel(_InputIterator __f, _Sentinel __l) {
   for (; __f != __l; ++__f)
 #ifdef _LIBCPP_CXX03_LANG
     push_back(*__f);
 #else
     emplace_back(*__f);
 #endif
 }
 
 template <class _Tp, class _Allocator>
 template <class _ForIter, __enable_if_t<__has_forward_iterator_category<_ForIter>::value, int> >
 void deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l) {
   __append_with_size(__f, std::distance(__f, __l));
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIterator>
 _LIBCPP_HIDE_FROM_ABI void deque<_Tp, _Allocator>::__append_with_size(_InputIterator __f, size_type __n) {
   allocator_type& __a       = __alloc();
   size_type __back_capacity = __back_spare();
   if (__n > __back_capacity)
     __add_back_capacity(__n - __back_capacity);
 
   // __n <= __back_capacity
   __annotate_increase_back(__n);
   for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
     _ConstructTransaction __tx(this, __br);
     for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) {
       __alloc_traits::construct(__a, std::__to_address(__tx.__pos_), *__f);
     }
   }
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::__append(size_type __n) {
   allocator_type& __a       = __alloc();
   size_type __back_capacity = __back_spare();
   if (__n > __back_capacity)
     __add_back_capacity(__n - __back_capacity);
   // __n <= __back_capacity
   __annotate_increase_back(__n);
   for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
     _ConstructTransaction __tx(this, __br);
     for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
       __alloc_traits::construct(__a, std::__to_address(__tx.__pos_));
     }
   }
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::__append(size_type __n, const value_type& __v) {
   allocator_type& __a       = __alloc();
   size_type __back_capacity = __back_spare();
   if (__n > __back_capacity)
     __add_back_capacity(__n - __back_capacity);
   // __n <= __back_capacity
   __annotate_increase_back(__n);
   for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
     _ConstructTransaction __tx(this, __br);
     for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
       __alloc_traits::construct(__a, std::__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 = __alloc();
   if (__back_spare() >= __block_size) {
     __start_ += __block_size;
     pointer __pt = __map_.back();
     __map_.pop_back();
     __map_.push_front(__pt);
   }
   // Else if __map_.size() < __map_.capacity() then we need to allocate 1 buffer
   else if (__map_.size() < __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 (__map_.__front_spare() > 0)
       __map_.push_front(__alloc_traits::allocate(__a, __block_size));
     else {
       __map_.push_back(__alloc_traits::allocate(__a, __block_size));
       // Done allocating, reorder capacity
       pointer __pt = __map_.back();
       __map_.pop_back();
       __map_.push_front(__pt);
     }
     __start_ = __map_.size() == 1 ? __block_size / 2 : __start_ + __block_size;
   }
   // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
   else {
     __split_buffer<pointer, __pointer_allocator&> __buf(
         std::max<size_type>(2 * __map_.capacity(), 1), 0, __map_.__alloc());
 
     typedef __allocator_destructor<_Allocator> _Dp;
     unique_ptr<pointer, _Dp> __hold(__alloc_traits::allocate(__a, __block_size), _Dp(__a, __block_size));
     __buf.push_back(__hold.get());
     __hold.release();
 
     for (__map_pointer __i = __map_.begin(); __i != __map_.end(); ++__i)
       __buf.push_back(*__i);
     std::swap(__map_.__first_, __buf.__first_);
     std::swap(__map_.__begin_, __buf.__begin_);
     std::swap(__map_.__end_, __buf.__end_);
     std::swap(__map_.__end_cap(), __buf.__end_cap());
     __start_ = __map_.size() == 1 ? __block_size / 2 : __start_ + __block_size;
   }
   __annotate_whole_block(0, __asan_poison);
 }
 
 // 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 = __alloc();
   size_type __nb      = __recommend_blocks(__n + __map_.empty());
   // Number of unused blocks at back:
   size_type __back_capacity = __back_spare() / __block_size;
   __back_capacity           = std::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) {
     __start_ += __block_size * __back_capacity;
     for (; __back_capacity > 0; --__back_capacity) {
       pointer __pt = __map_.back();
       __map_.pop_back();
       __map_.push_front(__pt);
     }
   }
   // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
   else if (__nb <= __map_.capacity() -
                        __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, __start_ += __block_size - (__map_.size() == 1)) {
       if (__map_.__front_spare() == 0)
         break;
       __map_.push_front(__alloc_traits::allocate(__a, __block_size));
       __annotate_whole_block(0, __asan_poison);
     }
     for (; __nb > 0; --__nb, ++__back_capacity)
       __map_.push_back(__alloc_traits::allocate(__a, __block_size));
     // Done allocating, reorder capacity
     __start_ += __back_capacity * __block_size;
     for (; __back_capacity > 0; --__back_capacity) {
       pointer __pt = __map_.back();
       __map_.pop_back();
       __map_.push_front(__pt);
       __annotate_whole_block(0, __asan_poison);
     }
   }
   // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
   else {
     size_type __ds = (__nb + __back_capacity) * __block_size - __map_.empty();
     __split_buffer<pointer, __pointer_allocator&> __buf(
         std::max<size_type>(2 * __map_.capacity(), __nb + __map_.size()), 0, __map_.__alloc());
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
       for (; __nb > 0; --__nb) {
         __buf.push_back(__alloc_traits::allocate(__a, __block_size));
         // ASan: this is empty container, we have to poison whole block
         __annotate_poison_block(std::__to_address(__buf.back()), std::__to_address(__buf.back() + __block_size));
       }
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __annotate_delete();
       for (__map_pointer __i = __buf.begin(); __i != __buf.end(); ++__i)
         __alloc_traits::deallocate(__a, *__i, __block_size);
       throw;
     }
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
     for (; __back_capacity > 0; --__back_capacity) {
       __buf.push_back(__map_.back());
       __map_.pop_back();
     }
     for (__map_pointer __i = __map_.begin(); __i != __map_.end(); ++__i)
       __buf.push_back(*__i);
     std::swap(__map_.__first_, __buf.__first_);
     std::swap(__map_.__begin_, __buf.__begin_);
     std::swap(__map_.__end_, __buf.__end_);
     std::swap(__map_.__end_cap(), __buf.__end_cap());
     __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 = __alloc();
   if (__front_spare() >= __block_size) {
     __start_ -= __block_size;
     pointer __pt = __map_.front();
     __map_.pop_front();
     __map_.push_back(__pt);
   }
   // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
   else if (__map_.size() < __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 (__map_.__back_spare() != 0)
       __map_.push_back(__alloc_traits::allocate(__a, __block_size));
     else {
       __map_.push_front(__alloc_traits::allocate(__a, __block_size));
       // Done allocating, reorder capacity
       pointer __pt = __map_.front();
       __map_.pop_front();
       __map_.push_back(__pt);
     }
     __annotate_whole_block(__map_.size() - 1, __asan_poison);
   }
   // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
   else {
     __split_buffer<pointer, __pointer_allocator&> __buf(
         std::max<size_type>(2 * __map_.capacity(), 1), __map_.size(), __map_.__alloc());
 
     typedef __allocator_destructor<_Allocator> _Dp;
     unique_ptr<pointer, _Dp> __hold(__alloc_traits::allocate(__a, __block_size), _Dp(__a, __block_size));
     __buf.push_back(__hold.get());
     __hold.release();
 
     for (__map_pointer __i = __map_.end(); __i != __map_.begin();)
       __buf.push_front(*--__i);
     std::swap(__map_.__first_, __buf.__first_);
     std::swap(__map_.__begin_, __buf.__begin_);
     std::swap(__map_.__end_, __buf.__end_);
     std::swap(__map_.__end_cap(), __buf.__end_cap());
     __annotate_whole_block(__map_.size() - 1, __asan_poison);
   }
 }
 
 // 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 = __alloc();
   size_type __nb      = __recommend_blocks(__n + __map_.empty());
   // Number of unused blocks at front:
   size_type __front_capacity = __front_spare() / __block_size;
   __front_capacity           = std::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) {
     __start_ -= __block_size * __front_capacity;
     for (; __front_capacity > 0; --__front_capacity) {
       pointer __pt = __map_.front();
       __map_.pop_front();
       __map_.push_back(__pt);
     }
   }
   // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
   else if (__nb <= __map_.capacity() -
                        __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 (__map_.__back_spare() == 0)
         break;
       __map_.push_back(__alloc_traits::allocate(__a, __block_size));
       __annotate_whole_block(__map_.size() - 1, __asan_poison);
     }
     for (; __nb > 0; --__nb, ++__front_capacity, __start_ += __block_size - (__map_.size() == 1)) {
       __map_.push_front(__alloc_traits::allocate(__a, __block_size));
       __annotate_whole_block(0, __asan_poison);
     }
     // Done allocating, reorder capacity
     __start_ -= __block_size * __front_capacity;
     for (; __front_capacity > 0; --__front_capacity) {
       pointer __pt = __map_.front();
       __map_.pop_front();
       __map_.push_back(__pt);
     }
   }
   // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
   else {
     size_type __ds = __front_capacity * __block_size;
     __split_buffer<pointer, __pointer_allocator&> __buf(
         std::max<size_type>(2 * __map_.capacity(), __nb + __map_.size()),
         __map_.size() - __front_capacity,
         __map_.__alloc());
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
       for (; __nb > 0; --__nb) {
         __buf.push_back(__alloc_traits::allocate(__a, __block_size));
         // ASan: this is an empty container, we have to poison the whole block
         __annotate_poison_block(std::__to_address(__buf.back()), std::__to_address(__buf.back() + __block_size));
       }
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __annotate_delete();
       for (__map_pointer __i = __buf.begin(); __i != __buf.end(); ++__i)
         __alloc_traits::deallocate(__a, *__i, __block_size);
       throw;
     }
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
     for (; __front_capacity > 0; --__front_capacity) {
       __buf.push_back(__map_.front());
       __map_.pop_front();
     }
     for (__map_pointer __i = __map_.end(); __i != __map_.begin();)
       __buf.push_front(*--__i);
     std::swap(__map_.__first_, __buf.__first_);
     std::swap(__map_.__begin_, __buf.__begin_);
     std::swap(__map_.__end_, __buf.__end_);
     std::swap(__map_.__end_cap(), __buf.__end_cap());
     __start_ -= __ds;
   }
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::pop_front() {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::pop_front called on an empty deque");
   size_type __old_sz    = size();
   size_type __old_start = __start_;
   allocator_type& __a   = __alloc();
   __alloc_traits::destroy(
       __a, std::__to_address(*(__map_.begin() + __start_ / __block_size) + __start_ % __block_size));
   --__size();
   ++__start_;
   __annotate_shrink_front(__old_sz, __old_start);
   __maybe_remove_front_spare();
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::pop_back() {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "deque::pop_back called on an empty deque");
   size_type __old_sz    = size();
   size_type __old_start = __start_;
   allocator_type& __a   = __alloc();
   size_type __p         = size() + __start_ - 1;
   __alloc_traits::destroy(__a, std::__to_address(*(__map_.begin() + __p / __block_size) + __p % __block_size));
   --__size();
   __annotate_shrink_back(__old_sz, __old_start);
   __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 = std::move(*__f);
   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;
     }
     if (__fb <= __vt && __vt < __fe)
       __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) -= __f - __r).__ptr_;
     __r = std::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 = std::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 = std::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 = __alloc();
   // as if
   //   for (; __f != __l; ++__r, ++__f, ++__size())
   //       __alloc_traits::construct(__a, std::addressof(*__r), std::move(*__f));
   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;
     }
     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, ++__size())
       __alloc_traits::construct(__a, std::addressof(*__r), std::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 = __alloc();
   // as if
   //   for (iterator __j = __l; __j != __f;)
   //   {
   //       __alloc_traitsconstruct(__a, std::addressof(*--__r), std::move(*--__j));
   //       --__start_;
   //       ++__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, std::addressof(*--__r), std::move(*--__le));
       --__start_;
       ++__size();
     }
     __n -= __bs;
     __l -= __bs - 1;
   }
 }
 
 template <class _Tp, class _Allocator>
 typename deque<_Tp, _Allocator>::iterator deque<_Tp, _Allocator>::erase(const_iterator __f) {
   _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
       __f != end(), "deque::erase(iterator) called with a non-dereferenceable iterator");
   size_type __old_sz    = size();
   size_type __old_start = __start_;
   iterator __b          = begin();
   difference_type __pos = __f - __b;
   iterator __p          = __b + __pos;
   allocator_type& __a   = __alloc();
   if (static_cast<size_t>(__pos) <= (size() - 1) / 2) { // erase from front
     std::move_backward(__b, __p, std::next(__p));
     __alloc_traits::destroy(__a, std::addressof(*__b));
     --__size();
     ++__start_;
     __annotate_shrink_front(__old_sz, __old_start);
     __maybe_remove_front_spare();
   } else { // erase from back
     iterator __i = std::move(std::next(__p), end(), __p);
     __alloc_traits::destroy(__a, std::addressof(*__i));
     --__size();
     __annotate_shrink_back(__old_sz, __old_start);
     __maybe_remove_back_spare();
   }
   return begin() + __pos;
 }
 
 template <class _Tp, class _Allocator>
 typename deque<_Tp, _Allocator>::iterator deque<_Tp, _Allocator>::erase(const_iterator __f, const_iterator __l) {
   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__f <= __l, "deque::erase(first, last) called with an invalid range");
   size_type __old_sz    = size();
   size_type __old_start = __start_;
   difference_type __n   = __l - __f;
   iterator __b          = begin();
   difference_type __pos = __f - __b;
   iterator __p          = __b + __pos;
   if (__n > 0) {
     allocator_type& __a = __alloc();
     if (static_cast<size_t>(__pos) <= (size() - __n) / 2) { // erase from front
       iterator __i = std::move_backward(__b, __p, __p + __n);
       for (; __b != __i; ++__b)
         __alloc_traits::destroy(__a, std::addressof(*__b));
       __size() -= __n;
       __start_ += __n;
       __annotate_shrink_front(__old_sz, __old_start);
       while (__maybe_remove_front_spare()) {
       }
     } else { // erase from back
       iterator __i = std::move(__p + __n, end(), __p);
       for (iterator __e = end(); __i != __e; ++__i)
         __alloc_traits::destroy(__a, std::addressof(*__i));
       __size() -= __n;
       __annotate_shrink_back(__old_sz, __old_start);
       while (__maybe_remove_back_spare()) {
       }
     }
   }
   return begin() + __pos;
 }
 
 template <class _Tp, class _Allocator>
 void deque<_Tp, _Allocator>::__erase_to_end(const_iterator __f) {
   size_type __old_sz    = size();
   size_type __old_start = __start_;
   iterator __e          = end();
   difference_type __n   = __e - __f;
   if (__n > 0) {
     allocator_type& __a   = __alloc();
     iterator __b          = begin();
     difference_type __pos = __f - __b;
     for (iterator __p = __b + __pos; __p != __e; ++__p)
       __alloc_traits::destroy(__a, std::addressof(*__p));
     __size() -= __n;
     __annotate_shrink_back(__old_sz, __old_start);
     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_v<allocator_type>)
 #endif
 {
   __map_.swap(__c.__map_);
   std::swap(__start_, __c.__start_);
   std::swap(__size(), __c.__size());
   std::__swap_allocator(__alloc(), __c.__alloc());
 }
 
 template <class _Tp, class _Allocator>
 inline void deque<_Tp, _Allocator>::clear() _NOEXCEPT {
   __annotate_delete();
   allocator_type& __a = __alloc();
   for (iterator __i = begin(), __e = end(); __i != __e; ++__i)
     __alloc_traits::destroy(__a, std::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;
   }
   __annotate_new(0);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI 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() && std::equal(__x.begin(), __x.end(), __y.begin());
 }
 
 #if _LIBCPP_STD_VER <= 17
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return !(__x == __y);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool operator<(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return std::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool operator>(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return __y < __x;
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool operator>=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return !(__x < __y);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool operator<=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return !(__y < __x);
 }
 
 #else // _LIBCPP_STD_VER <= 17
 
 template <class _Tp, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Tp>
 operator<=>(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y) {
   return std::lexicographical_compare_three_way(__x.begin(), __x.end(), __y.begin(), __y.end(), std::__synth_three_way);
 }
 
 #endif // _LIBCPP_STD_VER <= 17
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI void swap(deque<_Tp, _Allocator>& __x, deque<_Tp, _Allocator>& __y)
     _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
   __x.swap(__y);
 }
 
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp, class _Allocator, class _Up>
 inline _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::size_type
 erase(deque<_Tp, _Allocator>& __c, const _Up& __v) {
   auto __old_size = __c.size();
   __c.erase(std::remove(__c.begin(), __c.end(), __v), __c.end());
   return __old_size - __c.size();
 }
 
 template <class _Tp, class _Allocator, class _Predicate>
 inline _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::size_type
 erase_if(deque<_Tp, _Allocator>& __c, _Predicate __pred) {
   auto __old_size = __c.size();
   __c.erase(std::remove_if(__c.begin(), __c.end(), __pred), __c.end());
   return __old_size - __c.size();
 }
 
 template <>
 inline constexpr bool __format::__enable_insertable<std::deque<char>> = true;
 #  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template <>
 inline constexpr bool __format::__enable_insertable<std::deque<wchar_t>> = true;
 #  endif
 
 #endif // _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER >= 17
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace pmr {
 template <class _ValueT>
 using deque _LIBCPP_AVAILABILITY_PMR = std::deque<_ValueT, polymorphic_allocator<_ValueT>>;
 } // namespace pmr
 _LIBCPP_END_NAMESPACE_STD
 #endif
 
 _LIBCPP_POP_MACROS
 
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <__cxx03/algorithm>
 #  include <__cxx03/atomic>
 #  include <__cxx03/concepts>
 #  include <__cxx03/cstdlib>
 #  include <__cxx03/functional>
 #  include <__cxx03/iosfwd>
 #  include <__cxx03/iterator>
 #  include <__cxx03/type_traits>
 #  include <__cxx03/typeinfo>
 #endif
 
 #endif // _LIBCPP___CXX03_DEQUE

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