deque.tcc

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// Deque implementation (out of line) -*- C++ -*-
 
// Copyright (C) 2001-2022 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
 
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
 
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.
 
/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */
 
/** @file bits/deque.tcc
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{deque}
 */
 
#ifndef _DEQUE_TCC
#define _DEQUE_TCC 1
 
#include <bits/stl_algobase.h>
 
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
#if __cplusplus >= 201103L
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_default_initialize()
    {
      _Map_pointer __cur;
      __try
        {
          for (__cur = this->_M_impl._M_start._M_node;
               __cur < this->_M_impl._M_finish._M_node;
               ++__cur)
            std::__uninitialized_default_a(*__cur, *__cur + _S_buffer_size(),
                                           _M_get_Tp_allocator());
          std::__uninitialized_default_a(this->_M_impl._M_finish._M_first,
                                         this->_M_impl._M_finish._M_cur,
                                         _M_get_Tp_allocator());
        }
      __catch(...)
        {
          std::_Destroy(this->_M_impl._M_start, iterator(*__cur, __cur),
                        _M_get_Tp_allocator());
          __throw_exception_again;
        }
    }
#endif
 
  template <typename _Tp, typename _Alloc>
    deque<_Tp, _Alloc>&
    deque<_Tp, _Alloc>::
    operator=(const deque& __x)
    {
      if (std::__addressof(__x) != this)
        {
#if __cplusplus >= 201103L
          if (_Alloc_traits::_S_propagate_on_copy_assign())
            {
              if (!_Alloc_traits::_S_always_equal()
                  && _M_get_Tp_allocator() != __x._M_get_Tp_allocator())
                {
                  // Replacement allocator cannot free existing storage,
                  // so deallocate everything and take copy of __x's data.
                  _M_replace_map(__x, __x.get_allocator());
                  std::__alloc_on_copy(_M_get_Tp_allocator(),
                                       __x._M_get_Tp_allocator());
                  return *this;
                }
              std::__alloc_on_copy(_M_get_Tp_allocator(),
                                   __x._M_get_Tp_allocator());
            }
#endif
          const size_type __len = size();
          if (__len >= __x.size())
            _M_erase_at_end(std::copy(__x.begin(), __x.end(),
                                      this->_M_impl._M_start));
          else
            {
              const_iterator __mid = __x.begin() + difference_type(__len);
              std::copy(__x.begin(), __mid, this->_M_impl._M_start);
              _M_range_insert_aux(this->_M_impl._M_finish, __mid, __x.end(),
                                  std::random_access_iterator_tag());
            }
        }
      return *this;
    }
 
#if __cplusplus >= 201103L
  template<typename _Tp, typename _Alloc>
    template<typename... _Args>
#if __cplusplus > 201402L
      typename deque<_Tp, _Alloc>::reference
#else
      void
#endif
      deque<_Tp, _Alloc>::
      emplace_front(_Args&&... __args)
      {
        if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_first)
          {
            _Alloc_traits::construct(this->_M_impl,
                                     this->_M_impl._M_start._M_cur - 1,
                                     std::forward<_Args>(__args)...);
            --this->_M_impl._M_start._M_cur;
          }
        else
          _M_push_front_aux(std::forward<_Args>(__args)...);
#if __cplusplus > 201402L
        return front();
#endif
      }
 
  template<typename _Tp, typename _Alloc>
    template<typename... _Args>
#if __cplusplus > 201402L
      typename deque<_Tp, _Alloc>::reference
#else
      void
#endif
      deque<_Tp, _Alloc>::
      emplace_back(_Args&&... __args)
      {
        if (this->_M_impl._M_finish._M_cur
            != this->_M_impl._M_finish._M_last - 1)
          {
            _Alloc_traits::construct(this->_M_impl,
                                     this->_M_impl._M_finish._M_cur,
                                     std::forward<_Args>(__args)...);
            ++this->_M_impl._M_finish._M_cur;
          }
        else
          _M_push_back_aux(std::forward<_Args>(__args)...);
#if __cplusplus > 201402L
        return back();
#endif
      }
#endif
 
#if __cplusplus >= 201103L
  template<typename _Tp, typename _Alloc>
    template<typename... _Args>
      typename deque<_Tp, _Alloc>::iterator
      deque<_Tp, _Alloc>::
      emplace(const_iterator __position, _Args&&... __args)
      {
        if (__position._M_cur == this->_M_impl._M_start._M_cur)
          {
            emplace_front(std::forward<_Args>(__args)...);
            return this->_M_impl._M_start;
          }
        else if (__position._M_cur == this->_M_impl._M_finish._M_cur)
          {
            emplace_back(std::forward<_Args>(__args)...);
            iterator __tmp = this->_M_impl._M_finish;
            --__tmp;
            return __tmp;
          }
        else
          return _M_insert_aux(__position._M_const_cast(),
                               std::forward<_Args>(__args)...);
      }
#endif
 
  template <typename _Tp, typename _Alloc>
    typename deque<_Tp, _Alloc>::iterator
    deque<_Tp, _Alloc>::
#if __cplusplus >= 201103L
    insert(const_iterator __position, const value_type& __x)
#else
    insert(iterator __position, const value_type& __x)
#endif
    {
      if (__position._M_cur == this->_M_impl._M_start._M_cur)
        {
          push_front(__x);
          return this->_M_impl._M_start;
        }
      else if (__position._M_cur == this->_M_impl._M_finish._M_cur)
        {
          push_back(__x);
          iterator __tmp = this->_M_impl._M_finish;
          --__tmp;
          return __tmp;
        }
      else
        return _M_insert_aux(__position._M_const_cast(), __x);
   }
 
  template <typename _Tp, typename _Alloc>
    typename deque<_Tp, _Alloc>::iterator
    deque<_Tp, _Alloc>::
    _M_erase(iterator __position)
    {
      iterator __next = __position;
      ++__next;
      const difference_type __index = __position - begin();
      if (static_cast<size_type>(__index) < (size() >> 1))
        {
          if (__position != begin())
            _GLIBCXX_MOVE_BACKWARD3(begin(), __position, __next);
          pop_front();
        }
      else
        {
          if (__next != end())
            _GLIBCXX_MOVE3(__next, end(), __position);
          pop_back();
        }
      return begin() + __index;
    }
 
  template <typename _Tp, typename _Alloc>
    typename deque<_Tp, _Alloc>::iterator
    deque<_Tp, _Alloc>::
    _M_erase(iterator __first, iterator __last)
    {
      if (__first == __last)
        return __first;
      else if (__first == begin() && __last == end())
        {
          clear();
          return end();
        }
      else
        {
          const difference_type __n = __last - __first;
          const difference_type __elems_before = __first - begin();
          if (static_cast<size_type>(__elems_before) <= (size() - __n) / 2)
            {
              if (__first != begin())
                _GLIBCXX_MOVE_BACKWARD3(begin(), __first, __last);
              _M_erase_at_begin(begin() + __n);
            }
          else
            {
              if (__last != end())
                _GLIBCXX_MOVE3(__last, end(), __first);
              _M_erase_at_end(end() - __n);
            }
          return begin() + __elems_before;
        }
    }
 
  template <typename _Tp, class _Alloc>
    template <typename _InputIterator>
      void
      deque<_Tp, _Alloc>::
      _M_assign_aux(_InputIterator __first, _InputIterator __last,
                    std::input_iterator_tag)
      {
        iterator __cur = begin();
        for (; __first != __last && __cur != end(); ++__cur, (void)++__first)
          *__cur = *__first;
        if (__first == __last)
          _M_erase_at_end(__cur);
        else
          _M_range_insert_aux(end(), __first, __last,
                              std::__iterator_category(__first));
      }
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_fill_insert(iterator __pos, size_type __n, const value_type& __x)
    {
      if (__pos._M_cur == this->_M_impl._M_start._M_cur)
        {
          iterator __new_start = _M_reserve_elements_at_front(__n);
          __try
            {
              std::__uninitialized_fill_a(__new_start, this->_M_impl._M_start,
                                          __x, _M_get_Tp_allocator());
              this->_M_impl._M_start = __new_start;
            }
          __catch(...)
            {
              _M_destroy_nodes(__new_start._M_node,
                               this->_M_impl._M_start._M_node);
              __throw_exception_again;
            }
        }
      else if (__pos._M_cur == this->_M_impl._M_finish._M_cur)
        {
          iterator __new_finish = _M_reserve_elements_at_back(__n);
          __try
            {
              std::__uninitialized_fill_a(this->_M_impl._M_finish,
                                          __new_finish, __x,
                                          _M_get_Tp_allocator());
              this->_M_impl._M_finish = __new_finish;
            }
          __catch(...)
            {
              _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
                               __new_finish._M_node + 1);
              __throw_exception_again;
            }
        }
      else
        _M_insert_aux(__pos, __n, __x);
    }
 
#if __cplusplus >= 201103L
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_default_append(size_type __n)
    {
      if (__n)
        {
          iterator __new_finish = _M_reserve_elements_at_back(__n);
          __try
            {
              std::__uninitialized_default_a(this->_M_impl._M_finish,
                                             __new_finish,
                                             _M_get_Tp_allocator());
              this->_M_impl._M_finish = __new_finish;
            }
          __catch(...)
            {
              _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
                               __new_finish._M_node + 1);
              __throw_exception_again;
            }
        }
    }
 
  template <typename _Tp, typename _Alloc>
    bool
    deque<_Tp, _Alloc>::
    _M_shrink_to_fit()
    {
      const difference_type __front_capacity
        = (this->_M_impl._M_start._M_cur - this->_M_impl._M_start._M_first);
      if (__front_capacity == 0)
        return false;
 
      const difference_type __back_capacity
        = (this->_M_impl._M_finish._M_last - this->_M_impl._M_finish._M_cur);
      if (__front_capacity + __back_capacity < _S_buffer_size())
        return false;
 
      return std::__shrink_to_fit_aux<deque>::_S_do_it(*this);
    }
#endif
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_fill_initialize(const value_type& __value)
    {
      _Map_pointer __cur;
      __try
        {
          for (__cur = this->_M_impl._M_start._M_node;
               __cur < this->_M_impl._M_finish._M_node;
               ++__cur)
            std::__uninitialized_fill_a(*__cur, *__cur + _S_buffer_size(),
                                        __value, _M_get_Tp_allocator());
          std::__uninitialized_fill_a(this->_M_impl._M_finish._M_first,
                                      this->_M_impl._M_finish._M_cur,
                                      __value, _M_get_Tp_allocator());
        }
      __catch(...)
        {
          std::_Destroy(this->_M_impl._M_start, iterator(*__cur, __cur),
                        _M_get_Tp_allocator());
          __throw_exception_again;
        }
    }
 
  template <typename _Tp, typename _Alloc>
    template <typename _InputIterator>
      void
      deque<_Tp, _Alloc>::
      _M_range_initialize(_InputIterator __first, _InputIterator __last,
                          std::input_iterator_tag)
      {
        this->_M_initialize_map(0);
        __try
          {
            for (; __first != __last; ++__first)
#if __cplusplus >= 201103L
              emplace_back(*__first);
#else
              push_back(*__first);
#endif
          }
        __catch(...)
          {
            clear();
            __throw_exception_again;
          }
      }
 
  template <typename _Tp, typename _Alloc>
    template <typename _ForwardIterator>
      void
      deque<_Tp, _Alloc>::
      _M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
                          std::forward_iterator_tag)
      {
        const size_type __n = std::distance(__first, __last);
        this->_M_initialize_map(_S_check_init_len(__n, _M_get_Tp_allocator()));
 
        _Map_pointer __cur_node;
        __try
          {
            for (__cur_node = this->_M_impl._M_start._M_node;
                 __cur_node < this->_M_impl._M_finish._M_node;
                 ++__cur_node)
              {
                if (__n < _S_buffer_size())
                  __builtin_unreachable(); // See PR 100516
 
                _ForwardIterator __mid = __first;
                std::advance(__mid, _S_buffer_size());
                std::__uninitialized_copy_a(__first, __mid, *__cur_node,
                                            _M_get_Tp_allocator());
                __first = __mid;
              }
            std::__uninitialized_copy_a(__first, __last,
                                        this->_M_impl._M_finish._M_first,
                                        _M_get_Tp_allocator());
          }
        __catch(...)
          {
            std::_Destroy(this->_M_impl._M_start,
                          iterator(*__cur_node, __cur_node),
                          _M_get_Tp_allocator());
            __throw_exception_again;
          }
      }
 
  // Called only if _M_impl._M_finish._M_cur == _M_impl._M_finish._M_last - 1.
  template<typename _Tp, typename _Alloc>
#if __cplusplus >= 201103L
    template<typename... _Args>
      void
      deque<_Tp, _Alloc>::
      _M_push_back_aux(_Args&&... __args)
#else
      void
      deque<_Tp, _Alloc>::
      _M_push_back_aux(const value_type& __t)
#endif
      {
        if (size() == max_size())
          __throw_length_error(
              __N("cannot create std::deque larger than max_size()"));
 
        _M_reserve_map_at_back();
        *(this->_M_impl._M_finish._M_node + 1) = this->_M_allocate_node();
        __try
          {
#if __cplusplus >= 201103L
            _Alloc_traits::construct(this->_M_impl,
                                     this->_M_impl._M_finish._M_cur,
                                     std::forward<_Args>(__args)...);
#else
            this->_M_impl.construct(this->_M_impl._M_finish._M_cur, __t);
#endif
            this->_M_impl._M_finish._M_set_node(this->_M_impl._M_finish._M_node
                                                + 1);
            this->_M_impl._M_finish._M_cur = this->_M_impl._M_finish._M_first;
          }
        __catch(...)
          {
            _M_deallocate_node(*(this->_M_impl._M_finish._M_node + 1));
            __throw_exception_again;
          }
      }
 
  // Called only if _M_impl._M_start._M_cur == _M_impl._M_start._M_first.
  template<typename _Tp, typename _Alloc>
#if __cplusplus >= 201103L
    template<typename... _Args>
      void
      deque<_Tp, _Alloc>::
      _M_push_front_aux(_Args&&... __args)
#else
      void
      deque<_Tp, _Alloc>::
      _M_push_front_aux(const value_type& __t)
#endif
      {
        if (size() == max_size())
          __throw_length_error(
              __N("cannot create std::deque larger than max_size()"));
 
        _M_reserve_map_at_front();
        *(this->_M_impl._M_start._M_node - 1) = this->_M_allocate_node();
        __try
          {
            this->_M_impl._M_start._M_set_node(this->_M_impl._M_start._M_node
                                               - 1);
            this->_M_impl._M_start._M_cur = this->_M_impl._M_start._M_last - 1;
#if __cplusplus >= 201103L
            _Alloc_traits::construct(this->_M_impl,
                                     this->_M_impl._M_start._M_cur,
                                     std::forward<_Args>(__args)...);
#else
            this->_M_impl.construct(this->_M_impl._M_start._M_cur, __t);
#endif
          }
        __catch(...)
          {
            ++this->_M_impl._M_start;
            _M_deallocate_node(*(this->_M_impl._M_start._M_node - 1));
            __throw_exception_again;
          }
      }
 
  // Called only if _M_impl._M_finish._M_cur == _M_impl._M_finish._M_first.
  template <typename _Tp, typename _Alloc>
    void deque<_Tp, _Alloc>::
    _M_pop_back_aux()
    {
      _M_deallocate_node(this->_M_impl._M_finish._M_first);
      this->_M_impl._M_finish._M_set_node(this->_M_impl._M_finish._M_node - 1);
      this->_M_impl._M_finish._M_cur = this->_M_impl._M_finish._M_last - 1;
      _Alloc_traits::destroy(_M_get_Tp_allocator(),
                             this->_M_impl._M_finish._M_cur);
    }
 
  // Called only if _M_impl._M_start._M_cur == _M_impl._M_start._M_last - 1.
  // Note that if the deque has at least one element (a precondition for this
  // member function), and if
  //   _M_impl._M_start._M_cur == _M_impl._M_start._M_last,
  // then the deque must have at least two nodes.
  template <typename _Tp, typename _Alloc>
    void deque<_Tp, _Alloc>::
    _M_pop_front_aux()
    {
      _Alloc_traits::destroy(_M_get_Tp_allocator(),
                             this->_M_impl._M_start._M_cur);
      _M_deallocate_node(this->_M_impl._M_start._M_first);
      this->_M_impl._M_start._M_set_node(this->_M_impl._M_start._M_node + 1);
      this->_M_impl._M_start._M_cur = this->_M_impl._M_start._M_first;
    }
 
  template <typename _Tp, typename _Alloc>
    template <typename _InputIterator>
      void
      deque<_Tp, _Alloc>::
      _M_range_insert_aux(iterator __pos,
                          _InputIterator __first, _InputIterator __last,
                          std::input_iterator_tag)
      { std::copy(__first, __last, std::inserter(*this, __pos)); }
 
  template <typename _Tp, typename _Alloc>
    template <typename _ForwardIterator>
      void
      deque<_Tp, _Alloc>::
      _M_range_insert_aux(iterator __pos,
                          _ForwardIterator __first, _ForwardIterator __last,
                          std::forward_iterator_tag)
      {
        const size_type __n = std::distance(__first, __last);
        if (__pos._M_cur == this->_M_impl._M_start._M_cur)
          {
            iterator __new_start = _M_reserve_elements_at_front(__n);
            __try
              {
                std::__uninitialized_copy_a(__first, __last, __new_start,
                                            _M_get_Tp_allocator());
                this->_M_impl._M_start = __new_start;
              }
            __catch(...)
              {
                _M_destroy_nodes(__new_start._M_node,
                                 this->_M_impl._M_start._M_node);
                __throw_exception_again;
              }
          }
        else if (__pos._M_cur == this->_M_impl._M_finish._M_cur)
          {
            iterator __new_finish = _M_reserve_elements_at_back(__n);
            __try
              {
                std::__uninitialized_copy_a(__first, __last,
                                            this->_M_impl._M_finish,
                                            _M_get_Tp_allocator());
                this->_M_impl._M_finish = __new_finish;
              }
            __catch(...)
              {
                _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
                                 __new_finish._M_node + 1);
                __throw_exception_again;
              }
          }
        else
          _M_insert_aux(__pos, __first, __last, __n);
      }
 
  template<typename _Tp, typename _Alloc>
#if __cplusplus >= 201103L
    template<typename... _Args>
      typename deque<_Tp, _Alloc>::iterator
      deque<_Tp, _Alloc>::
      _M_insert_aux(iterator __pos, _Args&&... __args)
      {
        value_type __x_copy(std::forward<_Args>(__args)...); // XXX copy
#else
    typename deque<_Tp, _Alloc>::iterator
      deque<_Tp, _Alloc>::
      _M_insert_aux(iterator __pos, const value_type& __x)
      {
        value_type __x_copy = __x; // XXX copy
#endif
        difference_type __index = __pos - this->_M_impl._M_start;
        if (static_cast<size_type>(__index) < size() / 2)
          {
            push_front(_GLIBCXX_MOVE(front()));
            iterator __front1 = this->_M_impl._M_start;
            ++__front1;
            iterator __front2 = __front1;
            ++__front2;
            __pos = this->_M_impl._M_start + __index;
            iterator __pos1 = __pos;
            ++__pos1;
            _GLIBCXX_MOVE3(__front2, __pos1, __front1);
          }
        else
          {
            push_back(_GLIBCXX_MOVE(back()));
            iterator __back1 = this->_M_impl._M_finish;
            --__back1;
            iterator __back2 = __back1;
            --__back2;
            __pos = this->_M_impl._M_start + __index;
            _GLIBCXX_MOVE_BACKWARD3(__pos, __back2, __back1);
          }
        *__pos = _GLIBCXX_MOVE(__x_copy);
        return __pos;
      }
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_insert_aux(iterator __pos, size_type __n, const value_type& __x)
    {
      const difference_type __elems_before = __pos - this->_M_impl._M_start;
      const size_type __length = this->size();
      value_type __x_copy = __x;
      if (__elems_before < difference_type(__length / 2))
        {
          iterator __new_start = _M_reserve_elements_at_front(__n);
          iterator __old_start = this->_M_impl._M_start;
          __pos = this->_M_impl._M_start + __elems_before;
          __try
            {
              if (__elems_before >= difference_type(__n))
                {
                  iterator __start_n = (this->_M_impl._M_start
                                        + difference_type(__n));
                  std::__uninitialized_move_a(this->_M_impl._M_start,
                                              __start_n, __new_start,
                                              _M_get_Tp_allocator());
                  this->_M_impl._M_start = __new_start;
                  _GLIBCXX_MOVE3(__start_n, __pos, __old_start);
                  std::fill(__pos - difference_type(__n), __pos, __x_copy);
                }
              else
                {
                  std::__uninitialized_move_fill(this->_M_impl._M_start,
                                                 __pos, __new_start,
                                                 this->_M_impl._M_start,
                                                 __x_copy,
                                                 _M_get_Tp_allocator());
                  this->_M_impl._M_start = __new_start;
                  std::fill(__old_start, __pos, __x_copy);
                }
            }
          __catch(...)
            {
              _M_destroy_nodes(__new_start._M_node,
                               this->_M_impl._M_start._M_node);
              __throw_exception_again;
            }
        }
      else
        {
          iterator __new_finish = _M_reserve_elements_at_back(__n);
          iterator __old_finish = this->_M_impl._M_finish;
          const difference_type __elems_after =
            difference_type(__length) - __elems_before;
          __pos = this->_M_impl._M_finish - __elems_after;
          __try
            {
              if (__elems_after > difference_type(__n))
                {
                  iterator __finish_n = (this->_M_impl._M_finish
                                         - difference_type(__n));
                  std::__uninitialized_move_a(__finish_n,
                                              this->_M_impl._M_finish,
                                              this->_M_impl._M_finish,
                                              _M_get_Tp_allocator());
                  this->_M_impl._M_finish = __new_finish;
                  _GLIBCXX_MOVE_BACKWARD3(__pos, __finish_n, __old_finish);
                  std::fill(__pos, __pos + difference_type(__n), __x_copy);
                }
              else
                {
                  std::__uninitialized_fill_move(this->_M_impl._M_finish,
                                                 __pos + difference_type(__n),
                                                 __x_copy, __pos,
                                                 this->_M_impl._M_finish,
                                                 _M_get_Tp_allocator());
                  this->_M_impl._M_finish = __new_finish;
                  std::fill(__pos, __old_finish, __x_copy);
                }
            }
          __catch(...)
            {
              _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
                               __new_finish._M_node + 1);
              __throw_exception_again;
            }
        }
    }
 
  template <typename _Tp, typename _Alloc>
    template <typename _ForwardIterator>
      void
      deque<_Tp, _Alloc>::
      _M_insert_aux(iterator __pos,
                    _ForwardIterator __first, _ForwardIterator __last,
                    size_type __n)
      {
        const difference_type __elemsbefore = __pos - this->_M_impl._M_start;
        const size_type __length = size();
        if (static_cast<size_type>(__elemsbefore) < __length / 2)
          {
            iterator __new_start = _M_reserve_elements_at_front(__n);
            iterator __old_start = this->_M_impl._M_start;
            __pos = this->_M_impl._M_start + __elemsbefore;
            __try
              {
                if (__elemsbefore >= difference_type(__n))
                  {
                    iterator __start_n = (this->_M_impl._M_start
                                          + difference_type(__n));
                    std::__uninitialized_move_a(this->_M_impl._M_start,
                                                __start_n, __new_start,
                                                _M_get_Tp_allocator());
                    this->_M_impl._M_start = __new_start;
                    _GLIBCXX_MOVE3(__start_n, __pos, __old_start);
                    std::copy(__first, __last, __pos - difference_type(__n));
                  }
                else
                  {
                    _ForwardIterator __mid = __first;
                    std::advance(__mid, difference_type(__n) - __elemsbefore);
                    std::__uninitialized_move_copy(this->_M_impl._M_start,
                                                   __pos, __first, __mid,
                                                   __new_start,
                                                   _M_get_Tp_allocator());
                    this->_M_impl._M_start = __new_start;
                    std::copy(__mid, __last, __old_start);
                  }
              }
            __catch(...)
              {
                _M_destroy_nodes(__new_start._M_node,
                                 this->_M_impl._M_start._M_node);
                __throw_exception_again;
              }
          }
        else
        {
          iterator __new_finish = _M_reserve_elements_at_back(__n);
          iterator __old_finish = this->_M_impl._M_finish;
          const difference_type __elemsafter =
            difference_type(__length) - __elemsbefore;
          __pos = this->_M_impl._M_finish - __elemsafter;
          __try
            {
              if (__elemsafter > difference_type(__n))
                {
                  iterator __finish_n = (this->_M_impl._M_finish
                                         - difference_type(__n));
                  std::__uninitialized_move_a(__finish_n,
                                              this->_M_impl._M_finish,
                                              this->_M_impl._M_finish,
                                              _M_get_Tp_allocator());
                  this->_M_impl._M_finish = __new_finish;
                  _GLIBCXX_MOVE_BACKWARD3(__pos, __finish_n, __old_finish);
                  std::copy(__first, __last, __pos);
                }
              else
                {
                  _ForwardIterator __mid = __first;
                  std::advance(__mid, __elemsafter);
                  std::__uninitialized_copy_move(__mid, __last, __pos,
                                                 this->_M_impl._M_finish,
                                                 this->_M_impl._M_finish,
                                                 _M_get_Tp_allocator());
                  this->_M_impl._M_finish = __new_finish;
                  std::copy(__first, __mid, __pos);
                }
            }
          __catch(...)
            {
              _M_destroy_nodes(this->_M_impl._M_finish._M_node + 1,
                               __new_finish._M_node + 1);
              __throw_exception_again;
            }
        }
      }
 
   template<typename _Tp, typename _Alloc>
     void
     deque<_Tp, _Alloc>::
     _M_destroy_data_aux(iterator __first, iterator __last)
     {
       for (_Map_pointer __node = __first._M_node + 1;
            __node < __last._M_node; ++__node)
         std::_Destroy(*__node, *__node + _S_buffer_size(),
                       _M_get_Tp_allocator());
 
       if (__first._M_node != __last._M_node)
         {
           std::_Destroy(__first._M_cur, __first._M_last,
                         _M_get_Tp_allocator());
           std::_Destroy(__last._M_first, __last._M_cur,
                         _M_get_Tp_allocator());
         }
       else
         std::_Destroy(__first._M_cur, __last._M_cur,
                       _M_get_Tp_allocator());
     }
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_new_elements_at_front(size_type __new_elems)
    {
      if (this->max_size() - this->size() < __new_elems)
        __throw_length_error(__N("deque::_M_new_elements_at_front"));
 
      const size_type __new_nodes = ((__new_elems + _S_buffer_size() - 1)
                                     / _S_buffer_size());
      _M_reserve_map_at_front(__new_nodes);
      size_type __i;
      __try
        {
          for (__i = 1; __i <= __new_nodes; ++__i)
            *(this->_M_impl._M_start._M_node - __i) = this->_M_allocate_node();
        }
      __catch(...)
        {
          for (size_type __j = 1; __j < __i; ++__j)
            _M_deallocate_node(*(this->_M_impl._M_start._M_node - __j));
          __throw_exception_again;
        }
    }
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_new_elements_at_back(size_type __new_elems)
    {
      if (this->max_size() - this->size() < __new_elems)
        __throw_length_error(__N("deque::_M_new_elements_at_back"));
 
      const size_type __new_nodes = ((__new_elems + _S_buffer_size() - 1)
                                     / _S_buffer_size());
      _M_reserve_map_at_back(__new_nodes);
      size_type __i;
      __try
        {
          for (__i = 1; __i <= __new_nodes; ++__i)
            *(this->_M_impl._M_finish._M_node + __i) = this->_M_allocate_node();
        }
      __catch(...)
        {
          for (size_type __j = 1; __j < __i; ++__j)
            _M_deallocate_node(*(this->_M_impl._M_finish._M_node + __j));
          __throw_exception_again;
        }
    }
 
  template <typename _Tp, typename _Alloc>
    void
    deque<_Tp, _Alloc>::
    _M_reallocate_map(size_type __nodes_to_add, bool __add_at_front)
    {
      const size_type __old_num_nodes
        = this->_M_impl._M_finish._M_node - this->_M_impl._M_start._M_node + 1;
      const size_type __new_num_nodes = __old_num_nodes + __nodes_to_add;
 
      _Map_pointer __new_nstart;
      if (this->_M_impl._M_map_size > 2 * __new_num_nodes)
        {
          __new_nstart = this->_M_impl._M_map + (this->_M_impl._M_map_size
                                         - __new_num_nodes) / 2
                         + (__add_at_front ? __nodes_to_add : 0);
          if (__new_nstart < this->_M_impl._M_start._M_node)
            std::copy(this->_M_impl._M_start._M_node,
                      this->_M_impl._M_finish._M_node + 1,
                      __new_nstart);
          else
            std::copy_backward(this->_M_impl._M_start._M_node,
                               this->_M_impl._M_finish._M_node + 1,
                               __new_nstart + __old_num_nodes);
        }
      else
        {
          size_type __new_map_size = this->_M_impl._M_map_size
                                     + std::max(this->_M_impl._M_map_size,
                                                __nodes_to_add) + 2;
 
          _Map_pointer __new_map = this->_M_allocate_map(__new_map_size);
          __new_nstart = __new_map + (__new_map_size - __new_num_nodes) / 2
                         + (__add_at_front ? __nodes_to_add : 0);
          std::copy(this->_M_impl._M_start._M_node,
                    this->_M_impl._M_finish._M_node + 1,
                    __new_nstart);
          _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
 
          this->_M_impl._M_map = __new_map;
          this->_M_impl._M_map_size = __new_map_size;
        }
 
      this->_M_impl._M_start._M_set_node(__new_nstart);
      this->_M_impl._M_finish._M_set_node(__new_nstart + __old_num_nodes - 1);
    }
 
_GLIBCXX_END_NAMESPACE_CONTAINER
 
  // Overload for deque::iterators, exploiting the "segmented-iterator
  // optimization".
  template<typename _Tp, typename _VTp>
    void
    __fill_a1(const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>& __first,
              const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>& __last,
              const _VTp& __value)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> _Iter;
      if (__first._M_node != __last._M_node)
        {
          std::__fill_a1(__first._M_cur, __first._M_last, __value);
 
          for (typename _Iter::_Map_pointer __node = __first._M_node + 1;
               __node < __last._M_node; ++__node)
            std::__fill_a1(*__node, *__node + _Iter::_S_buffer_size(), __value);
 
          std::__fill_a1(__last._M_first, __last._M_cur, __value);
        }
      else
        std::__fill_a1(__first._M_cur, __last._M_cur, __value);
    }
 
  template<bool _IsMove,
           typename _Tp, typename _Ref, typename _Ptr, typename _OI>
    _OI
    __copy_move_dit(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first,
                    _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __last,
                    _OI __result)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> _Iter;
      if (__first._M_node != __last._M_node)
        {
          __result
            = std::__copy_move_a1<_IsMove>(__first._M_cur, __first._M_last,
                                           __result);
 
          for (typename _Iter::_Map_pointer __node = __first._M_node + 1;
               __node != __last._M_node; ++__node)
            __result
              = std::__copy_move_a1<_IsMove>(*__node,
                                             *__node + _Iter::_S_buffer_size(),
                                             __result);
 
          return std::__copy_move_a1<_IsMove>(__last._M_first, __last._M_cur,
                                              __result);
        }
 
      return std::__copy_move_a1<_IsMove>(__first._M_cur, __last._M_cur,
                                          __result);
    }
 
  template<bool _IsMove,
           typename _Tp, typename _Ref, typename _Ptr, typename _OI>
    _OI
    __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first,
                   _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __last,
                   _OI __result)
    { return __copy_move_dit<_IsMove>(__first, __last, __result); }
 
  template<bool _IsMove,
           typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
    _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
    __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr> __first,
                   _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr> __last,
                   _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*> __result)
    { return __copy_move_dit<_IsMove>(__first, __last, __result); }
 
  template<bool _IsMove, typename _II, typename _Tp>
    typename __gnu_cxx::__enable_if<
      __is_random_access_iter<_II>::__value,
      _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
    __copy_move_a1(_II __first, _II __last,
                   _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> _Iter;
      typedef typename _Iter::difference_type difference_type;
 
      difference_type __len = __last - __first;
      while (__len > 0)
        {
          const difference_type __clen
            = std::min(__len, __result._M_last - __result._M_cur);
          std::__copy_move_a1<_IsMove>(__first, __first + __clen,
                                       __result._M_cur);
 
          __first += __clen;
          __result += __clen;
          __len -= __clen;
        }
 
      return __result;
    }
 
  template<bool _IsMove, typename _CharT>
    typename __gnu_cxx::__enable_if<
      __is_char<_CharT>::__value,
      _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
    __copy_move_a2(
        istreambuf_iterator<_CharT, char_traits<_CharT> > __first,
        istreambuf_iterator<_CharT, char_traits<_CharT> > __last,
        _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> __result)
    {
      if (__first == __last)
        return __result;
 
      for (;;)
        {
          const std::ptrdiff_t __len = __result._M_last - __result._M_cur;
          const std::ptrdiff_t __nb
            = std::__copy_n_a(__first, __len, __result._M_cur, false)
            - __result._M_cur;
          __result += __nb;
 
          if (__nb != __len)
            break;
        }
 
      return __result;
    }
 
  template<typename _CharT, typename _Size>
    typename __gnu_cxx::__enable_if<
      __is_char<_CharT>::__value,
      _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
    __copy_n_a(
      istreambuf_iterator<_CharT, char_traits<_CharT> > __it, _Size __size,
      _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> __result,
      bool __strict)
    {
      if (__size == 0)
        return __result;
 
      do
        {
          const _Size __len
            = std::min<_Size>(__result._M_last - __result._M_cur, __size);
          std::__copy_n_a(__it, __len, __result._M_cur, __strict);
          __result += __len;
          __size -= __len;
        }
      while (__size != 0);
      return __result;
    }
 
  template<bool _IsMove,
           typename _Tp, typename _Ref, typename _Ptr, typename _OI>
    _OI
    __copy_move_backward_dit(
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __last,
                _OI __result)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> _Iter;
      if (__first._M_node != __last._M_node)
        {
          __result = std::__copy_move_backward_a1<_IsMove>(
                __last._M_first, __last._M_cur, __result);
 
          for (typename _Iter::_Map_pointer __node = __last._M_node - 1;
               __node != __first._M_node; --__node)
            __result = std::__copy_move_backward_a1<_IsMove>(
                *__node, *__node + _Iter::_S_buffer_size(), __result);
 
          return std::__copy_move_backward_a1<_IsMove>(
                        __first._M_cur, __first._M_last, __result);
        }
 
      return std::__copy_move_backward_a1<_IsMove>(
                __first._M_cur, __last._M_cur, __result);
    }
 
  template<bool _IsMove,
           typename _Tp, typename _Ref, typename _Ptr, typename _OI>
    _OI
    __copy_move_backward_a1(
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __last,
                _OI __result)
    { return __copy_move_backward_dit<_IsMove>(__first, __last, __result); }
 
  template<bool _IsMove,
           typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
    _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
    __copy_move_backward_a1(
                _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr> __first,
                _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr> __last,
                _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*> __result)
    { return __copy_move_backward_dit<_IsMove>(__first, __last, __result); }
 
  template<bool _IsMove, typename _II, typename _Tp>
    typename __gnu_cxx::__enable_if<
      __is_random_access_iter<_II>::__value,
      _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
    __copy_move_backward_a1(_II __first, _II __last,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> __result)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> _Iter;
      typedef typename _Iter::difference_type difference_type;
 
      difference_type __len = __last - __first;
      while (__len > 0)
        {
          difference_type __rlen = __result._M_cur - __result._M_first;
          _Tp* __rend = __result._M_cur;
          if (!__rlen)
            {
              __rlen = _Iter::_S_buffer_size();
              __rend = *(__result._M_node - 1) + __rlen;
            }
 
          const difference_type __clen = std::min(__len, __rlen);
          std::__copy_move_backward_a1<_IsMove>(__last - __clen, __last, __rend);
 
          __last -= __clen;
          __result -= __clen;
          __len -= __clen;
        }
 
      return __result;
    }
 
  template<typename _Tp, typename _Ref, typename _Ptr, typename _II>
    bool
    __equal_dit(
        const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>& __first1,
        const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>& __last1,
        _II __first2)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> _Iter;
      if (__first1._M_node != __last1._M_node)
        {
          if (!std::__equal_aux1(__first1._M_cur, __first1._M_last, __first2))
            return false;
 
          __first2 += __first1._M_last - __first1._M_cur;
          for (typename _Iter::_Map_pointer __node = __first1._M_node + 1;
               __node != __last1._M_node;
               __first2 += _Iter::_S_buffer_size(), ++__node)
            if (!std::__equal_aux1(*__node, *__node + _Iter::_S_buffer_size(),
                                  __first2))
              return false;
 
          return std::__equal_aux1(__last1._M_first, __last1._M_cur, __first2);
        }
 
      return std::__equal_aux1(__first1._M_cur, __last1._M_cur, __first2);
    }
 
  template<typename _Tp, typename _Ref, typename _Ptr, typename _II>
    typename __gnu_cxx::__enable_if<
      __is_random_access_iter<_II>::__value, bool>::__type
    __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first1,
                 _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __last1,
                 _II __first2)
    { return std::__equal_dit(__first1, __last1, __first2); }
 
  template<typename _Tp1, typename _Ref1, typename _Ptr1,
           typename _Tp2, typename _Ref2, typename _Ptr2>
    bool
    __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __first1,
                 _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __last1,
                 _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2> __first2)
    { return std::__equal_dit(__first1, __last1, __first2); }
 
  template<typename _II, typename _Tp, typename _Ref, typename _Ptr>
    typename __gnu_cxx::__enable_if<
      __is_random_access_iter<_II>::__value, bool>::__type
    __equal_aux1(_II __first1, _II __last1,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> __first2)
    {
      typedef _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr> _Iter;
      typedef typename _Iter::difference_type difference_type;
 
      difference_type __len = __last1 - __first1;
      while (__len > 0)
        {
          const difference_type __clen
            = std::min(__len, __first2._M_last - __first2._M_cur);
          if (!std::__equal_aux1(__first1, __first1 + __clen, __first2._M_cur))
            return false;
 
          __first1 += __clen;
          __len -= __clen;
          __first2 += __clen;
        }
 
      return true;
    }
 
  template<typename _Tp1, typename _Ref, typename _Ptr, typename _Tp2>
    int
    __lex_cmp_dit(
        _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref, _Ptr> __first1,
        _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref, _Ptr> __last1,
        const _Tp2* __first2, const _Tp2* __last2)
    {
      const bool __simple =
        (__is_memcmp_ordered_with<_Tp1, _Tp2>::__value
         && __is_pointer<_Ptr>::__value
#if __cplusplus > 201703L && __cpp_lib_concepts
         // For C++20 iterator_traits<volatile T*>::value_type is non-volatile
         // so __is_byte<T> could be true, but we can't use memcmp with
         // volatile data.
         && !is_volatile_v<_Tp1>
         && !is_volatile_v<_Tp2>
#endif
         );
      typedef std::__lexicographical_compare<__simple> _Lc;
 
      while (__first1._M_node != __last1._M_node)
        {
          const ptrdiff_t __len1 = __first1._M_last - __first1._M_cur;
          const ptrdiff_t __len2 = __last2 - __first2;
          const ptrdiff_t __len = std::min(__len1, __len2);
          // if __len1 > __len2 this will return a positive value:
          if (int __ret = _Lc::__3way(__first1._M_cur, __first1._M_last,
                                      __first2, __first2 + __len))
            return __ret;
 
          __first1 += __len;
          __first2 += __len;
        }
      return _Lc::__3way(__first1._M_cur, __last1._M_cur,
                         __first2, __last2);
    }
 
  template<typename _Tp1, typename _Ref1, typename _Ptr1,
           typename _Tp2>
    inline bool
    __lexicographical_compare_aux1(
        _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __first1,
        _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __last1,
        _Tp2* __first2, _Tp2* __last2)
    { return std::__lex_cmp_dit(__first1, __last1, __first2, __last2) < 0; }
 
  template<typename _Tp1,
           typename _Tp2, typename _Ref2, typename _Ptr2>
    inline  bool
    __lexicographical_compare_aux1(_Tp1* __first1, _Tp1* __last1,
        _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2> __first2,
        _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2> __last2)
    { return std::__lex_cmp_dit(__first2, __last2, __first1, __last1) > 0; }
 
  template<typename _Tp1, typename _Ref1, typename _Ptr1,
           typename _Tp2, typename _Ref2, typename _Ptr2>
    inline bool
    __lexicographical_compare_aux1(
                _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __first1,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1> __last1,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2> __first2,
                _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2> __last2)
    {
      const bool __simple =
        (__is_memcmp_ordered_with<_Tp1, _Tp2>::__value
         && __is_pointer<_Ptr1>::__value
         && __is_pointer<_Ptr2>::__value
#if __cplusplus > 201703L && __cpp_lib_concepts
         // For C++20 iterator_traits<volatile T*>::value_type is non-volatile
         // so __is_byte<T> could be true, but we can't use memcmp with
         // volatile data.
         && !is_volatile_v<_Tp1>
         && !is_volatile_v<_Tp2>
#endif
         );
      typedef std::__lexicographical_compare<__simple> _Lc;
 
      while (__first1 != __last1)
        {
          const ptrdiff_t __len2 = __first2._M_node == __last2._M_node
            ? __last2._M_cur - __first2._M_cur
            : __first2._M_last - __first2._M_cur;
          if (__len2 == 0)
            return false;
          const ptrdiff_t __len1 = __first1._M_node == __last1._M_node
            ? __last1._M_cur - __first1._M_cur
            : __first1._M_last - __first1._M_cur;
          const ptrdiff_t __len = std::min(__len1, __len2);
          if (int __ret = _Lc::__3way(__first1._M_cur, __first1._M_cur + __len,
                                      __first2._M_cur, __first2._M_cur + __len))
            return __ret < 0;
 
          __first1 += __len;
          __first2 += __len;
        }
 
      return __last2 != __first2;
    }
 
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
 
#endif