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 //////////////////////////////////////////////////////////////////////////////
 //
 // (C) Copyright Ion Gaztanaga 2005-2015. Distributed under the Boost
 // Software License, Version 1.0. (See accompanying file
 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 // See http://www.boost.org/libs/container for documentation.
 //
 //////////////////////////////////////////////////////////////////////////////
 #ifndef BOOST_CONTAINER_DEQUE_HPP
 #define BOOST_CONTAINER_DEQUE_HPP
 
 #ifndef BOOST_CONFIG_HPP
 #  include <boost/config.hpp>
 #endif
 
 #if defined(BOOST_HAS_PRAGMA_ONCE)
 #  pragma once
 #endif
 
 #include <boost/container/detail/config_begin.hpp>
 #include <boost/container/detail/workaround.hpp>
 // container
 #include <boost/container/allocator_traits.hpp>
 #include <boost/container/container_fwd.hpp>
 #include <boost/container/new_allocator.hpp> //new_allocator
 #include <boost/container/throw_exception.hpp>
 #include <boost/container/options.hpp>
 // container/detail
 #include <boost/container/detail/advanced_insert_int.hpp>
 #include <boost/container/detail/algorithm.hpp> //algo_equal(), algo_lexicographical_compare
 #include <boost/container/detail/alloc_helpers.hpp>
 #include <boost/container/detail/copy_move_algo.hpp>
 #include <boost/container/detail/iterator.hpp>
 #include <boost/move/detail/iterator_to_raw_pointer.hpp>
 #include <boost/container/detail/iterators.hpp>
 #include <boost/container/detail/min_max.hpp>
 #include <boost/container/detail/mpl.hpp>
 #include <boost/move/detail/to_raw_pointer.hpp>
 #include <boost/container/detail/type_traits.hpp>
 // move
 #include <boost/move/adl_move_swap.hpp>
 #include <boost/move/iterator.hpp>
 #include <boost/move/traits.hpp>
 #include <boost/move/utility_core.hpp>
 // move/detail
 #if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 #include <boost/move/detail/fwd_macros.hpp>
 #endif
 #include <boost/move/detail/move_helpers.hpp>
 // other
 #include <boost/assert.hpp>
 // std
 #include <cstddef>
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 #include <initializer_list>
 #endif
 
 namespace boost {
 namespace container {
 
 #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 template <class T, class Allocator, class Options>
 class deque;
 
 template <class T>
 struct deque_value_traits
 {
    typedef T value_type;
    BOOST_STATIC_CONSTEXPR bool trivial_dctr = dtl::is_trivially_destructible<value_type>::value;
    BOOST_STATIC_CONSTEXPR bool trivial_dctr_after_move = ::boost::has_trivial_destructor_after_move<value_type>::value;
 };
 
 template<class T, std::size_t BlockBytes, std::size_t BlockSize>
 struct deque_block_size
 {
    BOOST_CONTAINER_STATIC_ASSERT_MSG(!(BlockBytes && BlockSize), "BlockBytes and BlockSize can't be specified at the same time");
    BOOST_STATIC_CONSTEXPR std::size_t block_bytes = BlockBytes ? BlockBytes : 512u;
    BOOST_STATIC_CONSTEXPR std::size_t value       = BlockSize ? BlockSize : (sizeof(T) < block_bytes ? (block_bytes/sizeof(T)) : std::size_t(1));
 };
 
 namespace dtl {
 
 // Class invariants:
 //  For any nonsingular iterator i:
 //    i.node is the address of an element in the map array.  The
 //      contents of i.node is a pointer to the beginning of a node.
 //    i.first == //(i.node)
 //    i.last  == i.first + node_size
 //    i.cur is a pointer in the range [i.first, i.last).  NOTE:
 //      the implication of this is that i.cur is always a dereferenceable
 //      pointer, even if i is a past-the-end iterator.
 //  Start and Finish are always nonsingular iterators.  NOTE: this means
 //    that an empty deque must have one node, and that a deque
 //    with N elements, where N is the buffer size, must have two nodes.
 //  For every node other than start.node and finish.node, every element
 //    in the node is an initialized object.  If start.node == finish.node,
 //    then [start.cur, finish.cur) are initialized objects, and
 //    the elements outside that range are uninitialized storage.  Otherwise,
 //    [start.cur, start.last) and [finish.first, finish.cur) are initialized
 //    objects, and [start.first, start.cur) and [finish.cur, finish.last)
 //    are uninitialized storage.
 //  [map, map + map_size) is a valid, non-empty range.
 //  [start.node, finish.node] is a valid range contained within
 //    [map, map + map_size).
 //  A pointer in the range [map, map + map_size) points to an allocated node
 //    if and only if the pointer is in the range [start.node, finish.node].
 
 #define BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL 0
 
 #if BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL == 0
 template<class Pointer, bool IsConst>
 class deque_iterator
 {
    public:
    typedef std::random_access_iterator_tag                                          iterator_category;
    typedef typename boost::intrusive::pointer_traits<Pointer>::element_type         value_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::difference_type      difference_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::size_type            size_type;
    typedef typename if_c
       < IsConst
       , typename boost::intrusive::pointer_traits<Pointer>::template
                                  rebind_pointer<const value_type>::type
       , Pointer
       >::type                                                                       pointer;
    typedef typename if_c
       < IsConst
       , const value_type&
       , value_type&
       >::type                                                                       reference;
 
    class nat;
    typedef typename dtl::if_c< IsConst
                              , deque_iterator<Pointer, false>
                              , nat>::type                                           nonconst_iterator;
 
    typedef Pointer                                                                  val_alloc_ptr;
    typedef typename boost::intrusive::pointer_traits<Pointer>::
       template rebind_pointer<Pointer>::type                                        index_pointer;
 
    Pointer m_cur;
    Pointer m_first;
    Pointer m_last;
    index_pointer  m_node;
 
    public:
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_cur()          const  {  return m_cur;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_first()        const  {  return m_first;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_last()         const  {  return m_last;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline index_pointer get_node()   const  {  return m_node;  }
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, difference_type block_size) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_first(*y), m_last(*y + block_size), m_node(y)
    {}
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, size_type block_size) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_first(*y), m_last(*y + difference_type(block_size)), m_node(y)
    {}
 
    inline deque_iterator() BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(), m_first(), m_last(), m_node()  //Value initialization to achieve "null iterators" (N3644)
    {}
 
    inline deque_iterator(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_first(x.get_first()), m_last(x.get_last()), m_node(x.get_node())
    {}
 
    inline deque_iterator(const nonconst_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_first(x.get_first()), m_last(x.get_last()), m_node(x.get_node())
    {}
 
    inline deque_iterator(Pointer cur, Pointer first, Pointer last, index_pointer node) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(cur), m_first(first), m_last(last), m_node(node)
    {}
 
    inline deque_iterator& operator=(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
    {  m_cur = x.get_cur(); m_first = x.get_first(); m_last = x.get_last(); m_node = x.get_node(); return *this; }
 
    inline deque_iterator<Pointer, false> unconst() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       return deque_iterator<Pointer, false>(this->get_cur(), this->get_first(), this->get_last(), this->get_node());
    }
 
    inline reference operator*() const BOOST_NOEXCEPT_OR_NOTHROW
       { return *this->m_cur; }
 
    inline pointer operator->() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD difference_type operator-(const deque_iterator& x) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       if(!this->m_cur && !x.m_cur){
          return 0;
       }
       const difference_type block_size = m_last - m_first;
       BOOST_ASSERT(block_size);
       return block_size * (this->m_node - x.m_node - 1) +
          (this->m_cur - this->m_first) + (x.m_last - x.m_cur);
    }
 
    deque_iterator& operator++() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       ++this->m_cur;
       if (this->m_cur == this->m_last) {
          const difference_type block_size = m_last - m_first;
          BOOST_ASSERT(block_size);
          this->priv_set_node(this->m_node + 1, block_size);
          this->m_cur = this->m_first;
       }
       return *this;
    }
 
    inline deque_iterator operator++(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       ++*this;
       return tmp;
    }
 
    deque_iterator& operator--() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       if (this->m_cur == this->m_first) {
          const difference_type block_size = m_last - m_first;
          BOOST_ASSERT(block_size);
          this->priv_set_node(this->m_node - 1, block_size);
          this->m_cur = this->m_last;
       }
       --this->m_cur;
       return *this;
    }
 
    inline deque_iterator operator--(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       --*this;
       return tmp;
    }
 
    deque_iterator& operator+=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {
       if (!n)
          return *this;
       BOOST_ASSERT(!!m_cur);
       const difference_type offset = n + (this->m_cur - this->m_first);
       const difference_type block_size = m_last - m_first;
       BOOST_ASSERT(block_size);
       if (offset >= 0 && offset < block_size)
          this->m_cur += difference_type(n);
       else {
          const difference_type node_offset =
             offset > 0 ? (offset / block_size)
                        : (-difference_type((-offset - 1) / block_size) - 1);
          this->priv_set_node(this->m_node + node_offset, size_type(block_size));
          this->m_cur = this->m_first +
          (offset - node_offset * block_size);
       }
       return *this;
    }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator+(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp += n;  }
 
    inline
       deque_iterator& operator-=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
       { return *this += -n; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator-(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp -= n;  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference operator[](difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       { return *(*this + n); }
 
    //Comparisons
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator==(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur == r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator!=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur != r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       {  return (l.m_node == r.m_node) ? (l.m_cur < r.m_cur) : (l.m_node < r.m_node);  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return r < l; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(r < l); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(l < r); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend deque_iterator operator+(difference_type n, deque_iterator x) BOOST_NOEXCEPT_OR_NOTHROW
       {  return x += n;  }
 
    inline void priv_set_node(index_pointer new_node, size_type block_size) BOOST_NOEXCEPT_OR_NOTHROW
    {  return this->priv_set_node(new_node, difference_type(block_size)); }
 
    inline void priv_set_node(index_pointer new_node, difference_type block_size) BOOST_NOEXCEPT_OR_NOTHROW
    {
       this->m_node = new_node;
       this->m_first = *new_node;
       this->m_last = this->m_first + block_size;
    }
 };
 
 #elif BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL == 1
 
 template<class Pointer, bool IsConst, unsigned BlockBytes, unsigned BlockSize>
 class deque_iterator
 {
    public:
    typedef std::random_access_iterator_tag                                          iterator_category;
    typedef typename boost::intrusive::pointer_traits<Pointer>::element_type         value_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::difference_type      difference_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::size_type            size_type;
    typedef typename if_c
       < IsConst
       , typename boost::intrusive::pointer_traits<Pointer>::template
                                  rebind_pointer<const value_type>::type
       , Pointer
       >::type                                                                       pointer;
    typedef typename if_c
       < IsConst
       , const value_type&
       , value_type&
       >::type                                                                       reference;
 
    BOOST_CONSTEXPR inline static size_type get_block_size() BOOST_NOEXCEPT_OR_NOTHROW
       { return deque_block_size<value_type, BlockBytes, BlockSize>::value; }
 
    BOOST_CONSTEXPR inline static difference_type get_block_ssize() BOOST_NOEXCEPT_OR_NOTHROW
       { return difference_type((get_block_size())); }
 
    class nat;
    typedef typename dtl::if_c< IsConst
                              , deque_iterator<Pointer, false, BlockBytes, BlockSize>
                              , nat>::type                                           nonconst_iterator;
 
    typedef Pointer                                                                  val_alloc_ptr;
    typedef typename boost::intrusive::pointer_traits<Pointer>::
       template rebind_pointer<Pointer>::type                                        index_pointer;
 
    Pointer m_cur;
    Pointer m_first;
    index_pointer  m_node;
 
    public:
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_cur()          const  {  return m_cur;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_first()        const  {  return m_first;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_last()         const  { return m_first + get_block_ssize(); }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline index_pointer get_node()   const  {  return m_node;  }
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, difference_type ) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_first(*y), m_node(y)
    {}
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, size_type ) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_first(*y), m_node(y)
    {}
 
    inline deque_iterator() BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(), m_first(), m_node()  //Value initialization to achieve "null iterators" (N3644)
    {}
 
    inline deque_iterator(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_first(x.get_first()), m_node(x.get_node())
    {}
 
    inline deque_iterator(const nonconst_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_first(x.get_first()), m_node(x.get_node())
    {}
 
    inline deque_iterator(Pointer cur, Pointer first, index_pointer node) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(cur), m_first(first), m_node(node)
    {}
 
    inline deque_iterator& operator=(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
    {  m_cur = x.get_cur(); m_first = x.get_first(); m_node = x.get_node(); return *this; }
 
    inline nonconst_iterator unconst() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       return nonconst_iterator(this->get_cur(), this->get_first(), this->get_node());
    }
 
    inline reference operator*() const BOOST_NOEXCEPT_OR_NOTHROW
       { return *this->m_cur; }
 
    inline pointer operator->() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD difference_type operator-(const deque_iterator& x) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       if(!this->m_cur && !x.m_cur){
          return 0;
       }
       const difference_type block_size = get_block_ssize();
       BOOST_ASSERT(block_size);
       return block_size * (this->m_node - x.m_node - 1) +
          (this->m_cur - this->m_first) + ((x.m_first+block_size) - x.m_cur);
    }
 
    deque_iterator& operator++() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       ++this->m_cur;
       const difference_type block_size = get_block_ssize();
       if (this->m_cur == (this->m_first+block_size)) {
 
          BOOST_ASSERT(block_size);
          ++this->m_node;
          this->m_first = *this->m_node;
          this->m_cur = this->m_first;
       }
       return *this;
    }
 
    inline deque_iterator operator++(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       ++*this;
       return tmp;
    }
 
    deque_iterator& operator--() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       if (this->m_cur == this->m_first) {
          --this->m_node;
          this->m_first = *this->m_node;
          this->m_cur = this->m_first + get_block_ssize();
       }
       --this->m_cur;
       return *this;
    }
 
    inline deque_iterator operator--(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       --*this;
       return tmp;
    }
 
    deque_iterator& operator+=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {
       if (!n)
          return *this;
       BOOST_ASSERT(!!m_cur);
       const difference_type offset = n + (this->m_cur - this->m_first);
       const difference_type block_size = get_block_ssize();
       BOOST_ASSERT(block_size);
       if (offset >= 0 && offset < block_size)
          this->m_cur += difference_type(n);
       else {
          const difference_type node_offset =
             offset > 0 ? (offset / block_size)
                        : (-difference_type((-offset - 1) / block_size) - 1);
          this->m_node += node_offset;
          this->m_first = *this->m_node;
          this->m_cur = this->m_first + (offset - node_offset * block_size);
       }
       return *this;
    }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator+(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp += n;  }
 
    inline
       deque_iterator& operator-=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
       { return *this += -n; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator-(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp -= n;  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference operator[](difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       { return *(*this + n); }
 
    //Comparisons
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator==(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur == r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator!=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur != r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       {  return (l.m_node == r.m_node) ? (l.m_cur < r.m_cur) : (l.m_node < r.m_node);  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return r < l; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(r < l); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(l < r); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend deque_iterator operator+(difference_type n, deque_iterator x) BOOST_NOEXCEPT_OR_NOTHROW
       {  return x += n;  }
 
    inline void priv_set_node(index_pointer new_node, size_type ) BOOST_NOEXCEPT_OR_NOTHROW
    {  return this->priv_set_node(new_node, difference_type()); }
 
    inline void priv_set_node(index_pointer new_node, difference_type) BOOST_NOEXCEPT_OR_NOTHROW
    {
       this->m_node = new_node;
       this->m_first = *new_node;
    }
 };
 
 #elif BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL == 2
 
 template<class Pointer, bool IsConst, unsigned BlockBytes, unsigned BlockSize>
 class deque_iterator
 {
    public:
    typedef std::random_access_iterator_tag                                          iterator_category;
    typedef typename boost::intrusive::pointer_traits<Pointer>::element_type         value_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::difference_type      difference_type;
    typedef typename boost::intrusive::pointer_traits<Pointer>::size_type            size_type;
    typedef typename if_c
       < IsConst
       , typename boost::intrusive::pointer_traits<Pointer>::template
                                  rebind_pointer<const value_type>::type
       , Pointer
       >::type                                                                       pointer;
    typedef typename if_c
       < IsConst
       , const value_type&
       , value_type&
       >::type                                                                       reference;
 
    BOOST_CONSTEXPR inline static size_type get_block_size() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_CONTAINER_STATIC_ASSERT((deque_block_size<value_type, BlockBytes, BlockSize>::value));
       return deque_block_size<value_type, BlockBytes, BlockSize>::value;
    }
 
    BOOST_CONSTEXPR inline static difference_type get_block_ssize() BOOST_NOEXCEPT_OR_NOTHROW
       { return difference_type((get_block_size())); }
 
    class nat;
    typedef typename dtl::if_c< IsConst
                              , deque_iterator<Pointer, false, BlockBytes, BlockSize>
                              , nat>::type                                           nonconst_iterator;
 
    typedef Pointer                                                                  val_alloc_ptr;
    typedef typename boost::intrusive::pointer_traits<Pointer>::
       template rebind_pointer<Pointer>::type                                        index_pointer;
 
    Pointer m_cur;
    index_pointer  m_node;
 
    public:
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_cur()          const  {  return m_cur;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_first()        const  {  return *m_node;  }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline Pointer get_last()         const  { return *m_node + get_block_ssize(); }
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline index_pointer get_node()   const  {  return m_node;  }
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, difference_type ) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_node(y)
    {}
 
    inline deque_iterator(val_alloc_ptr x, index_pointer y, size_type ) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x), m_node(y)
    {}
 
    inline deque_iterator() BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(), m_node()  //Value initialization to achieve "null iterators" (N3644)
    {}
 
    inline deque_iterator(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_node(x.get_node())
    {}
 
    inline deque_iterator(const nonconst_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(x.get_cur()), m_node(x.get_node())
    {}
 
    inline deque_iterator(Pointer cur, index_pointer node) BOOST_NOEXCEPT_OR_NOTHROW
       : m_cur(cur), m_node(node)
    {}
 
    inline deque_iterator& operator=(const deque_iterator& x) BOOST_NOEXCEPT_OR_NOTHROW
    {  m_cur = x.get_cur(); m_node = x.get_node(); return *this; }
 
    inline nonconst_iterator unconst() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       return nonconst_iterator(this->get_cur(), this->get_node());
    }
 
    inline reference operator*() const BOOST_NOEXCEPT_OR_NOTHROW
       { return *this->m_cur; }
 
    inline pointer operator->() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD difference_type operator-(const deque_iterator& x) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       if(!this->m_cur && !x.m_cur){
          return 0;
       }
       const difference_type block_size = get_block_ssize();
       BOOST_ASSERT(block_size);
       return block_size * (this->m_node - x.m_node - 1) +
          (this->m_cur - this->get_first()) + (x.get_last() - x.m_cur);
    }
 
    deque_iterator& operator++() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       ++this->m_cur;
       if (this->m_cur == (this->get_last())) {
 
          ++this->m_node;
          this->m_cur = *this->m_node;
       }
       return *this;
    }
 
    inline deque_iterator operator++(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       ++*this;
       return tmp;
    }
 
    deque_iterator& operator--() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       if (this->m_cur == this->get_first()) {
          --this->m_node;
          this->m_cur = this->get_last();
       }
       --this->m_cur;
       return *this;
    }
 
    inline deque_iterator operator--(int) BOOST_NOEXCEPT_OR_NOTHROW
    {
       deque_iterator tmp(*this);
       --*this;
       return tmp;
    }
 
    deque_iterator& operator+=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {
       if (!n)
          return *this;
       BOOST_ASSERT(!!m_cur);
       const difference_type offset = n + (this->m_cur - this->get_first());
       const difference_type block_size = get_block_ssize();
       BOOST_ASSERT(block_size);
       if (offset >= 0 && offset < block_size)
          this->m_cur += difference_type(n);
       else {
          const difference_type node_offset =
             offset > 0 ? (offset / block_size)
                        : (-difference_type((-offset - 1) / block_size) - 1);
          this->m_node += node_offset;
          this->m_cur = this->get_first() + (offset - node_offset * block_size);
       }
       return *this;
    }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator+(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp += n;  }
 
    inline
       deque_iterator& operator-=(difference_type n) BOOST_NOEXCEPT_OR_NOTHROW
       { return *this += -n; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       deque_iterator operator-(difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
       {  deque_iterator tmp(*this); return tmp -= n;  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference operator[](difference_type n) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!!m_cur);
       const difference_type offset = n + (this->m_cur - this->get_first());
       const difference_type block_size = get_block_ssize();
       if (offset >= 0 && offset < block_size)
          return this->m_cur[difference_type(n)];
       else {
          const difference_type node_offset = offset > 0
             ? (offset / block_size)
             : (-difference_type((-offset - 1) / block_size) - 1);
          return (this->m_node[node_offset]) [offset - node_offset * block_size];
       }
    }
 
    //Comparisons
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator==(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur == r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator!=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return l.m_cur != r.m_cur; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       {  return (l.m_node == r.m_node) ? (l.m_cur < r.m_cur) : (l.m_node < r.m_node);  }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return r < l; }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(r < l); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>=(const deque_iterator& l, const deque_iterator& r) BOOST_NOEXCEPT_OR_NOTHROW
       { return !(l < r); }
 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend deque_iterator operator+(difference_type n, deque_iterator x) BOOST_NOEXCEPT_OR_NOTHROW
       {  return x += n;  }
 
    inline void priv_set_node(index_pointer new_node, size_type ) BOOST_NOEXCEPT_OR_NOTHROW
    {  return this->priv_set_node(new_node, difference_type()); }
 
    inline void priv_set_node(index_pointer new_node, difference_type) BOOST_NOEXCEPT_OR_NOTHROW
    {
       this->m_node = new_node;
    }
 };
 
 #else
 
 #error "Invalid BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL"
 
 #endif
 }  //namespace dtl {
 
 template<class Options>
 struct get_deque_opt
 {
    typedef Options type;
 };
 
 template<>
 struct get_deque_opt<void>
 {
    typedef deque_null_opt type;
 };
 
 // Deque base class.  It has two purposes.  First, its constructor
 //  and destructor allocate (but don't initialize) storage.  This makes
 //  exception safety easier.
 template <class Allocator, class Options>
 class deque_base
 {
    BOOST_COPYABLE_AND_MOVABLE(deque_base)
    public:
    typedef allocator_traits<Allocator>                            val_alloc_traits_type;
    typedef typename val_alloc_traits_type::value_type             val_alloc_val;
    typedef typename val_alloc_traits_type::pointer                val_alloc_ptr;
    typedef typename val_alloc_traits_type::const_pointer          val_alloc_cptr;
    typedef typename val_alloc_traits_type::reference              val_alloc_ref;
    typedef typename val_alloc_traits_type::const_reference        val_alloc_cref;
    typedef typename val_alloc_traits_type::difference_type        val_alloc_diff;
    typedef typename val_alloc_traits_type::size_type              val_alloc_size;
    typedef typename val_alloc_traits_type::template
       portable_rebind_alloc<val_alloc_ptr>::type                  ptr_alloc_t;
    typedef allocator_traits<ptr_alloc_t>                          ptr_alloc_traits_type;
    typedef typename ptr_alloc_traits_type::value_type             ptr_alloc_val;
    typedef typename ptr_alloc_traits_type::pointer                ptr_alloc_ptr;
    typedef typename ptr_alloc_traits_type::const_pointer          ptr_alloc_cptr;
    typedef typename ptr_alloc_traits_type::reference              ptr_alloc_ref;
    typedef typename ptr_alloc_traits_type::const_reference        ptr_alloc_cref;
    typedef Allocator                                                      allocator_type;
    typedef allocator_type                                         stored_allocator_type;
    typedef val_alloc_size                                         size_type;
    typedef val_alloc_diff                                         difference_type;
 
    private:
    typedef typename get_deque_opt<Options>::type                  options_type;
 
    protected:
    #if BOOST_CONTAINER_DEQUE_LIGHTER_ITERATOR_LEVEL == 0
    typedef dtl::deque_iterator<val_alloc_ptr, false> iterator;
    typedef dtl::deque_iterator<val_alloc_ptr, true> const_iterator;
    #else
    typedef dtl::deque_iterator<val_alloc_ptr, false, options_type::block_bytes, options_type::block_size> iterator;
    typedef dtl::deque_iterator<val_alloc_ptr, true, options_type::block_bytes, options_type::block_size> const_iterator;
    #endif
 
    BOOST_CONSTEXPR inline static val_alloc_diff get_block_ssize() BOOST_NOEXCEPT_OR_NOTHROW
       { return val_alloc_diff((get_block_size())); }
 
    BOOST_CONSTEXPR inline static size_type get_block_size() BOOST_NOEXCEPT_OR_NOTHROW
       { return deque_block_size<val_alloc_val, options_type::block_bytes, options_type::block_size>::value; }
 
    typedef deque_value_traits<val_alloc_val>             traits_t;
    typedef ptr_alloc_t                                   map_allocator_type;
 
    inline val_alloc_ptr priv_allocate_node()
       {  return this->alloc().allocate(get_block_size());  }
 
    inline void priv_deallocate_node(val_alloc_ptr p) BOOST_NOEXCEPT_OR_NOTHROW
       {  this->alloc().deallocate(p, get_block_size());  }
 
    inline ptr_alloc_ptr priv_allocate_map(size_type n)
       { return this->ptr_alloc().allocate(n); }
 
    inline void priv_deallocate_map(ptr_alloc_ptr p, size_type n) BOOST_NOEXCEPT_OR_NOTHROW
       { this->ptr_alloc().deallocate(p, n); }
 
    inline deque_base(size_type num_elements, const allocator_type& a)
       :  members_(a)
    { this->priv_initialize_map(num_elements); }
 
    inline explicit deque_base(const allocator_type& a)
       :  members_(a)
    {}
 
    inline deque_base()
       :  members_()
    {}
 
    inline explicit deque_base(BOOST_RV_REF(deque_base) x)
       :  members_( boost::move(x.ptr_alloc())
                  , boost::move(x.alloc()) )
    {}
 
    ~deque_base()
    {
       if (this->members_.m_map) {
          this->priv_destroy_nodes(this->members_.m_start.m_node, this->members_.m_finish.m_node + 1);
          this->priv_deallocate_map(this->members_.m_map, this->members_.m_map_size);
       }
    }
 
    private:
    deque_base(const deque_base&);
 
    protected:
 
    void swap_members(deque_base &x) BOOST_NOEXCEPT_OR_NOTHROW
    {
       ::boost::adl_move_swap(this->members_.m_start, x.members_.m_start);
       ::boost::adl_move_swap(this->members_.m_finish, x.members_.m_finish);
       ::boost::adl_move_swap(this->members_.m_map, x.members_.m_map);
       ::boost::adl_move_swap(this->members_.m_map_size, x.members_.m_map_size);
    }
 
    void priv_initialize_map(size_type num_elements)
    {
 //      if(num_elements){
          size_type num_nodes = num_elements / get_block_size() + 1;
 
          this->members_.m_map_size = dtl::max_value((size_type) InitialMapSize, num_nodes + 2);
          this->members_.m_map = this->priv_allocate_map(this->members_.m_map_size);
 
          ptr_alloc_ptr nstart = this->members_.m_map + difference_type(this->members_.m_map_size - num_nodes) / 2;
          ptr_alloc_ptr nfinish = nstart + difference_type(num_nodes);
 
          BOOST_CONTAINER_TRY {
             this->priv_create_nodes(nstart, nfinish);
          }
          BOOST_CONTAINER_CATCH(...){
             this->priv_deallocate_map(this->members_.m_map, this->members_.m_map_size);
             this->members_.m_map = 0;
             this->members_.m_map_size = 0;
             BOOST_CONTAINER_RETHROW
          }
          BOOST_CONTAINER_CATCH_END
 
          this->members_.m_start.priv_set_node(nstart, get_block_size());
          this->members_.m_finish.priv_set_node(nfinish - 1, get_block_size());
          this->members_.m_start.m_cur = this->members_.m_start.get_first();
          this->members_.m_finish.m_cur = this->members_.m_finish.get_first() + difference_type(num_elements % get_block_size());
 //      }
    }
 
    void priv_create_nodes(ptr_alloc_ptr nstart, ptr_alloc_ptr nfinish)
    {
       ptr_alloc_ptr cur = nstart;
       BOOST_CONTAINER_TRY {
          for (; cur < nfinish; ++cur)
             *cur = this->priv_allocate_node();
       }
       BOOST_CONTAINER_CATCH(...){
          this->priv_destroy_nodes(nstart, cur);
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
    }
 
    void priv_destroy_nodes(ptr_alloc_ptr nstart, ptr_alloc_ptr nfinish) BOOST_NOEXCEPT_OR_NOTHROW
    {
       for (ptr_alloc_ptr n = nstart; n < nfinish; ++n)
          this->priv_deallocate_node(*n);
    }
 
    void priv_clear_map() BOOST_NOEXCEPT_OR_NOTHROW
    {
       if (this->members_.m_map) {
          this->priv_destroy_nodes(this->members_.m_start.m_node, this->members_.m_finish.m_node + 1);
          this->priv_deallocate_map(this->members_.m_map, this->members_.m_map_size);
          this->members_.m_map = 0;
          this->members_.m_map_size = 0;
          this->members_.m_start = iterator();
          this->members_.m_finish = this->members_.m_start;
       }
    }
 
    enum { InitialMapSize = 8 };
 
    protected:
    struct members_holder
       :  public ptr_alloc_t
       ,  public allocator_type
    {
       members_holder()
          :  map_allocator_type(), allocator_type()
          ,  m_map(0), m_map_size(0)
          ,  m_start(), m_finish(m_start)
       {}
 
       explicit members_holder(const allocator_type &a)
          :  map_allocator_type(a), allocator_type(a)
          ,  m_map(0), m_map_size(0)
          ,  m_start(), m_finish(m_start)
       {}
 
       template<class ValAllocConvertible, class PtrAllocConvertible>
       members_holder(BOOST_FWD_REF(PtrAllocConvertible) pa, BOOST_FWD_REF(ValAllocConvertible) va)
          : map_allocator_type(boost::forward<PtrAllocConvertible>(pa))
          , allocator_type    (boost::forward<ValAllocConvertible>(va))
          , m_map(0), m_map_size(0)
          , m_start(), m_finish(m_start)
       {}
 
       ptr_alloc_ptr   m_map;
       val_alloc_size  m_map_size;
       iterator        m_start;
       iterator        m_finish;
    } members_;
 
    inline ptr_alloc_t &ptr_alloc() BOOST_NOEXCEPT_OR_NOTHROW
    {  return members_;  }
 
    inline const ptr_alloc_t &ptr_alloc() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return members_;  }
 
    inline allocator_type &alloc() BOOST_NOEXCEPT_OR_NOTHROW
    {  return members_;  }
 
    inline const allocator_type &alloc() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return members_;  }
 };
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 #ifdef BOOST_CONTAINER_DOXYGEN_INVOKED
 //! A double-ended queue is a sequence that supports random access to elements, constant time insertion
 //! and removal of elements at the end of the sequence, and linear time insertion and removal of elements in the middle.
 //!
 //! \tparam T The type of object that is stored in the deque
 //! \tparam A The allocator used for all internal memory management, use void
 //!   for the default allocator
 //! \tparam Options A type produced from \c boost::container::deque_options.
 template <class T, class Allocator = void, class Options = void>
 #else
 template <class T, class Allocator, class Options>
 #endif
 class deque : protected deque_base<typename real_allocator<T, Allocator>::type, Options>
 {
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
    typedef deque_base<typename real_allocator<T, Allocator>::type, Options> Base;
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    typedef typename real_allocator<T, Allocator>::type ValAllocator;
    typedef constant_iterator<T> c_it;
 
    public:
 
    //////////////////////////////////////////////
    //
    //                    types
    //
    //////////////////////////////////////////////
 
    typedef T                                                                           value_type;
    typedef ValAllocator                                                                allocator_type;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::pointer           pointer;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::const_pointer     const_pointer;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::reference         reference;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::const_reference   const_reference;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::size_type         size_type;
    typedef typename ::boost::container::allocator_traits<ValAllocator>::difference_type   difference_type;
    typedef BOOST_CONTAINER_IMPDEF(allocator_type)                                      stored_allocator_type;
    typedef BOOST_CONTAINER_IMPDEF(typename Base::iterator)                             iterator;
    typedef BOOST_CONTAINER_IMPDEF(typename Base::const_iterator)                       const_iterator;
    typedef BOOST_CONTAINER_IMPDEF(boost::container::reverse_iterator<iterator>)        reverse_iterator;
    typedef BOOST_CONTAINER_IMPDEF(boost::container::reverse_iterator<const_iterator>)  const_reverse_iterator;
 
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
    private:                      // Internal typedefs
 
    //`allocator_type::value_type` must match container's `value type`. If this
    //assertion fails, please review your allocator definition. 
    BOOST_CONTAINER_STATIC_ASSERT((dtl::is_same<value_type, typename allocator_traits<ValAllocator>::value_type>::value));
 
    BOOST_COPYABLE_AND_MOVABLE(deque)
    typedef typename Base::ptr_alloc_ptr index_pointer;
    typedef allocator_traits<ValAllocator>                  allocator_traits_type;
 
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
    using Base::get_block_ssize;
 
    public:
 
    using Base::get_block_size;
 
 
    //////////////////////////////////////////////
    //
    //          construct/copy/destroy
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Default constructors a deque.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor throws.
    //!
    //! <b>Complexity</b>: Constant.
    inline deque()
       BOOST_NOEXCEPT_IF(dtl::is_nothrow_default_constructible<ValAllocator>::value)
       : Base()
    {}
 
    //! <b>Effects</b>: Constructs a deque taking the allocator as parameter.
    //!
    //! <b>Throws</b>: Nothing
    //!
    //! <b>Complexity</b>: Constant.
    inline explicit deque(const allocator_type& a) BOOST_NOEXCEPT_OR_NOTHROW
       : Base(a)
    {}
 
    //! <b>Effects</b>: Constructs a deque
    //!   and inserts n value initialized values.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's value initialization throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline explicit deque(size_type n)
       : Base(n, allocator_type())
    {
       dtl::insert_value_initialized_n_proxy<ValAllocator> proxy;
       proxy.uninitialized_copy_n_and_update(this->alloc(), this->begin(), n);
       //deque_base will deallocate in case of exception...
    }
 
    //! <b>Effects</b>: Constructs a deque
    //!   and inserts n default initialized values.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's default initialization or copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    //!
    //! <b>Note</b>: Non-standard extension
    inline deque(size_type n, default_init_t)
       : Base(n, allocator_type())
    {
       dtl::insert_default_initialized_n_proxy<ValAllocator> proxy;
       proxy.uninitialized_copy_n_and_update(this->alloc(), this->begin(), n);
       //deque_base will deallocate in case of exception...
    }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts n value initialized values.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's value initialization throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline explicit deque(size_type n, const allocator_type &a)
       : Base(n, a)
    {
       dtl::insert_value_initialized_n_proxy<ValAllocator> proxy;
       proxy.uninitialized_copy_n_and_update(this->alloc(), this->begin(), n);
       //deque_base will deallocate in case of exception...
    }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts n default initialized values.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's default initialization or copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    //!
    //! <b>Note</b>: Non-standard extension
    inline deque(size_type n, default_init_t, const allocator_type &a)
       : Base(n, a)
    {
       dtl::insert_default_initialized_n_proxy<ValAllocator> proxy;
       proxy.uninitialized_copy_n_and_update(this->alloc(), this->begin(), n);
       //deque_base will deallocate in case of exception...
    }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts n copies of value.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline deque(size_type n, const value_type& value)
       : Base(n, allocator_type())
    { this->priv_fill_initialize(value); }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts n copies of value.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline deque(size_type n, const value_type& value, const allocator_type& a)
       : Base(n, a)
    { this->priv_fill_initialize(value); }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts a copy of the range [first, last) in the deque.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's constructor taking a dereferenced InIt throws.
    //!
    //! <b>Complexity</b>: Linear to the range [first, last).
    template <class InIt>
    inline deque(InIt first, InIt last
       #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
       , typename dtl::disable_if_convertible
          <InIt, size_type>::type * = 0
       #endif
       )
       : Base(allocator_type())
    {
       this->priv_range_initialize(first, last);
    }
 
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts a copy of the range [first, last) in the deque.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's constructor taking a dereferenced InIt throws.
    //!
    //! <b>Complexity</b>: Linear to the range [first, last).
    template <class InIt>
    inline deque(InIt first, InIt last, const allocator_type& a
       #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
       , typename dtl::disable_if_convertible
          <InIt, size_type>::type * = 0
       #endif
       )
       : Base(a)
    {
       this->priv_range_initialize(first, last);
    }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Constructs a deque that will use a copy of allocator a
    //!   and inserts a copy of the range [il.begin(), il.end()) in the deque.
    //!
    //! <b>Throws</b>: If allocator_type's default constructor
    //!   throws or T's constructor taking a dereferenced std::initializer_list iterator throws.
    //!
    //! <b>Complexity</b>: Linear to the range [il.begin(), il.end()).
    inline deque(std::initializer_list<value_type> il, const allocator_type& a = allocator_type())
       : Base(a)
    {
       this->priv_range_initialize(il.begin(), il.end());
    }
 #endif
 
    //! <b>Effects</b>: Copy constructs a deque.
    //!
    //! <b>Postcondition</b>: x == *this.
    //!
    //! <b>Complexity</b>: Linear to the elements x contains.
    inline deque(const deque& x)
       :  Base(allocator_traits_type::select_on_container_copy_construction(x.alloc()))
    {
       if(x.size()){
          this->priv_initialize_map(x.size());
          boost::container::uninitialized_copy_alloc
             (this->alloc(), x.begin(), x.end(), this->members_.m_start);
       }
    }
 
    //! <b>Effects</b>: Move constructor. Moves x's resources to *this.
    //!
    //! <b>Throws</b>: If allocator_type's copy constructor throws.
    //!
    //! <b>Complexity</b>: Constant.
    inline deque(BOOST_RV_REF(deque) x) BOOST_NOEXCEPT_OR_NOTHROW
       :  Base(BOOST_MOVE_BASE(Base, x))
    {  this->swap_members(x);   }
 
    //! <b>Effects</b>: Copy constructs a vector using the specified allocator.
    //!
    //! <b>Postcondition</b>: x == *this.
    //!
    //! <b>Throws</b>: If allocation
    //!   throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the elements x contains.
    deque(const deque& x, const allocator_type &a)
       :  Base(a)
    {
       if(x.size()){
          this->priv_initialize_map(x.size());
          boost::container::uninitialized_copy_alloc
             (this->alloc(), x.begin(), x.end(), this->members_.m_start);
       }
    }
 
    //! <b>Effects</b>: Move constructor using the specified allocator.
    //!                 Moves x's resources to *this if a == allocator_type().
    //!                 Otherwise copies values from x to *this.
    //!
    //! <b>Throws</b>: If allocation or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Constant if a == x.get_allocator(), linear otherwise.
    deque(BOOST_RV_REF(deque) x, const allocator_type &a)
       :  Base(a)
    {
       if(x.alloc() == a){
          this->swap_members(x);
       }
       else{
          if(x.size()){
             this->priv_initialize_map(x.size());
             boost::container::uninitialized_copy_alloc
                ( this->alloc(), boost::make_move_iterator(x.begin())
                , boost::make_move_iterator(x.end()), this->members_.m_start);
          }
       }
    }
 
    //! <b>Effects</b>: Destroys the deque. All stored values are destroyed
    //!   and used memory is deallocated.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Linear to the number of elements.
    inline ~deque() BOOST_NOEXCEPT_OR_NOTHROW
    {
       this->priv_destroy_range(this->members_.m_start, this->members_.m_finish);
    }
 
    //! <b>Effects</b>: Makes *this contain the same elements as x.
    //!
    //! <b>Postcondition</b>: this->size() == x.size(). *this contains a copy
    //! of each of x's elements.
    //!
    //! <b>Throws</b>: If memory allocation throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the number of elements in x.
    deque& operator= (BOOST_COPY_ASSIGN_REF(deque) x)
    {
       if (BOOST_LIKELY(&x != this)){
          allocator_type &this_alloc     = this->alloc();
          const allocator_type &x_alloc  = x.alloc();
          dtl::bool_<allocator_traits_type::
             propagate_on_container_copy_assignment::value> flag;
          if(flag && this_alloc != x_alloc){
             this->clear();
             this->shrink_to_fit();
          }
          dtl::assign_alloc(this->alloc(), x.alloc(), flag);
          dtl::assign_alloc(this->ptr_alloc(), x.ptr_alloc(), flag);
          this->assign(x.cbegin(), x.cend());
       }
       return *this;
    }
 
    //! <b>Effects</b>: Move assignment. All x's values are transferred to *this.
    //!
    //! <b>Throws</b>: If allocator_traits_type::propagate_on_container_move_assignment
    //!   is false and (allocation throws or value_type's move constructor throws)
    //!
    //! <b>Complexity</b>: Constant if allocator_traits_type::
    //!   propagate_on_container_move_assignment is true or
    //!   this->get>allocator() == x.get_allocator(). Linear otherwise.
    deque& operator= (BOOST_RV_REF(deque) x)
       BOOST_NOEXCEPT_IF(allocator_traits_type::propagate_on_container_move_assignment::value
                                   || allocator_traits_type::is_always_equal::value)
    {
       if (BOOST_LIKELY(this != &x)) {
          //We know resources can be transferred at comiple time if both allocators are
          //always equal or the allocator is going to be propagated
          const bool can_steal_resources_alloc
             =  allocator_traits_type::propagate_on_container_move_assignment::value
             || allocator_traits_type::is_always_equal::value;
          dtl::bool_<can_steal_resources_alloc> flag;
          this->priv_move_assign(boost::move(x), flag);
       }
       return *this;
    }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Makes *this contain the same elements as il.
    //!
    //! <b>Postcondition</b>: this->size() == il.size(). *this contains a copy
    //! of each of x's elements.
    //!
    //! <b>Throws</b>: If memory allocation throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the number of elements in il.
    inline deque& operator=(std::initializer_list<value_type> il)
    {
       this->assign(il.begin(), il.end());
       return *this;
    }
 #endif
 
    //! <b>Effects</b>: Assigns the n copies of val to *this.
    //!
    //! <b>Throws</b>: If memory allocation throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline void assign(size_type n, const T& val)
    {
       this->assign(c_it(val, n), c_it());
    }
 
    //! <b>Effects</b>: Assigns the the range [first, last) to *this.
    //!
    //! <b>Throws</b>: If memory allocation throws or
    //!   T's constructor from dereferencing InIt throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    template <class InIt>
    void assign(InIt first, InIt last
       #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
       , typename dtl::disable_if_or
          < void
          , dtl::is_convertible<InIt, size_type>
          , dtl::is_not_input_iterator<InIt>
          >::type * = 0
       #endif
       )
    {
       iterator cur = this->begin();
       for ( ; first != last && cur != end(); ++cur, ++first){
          *cur = *first;
       }
       if (first == last){
          this->erase(cur, this->cend());
       }
       else{
          this->insert(this->cend(), first, last);
       }
    }
 
    #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
    template <class FwdIt>
    void assign(FwdIt first, FwdIt last
       , typename dtl::disable_if_or
          < void
          , dtl::is_convertible<FwdIt, size_type>
          , dtl::is_input_iterator<FwdIt>
          >::type * = 0
       )
    {
       const size_type len = boost::container::iterator_udistance(first, last);
       if (len > size()) {
          FwdIt mid = first;
          boost::container::iterator_uadvance(mid, this->size());
          boost::container::copy(first, mid, begin());
          this->insert(this->cend(), mid, last);
       }
       else{
          this->erase(boost::container::copy(first, last, this->begin()), cend());
       }
    }
    #endif
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Assigns the the range [il.begin(), il.end()) to *this.
    //!
    //! <b>Throws</b>: If memory allocation throws or
    //!   T's constructor from dereferencing std::initializer_list iterator throws.
    //!
    //! <b>Complexity</b>: Linear to il.size().
    inline void assign(std::initializer_list<value_type> il)
    {   this->assign(il.begin(), il.end());   }
 #endif
 
    //! <b>Effects</b>: Returns a copy of the internal allocator.
    //!
    //! <b>Throws</b>: If allocator's copy constructor throws.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       allocator_type get_allocator() const BOOST_NOEXCEPT_OR_NOTHROW
    { return Base::alloc(); }
 
    //! <b>Effects</b>: Returns a reference to the internal allocator.
    //!
    //! <b>Throws</b>: Nothing
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const stored_allocator_type &get_stored_allocator() const BOOST_NOEXCEPT_OR_NOTHROW
    {  return Base::alloc(); }
 
    //////////////////////////////////////////////
    //
    //                iterators
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns a reference to the internal allocator.
    //!
    //! <b>Throws</b>: Nothing
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       stored_allocator_type &get_stored_allocator() BOOST_NOEXCEPT_OR_NOTHROW
    {  return Base::alloc(); }
 
    //! <b>Effects</b>: Returns an iterator to the first element contained in the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator begin() BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_start; }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator begin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_start; }
 
    //! <b>Effects</b>: Returns an iterator to the end of the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator end() BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_finish; }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator end() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_finish; }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the beginning
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reverse_iterator rbegin() BOOST_NOEXCEPT_OR_NOTHROW
       { return reverse_iterator(this->members_.m_finish); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator rbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return const_reverse_iterator(this->members_.m_finish); }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the end
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reverse_iterator rend() BOOST_NOEXCEPT_OR_NOTHROW
       { return reverse_iterator(this->members_.m_start); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator rend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return const_reverse_iterator(this->members_.m_start); }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator cbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_start; }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator cend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return this->members_.m_finish; }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator crbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return const_reverse_iterator(this->members_.m_finish); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator crend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return const_reverse_iterator(this->members_.m_start); }
 
    //////////////////////////////////////////////
    //
    //                capacity
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns true if the deque contains no elements.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       bool empty() const BOOST_NOEXCEPT_OR_NOTHROW
    { return this->members_.m_finish == this->members_.m_start; }
 
    //! <b>Effects</b>: Returns the number of the elements contained in the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return size_type(this->members_.m_finish - this->members_.m_start); }
 
    //! <b>Effects</b>: Returns the largest possible size of the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return allocator_traits_type::max_size(this->alloc()); }
 
    //! <b>Effects</b>: Inserts or erases elements at the end such that
    //!   the size becomes n. New elements are value initialized.
    //!
    //! <b>Throws</b>: If memory allocation throws, or T's constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the difference between size() and new_size.
    void resize(size_type new_size)
    {
       const size_type len = size();
       if (new_size < len)
          this->priv_erase_last_n(len - new_size);
       else{
          const size_type n = new_size - this->size();
          dtl::insert_value_initialized_n_proxy<ValAllocator> proxy;
          priv_insert_back_aux_impl(n, proxy);
       }
    }
 
    //! <b>Effects</b>: Inserts or erases elements at the end such that
    //!   the size becomes n. New elements are default initialized.
    //!
    //! <b>Throws</b>: If memory allocation throws, or T's constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the difference between size() and new_size.
    //!
    //! <b>Note</b>: Non-standard extension
    void resize(size_type new_size, default_init_t)
    {
       const size_type len = size();
       if (new_size < len)
          this->priv_erase_last_n(len - new_size);
       else{
          const size_type n = new_size - this->size();
          dtl::insert_default_initialized_n_proxy<ValAllocator> proxy;
          priv_insert_back_aux_impl(n, proxy);
       }
    }
 
    //! <b>Effects</b>: Inserts or erases elements at the end such that
    //!   the size becomes n. New elements are copy constructed from x.
    //!
    //! <b>Throws</b>: If memory allocation throws, or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to the difference between size() and new_size.
    void resize(size_type new_size, const value_type& x)
    {
       const size_type len = size();
       if (new_size < len)
          this->erase(this->members_.m_start + difference_type(new_size), this->members_.m_finish);
       else
          this->insert(this->members_.m_finish, new_size - len, x);
    }
 
    //! <b>Effects</b>: Tries to deallocate the excess of memory created
    //!   with previous allocations. The size of the deque is unchanged
    //!
    //! <b>Throws</b>: If memory allocation throws.
    //!
    //! <b>Complexity</b>: Constant.
    void shrink_to_fit()
    {
       //This deque implementation already
       //deallocates excess nodes when erasing
       //so there is nothing to do except for
       //empty deque
       if(this->empty()){
          this->priv_clear_map();
       }
    }
 
    //////////////////////////////////////////////
    //
    //               element access
    //
    //////////////////////////////////////////////
 
    //! <b>Requires</b>: !empty()
    //!
    //! <b>Effects</b>: Returns a reference to the first
    //!   element of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference front() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       return *this->members_.m_start;
    }
 
    //! <b>Requires</b>: !empty()
    //!
    //! <b>Effects</b>: Returns a const reference to the first element
    //!   from the beginning of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reference front() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       return *this->members_.m_start;
    }
 
    //! <b>Requires</b>: !empty()
    //!
    //! <b>Effects</b>: Returns a reference to the last
    //!   element of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference back() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       return *(end()-1);
    }
 
    //! <b>Requires</b>: !empty()
    //!
    //! <b>Effects</b>: Returns a const reference to the last
    //!   element of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reference back() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       return *(cend()-1);
    }
 
    //! <b>Requires</b>: size() > n.
    //!
    //! <b>Effects</b>: Returns a reference to the nth element
    //!   from the beginning of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference operator[](size_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(this->size() > n);
       return this->members_.m_start[difference_type(n)];
    }
 
    //! <b>Requires</b>: size() > n.
    //!
    //! <b>Effects</b>: Returns a const reference to the nth element
    //!   from the beginning of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reference operator[](size_type n) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(this->size() > n);
       return this->members_.m_start[difference_type(n)];
    }
 
    //! <b>Requires</b>: size() >= n.
    //!
    //! <b>Effects</b>: Returns an iterator to the nth element
    //!   from the beginning of the container. Returns end()
    //!   if n == size().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator nth(size_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(this->size() >= n);
       return iterator(this->begin()+difference_type(n));
    }
 
    //! <b>Requires</b>: size() >= n.
    //!
    //! <b>Effects</b>: Returns a const_iterator to the nth element
    //!   from the beginning of the container. Returns end()
    //!   if n == size().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator nth(size_type n) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(this->size() >= n);
       return const_iterator(this->cbegin()+difference_type(n));
    }
 
    //! <b>Requires</b>: begin() <= p <= end().
    //!
    //! <b>Effects</b>: Returns the index of the element pointed by p
    //!   and size() if p == end().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type index_of(iterator p) BOOST_NOEXCEPT_OR_NOTHROW
    {
       //Range checked priv_index_of
       return this->priv_index_of(p);
    }
 
    //! <b>Requires</b>: begin() <= p <= end().
    //!
    //! <b>Effects</b>: Returns the index of the element pointed by p
    //!   and size() if p == end().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Note</b>: Non-standard extension
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type index_of(const_iterator p) const BOOST_NOEXCEPT_OR_NOTHROW
    {
       //Range checked priv_index_of
       return this->priv_index_of(p);
    }
 
    //! <b>Requires</b>: size() > n.
    //!
    //! <b>Effects</b>: Returns a reference to the nth element
    //!   from the beginning of the container.
    //!
    //! <b>Throws</b>: range_error if n >= size()
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reference at(size_type n)
    {
       this->priv_throw_if_out_of_range(n);
       return (*this)[n];
    }
 
    //! <b>Requires</b>: size() > n.
    //!
    //! <b>Effects</b>: Returns a const reference to the nth element
    //!   from the beginning of the container.
    //!
    //! <b>Throws</b>: range_error if n >= size()
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reference at(size_type n) const
    {
       this->priv_throw_if_out_of_range(n);
       return (*this)[n];
    }
 
    //////////////////////////////////////////////
    //
    //                modifiers
    //
    //////////////////////////////////////////////
 
    #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Inserts an object of type T constructed with
    //!   std::forward<Args>(args)... in the beginning of the deque.
    //!
    //! <b>Returns</b>: A reference to the created object.
    //!
    //! <b>Throws</b>: If memory allocation throws or the in-place constructor throws.
    //!
    //! <b>Complexity</b>: Amortized constant time
    template <class... Args>
    reference emplace_front(BOOST_FWD_REF(Args)... args)
    {
       if(this->priv_push_front_simple_available()){
          reference r = *this->priv_push_front_simple_pos();
          allocator_traits_type::construct
             ( this->alloc()
             , this->priv_push_front_simple_pos()
             , boost::forward<Args>(args)...);
          this->priv_push_front_simple_commit();
          return r;
       }
       else{
          typedef dtl::insert_nonmovable_emplace_proxy<ValAllocator, Args...> type;
          return *this->priv_insert_front_aux_impl(1, type(boost::forward<Args>(args)...));
       }
    }
 
    //! <b>Effects</b>: Inserts an object of type T constructed with
    //!   std::forward<Args>(args)... in the end of the deque.
    //!
    //! <b>Returns</b>: A reference to the created object.
    //!
    //! <b>Throws</b>: If memory allocation throws or the in-place constructor throws.
    //!
    //! <b>Complexity</b>: Amortized constant time
    template <class... Args>
    reference emplace_back(BOOST_FWD_REF(Args)... args)
    {
       if(this->priv_push_back_simple_available()){
          reference r = *this->priv_push_back_simple_pos();
          allocator_traits_type::construct
             ( this->alloc()
             , this->priv_push_back_simple_pos()
             , boost::forward<Args>(args)...);
          this->priv_push_back_simple_commit();
          return r;
       }
       else{
          typedef dtl::insert_nonmovable_emplace_proxy<ValAllocator, Args...> type;
          return *this->priv_insert_back_aux_impl(1, type(boost::forward<Args>(args)...));
       }
    }
 
    //! <b>Requires</b>: p must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Inserts an object of type T constructed with
    //!   std::forward<Args>(args)... before p
    //!
    //! <b>Throws</b>: If memory allocation throws or the in-place constructor throws.
    //!
    //! <b>Complexity</b>: If p is end(), amortized constant time
    //!   Linear time otherwise.
    template <class... Args>
    iterator emplace(const_iterator p, BOOST_FWD_REF(Args)... args)
    {
       BOOST_ASSERT(this->priv_in_range_or_end(p));
       if(p == this->cbegin()){
          this->emplace_front(boost::forward<Args>(args)...);
          return this->begin();
       }
       else if(p == this->cend()){
          this->emplace_back(boost::forward<Args>(args)...);
          return (this->end()-1);
       }
       else{
          typedef dtl::insert_emplace_proxy<ValAllocator, Args...> type;
          return this->priv_insert_aux_impl(p, 1, type(boost::forward<Args>(args)...));
       }
    }
 
    #else //!defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    #define BOOST_CONTAINER_DEQUE_EMPLACE_CODE(N) \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N\
    reference emplace_front(BOOST_MOVE_UREF##N)\
    {\
       if(priv_push_front_simple_available()){\
          reference r = *this->priv_push_front_simple_pos();\
          allocator_traits_type::construct\
             ( this->alloc(), this->priv_push_front_simple_pos() BOOST_MOVE_I##N BOOST_MOVE_FWD##N);\
          priv_push_front_simple_commit();\
          return r;\
       }\
       else{\
          typedef dtl::insert_nonmovable_emplace_proxy##N\
                <ValAllocator BOOST_MOVE_I##N BOOST_MOVE_TARG##N> type;\
          return *priv_insert_front_aux_impl(1, type(BOOST_MOVE_FWD##N));\
       }\
    }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N\
    reference emplace_back(BOOST_MOVE_UREF##N)\
    {\
       if(priv_push_back_simple_available()){\
          reference r = *this->priv_push_back_simple_pos();\
          allocator_traits_type::construct\
             ( this->alloc(), this->priv_push_back_simple_pos() BOOST_MOVE_I##N BOOST_MOVE_FWD##N);\
          priv_push_back_simple_commit();\
          return r;\
       }\
       else{\
          typedef dtl::insert_nonmovable_emplace_proxy##N\
                <ValAllocator BOOST_MOVE_I##N BOOST_MOVE_TARG##N> type;\
          return *priv_insert_back_aux_impl(1, type(BOOST_MOVE_FWD##N));\
       }\
    }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N\
    iterator emplace(const_iterator p BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {\
       BOOST_ASSERT(this->priv_in_range_or_end(p));\
       if(p == this->cbegin()){\
          this->emplace_front(BOOST_MOVE_FWD##N);\
          return this->begin();\
       }\
       else if(p == cend()){\
          this->emplace_back(BOOST_MOVE_FWD##N);\
          return (--this->end());\
       }\
       else{\
          typedef dtl::insert_emplace_proxy_arg##N\
                <ValAllocator BOOST_MOVE_I##N BOOST_MOVE_TARG##N> type;\
          return this->priv_insert_aux_impl(p, 1, type(BOOST_MOVE_FWD##N));\
       }\
    }
    //
    BOOST_MOVE_ITERATE_0TO9(BOOST_CONTAINER_DEQUE_EMPLACE_CODE)
    #undef BOOST_CONTAINER_DEQUE_EMPLACE_CODE
 
    #endif   // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
    //! <b>Effects</b>: Inserts a copy of x at the front of the deque.
    //!
    //! <b>Throws</b>: If memory allocation throws or
    //!   T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Amortized constant time.
    void push_front(const T &x);
 
    //! <b>Effects</b>: Constructs a new element in the front of the deque
    //!   and moves the resources of x to this new element.
    //!
    //! <b>Throws</b>: If memory allocation throws.
    //!
    //! <b>Complexity</b>: Amortized constant time.
    void push_front(T &&x);
    #else
    BOOST_MOVE_CONVERSION_AWARE_CATCH(push_front, T, void, priv_push_front)
    #endif
 
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
    //! <b>Effects</b>: Inserts a copy of x at the end of the deque.
    //!
    //! <b>Throws</b>: If memory allocation throws or
    //!   T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Amortized constant time.
    void push_back(const T &x);
 
    //! <b>Effects</b>: Constructs a new element in the end of the deque
    //!   and moves the resources of x to this new element.
    //!
    //! <b>Throws</b>: If memory allocation throws.
    //!
    //! <b>Complexity</b>: Amortized constant time.
    void push_back(T &&x);
    #else
    BOOST_MOVE_CONVERSION_AWARE_CATCH(push_back, T, void, priv_push_back)
    #endif
 
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Requires</b>: p must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Insert a copy of x before p.
    //!
    //! <b>Returns</b>: an iterator to the inserted element.
    //!
    //! <b>Throws</b>: If memory allocation throws or x's copy constructor throws.
    //!
    //! <b>Complexity</b>: If p is end(), amortized constant time
    //!   Linear time otherwise.
    iterator insert(const_iterator p, const T &x);
 
    //! <b>Requires</b>: p must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Insert a new element before p with x's resources.
    //!
    //! <b>Returns</b>: an iterator to the inserted element.
    //!
    //! <b>Throws</b>: If memory allocation throws.
    //!
    //! <b>Complexity</b>: If p is end(), amortized constant time
    //!   Linear time otherwise.
    iterator insert(const_iterator p, T &&x);
    #else
    BOOST_MOVE_CONVERSION_AWARE_CATCH_1ARG(insert, T, iterator, priv_insert, const_iterator, const_iterator)
    #endif
 
    //! <b>Requires</b>: pos must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Insert n copies of x before pos.
    //!
    //! <b>Returns</b>: an iterator to the first inserted element or pos if n is 0.
    //!
    //! <b>Throws</b>: If memory allocation throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to n.
    inline iterator insert(const_iterator pos, size_type n, const value_type& x)
    {
       //Range check of p is done by insert()
       return this->insert(pos, c_it(x, n), c_it());
    }
 
    //! <b>Requires</b>: pos must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Insert a copy of the [first, last) range before pos.
    //!
    //! <b>Returns</b>: an iterator to the first inserted element or pos if first == last.
    //!
    //! <b>Throws</b>: If memory allocation throws, T's constructor from a
    //!   dereferenced InIt throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to distance [first, last).
    template <class InIt>
    iterator insert(const_iterator pos, InIt first, InIt last
       #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
       , typename dtl::disable_if_or
          < void
          , dtl::is_convertible<InIt, size_type>
          , dtl::is_not_input_iterator<InIt>
          >::type * = 0
       #endif
       )
    {
       BOOST_ASSERT(this->priv_in_range_or_end(pos));
       size_type n = 0;
       iterator it(pos.unconst());
       for(;first != last; ++first, ++n){
          it = this->emplace(it, *first);
          ++it;
       }
       it -= difference_type(n);
       return it;
    }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Requires</b>: pos must be a valid iterator of *this.
    //!
    //! <b>Effects</b>: Insert a copy of the [il.begin(), il.end()) range before pos.
    //!
    //! <b>Returns</b>: an iterator to the first inserted element or pos if il.begin() == il.end().
    //!
    //! <b>Throws</b>: If memory allocation throws, T's constructor from a
    //!   dereferenced std::initializer_list throws or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to distance [il.begin(), il.end()).
    inline iterator insert(const_iterator pos, std::initializer_list<value_type> il)
    {
       //Range check os pos is done in insert()
       return insert(pos, il.begin(), il.end());
    }
 #endif
 
    #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
    template <class FwdIt>
    inline iterator insert(const_iterator p, FwdIt first, FwdIt last
       #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
       , typename dtl::disable_if_or
          < void
          , dtl::is_convertible<FwdIt, size_type>
          , dtl::is_input_iterator<FwdIt>
          >::type * = 0
       #endif
       )
    {
       BOOST_ASSERT(this->priv_in_range_or_end(p));
       dtl::insert_range_proxy<ValAllocator, FwdIt> proxy(first);
       return priv_insert_aux_impl(p, boost::container::iterator_udistance(first, last), proxy);
    }
    #endif
 
    //! <b>Effects</b>: Removes the first element from the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant time.
    void pop_front() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       if (this->members_.m_start.m_cur != this->members_.m_start.get_last() - 1) {
          allocator_traits_type::destroy
             ( this->alloc()
             , boost::movelib::to_raw_pointer(this->members_.m_start.m_cur)
             );
          ++this->members_.m_start.m_cur;
       }
       else
          this->priv_pop_front_aux();
    }
 
    //! <b>Effects</b>: Removes the last element from the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant time.
    void pop_back() BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(!this->empty());
       if (this->members_.m_finish.m_cur != this->members_.m_finish.get_first()) {
          --this->members_.m_finish.m_cur;
          allocator_traits_type::destroy
             ( this->alloc()
             , boost::movelib::to_raw_pointer(this->members_.m_finish.m_cur)
             );
       }
       else
          this->priv_pop_back_aux();
    }
 
    //! <b>Effects</b>: Erases the element at p.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Linear to the elements between pos and the
    //!   last element (if pos is near the end) or the first element
    //!   if(pos is near the beginning).
    //!   Constant if pos is the first or the last element.
    iterator erase(const_iterator pos) BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(this->priv_in_range(pos));
       iterator next = pos.unconst();
       ++next;
       size_type index = size_type(pos - this->members_.m_start);
       if (index < (this->size()/2)) {
          boost::container::move_backward(this->begin(), pos.unconst(), next);
          pop_front();
       }
       else {
          boost::container::move(next, this->end(), pos.unconst());
          pop_back();
       }
       return this->members_.m_start + difference_type(index);
    }
 
    //! <b>Effects</b>: Erases the elements pointed by [first, last).
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Linear to the distance between first and
    //!   last plus the elements between pos and the
    //!   last element (if pos is near the end) or the first element
    //!   if(pos is near the beginning).
    iterator erase(const_iterator first, const_iterator last) BOOST_NOEXCEPT_OR_NOTHROW
    {
       BOOST_ASSERT(first == last ||
          (first < last && this->priv_in_range(first) && this->priv_in_range_or_end(last)));
       if (first == this->members_.m_start && last == this->members_.m_finish) {
          this->clear();
          return this->members_.m_finish;
       }
       else {
          const size_type n = static_cast<size_type>(last - first);
          const size_type elems_before = static_cast<size_type>(first - this->members_.m_start);
          if (elems_before < (this->size() - n) - elems_before) {
             boost::container::move_backward(begin(), first.unconst(), last.unconst());
             iterator new_start = this->members_.m_start + difference_type(n);
             this->priv_destroy_range(this->members_.m_start, new_start);
             this->priv_destroy_nodes(this->members_.m_start.m_node, new_start.m_node);
             this->members_.m_start = new_start;
          }
          else {
             boost::container::move(last.unconst(), end(), first.unconst());
             iterator new_finish = this->members_.m_finish - difference_type(n);
             this->priv_destroy_range(new_finish, this->members_.m_finish);
             this->priv_destroy_nodes(new_finish.m_node + 1, this->members_.m_finish.m_node + 1);
             this->members_.m_finish = new_finish;
          }
          return this->members_.m_start + difference_type(elems_before);
       }
    }
 
    //! <b>Effects</b>: Swaps the contents of *this and x.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    inline void swap(deque &x)
       BOOST_NOEXCEPT_IF(allocator_traits_type::propagate_on_container_swap::value
                                || allocator_traits_type::is_always_equal::value)
    {
       this->swap_members(x);
       dtl::bool_<allocator_traits_type::propagate_on_container_swap::value> flag;
       dtl::swap_alloc(this->alloc(), x.alloc(), flag);
       dtl::swap_alloc(this->ptr_alloc(), x.ptr_alloc(), flag);
    }
 
    //! <b>Effects</b>: Erases all the elements of the deque.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the deque.
    void clear() BOOST_NOEXCEPT_OR_NOTHROW
    {
       if (this->members_.m_finish != this->members_.m_start) {
   
          for (index_pointer node = this->members_.m_start.m_node + 1;
                node < this->members_.m_finish.m_node;
                ++node) {
             this->priv_destroy_range(*node, *node + get_block_ssize());
             this->priv_deallocate_node(*node);
          }
 
          if (this->members_.m_start.m_node != this->members_.m_finish.m_node) {
             this->priv_destroy_range(this->members_.m_start.m_cur, this->members_.m_start.get_last());
             this->priv_destroy_range(this->members_.m_finish.get_first(), this->members_.m_finish.m_cur);
             this->priv_deallocate_node(this->members_.m_finish.get_first());
          }
          else
             this->priv_destroy_range(this->members_.m_start.m_cur, this->members_.m_finish.m_cur);
 
          this->members_.m_finish = this->members_.m_start;
       }
    }
 
    //! <b>Effects</b>: Returns true if x and y are equal
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator==(const deque& x, const deque& y)
    {  return x.size() == y.size() && ::boost::container::algo_equal(x.begin(), x.end(), y.begin());  }
 
    //! <b>Effects</b>: Returns true if x and y are unequal
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator!=(const deque& x, const deque& y)
    {  return !(x == y); }
 
    //! <b>Effects</b>: Returns true if x is less than y
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<(const deque& x, const deque& y)
    {  return ::boost::container::algo_lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());  }
 
    //! <b>Effects</b>: Returns true if x is greater than y
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>(const deque& x, const deque& y)
    {  return y < x;  }
 
    //! <b>Effects</b>: Returns true if x is equal or less than y
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator<=(const deque& x, const deque& y)
    {  return !(y < x);  }
 
    //! <b>Effects</b>: Returns true if x is equal or greater than y
    //!
    //! <b>Complexity</b>: Linear to the number of elements in the container.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       friend bool operator>=(const deque& x, const deque& y)
    {  return !(x < y);  }
 
    //! <b>Effects</b>: x.swap(y)
    //!
    //! <b>Complexity</b>: Constant.
    inline friend void swap(deque& x, deque& y)
        BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT(x.swap(y)))
    {  x.swap(y);  }
 
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
 
    void priv_move_assign(BOOST_RV_REF(deque) x, dtl::bool_<true> /*steal_resources*/)
    {
       //Destroy objects but retain memory in case x reuses it in the future
       this->clear();
       //Move allocator if needed
       dtl::bool_<allocator_traits_type::propagate_on_container_move_assignment::value> flag;
       dtl::move_alloc(this->alloc(), x.alloc(), flag);
       dtl::move_alloc(this->ptr_alloc(), x.ptr_alloc(), flag);
       //Nothrow swap
       this->swap_members(x);
    }
 
    void priv_move_assign(BOOST_RV_REF(deque) x, dtl::bool_<false> /*steal_resources*/)
    {
       //We can't guarantee a compile-time equal allocator or propagation so fallback to runtime
       //Resources can be transferred if both allocators are equal
       if (this->alloc() == x.alloc()) {
          this->priv_move_assign(boost::move(x), dtl::true_());
       }
       else {
          this->assign(boost::make_move_iterator(x.begin()), boost::make_move_iterator(x.end()));
       }
    }
 
    inline size_type priv_index_of(const_iterator p) const
    {
       BOOST_ASSERT(this->cbegin() <= p);
       BOOST_ASSERT(p <= this->cend());
       return static_cast<size_type>(p - this->cbegin());
    }
 
    void priv_erase_last_n(size_type n)
    {
       if(n == this->size()) {
          this->clear();
       }
       else {
          iterator new_finish = this->members_.m_finish - difference_type(n);
          this->priv_destroy_range(new_finish, this->members_.m_finish);
          this->priv_destroy_nodes(new_finish.m_node + 1, this->members_.m_finish.m_node + 1);
          this->members_.m_finish = new_finish;
       }
    }
 
    void priv_throw_if_out_of_range(size_type n) const
    {
       if (n >= this->size())
          throw_out_of_range("deque::at out of range");
    }
 
    inline bool priv_in_range(const_iterator pos) const
    {
       return (this->begin() <= pos) && (pos < this->end());
    }
 
    inline bool priv_in_range_or_end(const_iterator pos) const
    {
       return (this->begin() <= pos) && (pos <= this->end());
    }
 
    template <class U>
    iterator priv_insert(const_iterator p, BOOST_FWD_REF(U) x)
    {
       BOOST_ASSERT(this->priv_in_range_or_end(p));
       if (p == cbegin()){
          this->push_front(::boost::forward<U>(x));
          return begin();
       }
       else if (p == cend()){
          this->push_back(::boost::forward<U>(x));
          return --end();
       }
       else {
          return priv_insert_aux_impl
             ( p, (size_type)1
             , dtl::get_insert_value_proxy<iterator, ValAllocator>(::boost::forward<U>(x)));
       }
    }
 
    template <class U>
    void priv_push_front(BOOST_FWD_REF(U) x)
    {
       if(this->priv_push_front_simple_available()){
          allocator_traits_type::construct
             ( this->alloc(), this->priv_push_front_simple_pos(), ::boost::forward<U>(x));
          this->priv_push_front_simple_commit();
       }
       else{
          priv_insert_aux_impl
             ( this->cbegin(), (size_type)1
             , dtl::get_insert_value_proxy<iterator, ValAllocator>(::boost::forward<U>(x)));
       }
    }
 
    template <class U>
    void priv_push_back(BOOST_FWD_REF(U) x)
    {
       if(this->priv_push_back_simple_available()){
          allocator_traits_type::construct
             ( this->alloc(), this->priv_push_back_simple_pos(), ::boost::forward<U>(x));
          this->priv_push_back_simple_commit();
       }
       else{
          priv_insert_aux_impl
             ( this->cend(), (size_type)1
             , dtl::get_insert_value_proxy<iterator, ValAllocator>(::boost::forward<U>(x)));
       }
    }
 
    inline bool priv_push_back_simple_available() const
    {
       return this->members_.m_map &&
          (this->members_.m_finish.m_cur != (this->members_.m_finish.get_last() - 1));
    }
 
    inline T *priv_push_back_simple_pos() const
    {
       return boost::movelib::to_raw_pointer(this->members_.m_finish.m_cur);
    }
 
    inline void priv_push_back_simple_commit()
    {
       ++this->members_.m_finish.m_cur;
    }
 
    inline bool priv_push_front_simple_available() const
    {
       return this->members_.m_map &&
          (this->members_.m_start.m_cur != this->members_.m_start.get_first());
    }
 
    inline T *priv_push_front_simple_pos() const
    {  return boost::movelib::to_raw_pointer(this->members_.m_start.m_cur) - 1;  }
 
    inline void priv_push_front_simple_commit()
    {  --this->members_.m_start.m_cur;   }
 
    void priv_destroy_range(iterator p, iterator p2)
    {
       (void)p; (void)p2;
       BOOST_IF_CONSTEXPR(!Base::traits_t::trivial_dctr){
          for(;p != p2; ++p){
             allocator_traits_type::destroy(this->alloc(), boost::movelib::iterator_to_raw_pointer(p));
          }
       }
    }
 
    void priv_destroy_range(pointer p, pointer p2)
    {
       (void)p; (void)p2;
       BOOST_IF_CONSTEXPR(!Base::traits_t::trivial_dctr){
          for(;p != p2; ++p){
             allocator_traits_type::destroy(this->alloc(), boost::movelib::iterator_to_raw_pointer(p));
          }
       }
    }
 
    template<class InsertProxy>
    iterator priv_insert_middle_aux_impl(const_iterator p, const size_type elemsbefore, const size_type length, const size_type n, InsertProxy proxy)
    {
       if (!this->members_.m_map) {
          this->priv_initialize_map(0);
          p = this->cbegin();
       }
 
       iterator pos(p.unconst());
       const size_type pos_n = size_type(p - this->cbegin());
 
       if (elemsbefore < length / 2) {
          const iterator new_start = this->priv_reserve_elements_at_front(n);
          const iterator old_start = this->members_.m_start;
          pos = this->members_.m_start + difference_type(elemsbefore);
          if (elemsbefore >= n) {
             const iterator start_n = this->members_.m_start + difference_type(n);
             BOOST_CONTAINER_TRY {
                ::boost::container::uninitialized_move_alloc
                   (this->alloc(), this->members_.m_start, start_n, new_start);
             }
             BOOST_CONTAINER_CATCH(...) {
                this->priv_destroy_nodes(new_start.m_node, this->members_.m_start.m_node);
                BOOST_CONTAINER_RETHROW
             }
             BOOST_CONTAINER_CATCH_END
             this->members_.m_start = new_start;
             boost::container::move(start_n, pos, old_start);
             proxy.copy_n_and_update(this->alloc(), pos - difference_type(n), n);
          }
          else {
             const size_type mid_count = n - elemsbefore;
             const iterator mid_start = old_start - difference_type(mid_count);
             BOOST_CONTAINER_TRY {
                proxy.uninitialized_copy_n_and_update(this->alloc(), mid_start, mid_count);
                this->members_.m_start = mid_start;
                ::boost::container::uninitialized_move_alloc(this->alloc(), old_start, pos, new_start);
             }
             BOOST_CONTAINER_CATCH(...) {
                this->priv_destroy_nodes(new_start.m_node, this->members_.m_start.m_node);
                BOOST_CONTAINER_RETHROW
             }
             BOOST_CONTAINER_CATCH_END
             this->members_.m_start = new_start;
             proxy.copy_n_and_update(this->alloc(), old_start, elemsbefore);
          }
       }
       else {
          const iterator new_finish = this->priv_reserve_elements_at_back(n);
          const iterator old_finish = this->members_.m_finish;
          const size_type elemsafter = length - elemsbefore;
 
          pos = old_finish - difference_type(elemsafter);
          if (elemsafter >= n) {
             iterator finish_n = old_finish - difference_type(n);
             BOOST_CONTAINER_TRY {
                ::boost::container::uninitialized_move_alloc(this->alloc(), finish_n, old_finish, old_finish);
             }
             BOOST_CONTAINER_CATCH(...) {
                this->priv_destroy_nodes(this->members_.m_finish.m_node + 1, new_finish.m_node + 1);
                BOOST_CONTAINER_RETHROW
             }
             BOOST_CONTAINER_CATCH_END
 
             this->members_.m_finish = new_finish;
             boost::container::move_backward(pos, finish_n, old_finish);
             proxy.copy_n_and_update(this->alloc(), pos, n);
          }
          else {
             const size_type raw_gap = n - elemsafter;
             BOOST_CONTAINER_TRY{
                ::boost::container::uninitialized_move_alloc
                   (this->alloc(), pos, old_finish, old_finish + difference_type(raw_gap));
                BOOST_CONTAINER_TRY{
                   proxy.copy_n_and_update(this->alloc(), pos, elemsafter);
                   proxy.uninitialized_copy_n_and_update(this->alloc(), old_finish, raw_gap);
                }
                BOOST_CONTAINER_CATCH(...) {
                   this->priv_destroy_range(old_finish, old_finish + difference_type(elemsafter));
                   BOOST_CONTAINER_RETHROW
                }
                BOOST_CONTAINER_CATCH_END
             }
             BOOST_CONTAINER_CATCH(...) {
                this->priv_destroy_nodes(this->members_.m_finish.m_node + 1, new_finish.m_node + 1);
                BOOST_CONTAINER_RETHROW
             }
             BOOST_CONTAINER_CATCH_END
             this->members_.m_finish = new_finish;
          }
       }
       return this->begin() + difference_type(pos_n);
    }
 
    template<class InsertProxy>
    iterator priv_insert_aux_impl(const_iterator p, size_type n, InsertProxy proxy)
    {
       iterator pos(p.unconst());
       const size_type elemsbefore = static_cast<size_type>(pos - this->members_.m_start);
       const size_type length = this->size();
 
       if (!elemsbefore) {
          return this->priv_insert_front_aux_impl(n, proxy);
       }
       else if (elemsbefore == length) {
          return this->priv_insert_back_aux_impl(n, proxy);
       }
       else {
          return this->priv_insert_middle_aux_impl(p, elemsbefore, length, n, proxy);
       }
    }
 
    template <class InsertProxy>
    iterator priv_insert_back_aux_impl(size_type n, InsertProxy proxy)
    {
       if(!this->members_.m_map){
          this->priv_initialize_map(0);
       }
 
       iterator new_finish = this->priv_reserve_elements_at_back(n);
       BOOST_CONTAINER_TRY{
          proxy.uninitialized_copy_n_and_update(this->alloc(), this->members_.m_finish, n);
       }
       BOOST_CONTAINER_CATCH(...) {
          this->priv_destroy_nodes(this->members_.m_finish.m_node + 1, new_finish.m_node + 1);
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
       this->members_.m_finish = new_finish;
       return iterator(this->members_.m_finish - difference_type(n));
    }
 
    template <class InsertProxy>
    iterator priv_insert_front_aux_impl(size_type n, InsertProxy proxy)
    {
       if(!this->members_.m_map){
          this->priv_initialize_map(0);
       }
 
       iterator new_start = this->priv_reserve_elements_at_front(n);
       BOOST_CONTAINER_TRY{
          proxy.uninitialized_copy_n_and_update(this->alloc(), new_start, n);
       }
       BOOST_CONTAINER_CATCH(...) {
          this->priv_destroy_nodes(new_start.m_node, this->members_.m_start.m_node);
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
 
       this->members_.m_start = new_start;
       return new_start;
    }
 
    inline iterator priv_fill_insert(const_iterator pos, size_type n, const value_type& x)
    {
       return this->insert(pos, c_it(x, n), c_it());
    }
 
    // Precondition: this->members_.m_start and this->members_.m_finish have already been initialized,
    // but none of the deque's elements have yet been constructed.
    void priv_fill_initialize(const value_type& value)
    {
       index_pointer cur = this->members_.m_start.m_node;
       BOOST_CONTAINER_TRY {
          for ( ; cur < this->members_.m_finish.m_node; ++cur){
             boost::container::uninitialized_fill_alloc
                (this->alloc(), *cur, *cur + get_block_ssize(), value);
          }
          boost::container::uninitialized_fill_alloc
             (this->alloc(), this->members_.m_finish.get_first(), this->members_.m_finish.m_cur, value);
       }
       BOOST_CONTAINER_CATCH(...){
          this->priv_destroy_range(this->members_.m_start, iterator(*cur, cur, get_block_size()));
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
    }
 
    template <class InIt>
    void priv_range_initialize(InIt first, InIt last, typename iterator_enable_if_tag<InIt, std::input_iterator_tag>::type* =0)
    {
       this->priv_initialize_map(0);
       BOOST_CONTAINER_TRY {
          for ( ; first != last; ++first)
             this->emplace_back(*first);
       }
       BOOST_CONTAINER_CATCH(...){
          this->clear();
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
    }
 
    template <class FwdIt>
    void priv_range_initialize(FwdIt first, FwdIt last, typename iterator_disable_if_tag<FwdIt, std::input_iterator_tag>::type* =0)
    {
       size_type n = 0;
       n = boost::container::iterator_udistance(first, last);
       this->priv_initialize_map(n);
 
       index_pointer cur_node = this->members_.m_start.m_node;
       BOOST_CONTAINER_TRY {
          for (; cur_node < this->members_.m_finish.m_node; ++cur_node) {
             FwdIt mid = first;
             boost::container::iterator_uadvance(mid, get_block_size());
             ::boost::container::uninitialized_copy_alloc(this->alloc(), first, mid, *cur_node);
             first = mid;
          }
          ::boost::container::uninitialized_copy_alloc(this->alloc(), first, last, this->members_.m_finish.get_first());
       }
       BOOST_CONTAINER_CATCH(...){
          this->priv_destroy_range(this->members_.m_start, iterator(*cur_node, cur_node, get_block_size()));
          BOOST_CONTAINER_RETHROW
       }
       BOOST_CONTAINER_CATCH_END
    }
 
    // Called only if this->members_.m_finish.m_cur == this->members_.m_finish.get_first().
    void priv_pop_back_aux() BOOST_NOEXCEPT_OR_NOTHROW
    {
       this->priv_deallocate_node(this->members_.m_finish.get_first());
       this->members_.m_finish.priv_set_node(this->members_.m_finish.m_node - 1, get_block_size());
       this->members_.m_finish.m_cur = this->members_.m_finish.get_last() - 1;
       allocator_traits_type::destroy
          ( this->alloc()
          , boost::movelib::to_raw_pointer(this->members_.m_finish.m_cur)
          );
    }
 
    // Called only if this->members_.m_start.m_cur == this->members_.m_start.get_last() - 1.  Note that
    // if the deque has at least one element (a precondition for this member
    // function), and if this->members_.m_start.m_cur == this->members_.m_start.get_last(), then the deque
    // must have at least two nodes.
    void priv_pop_front_aux() BOOST_NOEXCEPT_OR_NOTHROW
    {
       allocator_traits_type::destroy
          ( this->alloc()
          , boost::movelib::to_raw_pointer(this->members_.m_start.m_cur)
          );
       this->priv_deallocate_node(this->members_.m_start.get_first());
       this->members_.m_start.priv_set_node(this->members_.m_start.m_node + 1, get_block_size());
       this->members_.m_start.m_cur = this->members_.m_start.get_first();
    }
 
    iterator priv_reserve_elements_at_front(size_type n)
    {
       size_type vacancies = size_type(this->members_.m_start.m_cur - this->members_.m_start.get_first());
       if (n > vacancies){
          size_type new_elems = n-vacancies;
          size_type new_nodes = (new_elems + get_block_size() - 1u) / get_block_size();
          size_type s = (size_type)(this->members_.m_start.m_node - this->members_.m_map);
          if (new_nodes > s){
             this->priv_reallocate_map(new_nodes, true);
          }
          size_type i = 1;
          BOOST_CONTAINER_TRY {
             for (; i <= new_nodes; ++i)
                *(this->members_.m_start.m_node - difference_type(i)) = this->priv_allocate_node();
          }
          BOOST_CONTAINER_CATCH(...) {
             for (size_type j = 1; j < i; ++j)
                this->priv_deallocate_node(*(this->members_.m_start.m_node - difference_type(j)));
             BOOST_CONTAINER_RETHROW
          }
          BOOST_CONTAINER_CATCH_END
       }
       return this->members_.m_start - difference_type(n);
    }
 
    iterator priv_reserve_elements_at_back(size_type n)
    {
       size_type vacancies = size_type(this->members_.m_finish.get_last() - this->members_.m_finish.m_cur - 1);
       if (n > vacancies){
          size_type new_elems = size_type(n - vacancies);
          size_type new_nodes = size_type(new_elems + get_block_size() - 1u)/get_block_size();
          size_type s = (size_type)(this->members_.m_map_size - size_type(this->members_.m_finish.m_node - this->members_.m_map));
          if (new_nodes + 1 > s){
             this->priv_reallocate_map(new_nodes, false);
          }
          size_type i = 1;
          BOOST_CONTAINER_TRY {
             for (; i <= new_nodes; ++i)
                *(this->members_.m_finish.m_node + difference_type(i)) = this->priv_allocate_node();
          }
          BOOST_CONTAINER_CATCH(...) {
             for (size_type j = 1; j < i; ++j)
                this->priv_deallocate_node(*(this->members_.m_finish.m_node + difference_type(j)));
             BOOST_CONTAINER_RETHROW
          }
          BOOST_CONTAINER_CATCH_END
       }
       return this->members_.m_finish + difference_type(n);
    }
 
    void priv_reallocate_map(size_type nodes_to_add, bool add_at_front)
    {
       size_type old_num_nodes = size_type(this->members_.m_finish.m_node - this->members_.m_start.m_node + 1);
       size_type new_num_nodes = old_num_nodes + nodes_to_add;
 
       index_pointer new_nstart;
       if (this->members_.m_map_size > 2 * new_num_nodes) {
          new_nstart = this->members_.m_map + difference_type(this->members_.m_map_size - new_num_nodes) / 2
                            + difference_type(add_at_front ? nodes_to_add : 0u);
          if (new_nstart < this->members_.m_start.m_node)
             boost::container::move(this->members_.m_start.m_node, this->members_.m_finish.m_node + 1, new_nstart);
          else
             boost::container::move_backward
                (this->members_.m_start.m_node, this->members_.m_finish.m_node + 1, new_nstart + difference_type(old_num_nodes));
       }
       else {
          size_type new_map_size =
             this->members_.m_map_size + dtl::max_value(this->members_.m_map_size, nodes_to_add) + 2;
 
          index_pointer new_map = this->priv_allocate_map(new_map_size);
          new_nstart = new_map + difference_type(new_map_size - new_num_nodes) / 2
                               + difference_type(add_at_front ? nodes_to_add : 0u);
          boost::container::move(this->members_.m_start.m_node, this->members_.m_finish.m_node + 1, new_nstart);
          this->priv_deallocate_map(this->members_.m_map, this->members_.m_map_size);
 
          this->members_.m_map = new_map;
          this->members_.m_map_size = new_map_size;
       }
 
       this->members_.m_start.priv_set_node(new_nstart, get_block_size());
       this->members_.m_finish.priv_set_node(new_nstart + difference_type(old_num_nodes - 1u), get_block_size());
    }
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 };
 
 #ifndef BOOST_CONTAINER_NO_CXX17_CTAD
 template <typename InputIterator>
 deque(InputIterator, InputIterator) -> deque<typename iterator_traits<InputIterator>::value_type>;
 template <typename InputIterator, typename Allocator>
 deque(InputIterator, InputIterator, Allocator const&) -> deque<typename iterator_traits<InputIterator>::value_type, Allocator>;
 #endif
 
 }  //namespace container
 }  //namespace boost
 
 #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 namespace boost {
 
 //!has_trivial_destructor_after_move<> == true_type
 //!specialization for optimizations
 template <class T, class Allocator, class Options>
 struct has_trivial_destructor_after_move<boost::container::deque<T, Allocator, Options> >
 {
    typedef typename boost::container::deque<T, Allocator, Options>::allocator_type allocator_type;
    typedef typename ::boost::container::allocator_traits<allocator_type>::pointer pointer;
    BOOST_STATIC_CONSTEXPR bool value = ::boost::has_trivial_destructor_after_move<allocator_type>::value &&
                              ::boost::has_trivial_destructor_after_move<pointer>::value;
 };
 
 }
 
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 #include <boost/container/detail/config_end.hpp>
 
 #endif //   #ifndef  BOOST_CONTAINER_DEQUE_HPP