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 //////////////////////////////////////////////////////////////////////////////
 //
 // (C) Copyright Ion Gaztanaga 2005-2013. 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_FLAT_MAP_HPP
 #define BOOST_CONTAINER_FLAT_MAP_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>
 // container/detail
 #include <boost/container/detail/flat_tree.hpp>
 #include <boost/container/detail/type_traits.hpp>
 #include <boost/container/detail/mpl.hpp>
 #include <boost/container/detail/algorithm.hpp> //equal()
 #include <boost/container/detail/container_or_allocator_rebind.hpp>
 #include <boost/container/detail/pair.hpp>
 // move
 #include <boost/move/utility_core.hpp>
 #include <boost/move/traits.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>
 #include <boost/move/detail/force_ptr.hpp>
 // intrusive
 #include <boost/intrusive/detail/minimal_pair_header.hpp>      //pair
 #include <boost/intrusive/detail/minimal_less_equal_header.hpp>//less, equal
 
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 #include <initializer_list>
 #endif
 
 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 #define BOOST_CONTAINER_STD_PAIR_IS_MOVABLE
 #endif
 
 //for C++03 compilers, were type-puning is the only option for std::pair
 //disable strict aliasing to reduce problems.
 #if defined(BOOST_GCC) && (BOOST_GCC >= 100000) && !defined(BOOST_CONTAINER_STD_PAIR_IS_MOVABLE)
 #pragma GCC push_options
 #pragma GCC optimize("no-strict-aliasing")
 #endif
 
 namespace boost {
 namespace container {
 
 #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 template <class Key, class T, class Compare, class AllocatorOrContainer>
 class flat_multimap;
 
 namespace dtl{
 
 #if defined(BOOST_CONTAINER_STD_PAIR_IS_MOVABLE)
 template<class D, class S>
 BOOST_CONTAINER_FORCEINLINE static D &force(S &s)
 {  return s; }
 
 template<class D, class S>
 BOOST_CONTAINER_FORCEINLINE static const D &force(const S &s)
 {  return s; }
 
 template<class D>
 BOOST_CONTAINER_FORCEINLINE static D force_copy(D s)
 {  return s; }
 
 #else //!BOOST_CONTAINER_DOXYGEN_INVOKED
 
 template<class D, class S>
 BOOST_CONTAINER_FORCEINLINE static D &force(S &s)
 {  return *move_detail::launder_cast<D*>(&s); }
 
 template<class D, class S>
 BOOST_CONTAINER_FORCEINLINE static const D &force(const S &s)
 {  return *move_detail::launder_cast<const D*>(&s); }
 
 template<class D, class S>
 BOOST_CONTAINER_FORCEINLINE static D force_copy(const S &s)
 {
    const D *const vp = move_detail::launder_cast<const D *>(&s);
    D ret_val(*vp);
    return ret_val;
 }
 #endif   //BOOST_CONTAINER_DOXYGEN_INVOKED
 
 }  //namespace dtl{
 
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 //! A flat_map is a kind of associative container that supports unique keys (contains at
 //! most one of each key value) and provides for fast retrieval of values of another
 //! type T based on the keys.
 //!
 //! A flat_map satisfies all of the requirements of a container, a reversible
 //! container and an associative container. A flat_map also provides
 //! most operations described for unique keys. For a
 //! flat_map<Key,T> the key_type is Key and the value_type is std::pair<Key,T>
 //! (unlike std::map<Key, T> which value_type is std::pair<<b>const</b> Key, T>).
 //!
 //! flat_map is similar to std::map but it's implemented by as an ordered sequence container.
 //! The underlying sequence container is by default <i>vector</i> but it can also work
 //! user-provided vector-like SequenceContainers (like <i>static_vector</i> or <i>small_vector</i>).
 //!
 //! Using vector-like sequence containers means that inserting a new element into a flat_map might invalidate
 //! previous iterators and references (unless that sequence container is <i>stable_vector</i> or a similar
 //! container that offers stable pointers and references). Similarly, erasing an element might invalidate
 //! iterators and references pointing to elements that come after (their keys are bigger) the erased element.
 //!
 //! This container provides random-access iterators.
 //!
 //! \tparam Key is the key_type of the map
 //! \tparam Value is the <code>mapped_type</code>
 //! \tparam Compare is the ordering function for Keys (e.g. <i>std::less<Key></i>).
 //! \tparam AllocatorOrContainer is either:
 //!   - The allocator to allocate <code>value_type</code>s (e.g. <i>allocator< std::pair<Key, T> > </i>).
 //!     (in this case <i>sequence_type</i> will be vector<value_type, AllocatorOrContainer>)
 //!   - The SequenceContainer to be used as the underlying <i>sequence_type</i>. It must be a vector-like
 //!     sequence container with random-access iterators.
 #ifdef BOOST_CONTAINER_DOXYGEN_INVOKED
 template <class Key, class T, class Compare = std::less<Key>, class AllocatorOrContainer = new_allocator< std::pair< Key, T> > >
 #else
 template <class Key, class T, class Compare, class AllocatorOrContainer>
 #endif
 class flat_map
 {
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
    BOOST_COPYABLE_AND_MOVABLE(flat_map)
    //This is the tree that we should store if pair was movable
    typedef std::pair<Key, T> std_pair_t;
    typedef dtl::flat_tree<
                            std_pair_t,
                            dtl::select1st<Key>,
                            Compare,
                            AllocatorOrContainer> tree_t;
 
    //This is the real tree stored here. It's based on a movable pair
    typedef dtl::pair<Key, T> dtl_pair_t;
 
    #ifdef BOOST_CONTAINER_STD_PAIR_IS_MOVABLE
    typedef std_pair_t impl_pair_t;
    #else
    typedef dtl_pair_t impl_pair_t;
    #endif
 
    typedef dtl::flat_tree< impl_pair_t,
                            dtl::select1st<Key>,
                            Compare,
                            #ifdef BOOST_CONTAINER_STD_PAIR_IS_MOVABLE
                            AllocatorOrContainer
                            #else
                            typename dtl::container_or_allocator_rebind<AllocatorOrContainer, impl_pair_t >::type
                            #endif
                            > impl_tree_t;
    impl_tree_t m_flat_tree;  // flat tree representing flat_map
 
    typedef typename impl_tree_t::value_type              impl_value_type;
    typedef typename impl_tree_t::const_iterator          impl_const_iterator;
    typedef typename impl_tree_t::iterator                impl_iterator;
    typedef typename impl_tree_t::allocator_type          impl_allocator_type;
    #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    typedef std::initializer_list<impl_value_type>        impl_initializer_list;
    #endif
 
    typedef dtl::flat_tree_value_compare
       < Compare
       , dtl::select1st<Key>
       , std::pair<Key, T> >                              value_compare_t;
    typedef typename tree_t::iterator                     iterator_t;
    typedef typename tree_t::const_iterator               const_iterator_t;
    typedef typename tree_t::reverse_iterator             reverse_iterator_t;
    typedef typename tree_t::const_reverse_iterator       const_reverse_iterator_t;
 
    public:
    typedef typename impl_tree_t::stored_allocator_type   impl_stored_allocator_type;
    typedef typename impl_tree_t::sequence_type           impl_sequence_type;
 
    inline impl_tree_t &tree()
    {  return m_flat_tree;  }
 
    inline const impl_tree_t &tree() const
    {  return m_flat_tree;  }
 
    private:
    typedef typename tree_t::get_stored_allocator_const_return_t         get_stored_allocator_const_return_t;
    typedef typename tree_t::get_stored_allocator_noconst_return_t       get_stored_allocator_noconst_return_t;
    typedef typename impl_tree_t::get_stored_allocator_const_return_t    impl_get_stored_allocator_const_return_t;
    typedef typename impl_tree_t::get_stored_allocator_noconst_return_t  impl_get_stored_allocator_noconst_return_t;
 
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
    public:
 
    //////////////////////////////////////////////
    //
    //                    types
    //
    //////////////////////////////////////////////
    typedef Key                                                                      key_type;
    typedef T                                                                        mapped_type;
    typedef Compare                                                                  key_compare;
    typedef std::pair<Key, T>                                                        value_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::sequence_type)                   sequence_type;
    typedef typename sequence_type::allocator_type                                   allocator_type;
    typedef ::boost::container::allocator_traits<allocator_type>                     allocator_traits_type;
    typedef typename sequence_type::pointer                                          pointer;
    typedef typename sequence_type::const_pointer                                    const_pointer;
    typedef typename sequence_type::reference                                        reference;
    typedef typename sequence_type::const_reference                                  const_reference;
    typedef typename sequence_type::size_type                                        size_type;
    typedef typename sequence_type::difference_type                                  difference_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::stored_allocator_type)           stored_allocator_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::value_compare)                   value_compare;
 
    typedef typename sequence_type::iterator                                         iterator;
    typedef typename sequence_type::const_iterator                                   const_iterator;
    typedef typename sequence_type::reverse_iterator                                 reverse_iterator;
    typedef typename sequence_type::const_reverse_iterator                           const_reverse_iterator;
    typedef BOOST_CONTAINER_IMPDEF(impl_value_type)                                  movable_value_type;
 
    //AllocatorOrContainer::value_type must be std::pair<Key, T>
    BOOST_CONTAINER_STATIC_ASSERT((dtl::is_same<std::pair<Key, T>, value_type>::value));
 
    //////////////////////////////////////////////
    //
    //          construct/copy/destroy
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Default constructs an empty flat_map.
    //!
    //! <b>Complexity</b>: Constant.
    inline flat_map() BOOST_NOEXCEPT_IF(dtl::is_nothrow_default_constructible<AllocatorOrContainer>::value &&
                                                             dtl::is_nothrow_default_constructible<Compare>::value)
       : m_flat_tree()
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified allocator.
    //!
    //! <b>Complexity</b>: Constant.
    inline explicit flat_map(const allocator_type& a)
       : m_flat_tree(dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified
    //! comparison object.
    //!
    //! <b>Complexity</b>: Constant.
    inline explicit flat_map(const Compare& comp)
       : m_flat_tree(comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified
    //! comparison object and allocator.
    //!
    //! <b>Complexity</b>: Constant.
    inline flat_map(const Compare& comp, const allocator_type& a)
       : m_flat_tree(comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map and
    //! and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline flat_map(InputIterator first, InputIterator last)
       : m_flat_tree(true, first, last)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified
    //! allocator, and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline flat_map(InputIterator first, InputIterator last, const allocator_type& a)
       : m_flat_tree(true, first, last, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline flat_map(InputIterator first, InputIterator last, const Compare& comp)
       : m_flat_tree(true, first, last, comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! allocator, and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline flat_map(InputIterator first, InputIterator last, const Compare& comp, const allocator_type& a)
       : m_flat_tree(true, first, last, comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map
    //! and inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_map(ordered_unique_range_t, InputIterator first, InputIterator last)
       : m_flat_tree(ordered_range, first, last)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_map(ordered_unique_range_t, InputIterator first, InputIterator last, const Compare& comp)
       : m_flat_tree(ordered_range, first, last, comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! allocator, and inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_map(ordered_unique_range_t, InputIterator first, InputIterator last, const Compare& comp, const allocator_type& a)
       : m_flat_tree(ordered_range, first, last, comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified allocator and
    //! inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
       flat_map(ordered_unique_range_t, InputIterator first, InputIterator last, const allocator_type& a)
       : m_flat_tree(ordered_range, first, last, Compare(), a)
    {}
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Constructs an empty flat_map and
    //! inserts elements from the range [il.begin() ,il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline flat_map(std::initializer_list<value_type> il)
      : m_flat_tree( true
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end())
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified
    //! allocator, and inserts elements from the range [il.begin() ,il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline flat_map(std::initializer_list<value_type> il, const allocator_type& a)
      : m_flat_tree( true
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end()
                   , dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! inserts elements from the range [il.begin() ,il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline flat_map(std::initializer_list<value_type> il, const Compare& comp)
      : m_flat_tree(true
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end()
                   , comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! allocator, and inserts elements from the range [il.begin() ,il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline flat_map(std::initializer_list<value_type> il, const Compare& comp, const allocator_type& a)
      : m_flat_tree(true
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end()
                   , comp
                   , dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using and
    //! inserts elements from the ordered unique range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate and must be
    //! unique values.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline flat_map(ordered_unique_range_t, std::initializer_list<value_type> il)
      : m_flat_tree(ordered_unique_range
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end())
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! inserts elements from the ordered unique range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate and must be
    //! unique values.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline flat_map(ordered_unique_range_t, std::initializer_list<value_type> il, const Compare& comp)
      : m_flat_tree(ordered_unique_range
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end()
                   , comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! allocator, and inserts elements from the ordered unique range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate and must be
    //! unique values.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline flat_map(ordered_unique_range_t, std::initializer_list<value_type> il, const Compare& comp, const allocator_type& a)
      : m_flat_tree( ordered_unique_range
                   , dtl::force<impl_initializer_list>(il).begin()
                   , dtl::force<impl_initializer_list>(il).end()
                   , comp
                   , dtl::force<const impl_allocator_type>(a))
    {}
 #endif
 
    //! <b>Effects</b>: Copy constructs a flat_map.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline flat_map(const flat_map& x)
       : m_flat_tree(x.m_flat_tree)
    {}
 
    //! <b>Effects</b>: Move constructs a flat_map.
    //!   Constructs *this using x's resources.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Postcondition</b>: x is emptied.
    inline flat_map(BOOST_RV_REF(flat_map) x)
       BOOST_NOEXCEPT_IF(boost::container::dtl::is_nothrow_move_constructible<Compare>::value)
       : m_flat_tree(boost::move(x.m_flat_tree))
    {}
 
    //! <b>Effects</b>: Copy constructs a flat_map using the specified allocator.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline flat_map(const flat_map& x, const allocator_type &a)
       : m_flat_tree(x.m_flat_tree, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Move constructs a flat_map using the specified allocator.
    //!   Constructs *this using x's resources.
    //!
    //! <b>Complexity</b>: Constant if x.get_allocator() == a, linear otherwise.
    inline flat_map(BOOST_RV_REF(flat_map) x, const allocator_type &a)
       : m_flat_tree(boost::move(x.m_flat_tree), dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Makes *this a copy of x.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline flat_map& operator=(BOOST_COPY_ASSIGN_REF(flat_map) x)
    {  m_flat_tree = x.m_flat_tree;   return *this;  }
 
    //! <b>Effects</b>: Move constructs a flat_map.
    //!   Constructs *this using x's resources.
    //!
    //! <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.
    inline flat_map& operator=(BOOST_RV_REF(flat_map) x)
       BOOST_NOEXCEPT_IF( (allocator_traits_type::propagate_on_container_move_assignment::value ||
                           allocator_traits_type::is_always_equal::value) &&
                            boost::container::dtl::is_nothrow_move_assignable<Compare>::value)
    {  m_flat_tree = boost::move(x.m_flat_tree);   return *this;  }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Assign elements from il to *this
    flat_map& operator=(std::initializer_list<value_type> il)
    {
       this->clear();
       this->insert(il.begin(), il.end());
       return *this;
    }
 #endif
 
    //! <b>Effects</b>: Returns a copy of the allocator that
    //!   was passed to the object's constructor.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       allocator_type get_allocator() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<allocator_type>(m_flat_tree.get_allocator()); }
 
    //! <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
       get_stored_allocator_noconst_return_t get_stored_allocator() BOOST_NOEXCEPT_OR_NOTHROW
    {
       impl_get_stored_allocator_noconst_return_t r = m_flat_tree.get_stored_allocator();
       return dtl::force<stored_allocator_type>(r);
    }
 
    //! <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
       get_stored_allocator_const_return_t get_stored_allocator() const BOOST_NOEXCEPT_OR_NOTHROW
    {
       impl_get_stored_allocator_const_return_t r = m_flat_tree.get_stored_allocator();
       return dtl::force<const stored_allocator_type>(r);
    }
 
    //////////////////////////////////////////////
    //
    //                iterators
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns an iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator begin() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<iterator>(m_flat_tree.begin()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator begin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.begin()); }
 
    //! <b>Effects</b>: Returns an iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator end() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<iterator>(m_flat_tree.end()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator end() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.end()); }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reverse_iterator rbegin() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<reverse_iterator>(m_flat_tree.rbegin()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator rbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.rbegin()); }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       reverse_iterator rend() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<reverse_iterator>(m_flat_tree.rend()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator rend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.rend()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator cbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.cbegin()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator cend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.cend()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator crbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.crbegin()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_reverse_iterator crend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.crend()); }
 
    //////////////////////////////////////////////
    //
    //                capacity
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns true if the container contains no elements.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       bool empty() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.empty(); }
 
    //! <b>Effects</b>: Returns the number of the elements contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.size(); }
 
    //! <b>Effects</b>: Returns the largest possible size of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.max_size(); }
 
    //! <b>Effects</b>: Number of elements for which memory has been allocated.
    //!   capacity() is always greater than or equal to size().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type capacity() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.capacity(); }
 
    //! <b>Effects</b>: If n is less than or equal to capacity(), or the
    //!   underlying container has no `reserve` member, this call has no
    //!   effect. Otherwise, it is a request for allocation of additional memory.
    //!   If the request is successful, then capacity() is greater than or equal to
    //!   n; otherwise, capacity() is unchanged. In either case, size() is unchanged.
    //!
    //! <b>Throws</b>: If memory allocation allocation throws or T's copy constructor throws.
    //!
    //! <b>Note</b>: If capacity() is less than "cnt", iterators and references to
    //!   to values might be invalidated.
    inline void reserve(size_type cnt)
       { m_flat_tree.reserve(cnt);   }
 
    //! <b>Effects</b>: Tries to deallocate the excess of memory created
    //    with previous allocations. The size of the vector is unchanged
    //!
    //! <b>Throws</b>: If memory allocation throws, or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to size().
    inline void shrink_to_fit()
       { m_flat_tree.shrink_to_fit(); }
 
    //////////////////////////////////////////////
    //
    //               element access
    //
    //////////////////////////////////////////////
 
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
    //! Effects: If there is no key equivalent to x in the flat_map, inserts
    //!   value_type(x, T()) into the flat_map.
    //!
    //! Returns: A reference to the mapped_type corresponding to x in *this.
    //!
    //! Complexity: Logarithmic search time plus linear insertion time in case no equivalent key is present.
    mapped_type &operator[](const key_type& k);
 
    //! Effects: If there is no key equivalent to x in the flat_map, inserts
    //! value_type(move(x), T()) into the flat_map (the key is move-constructed)
    //!
    //! Returns: A reference to the mapped_type corresponding to x in *this.
    //!
    //! Complexity: Logarithmic search time plus linear insertion time in case no equivalent key is present.
    mapped_type &operator[](key_type &&k);
    #elif defined(BOOST_MOVE_HELPERS_RETURN_SFINAE_BROKEN)
       //in compilers like GCC 3.4, we can't catch temporaries
       inline mapped_type& operator[](const key_type &k)         {  return this->priv_subscript(k);  }
       inline mapped_type& operator[](BOOST_RV_REF(key_type) k)  {  return this->priv_subscript(::boost::move(k));  }
    #else
       BOOST_MOVE_CONVERSION_AWARE_CATCH( operator[] , key_type, mapped_type&, this->priv_subscript)
    #endif
 
    //! Effects: If a key equivalent to k already exists in the container, assigns forward<M>(obj)
    //! to the mapped_type corresponding to the key k. If the key does not exist, inserts the new value
    //! as if by insert, constructing it from value_type(k, forward<M>(obj)).
    //! 
    //! No iterators or references are invalidated. If the insertion is successful, pointers and references
    //! to the element obtained while it is held in the node handle are invalidated, and pointers and
    //! references obtained to that element before it was extracted become valid.
    //!
    //! Returns: The bool component is true if the insertion took place and false if the assignment
    //!   took place. The iterator component is pointing at the element that was inserted or updated.
    //!
    //! Complexity: Logarithmic search time plus linear insertion time in case no equivalent key is present.
    template <class M>
    inline std::pair<iterator, bool> insert_or_assign(const key_type& k, BOOST_FWD_REF(M) obj)
    {
       return dtl::force_copy< std::pair<iterator, bool> >
          (this->m_flat_tree.insert_or_assign
             ( impl_const_iterator(), k, ::boost::forward<M>(obj))
          );
    }
 
    //! Effects: If a key equivalent to k already exists in the container, assigns forward<M>(obj)
    //! to the mapped_type corresponding to the key k. If the key does not exist, inserts the new value
    //! as if by insert, constructing it from value_type(k, move(obj)).
    //! 
    //! No iterators or references are invalidated. If the insertion is successful, pointers and references
    //! to the element obtained while it is held in the node handle are invalidated, and pointers and
    //! references obtained to that element before it was extracted become valid.
    //!
    //! Returns: The bool component is true if the insertion took place and false if the assignment
    //!   took place. The iterator component is pointing at the element that was inserted or updated.
    //!
    //! Complexity: Logarithmic in the size of the container.
    template <class M>
    inline std::pair<iterator, bool> insert_or_assign(BOOST_RV_REF(key_type) k, BOOST_FWD_REF(M) obj)
    {
       return dtl::force_copy< std::pair<iterator, bool> >
          (this->m_flat_tree.insert_or_assign
             ( impl_const_iterator(), ::boost::move(k), ::boost::forward<M>(obj))
          );
    }
 
    //! Effects: If a key equivalent to k already exists in the container, assigns forward<M>(obj)
    //! to the mapped_type corresponding to the key k. If the key does not exist, inserts the new value
    //! as if by insert, constructing it from value_type(k, forward<M>(obj)) and the new element
    //! to the container as close as possible to the position just before hint.
    //! 
    //! No iterators or references are invalidated. If the insertion is successful, pointers and references
    //! to the element obtained while it is held in the node handle are invalidated, and pointers and
    //! references obtained to that element before it was extracted become valid.
    //!
    //! Returns: The bool component is true if the insertion took place and false if the assignment
    //!   took place. The iterator component is pointing at the element that was inserted or updated.
    //!
    //! Complexity: Logarithmic in the size of the container in general, but amortized constant if
    //! the new element is inserted just before hint.
    template <class M>
    inline iterator insert_or_assign(const_iterator hint, const key_type& k, BOOST_FWD_REF(M) obj)
    {
       return dtl::force_copy<iterator>
          (this->m_flat_tree.insert_or_assign
             ( dtl::force_copy<impl_const_iterator>(hint)
             , k, ::boost::forward<M>(obj)).first
          );
    }
 
    //! Effects: If a key equivalent to k already exists in the container, assigns forward<M>(obj)
    //! to the mapped_type corresponding to the key k. If the key does not exist, inserts the new value
    //! as if by insert, constructing it from value_type(k, move(obj)) and the new element
    //! to the container as close as possible to the position just before hint.
    //! 
    //! No iterators or references are invalidated. If the insertion is successful, pointers and references
    //! to the element obtained while it is held in the node handle are invalidated, and pointers and
    //! references obtained to that element before it was extracted become valid.
    //!
    //! Returns: The bool component is true if the insertion took place and false if the assignment
    //!   took place. The iterator component is pointing at the element that was inserted or updated.
    //!
    //! Complexity: Logarithmic in the size of the container in general, but amortized constant if
    //! the new element is inserted just before hint.
    template <class M>
    inline iterator insert_or_assign(const_iterator hint, BOOST_RV_REF(key_type) k, BOOST_FWD_REF(M) obj)
    {
       return dtl::force_copy<iterator>
          (this->m_flat_tree.insert_or_assign
             ( dtl::force_copy<impl_const_iterator>(hint)
             , ::boost::move(k), ::boost::forward<M>(obj)).first
          );
    }
 
    //! @copydoc ::boost::container::flat_set::nth(size_type)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator nth(size_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {  return dtl::force_copy<iterator>(m_flat_tree.nth(n));  }
 
    //! @copydoc ::boost::container::flat_set::nth(size_type) const
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator nth(size_type n) const BOOST_NOEXCEPT_OR_NOTHROW
    {  return dtl::force_copy<const_iterator>(m_flat_tree.nth(n));  }
 
    //! @copydoc ::boost::container::flat_set::index_of(iterator)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type index_of(iterator p) BOOST_NOEXCEPT_OR_NOTHROW
    {  return m_flat_tree.index_of(dtl::force_copy<impl_iterator>(p));  }
 
    //! @copydoc ::boost::container::flat_set::index_of(const_iterator) const
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type index_of(const_iterator p) const BOOST_NOEXCEPT_OR_NOTHROW
    {  return m_flat_tree.index_of(dtl::force_copy<impl_const_iterator>(p));  }
 
    //! Returns: A reference to the element whose key is equivalent to x.
    //!
    //! Throws: An exception object of type out_of_range if no such element is present.
    //!
    //! Complexity: logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD T& at(const key_type& k)
    {
       iterator i = this->find(k);
       if(i == this->end()){
          throw_out_of_range("flat_map::at key not found");
       }
       return i->second;
    }
 
    //! Returns: A reference to the element whose key is equivalent to x.
    //!
    //! Throws: An exception object of type out_of_range if no such element is present.
    //!
    //! Complexity: logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD const T& at(const key_type& k) const
    {
       const_iterator i = this->find(k);
       if(i == this->end()){
          throw_out_of_range("flat_map::at key not found");
       }
       return i->second;
    }
 
    //////////////////////////////////////////////
    //
    //                modifiers
    //
    //////////////////////////////////////////////
 
    #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Inserts an object x of type T constructed with
    //!   std::forward<Args>(args)... if and only if there is no element in the container
    //!   with key equivalent to the key of x.
    //!
    //! <b>Returns</b>: The bool component of the returned pair is true if and only
    //!   if the insertion takes place, and the iterator component of the pair
    //!   points to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class... Args>
    inline std::pair<iterator,bool> emplace(BOOST_FWD_REF(Args)... args)
    {  return dtl::force_copy< std::pair<iterator, bool> >(m_flat_tree.emplace_unique(boost::forward<Args>(args)...)); }
 
    //! <b>Effects</b>: Inserts an object of type T constructed with
    //!   std::forward<Args>(args)... in the container if and only if there is
    //!   no element in the container with key equivalent to the key of x.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent
    //!   to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant if x is inserted
    //!   right before p) plus insertion linear to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class... Args>
    inline iterator emplace_hint(const_iterator hint, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.emplace_hint_unique( dtl::force_copy<impl_const_iterator>(hint)
                                          , boost::forward<Args>(args)...));
    }
 
    //! <b>Requires</b>: value_type shall be EmplaceConstructible into map from piecewise_construct, 
    //! forward_as_tuple(k), forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Effects</b>: If the map already contains an element whose key is equivalent to k, there is no effect. Otherwise
    //! inserts an object of type value_type constructed with piecewise_construct, forward_as_tuple(k),
    //! forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Returns</b>: The bool component of the returned pair is true if and only if the
    //! insertion took place. The returned iterator points to the map element whose key is equivalent to k.
    //! 
    //! <b>Complexity</b>: Logarithmic.
    template <class... Args>
    inline std::pair<iterator, bool> try_emplace(const key_type& k, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy< std::pair<iterator, bool> >(
          m_flat_tree.try_emplace(impl_const_iterator(), k, boost::forward<Args>(args)...));
    }
 
    //! <b>Requires</b>: value_type shall be EmplaceConstructible into map from piecewise_construct, 
    //! forward_as_tuple(k), forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Effects</b>: If the map already contains an element whose key is equivalent to k, there is no effect. Otherwise
    //! inserts an object of type value_type constructed with piecewise_construct, forward_as_tuple(k),
    //! forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Returns</b>: The returned iterator points to the map element whose key is equivalent to k.
    //! 
    //! <b>Complexity</b>: Logarithmic in general, but amortized constant if value
    //!   is inserted right before p.
    template <class... Args>
    inline iterator try_emplace(const_iterator hint, const key_type &k, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy<iterator>(m_flat_tree.try_emplace
          (dtl::force_copy<impl_const_iterator>(hint), k, boost::forward<Args>(args)...).first);
    }
 
    //! <b>Requires</b>: value_type shall be EmplaceConstructible into map from piecewise_construct, 
    //! forward_as_tuple(move(k)), forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Effects</b>: If the map already contains an element whose key is equivalent to k, there is no effect. Otherwise
    //! inserts an object of type value_type constructed with piecewise_construct, forward_as_tuple(move(k)),
    //! forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Returns</b>: The bool component of the returned pair is true if and only if the
    //! insertion took place. The returned iterator points to the map element whose key is equivalent to k.
    //! 
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion time in case the key is not present.
    template <class... Args>
    inline std::pair<iterator, bool> try_emplace(BOOST_RV_REF(key_type) k, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy< std::pair<iterator, bool> >
          (m_flat_tree.try_emplace(impl_const_iterator(), boost::move(k), boost::forward<Args>(args)...));
    }
 
    //! <b>Requires</b>: value_type shall be EmplaceConstructible into map from piecewise_construct, 
    //! forward_as_tuple(move(k)), forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Effects</b>: If the map already contains an element whose key is equivalent to k, there is no effect. Otherwise
    //! inserts an object of type value_type constructed with piecewise_construct, forward_as_tuple(move(k)),
    //! forward_as_tuple(forward<Args>(args)...).
    //! 
    //! <b>Returns</b>: The returned iterator points to the map element whose key is equivalent to k.
    //! 
    //! <b>Complexity</b>: Logarithmic in general, but amortized constant if value
    //!   is inserted right before p. Linear insertion time in case no equivalent key is present.
    template <class... Args>
    inline iterator try_emplace(const_iterator hint, BOOST_RV_REF(key_type) k, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.try_emplace(dtl::force_copy
             <impl_const_iterator>(hint), boost::move(k), boost::forward<Args>(args)...).first);
    }
 
    #else // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    #define BOOST_CONTAINER_FLAT_MAP_EMPLACE_CODE(N) \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline std::pair<iterator,bool> emplace(BOOST_MOVE_UREF##N)\
    {\
       return dtl::force_copy< std::pair<iterator, bool> >\
          (m_flat_tree.emplace_unique(BOOST_MOVE_FWD##N));\
    }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline iterator emplace_hint(const_iterator hint BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {\
       return dtl::force_copy<iterator>(m_flat_tree.emplace_hint_unique\
          (dtl::force_copy<impl_const_iterator>(hint) BOOST_MOVE_I##N BOOST_MOVE_FWD##N));\
    }\
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline std::pair<iterator, bool> try_emplace(const key_type& k BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {\
       return dtl::force_copy< std::pair<iterator, bool> >\
          (m_flat_tree.try_emplace(impl_const_iterator(), k BOOST_MOVE_I##N BOOST_MOVE_FWD##N));\
    }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline iterator try_emplace(const_iterator hint, const key_type &k BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {  return dtl::force_copy<iterator>(m_flat_tree.try_emplace\
          (dtl::force_copy<impl_const_iterator>(hint), k BOOST_MOVE_I##N BOOST_MOVE_FWD##N).first); }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline std::pair<iterator, bool> try_emplace(BOOST_RV_REF(key_type) k BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {\
       return dtl::force_copy< std::pair<iterator, bool> >\
          (m_flat_tree.try_emplace(impl_const_iterator(), boost::move(k) BOOST_MOVE_I##N BOOST_MOVE_FWD##N));\
    }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline iterator try_emplace(const_iterator hint, BOOST_RV_REF(key_type) k BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {  return dtl::force_copy<iterator>(m_flat_tree.try_emplace\
       (dtl::force_copy<impl_const_iterator>(hint), boost::move(k) BOOST_MOVE_I##N BOOST_MOVE_FWD##N).first); }\
    //
    BOOST_MOVE_ITERATE_0TO9(BOOST_CONTAINER_FLAT_MAP_EMPLACE_CODE)
    #undef BOOST_CONTAINER_FLAT_MAP_EMPLACE_CODE
 
    #endif   // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    //! <b>Effects</b>: Inserts x if and only if there is no element in the container
    //!   with key equivalent to the key of x.
    //!
    //! <b>Returns</b>: The bool component of the returned pair is true if and only
    //!   if the insertion takes place, and the iterator component of the pair
    //!   points to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline std::pair<iterator,bool> insert(const value_type& x)
    {  return dtl::force_copy<std::pair<iterator,bool> >(
          m_flat_tree.insert_unique(dtl::force<const impl_value_type>(x))); }
 
    //! <b>Effects</b>: Inserts a new value_type move constructed from the pair if and
    //! only if there is no element in the container with key equivalent to the key of x.
    //!
    //! <b>Returns</b>: The bool component of the returned pair is true if and only
    //!   if the insertion takes place, and the iterator component of the pair
    //!   points to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline std::pair<iterator,bool> insert(BOOST_RV_REF(value_type) x)
    {
       return dtl::force_copy<std::pair<iterator,bool> >(
          m_flat_tree.insert_unique(boost::move(dtl::force<impl_value_type>(x))));
    }
 
    //! <b>Effects</b>: Inserts a new value_type constructed from the pair if and
    //! only if there is no element in the container with key equivalent to the key of x.
    //!
    //! <b>Returns</b>: The bool component of the returned pair is true if and only
    //!   if the insertion takes place, and the iterator component of the pair
    //!   points to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class Pair>
    inline BOOST_CONTAINER_DOC1ST
          ( std::pair<iterator BOOST_MOVE_I bool>
          , typename dtl::enable_if_c<dtl::is_convertible<Pair BOOST_MOVE_I dtl_pair_t>::value
             BOOST_MOVE_I std::pair<iterator BOOST_MOVE_I bool> >::type)
       insert(BOOST_FWD_REF(Pair) x)
    {
       return dtl::force_copy<std::pair<iterator,bool> >
          (m_flat_tree.emplace_unique(boost::forward<Pair>(x)));
    }
 
    //! <b>Effects</b>: Inserts a copy of x in the container if and only if there is
    //!   no element in the container with key equivalent to the key of x.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent
    //!   to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant if x is inserted
    //!   right before p) plus insertion linear to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline iterator insert(const_iterator p, const value_type& x)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.insert_unique( dtl::force_copy<impl_const_iterator>(p)
                                   , dtl::force<const impl_value_type>(x)));
    }
 
    //! <b>Effects</b>: Inserts an element move constructed from x in the container.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant if x is inserted
    //!   right before p) plus insertion linear to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline iterator insert(const_iterator p, BOOST_RV_REF(value_type) x)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.insert_unique( dtl::force_copy<impl_const_iterator>(p)
                                    , boost::move(dtl::force<impl_value_type>(x))));
    }
 
    //! <b>Effects</b>: Inserts an element constructed from x in the container.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant if x is inserted
    //!   right before p) plus insertion linear to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class Pair>
    inline BOOST_CONTAINER_DOC1ST
          ( iterator
          , typename dtl::enable_if_c<dtl::is_convertible<Pair BOOST_MOVE_I dtl_pair_t>::value
             BOOST_MOVE_I iterator>::type)
       insert(const_iterator p, BOOST_FWD_REF(Pair) x)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.emplace_hint_unique(dtl::force_copy<impl_const_iterator>(p), boost::forward<Pair>(x)));
    }
 
    //! <b>Requires</b>: first, last are not iterators into *this.
    //!
    //! <b>Effects</b>: inserts each element from the range [first,last) if and only
    //!   if there is no element with key equivalent to the key of that element.
    //!
    //! <b>Complexity</b>: N log(size()+N).
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class InputIterator>
    inline void insert(InputIterator first, InputIterator last)
    {  m_flat_tree.insert_unique(first, last);  }
 
    //! <b>Requires</b>: first, last are not iterators into *this.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate and must be
    //! unique values.
    //!
    //! <b>Effects</b>: inserts each element from the range [first,last) if and only
    //!   if there is no element with key equivalent to the key of that element. This
    //!   function is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Complexity</b>: Linear.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline void insert(ordered_unique_range_t, InputIterator first, InputIterator last)
       {  m_flat_tree.insert_unique(ordered_unique_range, first, last); }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: inserts each element from the range [il.begin(), il.end()) if and only
    //!   if there is no element with key equivalent to the key of that element.
    //!
    //! <b>Complexity</b>: N log(N).
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline void insert(std::initializer_list<value_type> il)
    {
       m_flat_tree.insert_unique( dtl::force<impl_initializer_list>(il).begin()
                                , dtl::force<impl_initializer_list>(il).end());
    }
 
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate and must be
    //! unique values.
    //!
    //! <b>Effects</b>: inserts each element from the range [il.begin(), il.end()) if and only
    //!   if there is no element with key equivalent to the key of that element. This
    //!   function is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Complexity</b>: Linear.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline void insert(ordered_unique_range_t, std::initializer_list<value_type> il)
    {
       m_flat_tree.insert_unique(ordered_unique_range
                                , dtl::force<impl_initializer_list>(il).begin()
                                , dtl::force<impl_initializer_list>(il).end());
    }
 #endif
 
    //! <b>Requires</b>: this->get_allocator() == source.get_allocator().
    //!
    //! <b>Effects</b>: Move-inserts each element from source into *this a using
    //!   the comparison object of *this. If there is an element in a with key equivalent to the
    //!   key of an element from source, then that element is not moved from source.
    //!
    //! <b>Complexity</b>: Linear in this->size() + source.size().
    //!
    //! <b>Note</b>: Invalidates all iterators and references.
    template<class C2>
    inline void merge(flat_map<Key, T, C2, AllocatorOrContainer>& source)
    {  m_flat_tree.merge_unique(source.tree());   }
 
    //! @copydoc ::boost::container::flat_map::merge(flat_map<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(BOOST_RV_REF_BEG flat_map<Key, T, C2, AllocatorOrContainer> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<flat_map<Key, T, C2, AllocatorOrContainer>&>(source)); }
 
    //! @copydoc ::boost::container::flat_map::merge(flat_map<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(flat_multimap<Key, T, C2, AllocatorOrContainer>& source)
    {  m_flat_tree.merge_unique(source.tree());   }
 
    //! @copydoc ::boost::container::flat_map::merge(flat_map<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(BOOST_RV_REF_BEG flat_multimap<Key, T, C2, AllocatorOrContainer> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<flat_multimap<Key, T, C2, AllocatorOrContainer>&>(source));  }
 
    //! <b>Effects</b>: Erases the element pointed to by p.
    //!
    //! <b>Returns</b>: Returns an iterator pointing to the element immediately
    //!   following q prior to the element being erased. If no such element exists,
    //!   returns end().
    //!
    //! <b>Complexity</b>: Linear to the elements with keys bigger than p
    //!
    //! <b>Note</b>: Invalidates elements with keys
    //!   not less than the erased element.
    inline iterator erase(const_iterator p)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.erase(dtl::force_copy<impl_const_iterator>(p)));
    }
 
    //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
    //!
    //! <b>Returns</b>: Returns the number of erased elements (0/1).
    //!
    //! <b>Complexity</b>: Logarithmic search time plus erasure time
    //!   linear to the elements with bigger keys.
    inline size_type erase(const key_type& x)
       { return m_flat_tree.erase_unique(x); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
    //!
    //! <b>Returns</b>: Returns the number of erased elements (0/1).
    template <class K>
    inline BOOST_CONTAINER_DOC1ST
    (size_type
       , typename dtl::enable_if_c<
       dtl::is_transparent<key_compare>::value &&                  //transparent
       !dtl::is_convertible<K BOOST_MOVE_I iterator>::value &&     //not convertible to iterator
       !dtl::is_convertible<K BOOST_MOVE_I const_iterator>::value  //not convertible to const_iterator
       BOOST_MOVE_I size_type>::type)
       erase(const K& x)
    {  return m_flat_tree.erase_unique(x); }
 
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!
    //! <b>Returns</b>: Returns last.
    //!
    //! <b>Complexity</b>: size()*N where N is the distance from first to last.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus erasure time
    //!   linear to the elements with bigger keys.
    inline iterator erase(const_iterator first, const_iterator last)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.erase( dtl::force_copy<impl_const_iterator>(first)
                           , dtl::force_copy<impl_const_iterator>(last)));
    }
 
    //! <b>Effects</b>: Swaps the contents of *this and x.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    inline void swap(flat_map& x)
       BOOST_NOEXCEPT_IF(  allocator_traits_type::is_always_equal::value
                                  && boost::container::dtl::is_nothrow_swappable<Compare>::value )
    { m_flat_tree.swap(x.m_flat_tree); }
 
    //! <b>Effects</b>: erase(begin(),end()).
    //!
    //! <b>Postcondition</b>: size() == 0.
    //!
    //! <b>Complexity</b>: linear in size().
    inline void clear() BOOST_NOEXCEPT_OR_NOTHROW
       { m_flat_tree.clear(); }
 
    //////////////////////////////////////////////
    //
    //                observers
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns the comparison object out
    //!   of which a was constructed.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       key_compare key_comp() const
       { return dtl::force_copy<key_compare>(m_flat_tree.key_comp()); }
 
    //! <b>Effects</b>: Returns an object of value_compare constructed out
    //!   of the comparison object.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       value_compare value_comp() const
       { return value_compare(dtl::force_copy<key_compare>(m_flat_tree.key_comp())); }
 
    //////////////////////////////////////////////
    //
    //              map operations
    //
    //////////////////////////////////////////////
 
    //! <b>Returns</b>: An iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator find(const key_type& x)
       { return dtl::force_copy<iterator>(m_flat_tree.find(x)); }
 
    //! <b>Returns</b>: A const_iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator find(const key_type& x) const
       { return dtl::force_copy<const_iterator>(m_flat_tree.find(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator find(const K& x)
       { return dtl::force_copy<iterator>(m_flat_tree.find(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: A const_iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator find(const K& x) const
       { return dtl::force_copy<const_iterator>(m_flat_tree.find(x)); }
 
    //! <b>Returns</b>: The number of elements with key equivalent to x.
    //!
    //! <b>Complexity</b>: log(size())+count(k)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type count(const key_type& x) const
       {  return static_cast<size_type>(m_flat_tree.find(x) != m_flat_tree.end());  }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: The number of elements with key equivalent to x.
    //!
    //! <b>Complexity</b>: log(size())+count(k)
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type count(const K& x) const
       //Don't use find() != end optimization here as transparent comparators with key K might
       //return a different range than key_type (which can only return a single element range)
       {  return m_flat_tree.count(x);  }
 
    //! <b>Returns</b>: Returns true if there is an element with key
    //!   equivalent to key in the container, otherwise false.
    //!
    //! <b>Complexity</b>: log(size()).
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       bool contains(const key_type& x) const
       {  return m_flat_tree.find(x) != m_flat_tree.end();  }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: Returns true if there is an element with key
    //!   equivalent to key in the container, otherwise false.
    //!
    //! <b>Complexity</b>: log(size()).
    template<typename K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       bool contains(const K& x) const
       {  return m_flat_tree.find(x) != m_flat_tree.end();  }
 
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator lower_bound(const key_type& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Returns</b>: A const iterator pointing to the first element with key not
    //!   less than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator lower_bound(const key_type& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator lower_bound(const K& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: A const iterator pointing to the first element with key not
    //!   less than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator lower_bound(const K& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Returns</b>: An iterator pointing to the first element with key greater
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator upper_bound(const key_type& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Returns</b>: A const iterator pointing to the first element with key
    //!   greater than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator upper_bound(const key_type& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to the first element with key greater
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator upper_bound(const K& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: A const iterator pointing to the first element with key
    //!   greater than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator upper_bound(const K& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<iterator,iterator> equal_range(const key_type& x)
       {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.lower_bound_range(x)); }
 
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<const_iterator, const_iterator> equal_range(const key_type& x) const
       {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.lower_bound_range(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<iterator,iterator> equal_range(const K& x)
       //Don't use lower_bound_range optimization here as transparent comparators with key K might
       //return a different range than key_type (which can only return a single element range)
       {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.equal_range(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<const_iterator, const_iterator> equal_range(const K& x) const
       //Don't use lower_bound_range optimization here as transparent comparators with key K might
       //return a different range than key_type (which can only return a single element range)
       {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.equal_range(x)); }
 
    //! <b>Effects</b>: Extracts the internal sequence container.
    //!
    //! <b>Complexity</b>: Same as the move constructor of sequence_type, usually constant.
    //!
    //! <b>Postcondition</b>: this->empty()
    //!
    //! <b>Throws</b>: If secuence_type's move constructor throws 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline sequence_type extract_sequence()
    {
       return boost::move(dtl::force<sequence_type>(m_flat_tree.get_sequence_ref()));
    }
 
    //! <b>Effects</b>: Discards the internally hold sequence container and adopts the
    //!   one passed externally using the move assignment. Erases non-unique elements.
    //!
    //! <b>Complexity</b>: Assuming O(1) move assignment, O(NlogN) with N = seq.size()
    //!
    //! <b>Throws</b>: If the comparison or the move constructor throws
    inline void adopt_sequence(BOOST_RV_REF(sequence_type) seq)
    {  this->m_flat_tree.adopt_sequence_unique(boost::move(dtl::force<impl_sequence_type>(seq)));  }
 
    //! <b>Requires</b>: seq shall be ordered according to this->compare()
    //!   and shall contain unique elements.
    //!
    //! <b>Effects</b>: Discards the internally hold sequence container and adopts the
    //!   one passed externally using the move assignment.
    //!
    //! <b>Complexity</b>: Assuming O(1) move assignment, O(1)
    //!
    //! <b>Throws</b>: If the move assignment throws
    inline void adopt_sequence(ordered_unique_range_t, BOOST_RV_REF(sequence_type) seq)
    {  this->m_flat_tree.adopt_sequence_unique(ordered_unique_range_t(), boost::move(dtl::force<impl_sequence_type>(seq)));  }
 
    //! <b>Effects</b>: Returns a const view of the underlying sequence.
    //!
    //! <b>Complexity</b>: Constant
    //!
    //! <b>Throws</b>: Nothing
    inline const sequence_type & sequence() const BOOST_NOEXCEPT
    {  return dtl::force<sequence_type>(m_flat_tree.get_sequence_cref());  }
 
    //! <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 flat_map& x, const flat_map& 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 flat_map& x, const flat_map& 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 flat_map& x, const flat_map& 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 flat_map& x, const flat_map& 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 flat_map& x, const flat_map& 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 flat_map& x, const flat_map& y)
    {  return !(x < y);  }
 
    //! <b>Effects</b>: x.swap(y)
    //!
    //! <b>Complexity</b>: Constant.
    inline friend void swap(flat_map& x, flat_map& y)
        BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT(x.swap(y)))
    {  x.swap(y);  }
 
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
    mapped_type &priv_subscript(const key_type& k)
    {
       iterator i = this->lower_bound(k);
       // i->first is greater than or equivalent to k.
       if (i == end() || key_comp()(k, (*i).first)){
          dtl::value_init<mapped_type> m;
          impl_value_type v(k, ::boost::move(m.m_t));
          i = dtl::force_copy<iterator>(this->m_flat_tree.insert_equal(::boost::move(v)));
       }
       return (*i).second;
    }
    mapped_type &priv_subscript(BOOST_RV_REF(key_type) mk)
    {
       key_type &k = mk;
       iterator i = this->lower_bound(k);
       // i->first is greater than or equivalent to k.
       if (i == end() || key_comp()(k, (*i).first)) {
          dtl::value_init<mapped_type> m;
          impl_value_type v(::boost::move(k), ::boost::move(m.m_t));
          i = dtl::force_copy<iterator>(this->m_flat_tree.insert_equal(::boost::move(v)));
       }
       return (*i).second;
    }
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 };
 
 #ifndef BOOST_CONTAINER_NO_CXX17_CTAD
 
 template <typename InputIterator>
 flat_map(InputIterator, InputIterator) ->
    flat_map< it_based_non_const_first_type_t<InputIterator>
            , it_based_second_type_t<InputIterator>>;
 
 template < typename InputIterator, typename AllocatorOrCompare>
     flat_map(InputIterator, InputIterator, AllocatorOrCompare const&) ->
     flat_map< it_based_non_const_first_type_t<InputIterator>
             , it_based_second_type_t<InputIterator>
             , typename dtl::if_c< // Compare
                 dtl::is_allocator<AllocatorOrCompare>::value
                 , std::less<it_based_non_const_first_type_t<InputIterator>>
                 , AllocatorOrCompare
             >::type
             , typename dtl::if_c< // Allocator
                 dtl::is_allocator<AllocatorOrCompare>::value
                 , AllocatorOrCompare
                 , new_allocator<std::pair<it_based_non_const_first_type_t<InputIterator>, it_based_second_type_t<InputIterator>>>
                 >::type
             >;
 
 template < typename InputIterator, typename Compare, typename Allocator
          , typename = dtl::require_nonallocator_t<Compare>
          , typename = dtl::require_allocator_t<Allocator>>
 flat_map(InputIterator, InputIterator, Compare const&, Allocator const&) ->
    flat_map< it_based_non_const_first_type_t<InputIterator>
            , it_based_second_type_t<InputIterator>
            , Compare
            , Allocator>;
 
 template <typename InputIterator>
 flat_map(ordered_unique_range_t, InputIterator, InputIterator) ->
    flat_map< it_based_non_const_first_type_t<InputIterator>
            , it_based_second_type_t<InputIterator>>;
 
 template < typename InputIterator, typename AllocatorOrCompare>
 flat_map(ordered_unique_range_t, InputIterator, InputIterator, AllocatorOrCompare const&) ->
    flat_map< it_based_non_const_first_type_t<InputIterator>
            , it_based_second_type_t<InputIterator>
            , typename dtl::if_c<   // Compare
                dtl::is_allocator<AllocatorOrCompare>::value
                , std::less<it_based_non_const_first_type_t<InputIterator>>
                , AllocatorOrCompare
                >::type
            , typename dtl::if_c<   // Allocator
                dtl::is_allocator<AllocatorOrCompare>::value
                , AllocatorOrCompare
                , new_allocator<std::pair<it_based_non_const_first_type_t<InputIterator>, it_based_second_type_t<InputIterator>>>
                >::type
            >;
 
 template < typename InputIterator, typename Compare, typename Allocator
          , typename = dtl::require_nonallocator_t<Compare>
          , typename = dtl::require_allocator_t<Allocator>>
 flat_map(ordered_unique_range_t, InputIterator, InputIterator, Compare const&, Allocator const&) ->
    flat_map< it_based_non_const_first_type_t<InputIterator>
            , it_based_second_type_t<InputIterator>
            , Compare
            , Allocator>;
 
 #endif
 
 #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 }  //namespace container {
 
 //!has_trivial_destructor_after_move<> == true_type
 //!specialization for optimizations
 template <class Key, class T, class Compare, class AllocatorOrContainer>
 struct has_trivial_destructor_after_move<boost::container::flat_map<Key, T, Compare, AllocatorOrContainer> >
 {
    typedef typename boost::container::flat_map<Key, T, Compare, AllocatorOrContainer>::value_type value_t;
    typedef typename ::boost::container::dtl::container_or_allocator_rebind<AllocatorOrContainer, value_t>::type alloc_or_cont_t;
    typedef ::boost::container::dtl::flat_tree<value_t,::boost::container::dtl::select1st<Key>, Compare, alloc_or_cont_t> tree;
    BOOST_STATIC_CONSTEXPR bool value = ::boost::has_trivial_destructor_after_move<tree>::value;
 };
 
 namespace container {
 
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 //! A flat_multimap is a kind of associative container that supports equivalent keys
 //! (possibly containing multiple copies of the same key value) and provides for
 //! fast retrieval of values of another type T based on the keys. 
 //!
 //! A flat_multimap satisfies all of the requirements of a container and of a reversible
 //! container and of an associative container. For a
 //! flat_multimap<Key,T> the key_type is Key and the value_type is std::pair<Key,T>
 //! (unlike std::multimap<Key, T> which value_type is std::pair<<b>const</b> Key, T>).
 //!
 //! flat_multimap is similar to std::multimap but it's implemented by as an ordered sequence container.
 //! The underlying sequence container is by default <i>vector</i> but it can also work
 //! user-provided vector-like SequenceContainers (like <i>static_vector</i> or <i>small_vector</i>).
 //!
 //! Using vector-like sequence containers means that inserting a new element into a flat_multimap might invalidate
 //! previous iterators and references (unless that sequence container is <i>stable_vector</i> or a similar
 //! container that offers stable pointers and references). Similarly, erasing an element might invalidate
 //! iterators and references pointing to elements that come after (their keys are bigger) the erased element.
 //!
 //! This container provides random-access iterators.
 //!
 //! \tparam Key is the key_type of the map
 //! \tparam Value is the <code>mapped_type</code>
 //! \tparam Compare is the ordering function for Keys (e.g. <i>std::less<Key></i>).
 //! \tparam AllocatorOrContainer is either:
 //!   - The allocator to allocate <code>value_type</code>s (e.g. <i>allocator< std::pair<Key, T> > </i>).
 //!     (in this case <i>sequence_type</i> will be vector<value_type, AllocatorOrContainer>)
 //!   - The SequenceContainer to be used as the underlying <i>sequence_type</i>. It must be a vector-like
 //!     sequence container with random-access iterators.
 #ifdef BOOST_CONTAINER_DOXYGEN_INVOKED
 template <class Key, class T, class Compare = std::less<Key>, class AllocatorOrContainer = new_allocator< std::pair< Key, T> > >
 #else
 template <class Key, class T, class Compare, class AllocatorOrContainer>
 #endif
 class flat_multimap
 {
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
    BOOST_COPYABLE_AND_MOVABLE(flat_multimap)
    typedef std::pair<Key, T> std_pair_t;
    typedef dtl::flat_tree<
                            std_pair_t,
                            dtl::select1st<Key>,
                            Compare,
                            AllocatorOrContainer> tree_t;
    //This is the real tree stored here. It's based on a movable pair
    typedef dtl::pair<Key, T> dtl_pair_t;
    #ifdef BOOST_CONTAINER_STD_PAIR_IS_MOVABLE
    typedef std_pair_t impl_pair_t;
    #else
    typedef dtl_pair_t impl_pair_t;
    #endif
    typedef dtl::flat_tree<
                            impl_pair_t,
                            dtl::select1st<Key>,
                            Compare,
                            #ifdef BOOST_CONTAINER_STD_PAIR_IS_MOVABLE
                            AllocatorOrContainer
                            #else
                            typename dtl::container_or_allocator_rebind<AllocatorOrContainer, impl_pair_t >::type
                            #endif
                            > impl_tree_t;
    impl_tree_t m_flat_tree;  // flat tree representing flat_map
 
    typedef typename impl_tree_t::value_type              impl_value_type;
    typedef typename impl_tree_t::const_iterator          impl_const_iterator;
    typedef typename impl_tree_t::iterator                impl_iterator;
    typedef typename impl_tree_t::allocator_type          impl_allocator_type;
    #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    typedef std::initializer_list<impl_value_type>        impl_initializer_list;
    #endif
 
    typedef dtl::flat_tree_value_compare
       < Compare
       , dtl::select1st<Key>
       , std::pair<Key, T> >                                 value_compare_t;
    typedef typename tree_t::iterator                        iterator_t;
    typedef typename tree_t::const_iterator                  const_iterator_t;
    typedef typename tree_t::reverse_iterator                reverse_iterator_t;
    typedef typename tree_t::const_reverse_iterator          const_reverse_iterator_t;
 
    public:
    typedef typename impl_tree_t::stored_allocator_type      impl_stored_allocator_type;
    typedef typename impl_tree_t::sequence_type              impl_sequence_type;
 
    inline impl_tree_t &tree()
    {  return m_flat_tree;  }
 
    inline const impl_tree_t &tree() const
    {  return m_flat_tree;  }
 
    private:
    #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
    public:
 
    //////////////////////////////////////////////
    //
    //                    types
    //
    //////////////////////////////////////////////
    typedef Key                                                                      key_type;
    typedef T                                                                        mapped_type;
    typedef Compare                                                                  key_compare;
    typedef std::pair<Key, T>                                                        value_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::sequence_type)                   sequence_type;
    typedef typename sequence_type::allocator_type                                   allocator_type;
    typedef ::boost::container::allocator_traits<allocator_type>                     allocator_traits_type;
    typedef typename sequence_type::pointer                                          pointer;
    typedef typename sequence_type::const_pointer                                    const_pointer;
    typedef typename sequence_type::reference                                        reference;
    typedef typename sequence_type::const_reference                                  const_reference;
    typedef typename sequence_type::size_type                                        size_type;
    typedef typename sequence_type::difference_type                                  difference_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::stored_allocator_type)           stored_allocator_type;
    typedef typename BOOST_CONTAINER_IMPDEF(tree_t::value_compare)                   value_compare;
 
    typedef typename sequence_type::iterator                                         iterator;
    typedef typename sequence_type::const_iterator                                   const_iterator;
    typedef typename sequence_type::reverse_iterator                                 reverse_iterator;
    typedef typename sequence_type::const_reverse_iterator                           const_reverse_iterator;
    typedef BOOST_CONTAINER_IMPDEF(impl_value_type)                                  movable_value_type;
 
    //AllocatorOrContainer::value_type must be std::pair<Key, T>
    BOOST_CONTAINER_STATIC_ASSERT((dtl::is_same<std::pair<Key, T>, value_type>::value));
 
    //////////////////////////////////////////////
    //
    //          construct/copy/destroy
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Default constructs an empty flat_map.
    //!
    //! <b>Complexity</b>: Constant.
    inline flat_multimap()
       BOOST_NOEXCEPT_IF(dtl::is_nothrow_default_constructible<AllocatorOrContainer>::value &&
                         dtl::is_nothrow_default_constructible<Compare>::value)
       : m_flat_tree()
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified allocator.
    //!
    //! <b>Complexity</b>: Constant.
    inline explicit flat_multimap(const allocator_type& a)
       : m_flat_tree(dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison
    //!   object .
    //!
    //! <b>Complexity</b>: Constant.
    inline explicit flat_multimap(const Compare& comp)
       : m_flat_tree(comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison
    //!   object and allocator.
    //!
    //! <b>Complexity</b>: Constant.
    inline
    flat_multimap(const Compare& comp, const allocator_type& a)
       : m_flat_tree(comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap
    //!   and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline
    flat_multimap(InputIterator first, InputIterator last)
       : m_flat_tree(false, first, last)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified
    //!   allocator, and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline
    flat_multimap(InputIterator first, InputIterator last, const allocator_type& a)
       : m_flat_tree(false, first, last, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object
    //!   and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline
    flat_multimap(InputIterator first, InputIterator last, const Compare& comp)
       : m_flat_tree(false, first, last, comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object
    //!   and allocator, and inserts elements from the range [first ,last ).
    //!
    //! <b>Complexity</b>: Linear in N if the range [first ,last ) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    template <class InputIterator>
    inline
    flat_multimap(InputIterator first, InputIterator last, const Compare& comp, const allocator_type& a)
       : m_flat_tree(false, first, last, comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap
    //! and inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_multimap(ordered_range_t, InputIterator first, InputIterator last)
       : m_flat_tree(ordered_range, first, last)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object and
    //! inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_multimap(ordered_range_t, InputIterator first, InputIterator last, const Compare& comp)
       : m_flat_tree(ordered_range, first, last, comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object and
    //! allocator, and inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
    flat_multimap(ordered_range_t, InputIterator first, InputIterator last, const Compare& comp, const allocator_type& a)
       : m_flat_tree(ordered_range, first, last, comp, a)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object and
    //! inserts elements from the ordered range [first ,last). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline
       flat_multimap(ordered_range_t, InputIterator first, InputIterator last, const allocator_type &a)
       : m_flat_tree(ordered_range, first, last, Compare(), a)
    {}
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Constructs an empty flat_map and
    //! inserts elements from the range [il.begin(), il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline
    flat_multimap(std::initializer_list<value_type> il)
       : m_flat_tree( false
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end())
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified
    //! allocator, and inserts elements from the range [il.begin(), il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline
    flat_multimap(std::initializer_list<value_type> il, const allocator_type& a)
       : m_flat_tree(false
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end()
                    , dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! inserts elements from the range [il.begin(), il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline
    flat_multimap(std::initializer_list<value_type> il, const Compare& comp)
       : m_flat_tree(false
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end(), comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_map using the specified comparison object and
    //! allocator, and inserts elements from the range [il.begin(), il.end()).
    //!
    //! <b>Complexity</b>: Linear in N if the range [il.begin(), il.end()) is already sorted using
    //! the predicate and otherwise N logN, where N is last - first.
    inline
    flat_multimap(std::initializer_list<value_type> il, const Compare& comp, const allocator_type& a)
       : m_flat_tree( false
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end()
                    , comp, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap and
    //! inserts elements from the ordered range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline
    flat_multimap(ordered_range_t, std::initializer_list<value_type> il)
       : m_flat_tree( ordered_range
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end())
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object and
    //! inserts elements from the ordered range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline
    flat_multimap(ordered_range_t, std::initializer_list<value_type> il, const Compare& comp)
       : m_flat_tree( ordered_range
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end(), comp)
    {}
 
    //! <b>Effects</b>: Constructs an empty flat_multimap using the specified comparison object and
    //! allocator, and inserts elements from the ordered range [il.begin(), il.end()). This function
    //! is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate.
    //!
    //! <b>Complexity</b>: Linear in N.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline
    flat_multimap(ordered_range_t, std::initializer_list<value_type> il, const Compare& comp, const allocator_type& a)
       : m_flat_tree( ordered_range
                    , dtl::force<impl_initializer_list>(il).begin()
                    , dtl::force<impl_initializer_list>(il).end()
                    , comp, dtl::force<const impl_allocator_type>(a))
    {}
 #endif
 
    //! <b>Effects</b>: Copy constructs a flat_multimap.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline
    flat_multimap(const flat_multimap& x)
       : m_flat_tree(x.m_flat_tree)
    {}
 
    //! <b>Effects</b>: Move constructs a flat_multimap. Constructs *this using x's resources.
    //!
    //! <b>Complexity</b>: Constant.
    //!
    //! <b>Postcondition</b>: x is emptied.
    inline
    flat_multimap(BOOST_RV_REF(flat_multimap) x)
       BOOST_NOEXCEPT_IF(boost::container::dtl::is_nothrow_move_constructible<Compare>::value)
       : m_flat_tree(boost::move(x.m_flat_tree))
    {}
 
    //! <b>Effects</b>: Copy constructs a flat_multimap using the specified allocator.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline
    flat_multimap(const flat_multimap& x, const allocator_type &a)
       : m_flat_tree(x.m_flat_tree, dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Move constructs a flat_multimap using the specified allocator.
    //!                 Constructs *this using x's resources.
    //!
    //! <b>Complexity</b>: Constant if a == x.get_allocator(), linear otherwise.
    inline
    flat_multimap(BOOST_RV_REF(flat_multimap) x, const allocator_type &a)
       : m_flat_tree(boost::move(x.m_flat_tree), dtl::force<const impl_allocator_type>(a))
    {}
 
    //! <b>Effects</b>: Makes *this a copy of x.
    //!
    //! <b>Complexity</b>: Linear in x.size().
    inline
    flat_multimap& operator=(BOOST_COPY_ASSIGN_REF(flat_multimap) x)
       {  m_flat_tree = x.m_flat_tree;   return *this;  }
 
    //! <b>Effects</b>: this->swap(x.get()).
    //!
    //! <b>Complexity</b>: Constant.
    inline
    flat_multimap& operator=(BOOST_RV_REF(flat_multimap) x)
       BOOST_NOEXCEPT_IF( (allocator_traits_type::propagate_on_container_move_assignment::value ||
                           allocator_traits_type::is_always_equal::value) &&
                            boost::container::dtl::is_nothrow_move_assignable<Compare>::value)
       {  m_flat_tree = boost::move(x.m_flat_tree);   return *this;  }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: Assign content of il to *this
    //!
    //! <b>Complexity</b>: Linear in il.size().
    inline
    flat_multimap& operator=(std::initializer_list<value_type> il)
    {
       this->clear();
       this->insert(il.begin(), il.end());
       return *this;
    }
 #endif
 
    //! <b>Effects</b>: Returns a copy of the allocator that
    //!   was passed to the object's constructor.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    allocator_type get_allocator() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<allocator_type>(m_flat_tree.get_allocator()); }
 
    //! <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 dtl::force<stored_allocator_type>(m_flat_tree.get_stored_allocator()); }
 
    //! <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 dtl::force<const stored_allocator_type>(m_flat_tree.get_stored_allocator()); }
 
    //////////////////////////////////////////////
    //
    //                iterators
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns an iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    iterator begin() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<iterator>(m_flat_tree.begin()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_iterator begin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.begin()); }
 
    //! <b>Effects</b>: Returns an iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    iterator end() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<iterator>(m_flat_tree.end()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_iterator end() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.end()); }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    reverse_iterator rbegin() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<reverse_iterator>(m_flat_tree.rbegin()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_reverse_iterator rbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.rbegin()); }
 
    //! <b>Effects</b>: Returns a reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    reverse_iterator rend() BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<reverse_iterator>(m_flat_tree.rend()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_reverse_iterator rend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.rend()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the first element contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_iterator cbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.cbegin()); }
 
    //! <b>Effects</b>: Returns a const_iterator to the end of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_iterator cend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_iterator>(m_flat_tree.cend()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the beginning
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_reverse_iterator crbegin() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.crbegin()); }
 
    //! <b>Effects</b>: Returns a const_reverse_iterator pointing to the end
    //! of the reversed container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_reverse_iterator crend() const BOOST_NOEXCEPT_OR_NOTHROW
       { return dtl::force_copy<const_reverse_iterator>(m_flat_tree.crend()); }
 
    //////////////////////////////////////////////
    //
    //                capacity
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns true if the container contains no elements.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    bool empty() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.empty(); }
 
    //! <b>Effects</b>: Returns the number of the elements contained in the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    size_type size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.size(); }
 
    //! <b>Effects</b>: Returns the largest possible size of the container.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    size_type max_size() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.max_size(); }
 
    //! <b>Effects</b>: Number of elements for which memory has been allocated.
    //!   capacity() is always greater than or equal to size().
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    size_type capacity() const BOOST_NOEXCEPT_OR_NOTHROW
       { return m_flat_tree.capacity(); }
 
    //! <b>Effects</b>: If n is less than or equal to capacity(), or the
    //!   underlying container has no `reserve` member, this call has no
    //!   effect. Otherwise, it is a request for allocation of additional memory.
    //!   If the request is successful, then capacity() is greater than or equal to
    //!   n; otherwise, capacity() is unchanged. In either case, size() is unchanged.
    //!
    //! <b>Throws</b>: If memory allocation allocation throws or T's copy constructor throws.
    //!
    //! <b>Note</b>: If capacity() is less than "cnt", iterators and references to
    //!   to values might be invalidated.
    inline
    void reserve(size_type cnt)
       { m_flat_tree.reserve(cnt);   }
 
    //! <b>Effects</b>: Tries to deallocate the excess of memory created
    //    with previous allocations. The size of the vector is unchanged
    //!
    //! <b>Throws</b>: If memory allocation throws, or T's copy constructor throws.
    //!
    //! <b>Complexity</b>: Linear to size().
    inline
    void shrink_to_fit()
       { m_flat_tree.shrink_to_fit(); }
 
    //! @copydoc ::boost::container::flat_set::nth(size_type)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    iterator nth(size_type n) BOOST_NOEXCEPT_OR_NOTHROW
    {  return dtl::force_copy<iterator>(m_flat_tree.nth(n));  }
 
    //! @copydoc ::boost::container::flat_set::nth(size_type) const
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    const_iterator nth(size_type n) const BOOST_NOEXCEPT_OR_NOTHROW
    {  return dtl::force_copy<const_iterator>(m_flat_tree.nth(n));  }
 
    //! @copydoc ::boost::container::flat_set::index_of(iterator)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    size_type index_of(iterator p) BOOST_NOEXCEPT_OR_NOTHROW
    {  return m_flat_tree.index_of(dtl::force_copy<impl_iterator>(p));  }
 
    //! @copydoc ::boost::container::flat_set::index_of(const_iterator) const
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
    size_type index_of(const_iterator p) const BOOST_NOEXCEPT_OR_NOTHROW
    {  return m_flat_tree.index_of(dtl::force_copy<impl_const_iterator>(p));  }
 
    #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)... and returns the iterator pointing to the
    //!   newly inserted element.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class... Args>
    inline
    iterator emplace(BOOST_FWD_REF(Args)... args)
    {  return dtl::force_copy<iterator>(m_flat_tree.emplace_equal(boost::forward<Args>(args)...)); }
 
    //! <b>Effects</b>: Inserts an object of type T constructed with
    //!   std::forward<Args>(args)... in the container.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent
    //!   to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant time if the value
    //!   is to be inserted before p) plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class... Args>
    inline
    iterator emplace_hint(const_iterator hint, BOOST_FWD_REF(Args)... args)
    {
       return dtl::force_copy<iterator>(m_flat_tree.emplace_hint_equal
          (dtl::force_copy<impl_const_iterator>(hint), boost::forward<Args>(args)...));
    }
 
    #else // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    #define BOOST_CONTAINER_FLAT_MULTIMAP_EMPLACE_CODE(N) \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline iterator emplace(BOOST_MOVE_UREF##N)\
    {  return dtl::force_copy<iterator>(m_flat_tree.emplace_equal(BOOST_MOVE_FWD##N));  }\
    \
    BOOST_MOVE_TMPL_LT##N BOOST_MOVE_CLASS##N BOOST_MOVE_GT##N \
    inline iterator emplace_hint(const_iterator hint BOOST_MOVE_I##N BOOST_MOVE_UREF##N)\
    {\
       return dtl::force_copy<iterator>(m_flat_tree.emplace_hint_equal\
          (dtl::force_copy<impl_const_iterator>(hint) BOOST_MOVE_I##N BOOST_MOVE_FWD##N));\
    }\
    //
    BOOST_MOVE_ITERATE_0TO9(BOOST_CONTAINER_FLAT_MULTIMAP_EMPLACE_CODE)
    #undef BOOST_CONTAINER_FLAT_MULTIMAP_EMPLACE_CODE
 
    #endif   // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
    //! <b>Effects</b>: Inserts x and returns the iterator pointing to the
    //!   newly inserted element.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline iterator insert(const value_type& x)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.insert_equal(dtl::force<const impl_value_type>(x)));
    }
 
    //! <b>Effects</b>: Inserts a new value constructed from x and returns
    //!   the iterator pointing to the newly inserted element.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template<class Pair>
    inline BOOST_CONTAINER_DOC1ST
          ( iterator
          , typename dtl::enable_if_c<dtl::is_convertible<Pair BOOST_MOVE_I dtl_pair_t>::value
             BOOST_MOVE_I iterator >::type)
       insert(BOOST_FWD_REF(Pair) x)
    { return dtl::force_copy<iterator>(m_flat_tree.emplace_equal(boost::forward<Pair>(x))); }
 
    //! <b>Effects</b>: Inserts a copy of x in the container.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent
    //!   to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant time if the value
    //!   is to be inserted before p) plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline iterator insert(const_iterator p, const value_type& x)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.insert_equal( dtl::force_copy<impl_const_iterator>(p)
                                   , dtl::force<const impl_value_type>(x)));
    }
 
    //! <b>Effects</b>: Inserts a value constructed from x in the container.
    //!   p is a hint pointing to where the insert should start to search.
    //!
    //! <b>Returns</b>: An iterator pointing to the element with key equivalent
    //!   to the key of x.
    //!
    //! <b>Complexity</b>: Logarithmic search time (constant time if the value
    //!   is to be inserted before p) plus linear insertion
    //!   to the elements with bigger keys than x.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template<class Pair>
    inline BOOST_CONTAINER_DOC1ST
          ( iterator
          , typename dtl::enable_if_c<dtl::is_convertible<Pair BOOST_MOVE_I dtl_pair_t>::value
             BOOST_MOVE_I iterator>::type)
       insert(const_iterator p, BOOST_FWD_REF(Pair) x)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.emplace_hint_equal(dtl::force_copy<impl_const_iterator>(p), boost::forward<Pair>(x)));
    }
 
    //! <b>Requires</b>: first, last are not iterators into *this.
    //!
    //! <b>Effects</b>: inserts each element from the range [first,last) .
    //!
    //! <b>Complexity</b>: N log(N).
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    template <class InputIterator>
    inline void insert(InputIterator first, InputIterator last)
       {  m_flat_tree.insert_equal(first, last); }
 
    //! <b>Requires</b>: first, last are not iterators into *this.
    //!
    //! <b>Requires</b>: [first ,last) must be ordered according to the predicate.
    //!
    //! <b>Effects</b>: inserts each element from the range [first,last) if and only
    //!   if there is no element with key equivalent to the key of that element. This
    //!   function is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Complexity</b>: Linear.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    //!
    //! <b>Note</b>: Non-standard extension.
    template <class InputIterator>
    inline void insert(ordered_range_t, InputIterator first, InputIterator last)
       {  m_flat_tree.insert_equal(ordered_range, first, last); }
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
    //! <b>Effects</b>: inserts each element from the range [il.begin(), il.end()) .
    //!
    //! <b>Complexity</b>: N log(N).
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    inline void insert(std::initializer_list<value_type> il)
    {
       m_flat_tree.insert_equal( dtl::force<impl_initializer_list>(il).begin()
                               , dtl::force<impl_initializer_list>(il).end());
    }
 
    //! <b>Requires</b>: [il.begin(), il.end()) must be ordered according to the predicate.
    //!
    //! <b>Effects</b>: inserts each element from the range [il.begin(), il.end()) if and only
    //!   if there is no element with key equivalent to the key of that element. This
    //!   function is more efficient than the normal range creation for ordered ranges.
    //!
    //! <b>Complexity</b>: Linear.
    //!
    //! <b>Note</b>: If an element is inserted it might invalidate elements.
    //!
    //! <b>Note</b>: Non-standard extension.
    inline void insert(ordered_range_t, std::initializer_list<value_type> il)
    {
       m_flat_tree.insert_equal( ordered_range
                               , dtl::force<impl_initializer_list>(il).begin()
                               , dtl::force<impl_initializer_list>(il).end());
    }
 #endif
 
    //! <b>Requires</b>: this->get_allocator() == source.get_allocator().
    //!
    //! <b>Effects</b>: Move-inserts each element from source into *this a using
    //!   the comparison object of *this.
    //!
    //! <b>Complexity</b>: Linear in this->size() + source.size().
    //!
    //! <b>Note</b>: Invalidates all iterators and references.
    template<class C2>
    inline void merge(flat_multimap<Key, T, C2, AllocatorOrContainer>& source)
    {  m_flat_tree.merge_equal(source.tree());   }
 
    //! @copydoc ::boost::container::flat_multimap::merge(flat_multimap<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(BOOST_RV_REF_BEG flat_multimap<Key, T, C2, AllocatorOrContainer> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<flat_multimap<Key, T, C2, AllocatorOrContainer>&>(source)); }
 
    //! @copydoc ::boost::container::flat_multimap::merge(flat_multimap<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(flat_map<Key, T, C2, AllocatorOrContainer>& source)
    {  m_flat_tree.merge_equal(source.tree());   }
 
    //! @copydoc ::boost::container::flat_multimap::merge(flat_map<Key, T, C2, AllocatorOrContainer>&)
    template<class C2>
    inline void merge(BOOST_RV_REF_BEG flat_map<Key, T, C2, AllocatorOrContainer> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<flat_map<Key, T, C2, AllocatorOrContainer>&>(source)); }
 
    //! <b>Effects</b>: Erases the element pointed to by p.
    //!
    //! <b>Returns</b>: Returns an iterator pointing to the element immediately
    //!   following q prior to the element being erased. If no such element exists,
    //!   returns end().
    //!
    //! <b>Complexity</b>: Linear to the elements with keys bigger than p
    //!
    //! <b>Note</b>: Invalidates elements with keys
    //!   not less than the erased element.
    inline iterator erase(const_iterator p)
    {
       return dtl::force_copy<iterator>(
          m_flat_tree.erase(dtl::force_copy<impl_const_iterator>(p)));
    }
 
    //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
    //!
    //! <b>Returns</b>: Returns the number of erased elements.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus erasure time
    //!   linear to the elements with bigger keys.
    inline size_type erase(const key_type& x)
       { return m_flat_tree.erase(x); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
    //!
    //! <b>Returns</b>: Returns the number of erased elements.
    template <class K>
    inline BOOST_CONTAINER_DOC1ST
    (size_type
       , typename dtl::enable_if_c<
       dtl::is_transparent<key_compare>::value &&                  //transparent
       !dtl::is_convertible<K BOOST_MOVE_I iterator>::value &&     //not convertible to iterator
       !dtl::is_convertible<K BOOST_MOVE_I const_iterator>::value  //not convertible to const_iterator
       BOOST_MOVE_I size_type>::type)
       erase(const K& x)
       { return m_flat_tree.erase(x); }
 
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!
    //! <b>Returns</b>: Returns last.
    //!
    //! <b>Complexity</b>: size()*N where N is the distance from first to last.
    //!
    //! <b>Complexity</b>: Logarithmic search time plus erasure time
    //!   linear to the elements with bigger keys.
    inline iterator erase(const_iterator first, const_iterator last)
    {
       return dtl::force_copy<iterator>
          (m_flat_tree.erase( dtl::force_copy<impl_const_iterator>(first)
                            , dtl::force_copy<impl_const_iterator>(last)));
    }
 
    //! <b>Effects</b>: Swaps the contents of *this and x.
    //!
    //! <b>Throws</b>: Nothing.
    //!
    //! <b>Complexity</b>: Constant.
    inline void swap(flat_multimap& x)
       BOOST_NOEXCEPT_IF(  allocator_traits_type::is_always_equal::value
                                  && boost::container::dtl::is_nothrow_swappable<Compare>::value )
    { m_flat_tree.swap(x.m_flat_tree); }
 
    //! <b>Effects</b>: erase(begin(),end()).
    //!
    //! <b>Postcondition</b>: size() == 0.
    //!
    //! <b>Complexity</b>: linear in size().
    inline void clear() BOOST_NOEXCEPT_OR_NOTHROW
       { m_flat_tree.clear(); }
 
    //////////////////////////////////////////////
    //
    //                observers
    //
    //////////////////////////////////////////////
 
    //! <b>Effects</b>: Returns the comparison object out
    //!   of which a was constructed.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       key_compare key_comp() const
       { return dtl::force_copy<key_compare>(m_flat_tree.key_comp()); }
 
    //! <b>Effects</b>: Returns an object of value_compare constructed out
    //!   of the comparison object.
    //!
    //! <b>Complexity</b>: Constant.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       value_compare value_comp() const
       { return value_compare(dtl::force_copy<key_compare>(m_flat_tree.key_comp())); }
 
    //////////////////////////////////////////////
    //
    //              map operations
    //
    //////////////////////////////////////////////
 
    //! <b>Returns</b>: An iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator find(const key_type& x)
       { return dtl::force_copy<iterator>(m_flat_tree.find(x)); }
 
    //! <b>Returns</b>: An const_iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator find(const key_type& x) const
       { return dtl::force_copy<const_iterator>(m_flat_tree.find(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator find(const K& x)
       { return dtl::force_copy<iterator>(m_flat_tree.find(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An const_iterator pointing to an element with the key
    //!   equivalent to x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator find(const K& x) const
       { return dtl::force_copy<const_iterator>(m_flat_tree.find(x)); }
 
    //! <b>Returns</b>: The number of elements with key equivalent to x.
    //!
    //! <b>Complexity</b>: log(size())+count(k)
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type count(const key_type& x) const
       { return m_flat_tree.count(x); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: The number of elements with key equivalent to x.
    //!
    //! <b>Complexity</b>: log(size())+count(k)
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       size_type count(const K& x) const
       { return m_flat_tree.count(x); }
 
    //! <b>Returns</b>: Returns true if there is an element with key
    //!   equivalent to key in the container, otherwise false.
    //!
    //! <b>Complexity</b>: log(size()).
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD  inline
       bool contains(const key_type& x) const
       {  return m_flat_tree.find(x) != m_flat_tree.end();  }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: Returns true if there is an element with key
    //!   equivalent to key in the container, otherwise false.
    //!
    //! <b>Complexity</b>: log(size()).
    template<typename K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       bool contains(const K& x) const
       {  return m_flat_tree.find(x) != m_flat_tree.end();  }
 
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator lower_bound(const key_type& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator lower_bound(const key_type& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator lower_bound(const K& x)
       {  return dtl::force_copy<iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to the first element with key not less
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator lower_bound(const K& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.lower_bound(x)); }
 
    //! <b>Returns</b>: An iterator pointing to the first element with key greater
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator upper_bound(const key_type& x)
       {return dtl::force_copy<iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Returns</b>: A const iterator pointing to the first element with key
    //!   greater than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator upper_bound(const key_type& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: An iterator pointing to the first element with key greater
    //!   than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       iterator upper_bound(const K& x)
       {return dtl::force_copy<iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Returns</b>: A const iterator pointing to the first element with key
    //!   greater than x, or end() if such an element is not found.
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       const_iterator upper_bound(const K& x) const
       {  return dtl::force_copy<const_iterator>(m_flat_tree.upper_bound(x)); }
 
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<iterator,iterator> equal_range(const key_type& x)
       {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.equal_range(x));   }
 
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<const_iterator, const_iterator> equal_range(const key_type& x) const
       {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.equal_range(x));   }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<iterator,iterator> equal_range(const K& x)
       {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.equal_range(x));   }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
    //!
    //! <b>Effects</b>: Equivalent to std::make_pair(this->lower_bound(k), this->upper_bound(k)).
    //!
    //! <b>Complexity</b>: Logarithmic
    template<class K>
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       std::pair<const_iterator, const_iterator> equal_range(const K& x) const
       {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.equal_range(x));   }
 
    //! <b>Effects</b>: Extracts the internal sequence container.
    //!
    //! <b>Complexity</b>: Same as the move constructor of sequence_type, usually constant.
    //!
    //! <b>Postcondition</b>: this->empty()
    //!
    //! <b>Throws</b>: If secuence_type's move constructor throws 
    BOOST_CONTAINER_ATTRIBUTE_NODISCARD inline
       sequence_type extract_sequence()
    {  return boost::move(dtl::force<sequence_type>(m_flat_tree.get_sequence_ref()));   }
 
    //! <b>Effects</b>: Discards the internally hold sequence container and adopts the
    //!   one passed externally using the move assignment.
    //!
    //! <b>Complexity</b>: Assuming O(1) move assignment, O(NlogN) with N = seq.size()
    //!
    //! <b>Throws</b>: If the comparison or the move constructor throws
    inline void adopt_sequence(BOOST_RV_REF(sequence_type) seq)
    {  this->m_flat_tree.adopt_sequence_equal(boost::move(dtl::force<impl_sequence_type>(seq)));  }
 
    //! <b>Requires</b>: seq shall be ordered according to this->compare().
    //!
    //! <b>Effects</b>: Discards the internally hold sequence container and adopts the
    //!   one passed externally using the move assignment.
    //!
    //! <b>Complexity</b>: Assuming O(1) move assignment, O(1)
    //!
    //! <b>Throws</b>: If the move assignment throws
    inline void adopt_sequence(ordered_range_t, BOOST_RV_REF(sequence_type) seq)
    {  this->m_flat_tree.adopt_sequence_equal(ordered_range_t(), boost::move(dtl::force<impl_sequence_type>(seq)));  }
 
    //! <b>Effects</b>: Returns a const view of the underlying sequence.
    //!
    //! <b>Complexity</b>: Constant
    //!
    //! <b>Throws</b>: Nothing
    inline const sequence_type & sequence() const BOOST_NOEXCEPT
    {  return dtl::force<sequence_type>(m_flat_tree.get_sequence_cref());  }
 
    //! <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 flat_multimap& x, const flat_multimap& 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 flat_multimap& x, const flat_multimap& 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 flat_multimap& x, const flat_multimap& 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 flat_multimap& x, const flat_multimap& 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 flat_multimap& x, const flat_multimap& 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 flat_multimap& x, const flat_multimap& y)
    {  return !(x < y);  }
 
    //! <b>Effects</b>: x.swap(y)
    //!
    //! <b>Complexity</b>: Constant.
    inline friend void swap(flat_multimap& x, flat_multimap& y)
        BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT(x.swap(y)))
    {  x.swap(y);  }
 };
 
 #if defined(BOOST_GCC) && (BOOST_GCC >= 100000) && !defined(BOOST_CONTAINER_STD_PAIR_IS_MOVABLE)
 #pragma GCC pop_options
 #endif
 
 #ifndef BOOST_CONTAINER_NO_CXX17_CTAD
 
 template <typename InputIterator>
 flat_multimap(InputIterator, InputIterator) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>>;
 
 template < typename InputIterator, typename AllocatorOrCompare>
 flat_multimap(InputIterator, InputIterator, AllocatorOrCompare const&) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>
                 , typename dtl::if_c<   // Compare
                     dtl::is_allocator<AllocatorOrCompare>::value
                     , std::less<it_based_non_const_first_type_t<InputIterator>>
                     , AllocatorOrCompare
                     >::type
                 , typename dtl::if_c<   // Allocator
                     dtl::is_allocator<AllocatorOrCompare>::value
                     , AllocatorOrCompare
                     , new_allocator<std::pair<it_based_non_const_first_type_t<InputIterator>, it_based_second_type_t<InputIterator>>>
                     >::type
                 >;
 
 template < typename InputIterator, typename Compare, typename Allocator
          , typename = dtl::require_nonallocator_t<Compare>
          , typename = dtl::require_allocator_t<Allocator>>
 flat_multimap(InputIterator, InputIterator, Compare const&, Allocator const&) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>
                 , Compare
                 , Allocator>;
 
 template <typename InputIterator>
 flat_multimap(ordered_range_t, InputIterator, InputIterator) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>>;
 
 template < typename InputIterator, typename AllocatorOrCompare>
 flat_multimap(ordered_range_t, InputIterator, InputIterator, AllocatorOrCompare const&) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>
                 , typename dtl::if_c<   // Compare
                     dtl::is_allocator<AllocatorOrCompare>::value
                     , std::less<it_based_non_const_first_type_t<InputIterator>>
                     , AllocatorOrCompare
                     >::type
                 , typename dtl::if_c<   // Allocator
                     dtl::is_allocator<AllocatorOrCompare>::value
                     , AllocatorOrCompare
                     , new_allocator<std::pair<it_based_non_const_first_type_t<InputIterator>, it_based_second_type_t<InputIterator>>>
                     >::type
                 >;
 
 template < typename InputIterator, typename Compare, typename Allocator
          , typename = dtl::require_nonallocator_t<Compare>
          , typename = dtl::require_allocator_t<Allocator>>
 flat_multimap(ordered_range_t, InputIterator, InputIterator, Compare const&, Allocator const&) ->
    flat_multimap< it_based_non_const_first_type_t<InputIterator>
                 , it_based_second_type_t<InputIterator>
                 , Compare
                 , Allocator>;
 
 #endif
 
 }}
 
 #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 namespace boost {
 
 //!has_trivial_destructor_after_move<> == true_type
 //!specialization for optimizations
 template <class Key, class T, class Compare, class AllocatorOrContainer>
 struct has_trivial_destructor_after_move< boost::container::flat_multimap<Key, T, Compare, AllocatorOrContainer> >
 {
    typedef typename boost::container::flat_multimap<Key, T, Compare, AllocatorOrContainer>::value_type value_t;
    typedef typename ::boost::container::dtl::container_or_allocator_rebind<AllocatorOrContainer, value_t>::type alloc_or_cont_t;
    typedef ::boost::container::dtl::flat_tree<value_t,::boost::container::dtl::select1st<Key>, Compare, alloc_or_cont_t> tree;
    BOOST_STATIC_CONSTEXPR bool value = ::boost::has_trivial_destructor_after_move<tree>::value;
 };
 
 }  //namespace boost {
 
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
 
 #include <boost/container/detail/config_end.hpp>
 
 #endif   // BOOST_CONTAINER_FLAT_MAP_HPP