is not passed through to html or pdf. So 
 is used in code section below.  Ugly :-(
Ideally want a link to capacity_control, but this would require include details
and this would expose all the functions in details.
There must be a better way of doing this.
*/

    /*! Capacity controller of the space optimized circular buffer.

    \see capacity_control in details.hpp.


class capacity_control

{

   size_type m_capacity;  // Available capacity.

   size_type m_min_capacity; // Minimum capacity.

public:

   capacity_control(size_type capacity, size_type min_capacity = 0)

   : m_capacity(capacity), m_min_capacity(min_capacity)

     {};

   size_type %capacity() const { return m_capacity; }

   size_type min_capacity() const { return m_min_capacity; }

   operator size_type() const { return m_capacity; }

};





  
Always
    capacity >= min_capacity.
  
  

    The capacity() represents the capacity
    of the circular_buffer_space_optimized and
    the min_capacity() determines the minimal allocated size of its internal buffer.
 
 
The converting constructor of the capacity_control allows implicit conversion from
  size_type-like types which ensures compatibility of creating an instance of the
  circular_buffer_space_optimized with other STL containers.

  On the other hand the operator %size_type()
  provides implicit conversion to the size_type which allows to treat the
  capacity of the circular_buffer_space_optimized the same way as in the
  circular_buffer.

    */
    typedef cb_details::capacity_control capacity_type;

// Inherited

    using circular_buffer::get_allocator;
    using circular_buffer::begin;
    using circular_buffer::end;
    using circular_buffer::rbegin;
    using circular_buffer::rend;
    using circular_buffer::at;
    using circular_buffer::front;
    using circular_buffer::back;
    using circular_buffer::array_one;
    using circular_buffer::array_two;
    using circular_buffer::linearize;
    using circular_buffer::is_linearized;
    using circular_buffer::rotate;
    using circular_buffer::size;
    using circular_buffer::max_size;
    using circular_buffer::empty;

#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
    reference operator [] (size_type n) { return circular_buffer::operator[](n); }
    const_reference operator [] (size_type n) const { return circular_buffer::operator[](n); }
#else
    using circular_buffer::operator[];
#endif

private:
// Member variables

    //! The capacity controller of the space optimized circular buffer.
    capacity_type m_capacity_ctrl;

public:
// Overridden

    //! Is the circular_buffer_space_optimized full?
    /*!
        \return true if the number of elements stored in the circular_buffer_space_optimized
                equals the capacity of the circular_buffer_space_optimized; false otherwise.
        \throws Nothing.
        \par Exception Safety
             No-throw.
        \par Iterator Invalidation
             Does not invalidate any iterators.
        \par Complexity
             Constant (in the size of the circular_buffer_space_optimized).
        \sa empty()
    */
    bool full() const BOOST_NOEXCEPT { return m_capacity_ctrl == size(); }

    /*! \brief Get the maximum number of elements which can be inserted into the
               circular_buffer_space_optimized without overwriting any of already stored elements.
        \return capacity().%capacity() - size()
        \throws Nothing.
        \par Exception Safety
             No-throw.
        \par Iterator Invalidation
             Does not invalidate any iterators.
        \par Complexity
             Constant (in the size of the circular_buffer_space_optimized).
        \sa capacity(), size(), max_size()
    */
    size_type reserve() const BOOST_NOEXCEPT { return m_capacity_ctrl - size(); }

    //! Get the capacity of the circular_buffer_space_optimized.
    /*!
        \return The capacity controller representing the maximum number of elements which can be stored in the
                circular_buffer_space_optimized and the minimal allocated size of the internal buffer.
        \throws Nothing.
        \par Exception Safety
             No-throw.
        \par Iterator Invalidation
             Does not invalidate any iterators.
        \par Complexity
             Constant (in the size of the circular_buffer_space_optimized).
        \sa reserve(), size(), max_size(),
            set_capacity(const capacity_type&)
    */
    const capacity_type& capacity() const BOOST_NOEXCEPT { return m_capacity_ctrl; }

#if defined(BOOST_CB_TEST)

    // Return the current capacity of the adapted circular buffer.
    /*
       \note This method is not intended to be used directly by the user.
             It is defined only for testing purposes.
    */
    size_type internal_capacity() const BOOST_NOEXCEPT { return circular_buffer::capacity(); }

#endif // #if defined(BOOST_CB_TEST)

    /*! \brief Change the capacity (and the minimal guaranteed amount of allocated memory) of the
               circular_buffer_space_optimized.
        \post capacity() == capacity_ctrl \&\& size() \<= capacity_ctrl.capacity()


              If the current number of elements stored in the circular_buffer_space_optimized is greater
              than the desired new capacity then number of [size() - capacity_ctrl.capacity()] last
              elements will be removed and the new size will be equal to capacity_ctrl.capacity().


              If the current number of elements stored in the circular_buffer_space_optimized is lower
              than the new capacity then the amount of allocated memory in the internal buffer may be accommodated as
              necessary but it will never drop below capacity_ctrl.min_capacity().
        \param capacity_ctrl The new capacity controller.
        \throws "An allocation error" if memory is exhausted, (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Strong.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in min[size(), capacity_ctrl.%capacity()]).
        \note To explicitly clear the extra allocated memory use the shrink-to-fit technique:


              %boost::%circular_buffer_space_optimized\ cb(1000);

              ...

              %boost::%circular_buffer_space_optimized\(cb).swap(cb);


              For more information about the shrink-to-fit technique in STL see
              http://www.gotw.ca/gotw/054.htm.
        \sa rset_capacity(const capacity_type&),
            \link resize() resize(size_type, const_reference)\endlink
    */
    void set_capacity(const capacity_type& capacity_ctrl) {
        m_capacity_ctrl = capacity_ctrl;
        if (capacity_ctrl < size()) {
            iterator e = end();
            circular_buffer::erase(e - (size() - capacity_ctrl), e);
        }
        adjust_min_capacity();
    }

    //! Change the size of the circular_buffer_space_optimized.
    /*!
        \post size() == new_size \&\& capacity().%capacity() >= new_size


              If the new size is greater than the current size, copies of item will be inserted at the
              back of the of the circular_buffer_space_optimized in order to achieve the desired
              size. In the case the resulting size exceeds the current capacity the capacity will be set to
              new_size.


              If the current number of elements stored in the circular_buffer_space_optimized is greater
              than the desired new size then number of [size() - new_size] last elements will be
              removed. (The capacity will remain unchanged.)


              The amount of allocated memory in the internal buffer may be accommodated as necessary.
        \param new_size The new size.
        \param item The element the circular_buffer_space_optimized will be filled with in order to gain
                    the requested size. (See the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the new size of the circular_buffer_space_optimized).
        \sa \link rresize() rresize(size_type, const_reference)\endlink,
            set_capacity(const capacity_type&)
    */
    void resize(size_type new_size, param_value_type item = value_type()) {
        if (new_size > size()) {
            if (new_size > m_capacity_ctrl)
                m_capacity_ctrl = capacity_type(new_size, m_capacity_ctrl.min_capacity());
            insert(end(), new_size - size(), item);
        } else {
            iterator e = end();
            erase(e - (size() - new_size), e);
        }
    }

    /*! \brief Change the capacity (and the minimal guaranteed amount of allocated memory) of the
               circular_buffer_space_optimized.
        \post capacity() == capacity_ctrl \&\& size() \<= capacity_ctrl


              If the current number of elements stored in the circular_buffer_space_optimized is greater
              than the desired new capacity then number of [size() - capacity_ctrl.capacity()]
              first elements will be removed and the new size will be equal to
              capacity_ctrl.capacity().


              If the current number of elements stored in the circular_buffer_space_optimized is lower
              than the new capacity then the amount of allocated memory in the internal buffer may be accommodated as
              necessary but it will never drop below capacity_ctrl.min_capacity().
        \param capacity_ctrl The new capacity controller.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Strong.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in min[size(), capacity_ctrl.%capacity()]).
        \sa set_capacity(const capacity_type&),
            \link rresize() rresize(size_type, const_reference)\endlink
    */
    void rset_capacity(const capacity_type& capacity_ctrl) {
        m_capacity_ctrl = capacity_ctrl;
        if (capacity_ctrl < size()) {
            iterator b = begin();
            circular_buffer::rerase(b, b + (size() - capacity_ctrl));
        }
        adjust_min_capacity();
    }

    //! Change the size of the circular_buffer_space_optimized.
    /*!
        \post size() == new_size \&\& capacity().%capacity() >= new_size


              If the new size is greater than the current size, copies of item will be inserted at the
              front of the of the circular_buffer_space_optimized in order to achieve the desired
              size. In the case the resulting size exceeds the current capacity the capacity will be set to
              new_size.


              If the current number of elements stored in the circular_buffer_space_optimized is greater
              than the desired new size then number of [size() - new_size] first elements will be
              removed. (The capacity will remain unchanged.)


              The amount of allocated memory in the internal buffer may be accommodated as necessary.
        \param new_size The new size.
        \param item The element the circular_buffer_space_optimized will be filled with in order to gain
                    the requested size. (See the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the new size of the circular_buffer_space_optimized).
        \sa \link resize() resize(size_type, const_reference)\endlink,
            rset_capacity(const capacity_type&)
    */
    void rresize(size_type new_size, param_value_type item = value_type()) {
        if (new_size > size()) {
            if (new_size > m_capacity_ctrl)
                m_capacity_ctrl = capacity_type(new_size, m_capacity_ctrl.min_capacity());
            rinsert(begin(), new_size - size(), item);
        } else {
            rerase(begin(), end() - new_size);
        }
    }

    //! Create an empty space optimized circular buffer with zero capacity.
    /*!
        \post capacity().%capacity() == 0 \&\& capacity().min_capacity() == 0 \&\& size() == 0
        \param alloc The allocator.
        \throws Nothing.
        \par Complexity
             Constant.
        \warning Since Boost version 1.36 the behaviour of this constructor has changed. Now it creates a space
                 optimized circular buffer with zero capacity.
    */
    explicit circular_buffer_space_optimized(const allocator_type& alloc = allocator_type()) BOOST_NOEXCEPT
    : circular_buffer(0, alloc)
    , m_capacity_ctrl(0) {}

    //! Create an empty space optimized circular buffer with the specified capacity.
    /*!
        \post capacity() == capacity_ctrl \&\& size() == 0


              The amount of allocated memory in the internal buffer is capacity_ctrl.min_capacity().
        \param capacity_ctrl The capacity controller representing the maximum number of elements which can be stored in
                             the circular_buffer_space_optimized and the minimal allocated size of the
                             internal buffer.
        \param alloc The allocator.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \par Complexity
             Constant.
    */
    explicit circular_buffer_space_optimized(capacity_type capacity_ctrl,
        const allocator_type& alloc = allocator_type())
    : circular_buffer(capacity_ctrl.min_capacity(), alloc)
    , m_capacity_ctrl(capacity_ctrl) {}

    /*! \brief Create a full space optimized circular buffer with the specified capacity filled with
               capacity_ctrl.%capacity() copies of item.
        \post capacity() == capacity_ctrl \&\& full() \&\& (*this)[0] == item \&\& (*this)[1] == item \&\& ...
              \&\& (*this) [capacity_ctrl.%capacity() - 1] == item 


              The amount of allocated memory in the internal buffer is capacity_ctrl.capacity().
        \param capacity_ctrl The capacity controller representing the maximum number of elements which can be stored in
                             the circular_buffer_space_optimized and the minimal allocated size of the
                             internal buffer.
        \param item The element the created circular_buffer_space_optimized will be filled with.
        \param alloc The allocator.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \throws Whatever T::T(const T&) throws.
        \par Complexity
             Linear (in the capacity_ctrl.%capacity()).
    */
    circular_buffer_space_optimized(capacity_type capacity_ctrl, param_value_type item,
        const allocator_type& alloc = allocator_type())
    : circular_buffer(capacity_ctrl.capacity(), item, alloc)
    , m_capacity_ctrl(capacity_ctrl) {}

    /*! \brief Create a space optimized circular buffer with the specified capacity filled with n copies
               of item.
        \pre capacity_ctrl.%capacity() >= n
        \post capacity() == capacity_ctrl \&\& size() == n \&\& (*this)[0] == item \&\& (*this)[1] == item
              \&\& ... \&\& (*this)[n - 1] == item


              The amount of allocated memory in the internal buffer is
              max[n, capacity_ctrl.min_capacity()].
        \param capacity_ctrl The capacity controller representing the maximum number of elements which can be stored in
                             the circular_buffer_space_optimized and the minimal allocated size of the
                             internal buffer.
        \param n The number of elements the created circular_buffer_space_optimized will be filled with.
        \param item The element the created circular_buffer_space_optimized will be filled with.
        \param alloc The allocator.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Complexity
             Linear (in the n).
    */
    circular_buffer_space_optimized(capacity_type capacity_ctrl, size_type n, param_value_type item,
        const allocator_type& alloc = allocator_type())
    : circular_buffer(init_capacity(capacity_ctrl, n), n, item, alloc)
    , m_capacity_ctrl(capacity_ctrl) {}

    //! The copy constructor.
    /*!
        Creates a copy of the specified circular_buffer_space_optimized.
        \post *this == cb


              The amount of allocated memory in the internal buffer is cb.size().
        \param cb The circular_buffer_space_optimized to be copied.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Complexity
             Linear (in the size of cb).
    */
    circular_buffer_space_optimized(const circular_buffer_space_optimized& cb)
    : circular_buffer(cb.begin(), cb.end(), cb.get_allocator())
    , m_capacity_ctrl(cb.m_capacity_ctrl) {}

#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
    //! The move constructor.
    /*! \brief Move constructs a circular_buffer_space_optimized from cb, 
                leaving cb empty.
        \pre C++ compiler with rvalue references support.
        \post cb.empty()
        \param cb circular_buffer to 'steal' value from.
        \throws Nothing.
        \par Constant.
    */
    circular_buffer_space_optimized(circular_buffer_space_optimized&& cb) BOOST_NOEXCEPT
    : circular_buffer()
    , m_capacity_ctrl(0) {
        cb.swap(*this);
    }
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES

    //! Create a full space optimized circular buffer filled with a copy of the range.
    /*!
        \pre Valid range [first, last).

             first and last have to meet the requirements of
             InputIterator.
        \post capacity().%capacity() == std::distance(first, last) \&\& capacity().min_capacity() == 0 \&\&
              full() \&\& (*this)[0]== *first \&\& (*this)[1] == *(first + 1) \&\& ... \&\&
              (*this)[std::distance(first, last) - 1] == *(last - 1)


              The amount of allocated memory in the internal buffer is std::distance(first, last).
        \param first The beginning of the range to be copied.
        \param last The end of the range to be copied.
        \param alloc The allocator.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept 
                and InputIterator is a move iterator.
        \par Complexity
             Linear (in the std::distance(first, last)).
    */
    template 
    circular_buffer_space_optimized(InputIterator first, InputIterator last,
        const allocator_type& alloc = allocator_type())
    : circular_buffer(first, last, alloc)
    , m_capacity_ctrl(circular_buffer::capacity()) {}

    /*! \brief Create a space optimized circular buffer with the specified capacity (and the minimal guaranteed amount
               of allocated memory) filled with a copy of the range.
        \pre Valid range [first, last).

             first and last have to meet the requirements of
             InputIterator.
        \post capacity() == capacity_ctrl \&\& size() \<= std::distance(first, last) \&\& (*this)[0]==
              *(last - capacity_ctrl.%capacity()) \&\& (*this)[1] == *(last - capacity_ctrl.%capacity() + 1) \&\& ...
              \&\& (*this)[capacity_ctrl.%capacity() - 1] == *(last - 1)


              If the number of items to be copied from the range [first, last) is greater than the
              specified capacity_ctrl.%capacity() then only elements from the range
              [last - capacity_ctrl.%capacity(), last) will be copied.


              The amount of allocated memory in the internal buffer is max[capacity_ctrl.min_capacity(),
              min[capacity_ctrl.%capacity(), std::distance(first, last)]].
        \param capacity_ctrl The capacity controller representing the maximum number of elements which can be stored in
                             the circular_buffer_space_optimized and the minimal allocated size of the
                             internal buffer.
        \param first The beginning of the range to be copied.
        \param last The end of the range to be copied.
        \param alloc The allocator.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Complexity
             Linear (in std::distance(first, last); in
             min[capacity_ctrl.%capacity(), std::distance(first, last)] if the InputIterator
             is a RandomAccessIterator).
    */
    template 
    circular_buffer_space_optimized(capacity_type capacity_ctrl, InputIterator first, InputIterator last,
        const allocator_type& alloc = allocator_type())
    : circular_buffer(
        init_capacity(capacity_ctrl, first, last, is_integral()),
        first, last, alloc)
    , m_capacity_ctrl(capacity_ctrl) {
        reduce_capacity(
            is_same< BOOST_DEDUCED_TYPENAME std::iterator_traits::iterator_category, std::input_iterator_tag >());
    }

#if defined(BOOST_CB_NEVER_DEFINED)
// This section will never be compiled - the default destructor will be generated instead.
// Declared only for documentation purpose.

    //! The destructor.
    /*!
        Destroys the circular_buffer_space_optimized.
        \throws Nothing.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (including
             iterators equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa clear()
    */
    ~circular_buffer_space_optimized();

    //! no-comment
    void erase_begin(size_type n);

    //! no-comment
    void erase_end(size_type n);

#endif // #if defined(BOOST_CB_NEVER_DEFINED)

    //! The assign operator.
    /*!
        Makes this circular_buffer_space_optimized to become a copy of the specified
        circular_buffer_space_optimized.
        \post *this == cb


              The amount of allocated memory in the internal buffer is cb.size().
        \param cb The circular_buffer_space_optimized to be copied.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \throws Whatever T::T(const T&) throws.
        \par Exception Safety
             Strong.
        \par Iterator Invalidation
             Invalidates all iterators pointing to this circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of cb).
        \sa \link assign(size_type, param_value_type) assign(size_type, const_reference)\endlink,
            \link assign(capacity_type, size_type, param_value_type)
            assign(capacity_type, size_type, const_reference)\endlink,
            assign(InputIterator, InputIterator),
            assign(capacity_type, InputIterator, InputIterator)
    */
    circular_buffer_space_optimized& operator = (const circular_buffer_space_optimized& cb) {
        if (this == &cb)
            return *this;
        circular_buffer::assign(cb.begin(), cb.end());
        m_capacity_ctrl = cb.m_capacity_ctrl;
        return *this;
    }

#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
    /*! \brief Move assigns content of cb to *this, leaving cb empty.
        \pre C++ compiler with rvalue references support.
        \post cb.empty()
        \param cb circular_buffer to 'steal' value from.
        \throws Nothing.
        \par Complexity
             Constant.
    */
    circular_buffer_space_optimized& operator = (circular_buffer_space_optimized&& cb) BOOST_NOEXCEPT {
        cb.swap(*this); // now `this` holds `cb`
        circular_buffer(get_allocator()) // temporary that holds initial `cb` allocator
            .swap(cb); // makes `cb` empty
        return *this;
    }
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES


    //! Assign n items into the space optimized circular buffer.
    /*!
        The content of the circular_buffer_space_optimized will be removed and replaced with
        n copies of the item.
        \post capacity().%capacity() == n \&\& capacity().min_capacity() == 0 \&\& size() == n \&\& (*this)[0] ==
              item \&\& (*this)[1] == item \&\& ... \&\& (*this) [n - 1] == item


              The amount of allocated memory in the internal buffer is n.
        \param n The number of elements the circular_buffer_space_optimized will be filled with.
        \param item The element the circular_buffer_space_optimized will be filled with.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the n).
        \sa \link operator=(const circular_buffer_space_optimized&) operator=\endlink,
            \link assign(capacity_type, size_type, param_value_type)
            assign(capacity_type, size_type, const_reference)\endlink,
            assign(InputIterator, InputIterator),
            assign(capacity_type, InputIterator, InputIterator)
    */
    void assign(size_type n, param_value_type item) {
        circular_buffer::assign(n, item);
        m_capacity_ctrl = capacity_type(n);
    }

    //! Assign n items into the space optimized circular buffer specifying the capacity.
    /*!
        The capacity of the circular_buffer_space_optimized will be set to the specified value and the
        content of the circular_buffer_space_optimized will be removed and replaced with n
        copies of the item.
        \pre capacity_ctrl.%capacity() >= n
        \post capacity() == capacity_ctrl \&\& size() == n \&\& (*this)[0] == item \&\& (*this)[1] == item
              \&\& ... \&\& (*this) [n - 1] == item 


              The amount of allocated memory will be max[n, capacity_ctrl.min_capacity()].
        \param capacity_ctrl The new capacity controller.
        \param n The number of elements the circular_buffer_space_optimized will be filled with.
        \param item The element the circular_buffer_space_optimized will be filled with.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the n).
        \sa \link operator=(const circular_buffer_space_optimized&) operator=\endlink,
            \link assign(size_type, param_value_type) assign(size_type, const_reference)\endlink,
            assign(InputIterator, InputIterator),
            assign(capacity_type, InputIterator, InputIterator)
    */
    void assign(capacity_type capacity_ctrl, size_type n, param_value_type item) {
       BOOST_CB_ASSERT(capacity_ctrl.capacity() >= n); // check for new capacity lower than n
       circular_buffer::assign((std::max)(capacity_ctrl.min_capacity(), n), n, item);
       m_capacity_ctrl = capacity_ctrl;
    }

    //! Assign a copy of the range into the space optimized circular buffer.
    /*!
        The content of the circular_buffer_space_optimized will be removed and replaced with copies of
        elements from the specified range.
        \pre Valid range [first, last).

             first and last have to meet the requirements of
             InputIterator.
        \post capacity().%capacity() == std::distance(first, last) \&\& capacity().min_capacity() == 0 \&\&
              size() == std::distance(first, last) \&\& (*this)[0]== *first \&\& (*this)[1] == *(first + 1) \&\& ...
              \&\& (*this)[std::distance(first, last) - 1] == *(last - 1)


              The amount of allocated memory in the internal buffer is std::distance(first, last).
        \param first The beginning of the range to be copied.
        \param last The end of the range to be copied.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept and 
                InputIterator is a move iterator.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the std::distance(first, last)).
        \sa \link operator=(const circular_buffer_space_optimized&) operator=\endlink,
            \link assign(size_type, param_value_type) assign(size_type, const_reference)\endlink,
            \link assign(capacity_type, size_type, param_value_type)
            assign(capacity_type, size_type, const_reference)\endlink,
            assign(capacity_type, InputIterator, InputIterator)
    */
    template 
    void assign(InputIterator first, InputIterator last) {
        circular_buffer::assign(first, last);
        m_capacity_ctrl = capacity_type(circular_buffer::capacity());
    }

    //! Assign a copy of the range into the space optimized circular buffer specifying the capacity.
    /*!
        The capacity of the circular_buffer_space_optimized will be set to the specified value and the
        content of the circular_buffer_space_optimized will be removed and replaced with copies of
        elements from the specified range.
        \pre Valid range [first, last).

             first and last have to meet the requirements of
             InputIterator.
        \post capacity() == capacity_ctrl \&\& size() \<= std::distance(first, last) \&\&
             (*this)[0]== *(last - capacity) \&\& (*this)[1] == *(last - capacity + 1) \&\& ... \&\&
             (*this)[capacity - 1] == *(last - 1)


             If the number of items to be copied from the range [first, last) is greater than the
             specified capacity then only elements from the range [last - capacity, last)
             will be copied.

 The amount of allocated memory in the internal buffer is
             max[std::distance(first, last), capacity_ctrl.min_capacity()].
        \param capacity_ctrl The new capacity controller.
        \param first The beginning of the range to be copied.
        \param last The end of the range to be copied.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept and 
                InputIterator is a move iterator.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in std::distance(first, last); in
             min[capacity_ctrl.%capacity(), std::distance(first, last)] if the InputIterator
             is a RandomAccessIterator).
        \sa \link operator=(const circular_buffer_space_optimized&) operator=\endlink,
            \link assign(size_type, param_value_type) assign(size_type, const_reference)\endlink,
            \link assign(capacity_type, size_type, param_value_type)
            assign(capacity_type, size_type, const_reference)\endlink,
            assign(InputIterator, InputIterator)
    */
    template 
    void assign(capacity_type capacity_ctrl, InputIterator first, InputIterator last) {
       m_capacity_ctrl = capacity_ctrl;
       circular_buffer::assign(capacity_ctrl, first, last);
    }

    //! Swap the contents of two space-optimized circular-buffers.
    /*!
        \post this contains elements of cb and vice versa; the capacity and the amount of
              allocated memory in the internal buffer of this equal to the capacity and the amount of
              allocated memory of cb and vice versa.
        \param cb The circular_buffer_space_optimized whose content will be swapped.
        \throws Nothing.
        \par Exception Safety
             No-throw.
        \par Iterator Invalidation
             Invalidates all iterators of both circular_buffer_space_optimized containers. (On the other
             hand the iterators still point to the same elements but within another container. If you want to rely on
             this feature you have to turn the __debug_support off,
             otherwise an assertion will report an error if such invalidated iterator is used.)
        \par Complexity
             Constant (in the size of the circular_buffer_space_optimized).
        \sa swap(circular_buffer&, circular_buffer&), 
            swap(circular_buffer_space_optimized&, circular_buffer_space_optimized&)


    */
    // Note link does not work right.  Asked on Doxygen forum for advice 23 May 2103.

    void swap(circular_buffer_space_optimized& cb) BOOST_NOEXCEPT {
        std::swap(m_capacity_ctrl, cb.m_capacity_ctrl);
        circular_buffer::swap(cb);
    }

    //! Insert a new element at the end of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then back() == item

              If the circular_buffer_space_optimized is full, the first element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param item The element to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_front() push_front(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_back(param_value_type item) {
        check_low_capacity();
        circular_buffer::push_back(item);
    }

    //! Insert a new element at the end of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then back() == item

              If the circular_buffer_space_optimized is full, the first element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param item The element to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_front() push_front(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_back(rvalue_type item) {
        check_low_capacity();
        circular_buffer::push_back(boost::move(item));
    }

    //! Insert a new element at the end of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then back() == item

              If the circular_buffer_space_optimized is full, the first element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T() throws. 
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_front() push_front(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_back() {
        check_low_capacity();
        circular_buffer::push_back();
    }

    //! Insert a new element at the beginning of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then front() == item

              If the circular_buffer_space_optimized is full, the last element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param item The element to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_back() push_back(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_front(param_value_type item) {
        check_low_capacity();
        circular_buffer::push_front(item);
    }

    //! Insert a new element at the beginning of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then front() == item

              If the circular_buffer_space_optimized is full, the last element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param item The element to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_back() push_back(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_front(rvalue_type item) {
        check_low_capacity();
        circular_buffer::push_front(boost::move(item));
    }

    //! Insert a new element at the beginning of the space optimized circular buffer.
    /*!
        \post if capacity().%capacity() > 0 then front() == item

              If the circular_buffer_space_optimized is full, the last element will be removed. If the
              capacity is 0, nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T() throws.
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link push_back() push_back(const_reference)\endlink, pop_back(),
            pop_front()
    */
    void push_front() {
        check_low_capacity();
        circular_buffer::push_front();
    }

    //! Remove the last element from the space optimized circular buffer.
    /*!
        \pre !empty()
        \post The last element is removed from the circular_buffer_space_optimized.


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa pop_front(), \link push_back() push_back(const_reference)\endlink,
            \link push_front() push_front(const_reference)\endlink
    */
    void pop_back() {
        circular_buffer::pop_back();
        check_high_capacity();
    }

    //! Remove the first element from the space optimized circular buffer.
    /*!
        \pre !empty()
        \post The first element is removed from the circular_buffer_space_optimized.


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa pop_back(), \link push_back() push_back(const_reference)\endlink,
            \link push_front() push_front(const_reference)\endlink
    */
    void pop_front() {
        circular_buffer::pop_front();
        check_high_capacity();
    }

    //! Insert an element at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted at the position pos.

              If the circular_buffer_space_optimized is full, the first element will be overwritten. If
              the circular_buffer_space_optimized is full and the pos points to
              begin(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the item will be inserted.
        \param item The element to be inserted.
        \return Iterator to the inserted element or begin() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
                Whatever T::operator = (const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator),
            \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator)
    */
    iterator insert(iterator pos, param_value_type item) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::insert(begin() + index, item);
    }

    //! Insert an element at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted at the position pos.

              If the circular_buffer_space_optimized is full, the first element will be overwritten. If
              the circular_buffer_space_optimized is full and the pos points to
              begin(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the item will be inserted.
        \param item The element to be inserted.
        \return Iterator to the inserted element or begin() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator),
            \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator)
    */
    iterator insert(iterator pos, rvalue_type item) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::insert(begin() + index, boost::move(item));
    }

    //! Insert an element at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted at the position pos.

              If the circular_buffer_space_optimized is full, the first element will be overwritten. If
              the circular_buffer_space_optimized is full and the pos points to
              begin(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the item will be inserted.
        \return Iterator to the inserted element or begin() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T() throws.
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator),
            \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator)
    */
    iterator insert(iterator pos) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::insert(begin() + index);
    }

    //! Insert n copies of the item at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The number of min[n, (pos - begin()) + reserve()] elements will be inserted at the position
              pos.
The number of min[pos - begin(), max[0, n - reserve()]] elements will
              be overwritten at the beginning of the circular_buffer_space_optimized.
(See
              Example for the explanation.)


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the items will be inserted.
        \param n The number of items the to be inserted.
        \param item The element whose copies will be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
                Whatever T::operator = (const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in min[capacity().%capacity(), size() + n]).
        \par Example
             Consider a circular_buffer_space_optimized with the capacity of 6 and the size of 4. Its
             internal buffer may look like the one below.


             |1|2|3|4| | |

             p ___^

After inserting 5 elements at the position p:


             insert(p, (size_t)5, 0);

actually only 4 elements get inserted and elements
             1 and 2 are overwritten. This is due to the fact the insert operation preserves
             the capacity. After insertion the internal buffer looks like this:

|0|0|0|0|3|4|

             
For comparison if the capacity would not be preserved the internal buffer would then result in
             |1|2|0|0|0|0|0|3|4|.
        \sa \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator),
            \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator)
    */
    void insert(iterator pos, size_type n, param_value_type item) {
        size_type index = pos - begin();
        check_low_capacity(n);
        circular_buffer::insert(begin() + index, n, item);
    }

    //! Insert the range [first, last) at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
Valid range [first, last) where first and last meet the
             requirements of an InputIterator.
        \post Elements from the range
              [first + max[0, distance(first, last) - (pos - begin()) - reserve()], last) will be
              inserted at the position pos.
The number of min[pos - begin(), max[0,
              distance(first, last) - reserve()]] elements will be overwritten at the beginning of the
              circular_buffer_space_optimized.
(See Example for the explanation.)


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the range will be inserted.
        \param first The beginning of the range to be inserted.
        \param last The end of the range to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in [size() + std::distance(first, last)]; in
             min[capacity().%capacity(), size() + std::distance(first, last)] if the
             InputIterator is a
             RandomAccessIterator).
        \par Example
             Consider a circular_buffer_space_optimized with the capacity of 6 and the size of 4. Its
             internal buffer may look like the one below.


             |1|2|3|4| | |

             p ___^

After inserting a range of elements at the position p:


             int array[] = { 5, 6, 7, 8, 9 };
insert(p, array, array + 5);


             actually only elements 6, 7, 8 and 9 from the
             specified range get inserted and elements 1 and 2 are overwritten. This is due
             to the fact the insert operation preserves the capacity. After insertion the internal buffer looks like
             this:

|6|7|8|9|3|4|

For comparison if the capacity would not be preserved the
             internal buffer would then result in |1|2|5|6|7|8|9|3|4|.
        \sa \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink, \link rinsert(iterator, param_value_type)
            rinsert(iterator, value_type)\endlink, \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator)
    */
    template 
    void insert(iterator pos, InputIterator first, InputIterator last) {
        insert(pos, first, last, is_integral());
    }

    //! Insert an element before the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted before the position pos.

              If the circular_buffer_space_optimized is full, the last element will be overwritten. If the
              circular_buffer_space_optimized is full and the pos points to
              end(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position before which the item will be inserted.
        \param item The element to be inserted.
        \return Iterator to the inserted element or end() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
                Whatever T::operator = (const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator),
            \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator)
    */
    iterator rinsert(iterator pos, param_value_type item) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::rinsert(begin() + index, item);
    }

    //! Insert an element before the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted before the position pos.

              If the circular_buffer_space_optimized is full, the last element will be overwritten. If the
              circular_buffer_space_optimized is full and the pos points to
              end(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position before which the item will be inserted.
        \param item The element to be inserted.
        \return Iterator to the inserted element or end() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator),
            \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator)
    */
    iterator rinsert(iterator pos, rvalue_type item) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::rinsert(begin() + index, boost::move(item));
    }

    //! Insert an element before the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The item will be inserted before the position pos.

              If the circular_buffer_space_optimized is full, the last element will be overwritten. If the
              circular_buffer_space_optimized is full and the pos points to
              end(), then the item will not be inserted. If the capacity is 0,
              nothing will be inserted.


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position before which the item will be inserted.
        \return Iterator to the inserted element or end() if the item is not inserted. (See
                the Effect.)
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T() throws.
                Whatever T::T(const T&) throws or nothing if T::T(T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator),
            \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator)
    */
    iterator rinsert(iterator pos) {
        size_type index = pos - begin();
        check_low_capacity();
        return circular_buffer::rinsert(begin() + index);
    }

    //! Insert n copies of the item before the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.
        \post The number of min[n, (end() - pos) + reserve()] elements will be inserted before the
              position pos.
The number of min[end() - pos, max[0, n - reserve()]] elements
              will be overwritten at the end of the circular_buffer_space_optimized.
(See
              Example for the explanation.)


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the items will be inserted.
        \param n The number of items the to be inserted.
        \param item The element whose copies will be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
                Whatever T::operator = (const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in min[capacity().%capacity(), size() + n]).
        \par Example
             Consider a circular_buffer_space_optimized with the capacity of 6 and the size of 4. Its
             internal buffer may look like the one below.


             |1|2|3|4| | |

             p ___^

After inserting 5 elements before the position p:


             rinsert(p, (size_t)5, 0);

actually only 4 elements get inserted and elements
             3 and 4 are overwritten. This is due to the fact the rinsert operation preserves
             the capacity. After insertion the internal buffer looks like this:

|1|2|0|0|0|0|

             
For comparison if the capacity would not be preserved the internal buffer would then result in
             |1|2|0|0|0|0|0|3|4|.
        \sa \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            rinsert(iterator, InputIterator, InputIterator),
            \link insert(iterator, param_value_type) insert(iterator, value_type)\endlink,
            \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator)
    */
    void rinsert(iterator pos, size_type n, param_value_type item) {
        size_type index = pos - begin();
        check_low_capacity(n);
        circular_buffer::rinsert(begin() + index, n, item);
    }

        //! Insert the range [first, last) before the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized or its
             end.

             Valid range [first, last) where first and last meet the
             requirements of an InputIterator.
        \post Elements from the range
              [first, last - max[0, distance(first, last) - (end() - pos) - reserve()]) will be inserted
              before the position pos.
The number of min[end() - pos, max[0,
              distance(first, last) - reserve()]] elements will be overwritten at the end of the
              circular_buffer.
(See Example for the explanation.)


              The amount of allocated memory in the internal buffer may be predictively increased.
        \param pos An iterator specifying the position where the range will be inserted.
        \param first The beginning of the range to be inserted.
        \param last The end of the range to be inserted.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::T(const T&) throws.
                Whatever T::operator = (const T&) throws.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in [size() + std::distance(first, last)]; in
             min[capacity().%capacity(), size() + std::distance(first, last)] if the
             InputIterator is a
             RandomAccessIterator).
        \par Example
             Consider a circular_buffer_space_optimized with the capacity of 6 and the size of 4. Its
             internal buffer may look like the one below.


             |1|2|3|4| | |

             p ___^

After inserting a range of elements before the position p:


             int array[] = { 5, 6, 7, 8, 9 };
insert(p, array, array + 5);


             actually only elements 5, 6, 7 and 8 from the
             specified range get inserted and elements 3 and 4 are overwritten. This is due
             to the fact the rinsert operation preserves the capacity. After insertion the internal buffer looks like
             this:

|1|2|5|6|7|8|

For comparison if the capacity would not be preserved the
             internal buffer would then result in |1|2|5|6|7|8|9|3|4|.
        \sa \link rinsert(iterator, param_value_type) rinsert(iterator, value_type)\endlink,
            \link rinsert(iterator, size_type, param_value_type)
            rinsert(iterator, size_type, value_type)\endlink, \link insert(iterator, param_value_type)
            insert(iterator, value_type)\endlink, \link insert(iterator, size_type, param_value_type)
            insert(iterator, size_type, value_type)\endlink,
            insert(iterator, InputIterator, InputIterator)
    */
    template 
    void rinsert(iterator pos, InputIterator first, InputIterator last) {
        rinsert(pos, first, last, is_integral());
    }

    //! Remove an element at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized (but not
             an end()).
        \post The element at the position pos is removed.


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \param pos An iterator pointing at the element to be removed.
        \return Iterator to the first element remaining beyond the removed element or end() if no such
                element exists.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::operator = (const T&) throws or 
                nothing if T::operator = (T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa erase(iterator, iterator), rerase(iterator),
            rerase(iterator, iterator), clear()
    */
    iterator erase(iterator pos) {
        iterator it = circular_buffer::erase(pos);
        size_type index = it - begin();
        check_high_capacity();
        return begin() + index;
    }

    //! Erase the range [first, last).
    /*!
        \pre Valid range [first, last).
        \post The elements from the range [first, last) are removed. (If first == last
              nothing is removed.)


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \param first The beginning of the range to be removed.
        \param last The end of the range to be removed.
        \return Iterator to the first element remaining beyond the removed elements or end() if no such
                element exists.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::operator = (const T&) throws or 
                nothing if T::operator = (T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa erase(iterator), rerase(iterator), rerase(iterator, iterator),
            clear()
    */
    iterator erase(iterator first, iterator last) {
        iterator it = circular_buffer::erase(first, last);
        size_type index = it - begin();
        check_high_capacity();
        return begin() + index;
    }

    //! Remove an element at the specified position.
    /*!
        \pre pos is a valid iterator pointing to the circular_buffer_space_optimized (but not
             an end()).


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \post The element at the position pos is removed.
        \param pos An iterator pointing at the element to be removed.
        \return Iterator to the first element remaining in front of the removed element or begin() if no
                such element exists.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::operator = (const T&) throws or 
                nothing if T::operator = (T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \note Basically there is no difference between erase(iterator) and this method. It is implemented
              only for consistency with the base circular_buffer.
        \sa erase(iterator), erase(iterator, iterator),
            rerase(iterator, iterator), clear()
    */
    iterator rerase(iterator pos) {
        iterator it = circular_buffer::rerase(pos);
        size_type index = it - begin();
        check_high_capacity();
        return begin() + index;
    }

    //! Erase the range [first, last).
    /*!
        \pre Valid range [first, last).
        \post The elements from the range [first, last) are removed. (If first == last
              nothing is removed.)


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \param first The beginning of the range to be removed.
        \param last The end of the range to be removed.
        \return Iterator to the first element remaining in front of the removed elements or begin() if no
                such element exists.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
                Whatever T::operator = (const T&) throws or 
                nothing if T::operator = (T&&) is noexcept.
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \note Basically there is no difference between erase(iterator, iterator) and this method. It is
              implemented only for consistency with the base
              .
        \sa erase(iterator), erase(iterator, iterator), rerase(iterator),
            clear()
    */
    iterator rerase(iterator first, iterator last) {
        iterator it = circular_buffer::rerase(first, last);
        size_type index = it - begin();
        check_high_capacity();
        return begin() + index;
    }

    //! Remove all stored elements from the space optimized circular buffer.
    /*!
        \post size() == 0


              The amount of allocated memory in the internal buffer may be predictively decreased.
        \throws "An allocation error" if memory is exhausted (std::bad_alloc if the standard allocator is
                used).
        \par Exception Safety
             Basic.
        \par Iterator Invalidation
             Invalidates all iterators pointing to the circular_buffer_space_optimized (except iterators
             equal to end()).
        \par Complexity
             Linear (in the size of the circular_buffer_space_optimized).
        \sa ~circular_buffer_space_optimized(), erase(iterator),
            erase(iterator, iterator), rerase(iterator),
            rerase(iterator, iterator)
    */
    void clear() { erase(begin(), end()); }

private:
// Helper methods

    /*! INTERNAL ONLY */
    void adjust_min_capacity() {
        if (m_capacity_ctrl.min_capacity() > circular_buffer::capacity())
            circular_buffer::set_capacity(m_capacity_ctrl.min_capacity());
        else
            check_high_capacity();
    }

    /*! INTERNAL ONLY */
    size_type ensure_reserve(size_type new_capacity, size_type buffer_size) const {
        if (buffer_size + new_capacity / 5 >= new_capacity)
            new_capacity *= 2; // ensure at least 20% reserve
        if (new_capacity > m_capacity_ctrl)
            return m_capacity_ctrl;
        return new_capacity;
    }

    /*! INTERNAL ONLY */
    void check_low_capacity(size_type n = 1) {
        size_type new_size = size() + n;
        size_type new_capacity = circular_buffer::capacity();
        if (new_size > new_capacity) {
            if (new_capacity == 0)
                new_capacity = 1;
            for (; new_size > new_capacity; new_capacity *= 2) {}
            circular_buffer::set_capacity(
                ensure_reserve(new_capacity, new_size));
        }
#if BOOST_CB_ENABLE_DEBUG
        this->invalidate_iterators_except(end());
#endif
    }

    /*! INTERNAL ONLY */
    void check_high_capacity() {
        size_type new_capacity = circular_buffer::capacity();
        while (new_capacity / 3 >= size()) { // (new_capacity / 3) -> avoid oscillations
            new_capacity /= 2;
            if (new_capacity <= m_capacity_ctrl.min_capacity()) {
                new_capacity = m_capacity_ctrl.min_capacity();
                break;
            }
        }
        circular_buffer::set_capacity(
            ensure_reserve(new_capacity, size()));
#if BOOST_CB_ENABLE_DEBUG
        this->invalidate_iterators_except(end());
#endif
    }

    /*! INTERNAL ONLY */
    void reduce_capacity(const true_type&) {
        circular_buffer::set_capacity((std::max)(m_capacity_ctrl.min_capacity(), size()));
    }

    /*! INTERNAL ONLY */
    void reduce_capacity(const false_type&) {}

    /*! INTERNAL ONLY */
    static size_type init_capacity(const capacity_type& capacity_ctrl, size_type n) {
        BOOST_CB_ASSERT(capacity_ctrl.capacity() >= n); // check for capacity lower than n
        return (std::max)(capacity_ctrl.min_capacity(), n);
    }

    /*! INTERNAL ONLY */
    template 
    static size_type init_capacity(const capacity_type& capacity_ctrl, IntegralType n, IntegralType,
        const true_type&) {
        return init_capacity(capacity_ctrl, static_cast(n));
    }

    /*! INTERNAL ONLY */
    template 
    static size_type init_capacity(const capacity_type& capacity_ctrl, Iterator first, Iterator last,
        const false_type&) {
        BOOST_CB_IS_CONVERTIBLE(Iterator, value_type); // check for invalid iterator type
#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581))
        return init_capacity(capacity_ctrl, first, last, std::iterator_traits::iterator_category());
#else
        return init_capacity(
            capacity_ctrl, first, last, BOOST_DEDUCED_TYPENAME std::iterator_traits::iterator_category());
#endif
    }

    /*! INTERNAL ONLY */
    template 
    static size_type init_capacity(const capacity_type& capacity_ctrl, InputIterator, InputIterator,
        const std::input_iterator_tag&) {
        return capacity_ctrl.capacity();
    }

    /*! INTERNAL ONLY */
    template 
    static size_type init_capacity(const capacity_type& capacity_ctrl, ForwardIterator first, ForwardIterator last,
        const std::forward_iterator_tag&) {
        BOOST_CB_ASSERT(std::distance(first, last) >= 0); // check for wrong range
        return (std::max)(capacity_ctrl.min_capacity(),
            (std::min)(capacity_ctrl.capacity(), static_cast(std::distance(first, last))));
    }

    /*! INTERNAL ONLY */
    template 
    void insert(const iterator& pos, IntegralType n, IntegralType item, const true_type&) {
        insert(pos, static_cast(n), static_cast(item));
    }

    /*! INTERNAL ONLY */
    template 
    void insert(const iterator& pos, Iterator first, Iterator last, const false_type&) {
        size_type index = pos - begin();
        check_low_capacity(std::distance(first, last));
        circular_buffer::insert(begin() + index, first, last);
    }

    /*! INTERNAL ONLY */
    template 
    void rinsert(const iterator& pos, IntegralType n, IntegralType item, const true_type&) {
        rinsert(pos, static_cast(n), static_cast(item));
    }

    /*! INTERNAL ONLY */
    template 
    void rinsert(const iterator& pos, Iterator first, Iterator last, const false_type&) {
        size_type index = pos - begin();
        check_low_capacity(std::distance(first, last));
        circular_buffer::rinsert(begin() + index, first, last);
    }
};

// Non-member functions

//! Test two space optimized circular buffers for equality.
template 
inline bool operator == (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return lhs.size() == rhs.size() &&
        std::equal(lhs.begin(), lhs.end(), rhs.begin());
}

//! Lexicographical comparison.
template 
inline bool operator < (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return std::lexicographical_compare(
        lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
}

#if !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) || BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))

//! Test two space optimized circular buffers for non-equality.
template 
inline bool operator != (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return !(lhs == rhs);
}

//! Lexicographical comparison.
template 
inline bool operator > (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return rhs < lhs;
}

//! Lexicographical comparison.
template 
inline bool operator <= (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return !(rhs < lhs);
}

//! Lexicographical comparison.
template 
inline bool operator >= (const circular_buffer_space_optimized& lhs,
    const circular_buffer_space_optimized& rhs) {
    return !(lhs < rhs);
}

//! Swap the contents of two space optimized circular buffers.
template 
inline void swap(circular_buffer_space_optimized& lhs,
    circular_buffer_space_optimized& rhs) BOOST_NOEXCEPT {
    lhs.swap(rhs);
}

#endif // #if !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) || BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))

} // namespace boost

#endif // #if !defined(BOOST_CIRCULAR_BUFFER_SPACE_OPTIMIZED_HPP)