Added intrusive flat map/multimap/set/multiset

src/intrusive_flat_map.h

@@ -0,0 +1,951 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_INTRUSIVE_FLAT_MAP__
+#define __ETL_INTRUSIVE_FLAT_MAP__
+
+#include <stddef.h>
+
+#include "exception.h"
+#include "vector.h"
+#include "ivector.h"
+#include "error_handler.h"
+
+#undef ETL_FILE
+#define ETL_FILE "30"
+
+//*****************************************************************************
+///\defgroup intrusive_flat_map intrusive_flat_map
+/// An intrusive_flat_map with the capacity defined at compile time.
+/// Has insertion of O(N) and search of O(logN)
+/// Duplicate entries are not allowed.
+///\ingroup containers
+//*****************************************************************************
+
+namespace etl
+{
+  //***************************************************************************
+  ///\ingroup intrusive_flat_map
+  /// Exception base for intrusive_flat_maps
+  //***************************************************************************
+  class intrusive_flat_map_exception : public exception
+  {
+  public:
+
+    intrusive_flat_map_exception(string_type what, string_type file_name, numeric_type line_number)
+      : exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_map
+  /// Vector full exception.
+  //***************************************************************************
+  class intrusive_flat_map_full : public intrusive_flat_map_exception
+  {
+  public:
+
+    intrusive_flat_map_full(string_type file_name, numeric_type line_number)
+      : intrusive_flat_map_exception(ETL_ERROR_TEXT("intrusive_flat_map: full", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_map
+  /// Vector out of bounds exception.
+  //***************************************************************************
+  class intrusive_flat_map_out_of_bounds : public intrusive_flat_map_exception
+  {
+  public:
+
+    intrusive_flat_map_out_of_bounds(string_type file_name, numeric_type line_number)
+      : intrusive_flat_map_exception(ETL_ERROR_TEXT("intrusive_flat_map:bounds", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The base class for specifically sized intrusive_flat_maps.
+  /// Can be used as a reference type for all intrusive_flat_maps containing a specific type.
+  ///\ingroup intrusive_flat_map
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare = std::less<TKey> >
+  class iintrusive_flat_map
+  {
+  public:
+
+    typedef size_t size_type;
+    typedef std::pair<TKey, TMapped> value_type;
+
+  private:
+
+    typedef etl::ivector<value_type*> lookup_t;
+
+  public:
+
+    typedef TKey              key_type;
+    typedef TMapped           mapped_type;
+    typedef TKeyCompare       key_compare;
+    typedef value_type&       reference;
+    typedef const value_type& const_reference;
+    typedef value_type*       pointer;
+    typedef const value_type* const_pointer;
+    typedef size_t            size_type;
+
+    //*************************************************************************
+    class iterator : public std::iterator<std::bidirectional_iterator_tag, value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_map;
+
+      iterator()
+      {
+      }
+
+      iterator(typename lookup_t::iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      iterator operator ++(int)
+      {
+        iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      iterator operator --(int)
+      {
+        iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return &(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const iterator& lhs, const iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const iterator& lhs, const iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::iterator ilookup;
+    };
+
+    //*************************************************************************
+    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_map;
+
+      const_iterator()
+      {
+      }
+
+      const_iterator(typename lookup_t::const_iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      const_iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator(const const_iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator =(const const_iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      const_iterator operator ++(int)
+      {
+        const_iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      const_iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      const_iterator operator --(int)
+      {
+        const_iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      const_pointer operator &() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::const_iterator ilookup;
+    };
+
+    typedef std::reverse_iterator<iterator>       reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    typedef typename std::iterator_traits<iterator>::difference_type difference_type;
+
+  protected:
+
+    typedef typename parameter_type<TKey>::type key_value_parameter_t;
+
+  private:
+
+    //*********************************************************************
+    /// How to compare elements and keys.
+    //*********************************************************************
+    class compare
+    {
+    public:
+
+      bool operator ()(const value_type& element, key_type key) const
+      {
+        return key_compare()(element.first, key);
+      }
+
+      bool operator ()(key_type key, const value_type& element) const
+      {
+        return key_compare()(key, element.first);
+      }
+    };
+
+  public:
+
+    //*********************************************************************
+    /// Returns an iterator to the beginning of the intrusive_flat_map.
+    ///\return An iterator to the beginning of the intrusive_flat_map.
+    //*********************************************************************
+    iterator begin()
+    {
+      return iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_map.
+    ///\return A const iterator to the beginning of the intrusive_flat_map.
+    //*********************************************************************
+    const_iterator begin() const
+    {
+      return const_iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns an iterator to the end of the intrusive_flat_map.
+    ///\return An iterator to the end of the intrusive_flat_map.
+    //*********************************************************************
+    iterator end()
+    {
+      return iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_map.
+    ///\return A const iterator to the end of the intrusive_flat_map.
+    //*********************************************************************
+    const_iterator end() const
+    {
+      return const_iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_map.
+    ///\return A const iterator to the beginning of the intrusive_flat_map.
+    //*********************************************************************
+    const_iterator cbegin() const
+    {
+      return const_iterator(lookup.cbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_map.
+    ///\return A const iterator to the end of the intrusive_flat_map.
+    //*********************************************************************
+    const_iterator cend() const
+    {
+      return const_iterator(lookup.cend());
+    }
+
+    //*********************************************************************
+    /// Returns an reverse iterator to the reverse beginning of the intrusive_flat_map.
+    ///\return Iterator to the reverse beginning of the intrusive_flat_map.
+    //*********************************************************************
+    reverse_iterator rbegin()
+    {
+      return reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_map.
+    ///\return Const iterator to the reverse beginning of the intrusive_flat_map.
+    //*********************************************************************
+    const_reverse_iterator rbegin() const
+    {
+      return reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a reverse iterator to the end + 1 of the intrusive_flat_map.
+    ///\return Reverse iterator to the end + 1 of the intrusive_flat_map.
+    //*********************************************************************
+    reverse_iterator rend()
+    {
+      return reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_map.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_map.
+    //*********************************************************************
+    const_reverse_iterator rend() const
+    {
+      return const_reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_map.
+    ///\return Const reverse iterator to the reverse beginning of the intrusive_flat_map.
+    //*********************************************************************
+    const_reverse_iterator crbegin() const
+    {
+      return const_reverse_iterator(lookup.crbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_map.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_map.
+    //*********************************************************************
+    const_reverse_iterator crend() const
+    {
+      return const_reverse_iterator(lookup.crend());
+    }
+
+    //*********************************************************************
+    /// Returns a reference to the value at index 'key'
+    ///\param i The index.
+    ///\return A reference to the value at index 'key'
+    //*********************************************************************
+    mapped_type& operator [](key_value_parameter_t key)
+    {
+      iterator i_element = lower_bound(key);
+
+      ETL_ASSERT(i_element != end(), ETL_ERROR(intrusive_flat_map_out_of_bounds));
+
+      return i_element->second;
+    }
+
+    //*********************************************************************
+    /// Returns a const reference to the value at index 'key'
+    ///\param i The index.
+    ///\return A const reference to the value at index 'key'
+    //*********************************************************************
+    const mapped_type& operator [](key_value_parameter_t key) const
+    {
+      iterator i_element = lower_bound(key);
+
+      ETL_ASSERT(i_element != end(), ETL_ERROR(intrusive_flat_map_out_of_bounds));
+
+      return i_element->second;
+    }
+
+    //*********************************************************************
+    /// Returns a reference to the value at index 'key'
+    /// If asserts or exceptions are enabled, emits an etl::flat_map_out_of_bounds if the key is not in the range.
+    ///\param i The index.
+    ///\return A reference to the value at index 'key'
+    //*********************************************************************
+    mapped_type& at(key_value_parameter_t key)
+    {
+      iterator i_element = lower_bound(key);
+
+      ETL_ASSERT(i_element != end(), ETL_ERROR(intrusive_flat_map_out_of_bounds));
+
+      return i_element->second;
+    }
+
+    //*********************************************************************
+    /// Returns a const reference to the value at index 'key'
+    /// If asserts or exceptions are enabled, emits an etl::flat_map_out_of_bounds if the key is not in the range.
+    ///\param i The index.
+    ///\return A const reference to the value at index 'key'
+    //*********************************************************************
+    const mapped_type& at(key_value_parameter_t key) const
+    {
+      const_iterator i_element = lower_bound(key);
+
+      ETL_ASSERT(i_element != end(), ETL_ERROR(intrusive_flat_map_out_of_bounds));
+
+      return i_element->second;
+    }
+
+    //*********************************************************************
+    /// Assigns values to the intrusive_flat_map.
+    /// If ETL_THROW_EXCEPTIONS & _DEBUG are defined, emits flat_map_full if the intrusive_flat_map does not have enough free space.
+    /// If ETL_THROW_EXCEPTIONS & _DEBUG are defined, emits flat_map_iterator if the iterators are reversed.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*********************************************************************
+    template <typename TIterator>
+    void assign(TIterator first, TIterator last)
+    {
+#if defined(ETL_DEBUG)
+      difference_type count = std::distance(first, last);
+      ETL_ASSERT(count <= difference_type(capacity()), ETL_ERROR(intrusive_flat_map_full));
+#endif
+
+      clear();
+
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_map.
+    /// If asserts or exceptions are enabled, emits flat_map_full if the intrusive_flat_map is already full.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert(value_type& value)
+    {
+      iterator i_element = lower_bound(value.first);
+
+      return insert_at(i_element, value);
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_map.
+    /// If asserts or exceptions are enabled, emits flat_map_full if the intrusive_flat_map is already full.
+    ///\param position The position to insert at.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(iterator position, value_type& value)
+    {
+      return insert(value).first;
+    }
+
+    //*********************************************************************
+    /// Inserts a range of values to the intrusive_flat_map.
+    /// If asserts or exceptions are enabled, emits flat_map_full if the intrusive_flat_map does not have enough free space.
+    ///\param position The position to insert at.
+    ///\param first    The first element to add.
+    ///\param last     The last + 1 element to add.
+    //*********************************************************************
+    template <class TIterator>
+    void insert(TIterator first, TIterator last)
+    {
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param key The key to erase.
+    ///\return The number of elements erased. 0 or 1.
+    //*********************************************************************
+    size_t erase(key_value_parameter_t key)
+    {
+      iterator i_element = find(key);
+
+      if (i_element == end())
+      {
+        return 0;
+      }
+      else
+      {
+        lookup.erase(i_element.ilookup);
+        return 1;
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param i_element Iterator to the element.
+    //*********************************************************************
+    void erase(iterator i_element)
+    {
+      lookup.erase(i_element.ilookup);
+    }
+
+    //*********************************************************************
+    /// Erases a range of elements.
+    /// The range includes all the elements between first and last, including the
+    /// element pointed by first, but not the one pointed by last.
+    ///\param first Iterator to the first element.
+    ///\param last  Iterator to the last element.
+    //*********************************************************************
+    void erase(iterator first, iterator last)
+    {
+      lookup.erase(first.ilookup, last.ilookup);
+    }
+
+    //*************************************************************************
+    /// Clears the intrusive_flat_map.
+    //*************************************************************************
+    void clear()
+    {
+      erase(begin(), end());
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    iterator find(key_value_parameter_t key)
+    {
+      iterator itr = lower_bound(key);
+
+      if (itr != end())
+      {
+        if (!key_compare()(itr->first, key) && !key_compare()(key, itr->first))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    const_iterator find(key_value_parameter_t key) const
+    {
+      const_iterator itr = lower_bound(key);
+
+      if (itr != end())
+      {
+        if (!key_compare()(itr->first, key) && !key_compare()(key, itr->first))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Counts an element.
+    ///\param key The key to search for.
+    ///\return 1 if the key exists, otherwise 0.
+    //*********************************************************************
+    size_t count(key_value_parameter_t key) const
+    {
+      return (find(key) == end()) ? 0 : 1;
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator lower_bound(key_value_parameter_t key)
+    {
+      return std::lower_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator lower_bound(key_value_parameter_t key) const
+    {
+      return std::lower_bound(cbegin(), cend(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator upper_bound(key_value_parameter_t key)
+    {
+      return std::upper_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator upper_bound(key_value_parameter_t key) const
+    {
+      return std::upper_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<iterator, iterator> equal_range(key_value_parameter_t key)
+    {
+      iterator i_lower = std::lower_bound(begin(), end(), key, compare());
+
+      return std::make_pair(i_lower, std::upper_bound(i_lower, end(), key, compare()));
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<const_iterator, const_iterator> equal_range(key_value_parameter_t key) const
+    {
+      const_iterator i_lower = std::lower_bound(cbegin(), cend(), key, compare());
+
+      return std::make_pair(i_lower, std::upper_bound(i_lower, cend(), key, compare()));
+    }
+
+    //*************************************************************************
+    /// Gets the current size of the intrusive_flat_map.
+    ///\return The current size of the intrusive_flat_map.
+    //*************************************************************************
+    size_type size() const
+    {
+      return lookup.size();
+    }
+
+    //*************************************************************************
+    /// Checks the 'empty' state of the intrusive_flat_map.
+    ///\return <b>true</b> if empty.
+    //*************************************************************************
+    bool empty() const
+    {
+      return lookup.empty();
+    }
+
+    //*************************************************************************
+    /// Checks the 'full' state of the intrusive_flat_map.
+    ///\return <b>true</b> if full.
+    //*************************************************************************
+    bool full() const
+    {
+      return lookup.full();
+    }
+
+    //*************************************************************************
+    /// Returns the capacity of the intrusive_flat_map.
+    ///\return The capacity of the intrusive_flat_map.
+    //*************************************************************************
+    size_type capacity() const
+    {
+      return lookup.capacity();
+    }
+
+    //*************************************************************************
+    /// Returns the maximum possible size of the intrusive_flat_map.
+    ///\return The maximum size of the intrusive_flat_map.
+    //*************************************************************************
+    size_type max_size() const
+    {
+      return lookup.max_size();
+    }
+
+    //*************************************************************************
+    /// Returns the remaining capacity.
+    ///\return The remaining capacity.
+    //*************************************************************************
+    size_t available() const
+    {
+      return lookup.available();
+    }
+
+  protected:
+
+    //*********************************************************************
+    /// Constructor.
+    //*********************************************************************
+    iintrusive_flat_map(lookup_t& lookup_)
+      : lookup(lookup_)
+    {
+    }
+
+  private:
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_map.
+    ///\param i_element The place to insert.
+    ///\param value     The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert_at(iterator i_element, value_type& value)
+    {
+      std::pair<iterator, bool> result(end(), false);
+
+      if (i_element == end())
+      {
+        // At the end.
+        ETL_ASSERT(!lookup.full(), ETL_ERROR(intrusive_flat_map_full));
+
+        lookup.push_back(&value);
+        result.first = --end();
+        result.second = true;
+      }
+      else
+      {
+        // Not at the end.
+        result.first = i_element;
+
+        // Existing element?
+        if (value.first != i_element->first)
+        {
+          // A new one.
+          ETL_ASSERT(!lookup.full(), ETL_ERROR(intrusive_flat_map_full));
+          lookup.insert(i_element.ilookup, &value);
+          result.second = true;
+        }
+      }
+
+      return result;
+    }
+
+    // Disable copy construction and assignment.
+    iintrusive_flat_map(const iintrusive_flat_map&);
+    iintrusive_flat_map& operator = (const iintrusive_flat_map&);
+
+    lookup_t& lookup;
+  };
+
+  //***************************************************************************
+  /// Equal operator.
+  ///\param lhs Reference to the first intrusive_flat_map.
+  ///\param rhs Reference to the second intrusive_flat_map.
+  ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_map
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare>
+  bool operator ==(const etl::iintrusive_flat_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iintrusive_flat_map<TKey, TMapped, TKeyCompare>& rhs)
+  {
+    return (lhs.size() == rhs.size()) && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+  }
+
+  //***************************************************************************
+  /// Not equal operator.
+  ///\param lhs Reference to the first intrusive_flat_map.
+  ///\param rhs Reference to the second intrusive_flat_map.
+  ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_map
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare>
+  bool operator !=(const etl::iintrusive_flat_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iintrusive_flat_map<TKey, TMapped, TKeyCompare>& rhs)
+  {
+    return !(lhs == rhs);
+  }
+
+  //***************************************************************************
+  /// A intrusive_flat_map implementation that uses a fixed size buffer.
+  ///\tparam TKey     The key type.
+  ///\tparam TValue   The value type.
+  ///\tparam TCompare The type to compare keys. Default = std::less<TKey>
+  ///\tparam MAX_SIZE_ The maximum number of elements that can be stored.
+  ///\ingroup intrusive_flat_map
+  //***************************************************************************
+  template <typename TKey, typename TValue, const size_t MAX_SIZE_, typename TCompare = std::less<TKey> >
+  class intrusive_flat_map : public iintrusive_flat_map<TKey, TValue, TCompare>
+  {
+  public:
+
+    static const size_t MAX_SIZE = MAX_SIZE_;
+
+    //*************************************************************************
+    /// Constructor.
+    //*************************************************************************
+    intrusive_flat_map()
+      : iintrusive_flat_map<TKey, TValue, TCompare>(lookup)
+    {
+    }
+
+    //*************************************************************************
+    /// Constructor, from an iterator range.
+    ///\tparam TIterator The iterator type.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*************************************************************************
+    template <typename TIterator>
+    intrusive_flat_map(TIterator first, TIterator last)
+      : iintrusive_flat_map<TKey, TValue, TCompare>(lookup)
+    {
+      iintrusive_flat_map<TKey, TValue, TCompare>::assign(first, last);
+    }
+
+    //*************************************************************************
+    /// Destructor.
+    //*************************************************************************
+    ~intrusive_flat_map()
+    {
+      iintrusive_flat_map<TKey, TValue, TCompare>::clear();
+    }
+
+    //*************************************************************************
+    /// Assignment operator.
+    //*************************************************************************
+    intrusive_flat_map& operator = (const intrusive_flat_map& rhs)
+    {
+      if (&rhs != this)
+      {
+        iintrusive_flat_map<TKey, TValue, TCompare>::assign(rhs.cbegin(), rhs.cend());
+      }
+
+      return *this;
+    }
+
+  private:
+
+    intrusive_flat_map(const intrusive_flat_map&);
+
+    typedef typename iintrusive_flat_map<TKey, TValue, TCompare>::value_type node_t;
+
+    // The vector that stores pointers to the nodes.
+    etl::vector<node_t*, MAX_SIZE> lookup;
+  };
+
+}
+
+#undef ETL_FILE
+
+#endif

src/intrusive_flat_multimap.h

@@ -0,0 +1,864 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_INTRUSIVE_FLAT_MULTIMAP_BASE__
+#define __ETL_INTRUSIVE_FLAT_MULTIMAP_BASE__
+
+#include <stddef.h>
+
+#include "exception.h"
+#include "ivector.h"
+#include "error_handler.h"
+#include "debug_count.h"
+#include "vector.h"
+#include "ivector.h"
+
+#undef ETL_FILE
+#define ETL_FILE "31"
+
+namespace etl
+{
+  //***************************************************************************
+  ///\ingroup intrusive_flat_multimap
+  /// Exception base for intrusive_flat_multimaps
+  //***************************************************************************
+  class intrusive_flat_multimap_exception : public exception
+  {
+  public:
+
+    intrusive_flat_multimap_exception(string_type what, string_type file_name, numeric_type line_number)
+      : exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_multimap
+  /// Vector full exception.
+  //***************************************************************************
+  class intrusive_flat_multimap_full : public intrusive_flat_multimap_exception
+  {
+  public:
+
+    intrusive_flat_multimap_full(string_type file_name, numeric_type line_number)
+      : intrusive_flat_multimap_exception(ETL_ERROR_TEXT("intrusive_flat_multimap:full", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The base class for specifically sized intrusive_flat_multimaps.
+  /// Can be used as a reference type for all intrusive_flat_multimaps containing a specific type.
+  ///\ingroup intrusive_flat_multimap
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare = std::less<TKey> >
+  class iintrusive_flat_multimap
+  {
+  public:
+
+    typedef std::pair<TKey, TMapped> value_type;
+    typedef size_t size_type;
+
+  private:
+
+    typedef etl::ivector<value_type*> lookup_t;
+
+  public:
+
+    typedef TKey              key_type;
+    typedef TMapped           mapped_type;
+    typedef TKeyCompare       key_compare;
+    typedef value_type&       reference;
+    typedef const value_type& const_reference;
+    typedef value_type*       pointer;
+    typedef const value_type* const_pointer;
+    typedef size_t            size_type;
+
+    //*************************************************************************
+    class iterator : public std::iterator<std::bidirectional_iterator_tag, value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_multimap;
+
+      iterator()
+      {
+      }
+
+      iterator(typename lookup_t::iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      iterator operator ++(int)
+      {
+        iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      iterator operator --(int)
+      {
+        iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return &(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const iterator& lhs, const iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const iterator& lhs, const iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::iterator ilookup;
+    };
+
+    //*************************************************************************
+    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_multimap;
+
+      const_iterator()
+      {
+      }
+
+      const_iterator(typename lookup_t::const_iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      const_iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator(const const_iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator =(const const_iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      const_iterator operator ++(int)
+      {
+        const_iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      const_iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      const_iterator operator --(int)
+      {
+        const_iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      const_pointer operator &() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::const_iterator ilookup;
+    };
+
+    typedef std::reverse_iterator<iterator>       reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    typedef typename std::iterator_traits<iterator>::difference_type difference_type;
+
+  protected:
+
+    typedef typename parameter_type<TKey>::type key_value_parameter_t;
+
+  private:
+
+    //*********************************************************************
+    /// How to compare elements and keys.
+    //*********************************************************************
+    class compare
+    {
+    public:
+
+      bool operator ()(const value_type& element, key_type key) const
+      {
+        return key_compare()(element.first, key);
+      }
+
+      bool operator ()(key_type key, const value_type& element) const
+      {
+        return key_compare()(key, element.first);
+      }
+    };
+
+  public:
+
+    //*********************************************************************
+    /// Returns an iterator to the beginning of the intrusive_flat_multimap.
+    ///\return An iterator to the beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    iterator begin()
+    {
+      return iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_multimap.
+    ///\return A const iterator to the beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_iterator begin() const
+    {
+      return const_iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns an iterator to the end of the intrusive_flat_multimap.
+    ///\return An iterator to the end of the intrusive_flat_multimap.
+    //*********************************************************************
+    iterator end()
+    {
+      return iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_multimap.
+    ///\return A const iterator to the end of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_iterator end() const
+    {
+      return const_iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_multimap.
+    ///\return A const iterator to the beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_iterator cbegin() const
+    {
+      return const_iterator(lookup.cbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_multimap.
+    ///\return A const iterator to the end of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_iterator cend() const
+    {
+      return const_iterator(lookup.cend());
+    }
+
+    //*********************************************************************
+    /// Returns an reverse iterator to the reverse beginning of the intrusive_flat_multimap.
+    ///\return Iterator to the reverse beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    reverse_iterator rbegin()
+    {
+      return reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_multimap.
+    ///\return Const iterator to the reverse beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_reverse_iterator rbegin() const
+    {
+      return const_reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    ///\return Reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    //*********************************************************************
+    reverse_iterator rend()
+    {
+      return reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_reverse_iterator rend() const
+    {
+      return const_reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_multimap.
+    ///\return Const reverse iterator to the reverse beginning of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_reverse_iterator crbegin() const
+    {
+      return const_reverse_iterator(lookup.crbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_multimap.
+    //*********************************************************************
+    const_reverse_iterator crend() const
+    {
+      return const_reverse_iterator(lookup.crend());
+    }
+
+    //*********************************************************************
+    /// Assigns values to the intrusive_flat_multimap.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multimap_full if the intrusive_flat_multimap does not have enough free space.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multimap_iterator if the iterators are reversed.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*********************************************************************
+    template <typename TIterator>
+    void assign(TIterator first, TIterator last)
+    {
+#if defined(ETL_DEBUG)
+      difference_type count = std::distance(first, last);
+      ETL_ASSERT(count <= difference_type(capacity()), ETL_ERROR(intrusive_flat_multimap_full));
+#endif
+
+      clear();
+
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_multimap.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multimap_full if the intrusive_flat_multimap is already full.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert(value_type& value)
+    {
+      ETL_ASSERT(!lookup.full(), ETL_ERROR(intrusive_flat_multimap_full));
+
+      std::pair<iterator, bool> result(end(), false);
+
+      iterator i_element = lower_bound(value.first);
+
+      return insert_at(i_element, value);
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the flast_multi.
+    /// If asserts or exceptions are enabled, emits flat_map_full if the flat_map is already full.
+    ///\param position The position to insert at.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(iterator position, const value_type& value)
+    {
+      return insert(value).first;
+    }
+
+    //*********************************************************************
+    /// Inserts a range of values to the intrusive_flat_multimap.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multimap_full if the intrusive_flat_multimap does not have enough free space.
+    ///\param position The position to insert at.
+    ///\param first    The first element to add.
+    ///\param last     The last + 1 element to add.
+    //*********************************************************************
+    template <class TIterator>
+    void insert(TIterator first, TIterator last)
+    {
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param key The key to erase.
+    ///\return The number of elements erased. 0 or 1.
+    //*********************************************************************
+    size_t erase(key_value_parameter_t key)
+    {
+      std::pair<iterator, iterator> range = equal_range(key);
+
+      if (range.first == end())
+      {
+        return 0;
+      }
+      else
+      {
+        size_t count = std::distance(range.first, range.second);
+        erase(range.first, range.second);
+        return count;
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param i_element Iterator to the element.
+    //*********************************************************************
+    void erase(iterator i_element)
+    {
+      lookup.erase(i_element.ilookup);
+    }
+
+    //*********************************************************************
+    /// Erases a range of elements.
+    /// The range includes all the elements between first and last, including the
+    /// element pointed by first, but not the one pointed by last.
+    ///\param first Iterator to the first element.
+    ///\param last  Iterator to the last element.
+    //*********************************************************************
+    void erase(iterator first, iterator last)
+    {
+      lookup.erase(first.ilookup, last.ilookup);
+    }
+
+    //*************************************************************************
+    /// Clears the intrusive_flat_multimap.
+    //*************************************************************************
+    void clear()
+    {
+      erase(begin(), end());
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    iterator find(key_value_parameter_t key)
+    {
+      iterator itr = lower_bound(key);
+
+      if (itr != end())
+      {
+        if (!key_compare()(itr->first, key) && !key_compare()(key, itr->first))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    const_iterator find(key_value_parameter_t key) const
+    {
+      const_iterator itr = lower_bound(key);
+
+      if (itr != end())
+      {
+        if (!key_compare()(itr->first, key) && !key_compare()(key, itr->first))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Counts an element.
+    ///\param key The key to search for.
+    ///\return 1 if the key exists, otherwise 0.
+    //*********************************************************************
+    size_t count(key_value_parameter_t key) const
+    {
+      std::pair<const_iterator, const_iterator> range = equal_range(key);
+
+      return std::distance(range.first, range.second);
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator lower_bound(key_value_parameter_t key)
+    {
+      return std::lower_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator lower_bound(key_value_parameter_t key) const
+    {
+      return std::lower_bound(cbegin(), cend(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator upper_bound(key_value_parameter_t key)
+    {
+      return std::upper_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator upper_bound(key_value_parameter_t key) const
+    {
+      return std::upper_bound(begin(), end(), key, compare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<iterator, iterator> equal_range(key_value_parameter_t key)
+    {
+      iterator i_lower = std::lower_bound(begin(), end(), key, compare());
+
+      return std::make_pair(i_lower, std::upper_bound(i_lower, end(), key, compare()));
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<const_iterator, const_iterator> equal_range(key_value_parameter_t key) const
+    {
+      const_iterator i_lower = std::lower_bound(cbegin(), cend(), key, compare());
+
+      return std::make_pair(i_lower, std::upper_bound(i_lower, cend(), key, compare()));
+    }
+
+    //*************************************************************************
+    /// Gets the current size of the flat_multiset.
+    ///\return The current size of the flat_multiset.
+    //*************************************************************************
+    size_type size() const
+    {
+      return lookup.size();
+    }
+
+    //*************************************************************************
+    /// Checks the 'empty' state of the flat_multiset.
+    ///\return <b>true</b> if empty.
+    //*************************************************************************
+    bool empty() const
+    {
+      return lookup.empty();
+    }
+
+    //*************************************************************************
+    /// Checks the 'full' state of the flat_multiset.
+    ///\return <b>true</b> if full.
+    //*************************************************************************
+    bool full() const
+    {
+      return lookup.full();
+    }
+
+    //*************************************************************************
+    /// Returns the capacity of the flat_multiset.
+    ///\return The capacity of the flat_multiset.
+    //*************************************************************************
+    size_type capacity() const
+    {
+      return lookup.capacity();
+    }
+
+    //*************************************************************************
+    /// Returns the maximum possible size of the flat_multiset.
+    ///\return The maximum size of the flat_multiset.
+    //*************************************************************************
+    size_type max_size() const
+    {
+      return lookup.max_size();
+    }
+
+    //*************************************************************************
+    /// Returns the remaining capacity.
+    ///\return The remaining capacity.
+    //*************************************************************************
+    size_t available() const
+    {
+      return lookup.available();
+    }
+
+  protected:
+
+    //*********************************************************************
+    /// Constructor.
+    //*********************************************************************
+    iintrusive_flat_multimap(lookup_t& lookup_)
+      : lookup(lookup_)
+    {
+    }
+
+  private:
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_multimap.
+    ///\param i_element The place to insert.
+    ///\param value     The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert_at(iterator i_element, value_type& value)
+    {
+      std::pair<iterator, bool> result(end(), false);
+
+      if (i_element == end())
+      {
+        // At the end.
+        lookup.push_back(&value);
+        result.first = --end();
+        result.second = true;
+      }
+      else
+      {
+        // Not at the end.
+        lookup.insert(i_element.ilookup, &value);
+        result.first = i_element;
+        result.second = true;
+      }
+
+      return result;
+    }
+
+    // Disable copy construction and assignment.
+    iintrusive_flat_multimap(const iintrusive_flat_multimap&);
+    iintrusive_flat_multimap& operator = (const iintrusive_flat_multimap&);
+
+    lookup_t&  lookup;
+  };
+
+  //***************************************************************************
+  /// Equal operator.
+  ///\param lhs Reference to the first intrusive_flat_multimap.
+  ///\param rhs Reference to the second intrusive_flat_multimap.
+  ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_multimap
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare>
+  bool operator ==(const etl::iintrusive_flat_multimap<TKey, TMapped, TKeyCompare>& lhs, const etl::iintrusive_flat_multimap<TKey, TMapped, TKeyCompare>& rhs)
+  {
+    return (lhs.size() == rhs.size()) && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+  }
+
+  //***************************************************************************
+  /// Not equal operator.
+  ///\param lhs Reference to the first intrusive_flat_multimap.
+  ///\param rhs Reference to the second intrusive_flat_multimap.
+  ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_multimap
+  //***************************************************************************
+  template <typename TKey, typename TMapped, typename TKeyCompare>
+  bool operator !=(const etl::iintrusive_flat_multimap<TKey, TMapped, TKeyCompare>& lhs, const etl::iintrusive_flat_multimap<TKey, TMapped, TKeyCompare>& rhs)
+  {
+    return !(lhs == rhs);
+  }
+
+  template <typename TKey, typename TValue, const size_t MAX_SIZE_, typename TCompare = std::less<TKey> >
+  //***************************************************************************
+  /// A intrusive_flat_multimap implementation that uses a fixed size buffer.
+  ///\tparam TKey     The key type.
+  ///\tparam TValue   The value type.
+  ///\tparam TCompare The type to compare keys. Default = std::less<TKey>
+  ///\tparam MAX_SIZE_ The maximum number of elements that can be stored.
+  ///\ingroup intrusive_flat_multimap
+  //***************************************************************************
+  class intrusive_flat_multimap : public iintrusive_flat_multimap<TKey, TValue, TCompare>
+  {
+  public:
+
+    static const size_t MAX_SIZE = MAX_SIZE_;
+
+    //*************************************************************************
+    /// Constructor.
+    //*************************************************************************
+    intrusive_flat_multimap()
+      : iintrusive_flat_multimap<TKey, TValue, TCompare>(lookup)
+    {
+    }
+
+    //*************************************************************************
+    /// Copy constructor.
+    //*************************************************************************
+    intrusive_flat_multimap(const intrusive_flat_multimap& other)
+      : iintrusive_flat_multimap<TKey, TValue, TCompare>(lookup)
+    {
+      iintrusive_flat_multimap<TKey, TValue, TCompare>::assign(other.cbegin(), other.cend());
+    }
+
+    //*************************************************************************
+    /// Constructor, from an iterator range.
+    ///\tparam TIterator The iterator type.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*************************************************************************
+    template <typename TIterator>
+    intrusive_flat_multimap(TIterator first, TIterator last)
+      : iintrusive_flat_multimap<TKey, TValue, TCompare>(lookup)
+    {
+      iintrusive_flat_multimap<TKey, TValue, TCompare>::assign(first, last);
+    }
+
+    //*************************************************************************
+    /// Destructor.
+    //*************************************************************************
+    ~intrusive_flat_multimap()
+    {
+      iintrusive_flat_multimap<TKey, TValue, TCompare>::clear();
+    }
+
+  private:
+
+    typedef typename iintrusive_flat_multimap<TKey, TValue, TCompare>::value_type node_t;
+
+    // The vector that stores pointers to the nodes.
+    etl::vector<node_t*, MAX_SIZE> lookup;
+  };
+}
+
+#undef ETL_FILE
+
+#endif

src/intrusive_flat_multiset.h

@@ -0,0 +1,850 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_INTRUSIVE_FLAT_MULTISET__
+#define __ETL_INTRUSIVE_FLAT_MULTISET__
+
+#include <iterator>
+#include <algorithm>
+#include <functional>
+#include <utility>
+#include <stddef.h>
+
+#include "platform.h"
+#include "type_traits.h"
+#include "ivector.h"
+#include "vector.h"
+#include "ipool.h"
+#include "error_handler.h"
+#include "exception.h"
+
+#undef ETL_FILE
+#define ETL_FILE "33"
+
+namespace etl
+{
+  //***************************************************************************
+  ///\ingroup intrusive_flat_multiset
+  /// Exception base for intrusive_flat_multisets
+  //***************************************************************************
+  class intrusive_flat_multiset_exception : public exception
+  {
+  public:
+
+    intrusive_flat_multiset_exception(string_type what, string_type file_name, numeric_type line_number)
+      : exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_multiset
+  /// Vector full exception.
+  //***************************************************************************
+  class intrusive_flat_multiset_full : public intrusive_flat_multiset_exception
+  {
+  public:
+
+    intrusive_flat_multiset_full(string_type file_name, numeric_type line_number)
+      : intrusive_flat_multiset_exception(ETL_ERROR_TEXT("intrusive_flat_multiset:full", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_multiset
+  /// Vector iterator exception.
+  //***************************************************************************
+  class intrusive_flat_multiset_iterator : public intrusive_flat_multiset_exception
+  {
+  public:
+
+    intrusive_flat_multiset_iterator(string_type file_name, numeric_type line_number)
+      : intrusive_flat_multiset_exception(ETL_ERROR_TEXT("intrusive_flat_multiset:iterator", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The base class for specifically sized intrusive_flat_multisets.
+  /// Can be used as a reference type for all intrusive_flat_multisets containing a specific type.
+  ///\ingroup intrusive_flat_multiset
+  //***************************************************************************
+  template <typename T, typename TKeyCompare = std::less<T> >
+  class iintrusive_flat_multiset
+  {
+  public:
+
+    typedef T                 key_type;
+    typedef T                 value_type;
+    typedef TKeyCompare       key_compare;
+    typedef value_type&       reference;
+    typedef const value_type& const_reference;
+    typedef value_type*       pointer;
+    typedef const value_type* const_pointer;
+    typedef size_t            size_type;
+
+  private:
+
+    typedef etl::ivector<value_type*> lookup_t;
+
+  public:
+
+    //*************************************************************************
+    class iterator : public std::iterator<std::bidirectional_iterator_tag, value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_multiset;
+
+      iterator()
+      {
+      }
+
+      iterator(typename lookup_t::iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      iterator operator ++(int)
+      {
+        iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      iterator operator --(int)
+      {
+        iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return &(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const iterator& lhs, const iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const iterator& lhs, const iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::iterator ilookup;
+    };
+
+    //*************************************************************************
+    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_multiset;
+
+      const_iterator()
+      {
+      }
+
+      const_iterator(typename lookup_t::const_iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      const_iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator(const const_iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator =(const const_iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      const_iterator operator ++(int)
+      {
+        const_iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      const_iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      const_iterator operator --(int)
+      {
+        const_iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::const_iterator ilookup;
+    };
+
+  public:
+
+    typedef std::reverse_iterator<iterator>       reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    typedef typename std::iterator_traits<iterator>::difference_type difference_type;
+
+    //*********************************************************************
+    /// Returns an iterator to the beginning of the intrusive_flat_multiset.
+    ///\return An iterator to the beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    iterator begin()
+    {
+      return iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_multiset.
+    ///\return A const iterator to the beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_iterator begin() const
+    {
+      return const_iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns an iterator to the end of the intrusive_flat_multiset.
+    ///\return An iterator to the end of the intrusive_flat_multiset.
+    //*********************************************************************
+    iterator end()
+    {
+      return iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_multiset.
+    ///\return A const iterator to the end of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_iterator end() const
+    {
+      return const_iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_multiset.
+    ///\return A const iterator to the beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_iterator cbegin() const
+    {
+      return const_iterator(lookup.cbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_multiset.
+    ///\return A const iterator to the end of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_iterator cend() const
+    {
+      return const_iterator(lookup.cend());
+    }
+
+    //*********************************************************************
+    /// Returns an reverse iterator to the reverse beginning of the intrusive_flat_multiset.
+    ///\return Iterator to the reverse beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    reverse_iterator rbegin()
+    {
+      return reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_multiset.
+    ///\return Const iterator to the reverse beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_reverse_iterator rbegin() const
+    {
+      return const_reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    ///\return Reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    //*********************************************************************
+    reverse_iterator rend()
+    {
+      return reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_reverse_iterator rend() const
+    {
+      return const_reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_multiset.
+    ///\return Const reverse iterator to the reverse beginning of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_reverse_iterator crbegin() const
+    {
+      return const_reverse_iterator(lookup.crbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_multiset.
+    //*********************************************************************
+    const_reverse_iterator crend() const
+    {
+      return const_reverse_iterator(lookup.crend());
+    }
+
+    //*********************************************************************
+    /// Assigns values to the intrusive_flat_multiset.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multiset_full if the intrusive_flat_multiset does not have enough free space.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multiset_iterator if the iterators are reversed.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*********************************************************************
+    template <typename TIterator>
+    void assign(TIterator first, TIterator last)
+    {
+#if defined(ETL_DEBUG)
+      difference_type count = std::distance(first, last);
+      ETL_ASSERT(count <= difference_type(capacity()), ETL_ERROR(intrusive_flat_multiset_full));
+#endif
+
+      clear();
+
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_multiset.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multiset_full if the intrusive_flat_multiset is already full.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert(value_type& value)
+    {
+      std::pair<iterator, bool> result(end(), false);
+
+      ETL_ASSERT(!lookup.full(), ETL_ERROR(intrusive_flat_multiset_full));
+
+      iterator i_element = std::lower_bound(begin(), end(), value, TKeyCompare());
+
+      if (i_element == end())
+      {
+        // At the end. Doesn't exist.
+        lookup.push_back(&value);
+        result.first = --end();
+        result.second = true;
+      }
+      else
+      {
+        // Not at the end.
+        lookup.insert(i_element.ilookup, &value);
+        result.first = i_element;
+        result.second = true;
+      }
+
+      return result;
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_multiset.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multiset_full if the intrusive_flat_multiset is already full.
+    ///\param position The position to insert at.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(iterator position, value_type& value)
+    {
+      return insert(value).first;
+    }
+
+    //*********************************************************************
+    /// Inserts a range of values to the intrusive_flat_multiset.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_multiset_full if the intrusive_flat_multiset does not have enough free space.
+    ///\param position The position to insert at.
+    ///\param first    The first element to add.
+    ///\param last     The last + 1 element to add.
+    //*********************************************************************
+    template <class TIterator>
+    void insert(TIterator first, TIterator last)
+    {
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param key The key to erase.
+    ///\return The number of elements erased. 0 or 1.
+    //*********************************************************************
+    size_t erase(value_type& key)
+    {
+      std::pair<iterator, iterator> range = equal_range(key);
+
+      if (range.first == end())
+      {
+        return 0;
+      }
+      else
+      {
+        size_t count = std::distance(range.first, range.second);
+        erase(range.first, range.second);
+        return count;
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param i_element Iterator to the element.
+    //*********************************************************************
+    void erase(iterator i_element)
+    {
+      lookup.erase(i_element.ilookup);
+    }
+
+    //*********************************************************************
+    /// Erases a range of elements.
+    /// The range includes all the elements between first and last, including the
+    /// element pointed by first, but not the one pointed by last.
+    ///\param first Iterator to the first element.
+    ///\param last  Iterator to the last element.
+    //*********************************************************************
+    void erase(iterator first, iterator last)
+    {
+      lookup.erase(first.ilookup, last.ilookup);;
+    }
+
+    //*************************************************************************
+    /// Clears the intrusive_flat_multiset.
+    //*************************************************************************
+    void clear()
+    {
+      erase(begin(), end());
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    iterator find(value_type& key)
+    {
+      iterator itr = std::lower_bound(begin(), end(), key, TKeyCompare());
+
+      if (itr != end())
+      {
+        if (!key_compare()(*itr, key) && !key_compare()(key, *itr))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    const_iterator find(value_type& key) const
+    {
+      const_iterator itr = std::lower_bound(begin(), end(), key, TKeyCompare());
+
+      if (itr != end())
+      {
+        if (!key_compare()(*itr, key) && !key_compare()(key, *itr))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Counts an element.
+    ///\param key The key to search for.
+    ///\return 1 if the key exists, otherwise 0.
+    //*********************************************************************
+    size_t count(value_type& key) const
+    {
+      std::pair<const_iterator, const_iterator> range = equal_range(key);
+
+      return std::distance(range.first, range.second);
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator lower_bound(value_type& key)
+    {
+      return std::lower_bound(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator lower_bound(value_type& key) const
+    {
+      return std::lower_bound(cbegin(), cend(), key, TKeyCompare());
+    }
+    
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator upper_bound(value_type& key)
+    {
+      return std::upper_bound(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator upper_bound(value_type& key) const
+    {
+      return std::upper_bound(cbegin(), cend(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<iterator, iterator> equal_range(value_type& key)
+    {
+      return std::equal_range(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<const_iterator, const_iterator> equal_range(value_type& key) const
+    {
+      return std::equal_range(begin(), end(), key, TKeyCompare());
+    }
+
+    //*************************************************************************
+    /// Gets the current size of the intrusive_flat_multiset.
+    ///\return The current size of the intrusive_flat_multiset.
+    //*************************************************************************
+    size_type size() const
+    {
+      return lookup.size();
+    }
+
+    //*************************************************************************
+    /// Checks the 'empty' state of the intrusive_flat_multiset.
+    ///\return <b>true</b> if empty.
+    //*************************************************************************
+    bool empty() const
+    {
+      return lookup.empty();
+    }
+
+    //*************************************************************************
+    /// Checks the 'full' state of the intrusive_flat_multiset.
+    ///\return <b>true</b> if full.
+    //*************************************************************************
+    bool full() const
+    {
+      return lookup.full();
+    }
+
+    //*************************************************************************
+    /// Returns the capacity of the intrusive_flat_multiset.
+    ///\return The capacity of the intrusive_flat_multiset.
+    //*************************************************************************
+    size_type capacity() const
+    {
+      return lookup.capacity();
+    }
+
+    //*************************************************************************
+    /// Returns the maximum possible size of the intrusive_flat_multiset.
+    ///\return The maximum size of the intrusive_flat_multiset.
+    //*************************************************************************
+    size_type max_size() const
+    {
+      return lookup.max_size();
+    }
+
+    //*************************************************************************
+    /// Returns the remaining capacity.
+    ///\return The remaining capacity.
+    //*************************************************************************
+    size_t available() const
+    {
+      return lookup.available();
+    }
+
+  protected:
+
+    //*********************************************************************
+    /// Constructor.
+    //*********************************************************************
+    iintrusive_flat_multiset(lookup_t& lookup_)
+      : lookup(lookup_)
+    {
+    }
+
+  private:
+
+    // Disable copy construction.
+    iintrusive_flat_multiset(const iintrusive_flat_multiset&);
+    iintrusive_flat_multiset& operator =(const iintrusive_flat_multiset&);
+
+    lookup_t& lookup;
+  };
+
+  //***************************************************************************
+  /// An intrusive flat set
+  ///\ingroup intrusive_flat_multiset
+  //***************************************************************************
+  template <typename TKey, const size_t MAX_SIZE_, typename TKeyCompare = std::less<TKey> >
+  class intrusive_flat_multiset : public iintrusive_flat_multiset<TKey, TKeyCompare>
+  {
+  public:
+
+    static const size_t MAX_SIZE = MAX_SIZE_;
+
+    //*************************************************************************
+    /// Constructor.
+    //*************************************************************************
+    intrusive_flat_multiset()
+      : iintrusive_flat_multiset<TKey, TKeyCompare>(lookup)
+    {
+    }
+
+    //*************************************************************************
+    /// Copy constructor.
+    //*************************************************************************
+    intrusive_flat_multiset(const intrusive_flat_multiset& other)
+      : iintrusive_flat_multiset<TKey, TKeyCompare>(lookup)
+    {
+      iintrusive_flat_multiset<TKey, TKeyCompare>::assign(other.cbegin(), other.cend());
+    }
+
+    //*************************************************************************
+    /// Constructor, from an iterator range.
+    ///\tparam TIterator The iterator type.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*************************************************************************
+    template <typename TIterator>
+    intrusive_flat_multiset(TIterator first, TIterator last)
+      : iintrusive_flat_multiset<TKey, TKeyCompare>(lookup)
+    {
+      iintrusive_flat_multiset<TKey, TKeyCompare>::assign(first, last);
+    }
+
+    //*************************************************************************
+    /// Destructor.
+    //*************************************************************************
+    ~intrusive_flat_multiset()
+    {
+      iintrusive_flat_multiset<TKey, TKeyCompare>::clear();
+    }
+
+  private:
+
+    typedef TKey value_type;
+    
+    // The vector that stores pointers to the nodes.
+    etl::vector<value_type*, MAX_SIZE> lookup;
+  };
+
+  //***************************************************************************
+  /// Equal operator.
+  ///\param lhs Reference to the first intrusive_flat_multiset.
+  ///\param rhs Reference to the second intrusive_flat_multiset.
+  ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_multiset
+  //***************************************************************************
+  template <typename T, typename TKeyCompare>
+  bool operator ==(const etl::iintrusive_flat_multiset<T, TKeyCompare>& lhs, const etl::iintrusive_flat_multiset<T, TKeyCompare>& rhs)
+  {
+    return (lhs.size() == rhs.size()) && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+  }
+
+  //***************************************************************************
+  /// Not equal operator.
+  ///\param lhs Reference to the first intrusive_flat_multiset.
+  ///\param rhs Reference to the second intrusive_flat_multiset.
+  ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_multiset
+  //***************************************************************************
+  template <typename T, typename TKeyCompare>
+  bool operator !=(const etl::iintrusive_flat_multiset<T, TKeyCompare>& lhs, const etl::iintrusive_flat_multiset<T, TKeyCompare>& rhs)
+  {
+    return !(lhs == rhs);
+  }
+}
+
+#undef ETL_FILE
+#endif

src/intrusive_flat_set.h

@@ -0,0 +1,860 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_INTRUSIVE_FLAT_SET__
+#define __ETL_INTRUSIVE_FLAT_SET__
+
+#include <iterator>
+#include <algorithm>
+#include <functional>
+#include <utility>
+#include <stddef.h>
+
+#include "platform.h"
+#include "type_traits.h"
+#include "ipool.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "vector.h"
+#include "ivector.h"
+
+#undef ETL_FILE
+#define ETL_FILE "32"
+
+namespace etl
+{
+  //***************************************************************************
+  ///\ingroup intrusive_flat_set
+  /// Exception base for intrusive_flat_sets
+  //***************************************************************************
+  class intrusive_flat_set_exception : public exception
+  {
+  public:
+
+    intrusive_flat_set_exception(string_type what, string_type file_name, numeric_type line_number)
+      : exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_set
+  /// Vector full exception.
+  //***************************************************************************
+  class intrusive_flat_set_full : public intrusive_flat_set_exception
+  {
+  public:
+
+    intrusive_flat_set_full(string_type file_name, numeric_type line_number)
+      : intrusive_flat_set_exception(ETL_ERROR_TEXT("intrusive_flat_set:full", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup intrusive_flat_set
+  /// Vector iterator exception.
+  //***************************************************************************
+  class intrusive_flat_set_iterator : public intrusive_flat_set_exception
+  {
+  public:
+
+    intrusive_flat_set_iterator(string_type file_name, numeric_type line_number)
+      : intrusive_flat_set_exception(ETL_ERROR_TEXT("intrusive_flat_set:iterator", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The base class for specifically sized intrusive_flat_sets.
+  /// Can be used as a reference type for all intrusive_flat_sets containing a specific type.
+  ///\ingroup intrusive_flat_set
+  //***************************************************************************
+  template <typename T, typename TKeyCompare = std::less<T> >
+  class iintrusive_flat_set
+  {
+  public:
+
+    typedef T                 key_type;
+    typedef T                 value_type;
+    typedef TKeyCompare       key_compare;
+    typedef value_type&       reference;
+    typedef const value_type& const_reference;
+    typedef value_type*       pointer;
+    typedef const value_type* const_pointer;
+    typedef size_t            size_type;
+
+  private:
+
+    typedef etl::ivector<value_type*> lookup_t;
+
+  public:
+
+    //*************************************************************************
+    class iterator : public std::iterator<std::bidirectional_iterator_tag, value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_set;
+
+      iterator()
+      {
+      }
+
+      iterator(typename lookup_t::iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      iterator operator ++(int)
+      {
+        iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      iterator operator --(int)
+      {
+        iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return &(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const iterator& lhs, const iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const iterator& lhs, const iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::iterator ilookup;
+    };
+
+    //*************************************************************************
+    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const value_type>
+    {
+    public:
+
+      friend class iintrusive_flat_set;
+
+      const_iterator()
+      {
+      }
+
+      const_iterator(typename lookup_t::const_iterator ilookup)
+        : ilookup(ilookup)
+      {
+      }
+
+      const_iterator(const iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator(const const_iterator& other)
+        : ilookup(other.ilookup)
+      {
+      }
+
+      const_iterator& operator =(const iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator =(const const_iterator& other)
+      {
+        ilookup = other.ilookup;
+        return *this;
+      }
+
+      const_iterator& operator ++()
+      {
+        ++ilookup;
+        return *this;
+      }
+
+      const_iterator operator ++(int)
+      {
+        const_iterator temp(*this);
+        ++ilookup;
+        return temp;
+      }
+
+      const_iterator& operator --()
+      {
+        --ilookup;
+        return *this;
+      }
+
+      const_iterator operator --(int)
+      {
+        const_iterator temp(*this);
+        --ilookup;
+        return temp;
+      }
+
+      reference operator *()
+      {
+        return *(*ilookup);
+      }
+
+      const_reference operator *() const
+      {
+        return *(*ilookup);
+      }
+
+      pointer operator &()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator &() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      pointer operator ->()
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      const_pointer operator ->() const
+      {
+        return etl::addressof(*(*ilookup));
+      }
+
+      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return lhs.ilookup == rhs.ilookup;
+      }
+
+      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      typename lookup_t::const_iterator ilookup;
+    };
+
+  protected:
+
+    typedef typename parameter_type<T>::type parameter_t;
+
+  public:
+
+    typedef std::reverse_iterator<iterator>       reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    typedef typename std::iterator_traits<iterator>::difference_type difference_type;
+
+    //*********************************************************************
+    /// Returns an iterator to the beginning of the intrusive_flat_set.
+    ///\return An iterator to the beginning of the intrusive_flat_set.
+    //*********************************************************************
+    iterator begin()
+    {
+      return iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_set.
+    ///\return A const iterator to the beginning of the intrusive_flat_set.
+    //*********************************************************************
+    const_iterator begin() const
+    {
+      return const_iterator(lookup.begin());
+    }
+
+    //*********************************************************************
+    /// Returns an iterator to the end of the intrusive_flat_set.
+    ///\return An iterator to the end of the intrusive_flat_set.
+    //*********************************************************************
+    iterator end()
+    {
+      return iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_set.
+    ///\return A const iterator to the end of the intrusive_flat_set.
+    //*********************************************************************
+    const_iterator end() const
+    {
+      return const_iterator(lookup.end());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the beginning of the intrusive_flat_set.
+    ///\return A const iterator to the beginning of the intrusive_flat_set.
+    //*********************************************************************
+    const_iterator cbegin() const
+    {
+      return const_iterator(lookup.cbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator to the end of the intrusive_flat_set.
+    ///\return A const iterator to the end of the intrusive_flat_set.
+    //*********************************************************************
+    const_iterator cend() const
+    {
+      return const_iterator(lookup.cend());
+    }
+
+    //*********************************************************************
+    /// Returns an reverse iterator to the reverse beginning of the intrusive_flat_set.
+    ///\return Iterator to the reverse beginning of the intrusive_flat_set.
+    //*********************************************************************
+    reverse_iterator rbegin()
+    {
+      return reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_set.
+    ///\return Const iterator to the reverse beginning of the intrusive_flat_set.
+    //*********************************************************************
+    const_reverse_iterator rbegin() const
+    {
+      return const_reverse_iterator(lookup.rbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a reverse iterator to the end + 1 of the intrusive_flat_set.
+    ///\return Reverse iterator to the end + 1 of the intrusive_flat_set.
+    //*********************************************************************
+    reverse_iterator rend()
+    {
+      return reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_set.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_set.
+    //*********************************************************************
+    const_reverse_iterator rend() const
+    {
+      return const_reverse_iterator(lookup.rend());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the reverse beginning of the intrusive_flat_set.
+    ///\return Const reverse iterator to the reverse beginning of the intrusive_flat_set.
+    //*********************************************************************
+    const_reverse_iterator crbegin() const
+    {
+      return const_reverse_iterator(lookup.crbegin());
+    }
+
+    //*********************************************************************
+    /// Returns a const reverse iterator to the end + 1 of the intrusive_flat_set.
+    ///\return Const reverse iterator to the end + 1 of the intrusive_flat_set.
+    //*********************************************************************
+    const_reverse_iterator crend() const
+    {
+      return const_reverse_iterator(lookup.crend());
+    }
+
+    //*********************************************************************
+    /// Assigns values to the intrusive_flat_set.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_set_full if the intrusive_flat_set does not have enough free space.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_set_iterator if the iterators are reversed.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*********************************************************************
+    template <typename TIterator>
+    void assign(TIterator first, TIterator last)
+    {
+#if defined(ETL_DEBUG)
+      difference_type count = std::distance(first, last);
+      ETL_ASSERT(count <= difference_type(capacity()), ETL_ERROR(intrusive_flat_set_full));
+#endif
+
+      clear();
+
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_set.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_set_full if the intrusive_flat_set is already full.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    std::pair<iterator, bool> insert(value_type& value)
+    {
+      std::pair<iterator, bool> result(end(), false);
+
+      ETL_ASSERT(!lookup.full(), ETL_ERROR(intrusive_flat_set_full));
+
+      iterator i_element = std::lower_bound(begin(), end(), value, TKeyCompare());
+
+      if (i_element == end())
+      {
+        // At the end. Doesn't exist.
+        lookup.push_back(&value);
+        result.first = --end();
+        result.second = true;
+      }
+      else
+      {
+        // Not at the end.
+        // Does not exist already?
+        if (*i_element != value)
+        {
+          lookup.insert(i_element.ilookup, &value);
+          result.first = i_element;
+          result.second = true;
+        }
+        else
+        {
+          result.first = i_element;
+          result.second = false;
+        }
+      }
+
+      return result;
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the intrusive_flat_set.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_set_full if the intrusive_flat_set is already full.
+    ///\param position The position to insert at.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(iterator position, value_type& value)
+    {
+      return insert(value).first;
+    }
+
+    //*********************************************************************
+    /// Inserts a range of values to the intrusive_flat_set.
+    /// If asserts or exceptions are enabled, emits intrusive_flat_set_full if the intrusive_flat_set does not have enough free space.
+    ///\param position The position to insert at.
+    ///\param first    The first element to add.
+    ///\param last     The last + 1 element to add.
+    //*********************************************************************
+    template <class TIterator>
+    void insert(TIterator first, TIterator last)
+    {
+      while (first != last)
+      {
+        insert(*first++);
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param key The key to erase.
+    ///\return The number of elements erased. 0 or 1.
+    //*********************************************************************
+    size_t erase(value_type& key)
+    {
+      iterator i_element = find(key);
+
+      if (i_element == end())
+      {
+        return 0;
+      }
+      else
+      {
+        lookup.erase(i_element.ilookup);
+        return 1;
+      }
+    }
+
+    //*********************************************************************
+    /// Erases an element.
+    ///\param i_element Iterator to the element.
+    //*********************************************************************
+    void erase(iterator i_element)
+    {
+      lookup.erase(i_element.ilookup);
+    }
+
+    //*********************************************************************
+    /// Erases a range of elements.
+    /// The range includes all the elements between first and last, including the
+    /// element pointed by first, but not the one pointed by last.
+    ///\param first Iterator to the first element.
+    ///\param last  Iterator to the last element.
+    //*********************************************************************
+    void erase(iterator first, iterator last)
+    {
+      lookup.erase(first.ilookup, last.ilookup);;
+    }
+
+    //*************************************************************************
+    /// Clears the intrusive_flat_set.
+    //*************************************************************************
+    void clear()
+    {
+      erase(begin(), end());
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    iterator find(value_type& key)
+    {
+      iterator itr = std::lower_bound(begin(), end(), key, TKeyCompare());
+
+      if (itr != end())
+      {
+        if (!key_compare()(*itr, key) && !key_compare()(key, *itr))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Finds an element.
+    ///\param key The key to search for.
+    ///\return An iterator pointing to the element or end() if not found.
+    //*********************************************************************
+    const_iterator find(value_type& key) const
+    {
+      const_iterator itr = std::lower_bound(begin(), end(), key, TKeyCompare());
+
+      if (itr != end())
+      {
+        if (!key_compare()(*itr, key) && !key_compare()(key, *itr))
+        {
+          return itr;
+        }
+        else
+        {
+          return end();
+        }
+      }
+
+      return end();
+    }
+
+    //*********************************************************************
+    /// Counts an element.
+    ///\param key The key to search for.
+    ///\return 1 if the key exists, otherwise 0.
+    //*********************************************************************
+    size_t count(value_type& key) const
+    {
+      return (find(key) == end()) ? 0 : 1;
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator lower_bound(value_type& key)
+    {
+      return std::lower_bound(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the lower bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator lower_bound(value_type& key) const
+    {
+      return std::lower_bound(cbegin(), cend(), key, TKeyCompare());
+    }
+    
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    iterator upper_bound(value_type& key)
+    {
+      return std::upper_bound(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the upper bound of a key
+    ///\param key The key to search for.
+    ///\return An iterator.
+    //*********************************************************************
+    const_iterator upper_bound(value_type& key) const
+    {
+      return std::upper_bound(cbegin(), cend(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<iterator, iterator> equal_range(value_type& key)
+    {
+      return std::equal_range(begin(), end(), key, TKeyCompare());
+    }
+
+    //*********************************************************************
+    /// Finds the range of equal elements of a key
+    ///\param key The key to search for.
+    ///\return An iterator pair.
+    //*********************************************************************
+    std::pair<const_iterator, const_iterator> equal_range(value_type& key) const
+    {
+      return std::upper_bound(cbegin(), cend(), key, TKeyCompare());
+    }
+
+    //*************************************************************************
+    /// Gets the current size of the intrusive_flat_set.
+    ///\return The current size of the intrusive_flat_set.
+    //*************************************************************************
+    size_type size() const
+    {
+      return lookup.size();
+    }
+
+    //*************************************************************************
+    /// Checks the 'empty' state of the intrusive_flat_set.
+    ///\return <b>true</b> if empty.
+    //*************************************************************************
+    bool empty() const
+    {
+      return lookup.empty();
+    }
+
+    //*************************************************************************
+    /// Checks the 'full' state of the intrusive_flat_set.
+    ///\return <b>true</b> if full.
+    //*************************************************************************
+    bool full() const
+    {
+      return lookup.full();
+    }
+
+    //*************************************************************************
+    /// Returns the capacity of the intrusive_flat_set.
+    ///\return The capacity of the intrusive_flat_set.
+    //*************************************************************************
+    size_type capacity() const
+    {
+      return lookup.capacity();
+    }
+
+    //*************************************************************************
+    /// Returns the maximum possible size of the intrusive_flat_set.
+    ///\return The maximum size of the intrusive_flat_set.
+    //*************************************************************************
+    size_type max_size() const
+    {
+      return lookup.max_size();
+    }
+
+    //*************************************************************************
+    /// Returns the remaining capacity.
+    ///\return The remaining capacity.
+    //*************************************************************************
+    size_t available() const
+    {
+      return lookup.available();
+    }
+
+  protected:
+
+    //*********************************************************************
+    /// Constructor.
+    //*********************************************************************
+    iintrusive_flat_set(lookup_t& lookup_)
+      : lookup(lookup_)
+    {
+    }
+
+  private:
+
+    // Disable copy construction.
+    iintrusive_flat_set(const iintrusive_flat_set&);
+    iintrusive_flat_set& operator =(const iintrusive_flat_set&);
+
+    lookup_t& lookup;
+  };
+
+  //***************************************************************************
+  /// An intrusive flat set
+  ///\ingroup intrusive_flat_set
+  //***************************************************************************
+  template <typename TKey, const size_t MAX_SIZE_, typename TKeyCompare = std::less<TKey> >
+  class intrusive_flat_set : public iintrusive_flat_set<TKey, TKeyCompare>
+  {
+  public:
+
+    static const size_t MAX_SIZE = MAX_SIZE_;
+
+    //*************************************************************************
+    /// Constructor.
+    //*************************************************************************
+    intrusive_flat_set()
+      : iintrusive_flat_set<TKey, TKeyCompare>(lookup)
+    {
+    }
+
+    //*************************************************************************
+    /// Copy constructor.
+    //*************************************************************************
+    intrusive_flat_set(const intrusive_flat_set& other)
+      : iintrusive_flat_set<TKey, TKeyCompare>(lookup)
+    {
+      iintrusive_flat_set<TKey, TKeyCompare>::assign(other.cbegin(), other.cend());
+    }
+
+    //*************************************************************************
+    /// Constructor, from an iterator range.
+    ///\tparam TIterator The iterator type.
+    ///\param first The iterator to the first element.
+    ///\param last  The iterator to the last element + 1.
+    //*************************************************************************
+    template <typename TIterator>
+    intrusive_flat_set(TIterator first, TIterator last)
+      : iintrusive_flat_set<TKey, TKeyCompare>(lookup)
+    {
+      iintrusive_flat_set<TKey, TKeyCompare>::assign(first, last);
+    }
+
+    //*************************************************************************
+    /// Destructor.
+    //*************************************************************************
+    ~intrusive_flat_set()
+    {
+      iintrusive_flat_set<TKey, TKeyCompare>::clear();
+    }
+
+  private:
+
+    typedef TKey value_type;
+    
+    // The vector that stores pointers to the nodes.
+    etl::vector<value_type*, MAX_SIZE> lookup;
+  };
+
+  //***************************************************************************
+  /// Equal operator.
+  ///\param lhs Reference to the first intrusive_flat_set.
+  ///\param rhs Reference to the second intrusive_flat_set.
+  ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_set
+  //***************************************************************************
+  template <typename T, typename TKeyCompare>
+  bool operator ==(const etl::iintrusive_flat_set<T, TKeyCompare>& lhs, const etl::iintrusive_flat_set<T, TKeyCompare>& rhs)
+  {
+    return (lhs.size() == rhs.size()) && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+  }
+
+  //***************************************************************************
+  /// Not equal operator.
+  ///\param lhs Reference to the first intrusive_flat_set.
+  ///\param rhs Reference to the second intrusive_flat_set.
+  ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
+  ///\ingroup intrusive_flat_set
+  //***************************************************************************
+  template <typename T, typename TKeyCompare>
+  bool operator !=(const etl::iintrusive_flat_set<T, TKeyCompare>& lhs, const etl::iintrusive_flat_set<T, TKeyCompare>& rhs)
+  {
+    return !(lhs == rhs);
+  }
+}
+
+#undef ETL_FILE
+#endif

test/test_flat_set.cpp

@@ -40,45 +40,48 @@ SOFTWARE.
 
 #include "../src/flat_set.h"
 
-static const size_t SIZE = 10;
+namespace
+{
+  static const size_t SIZE = 10;
 
-typedef TestDataDC<std::string>  DC;
-typedef TestDataNDC<std::string> NDC;
+  typedef TestDataDC<std::string>  DC;
+  typedef TestDataNDC<std::string> NDC;
 
-typedef etl::flat_set<DC, SIZE>  DataDC;
-typedef etl::flat_set<NDC, SIZE> DataNDC;
-typedef etl::iflat_set<NDC>      IDataNDC;
+  typedef etl::flat_set<DC, SIZE>  DataDC;
+  typedef etl::flat_set<NDC, SIZE> DataNDC;
+  typedef etl::iflat_set<NDC>      IDataNDC;
 
-typedef std::set<DC>  Compare_DataDC;
-typedef std::set<NDC> Compare_DataNDC;
+  typedef std::set<DC>  Compare_DataDC;
+  typedef std::set<NDC> Compare_DataNDC;
 
-NDC NX = NDC("@");
-NDC NY = NDC("[");
+  NDC NX = NDC("@");
+  NDC NY = NDC("[");
 
-NDC N0 = NDC("A");
-NDC N1 = NDC("B");
-NDC N2 = NDC("C");
-NDC N3 = NDC("D");
-NDC N4 = NDC("E");
-NDC N5 = NDC("F");
-NDC N6 = NDC("G");
-NDC N7 = NDC("H");
-NDC N8 = NDC("I");
-NDC N9 = NDC("J");
-NDC N10 = NDC("K");
-NDC N11 = NDC("L");
-NDC N12 = NDC("M");
-NDC N13 = NDC("N");
-NDC N14 = NDC("O");
-NDC N15 = NDC("P");
-NDC N16 = NDC("Q");
-NDC N17 = NDC("R");
-NDC N18 = NDC("S");
-NDC N19 = NDC("T");
+  NDC N0 = NDC("A");
+  NDC N1 = NDC("B");
+  NDC N2 = NDC("C");
+  NDC N3 = NDC("D");
+  NDC N4 = NDC("E");
+  NDC N5 = NDC("F");
+  NDC N6 = NDC("G");
+  NDC N7 = NDC("H");
+  NDC N8 = NDC("I");
+  NDC N9 = NDC("J");
+  NDC N10 = NDC("K");
+  NDC N11 = NDC("L");
+  NDC N12 = NDC("M");
+  NDC N13 = NDC("N");
+  NDC N14 = NDC("O");
+  NDC N15 = NDC("P");
+  NDC N16 = NDC("Q");
+  NDC N17 = NDC("R");
+  NDC N18 = NDC("S");
+  NDC N19 = NDC("T");
 
-std::vector<NDC> initial_data;
-std::vector<NDC> excess_data;
-std::vector<NDC> different_data;
+  std::vector<NDC> initial_data;
+  std::vector<NDC> excess_data;
+  std::vector<NDC> different_data;
+}
 
 //*************************************************************************
 std::ostream& operator <<(std::ostream& os, const DataDC::iterator& itr)

test/test_intrusive_flat_map.cpp

@@ -0,0 +1,802 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include <UnitTest++/UnitTest++.h>
+
+#include <map>
+#include <array>
+#include <algorithm>
+#include <utility>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include <iostream>
+
+#include "data.h"
+
+#include "../src/intrusive_flat_map.h"
+
+namespace
+{
+  static const size_t SIZE = 10;
+
+  typedef TestDataDC<std::string>  DC;
+  typedef TestDataNDC<std::string> NDC;
+
+  typedef std::pair<int, DC>  ElementDC;
+  typedef std::pair<int, NDC> ElementNDC;
+
+  typedef etl::intrusive_flat_map<int, DC, SIZE>  DataDC;
+  typedef etl::intrusive_flat_map<int, NDC, SIZE> DataNDC;
+  typedef etl::iintrusive_flat_map<int, DC>       IDataDC;
+  typedef etl::iintrusive_flat_map<int, NDC>      IDataNDC;
+
+  typedef std::map<int, DC>  Compare_DataDC;
+  typedef std::map<int, NDC> Compare_DataNDC;
+
+  //*************************************************************************
+  template <typename T1, typename T2>
+  bool Check_Equal(T1 begin1, T1 end1, T2 begin2)
+  {
+    while (begin1 != end1)
+    {
+      if ((begin1->first != begin2->first) || (begin1->second != begin2->second))
+      {
+        return false;
+      }
+
+      ++begin1;
+      ++begin2;
+    }
+
+    return true;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::const_iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::const_iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  SUITE(test_flat_map)
+  {
+    NDC N0 = NDC("A");
+    NDC N1 = NDC("B");
+    NDC N2 = NDC("C");
+    NDC N3 = NDC("D");
+    NDC N4 = NDC("E");
+    NDC N5 = NDC("F");
+    NDC N6 = NDC("G");
+    NDC N7 = NDC("H");
+    NDC N8 = NDC("I");
+    NDC N9 = NDC("J");
+    NDC N10 = NDC("K");
+    NDC N11 = NDC("L");
+    NDC N12 = NDC("M");
+    NDC N13 = NDC("N");
+    NDC N14 = NDC("O");
+    NDC N15 = NDC("P");
+    NDC N16 = NDC("Q");
+    NDC N17 = NDC("R");
+    NDC N18 = NDC("S");
+    NDC N19 = NDC("T");
+
+    DC M0 = DC("A");
+    DC M1 = DC("B");
+    DC M2 = DC("C");
+    DC M3 = DC("D");
+    DC M4 = DC("E");
+    DC M5 = DC("F");
+    DC M6 = DC("G");
+    DC M7 = DC("H");
+    DC M8 = DC("I");
+    DC M9 = DC("J");
+    DC M10 = DC("K");
+    DC M11 = DC("L");
+    DC M12 = DC("M");
+    DC M13 = DC("N");
+    DC M14 = DC("O");
+    DC M15 = DC("P");
+    DC M16 = DC("Q");
+    DC M17 = DC("R");
+    DC M18 = DC("S");
+    DC M19 = DC("T");
+
+    std::vector<ElementDC>  initial_data_dc;
+    std::vector<ElementNDC> initial_data;
+    std::vector<ElementNDC> excess_data;
+    std::vector<ElementNDC> different_data;
+
+    //*************************************************************************
+    template <typename T1, typename T2>
+    bool Check_Equal(T1 begin1, T1 end1, T2 begin2)
+    {
+      while (begin1 != end1)
+      {
+        if ((begin1->first != begin2->first) || (begin1->second != begin2->second))
+        {
+          return false;
+        }
+
+        ++begin1;
+        ++begin2;
+      }
+
+      return true;
+    }
+
+    //*************************************************************************
+    struct SetupFixture
+    {
+      SetupFixture()
+      {
+        ElementNDC n[] =
+        {
+          ElementNDC(0, N0), ElementNDC(1, N1), ElementNDC(2, N2), ElementNDC(3, N3), ElementNDC(4, N4),
+          ElementNDC(5, N5), ElementNDC(6, N6), ElementNDC(7, N7), ElementNDC(8, N8), ElementNDC(9, N9)
+        };
+
+        ElementNDC n2[] =
+        {
+          ElementNDC(0, N0), ElementNDC(1, N1), ElementNDC(2, N2), ElementNDC(3, N3), ElementNDC(4, N4),
+          ElementNDC(5, N5), ElementNDC(6, N6), ElementNDC(7, N7), ElementNDC(8, N8), ElementNDC(9, N9),
+          ElementNDC(10, N10)
+        };
+
+        ElementNDC n3[] =
+        {
+          ElementNDC(10, N10), ElementNDC(11, N11), ElementNDC(12, N12), ElementNDC(13, N13), ElementNDC(14, N14),
+          ElementNDC(15, N15), ElementNDC(16, N16), ElementNDC(17, N17), ElementNDC(18, N18), ElementNDC(19, N19)
+        };
+
+        ElementDC n4[] =
+        {
+          ElementDC(0, M0), ElementDC(1, M1), ElementDC(2, M2), ElementDC(3, M3), ElementDC(4, M4),
+          ElementDC(5, M5), ElementDC(6, M6), ElementDC(7, M7), ElementDC(8, M8), ElementDC(9, M9)
+        };
+
+        initial_data.assign(std::begin(n), std::end(n));
+        excess_data.assign(std::begin(n2), std::end(n2));
+        different_data.assign(std::begin(n3), std::end(n3));
+        initial_data_dc.assign(std::begin(n4), std::end(n4));
+      }
+    };
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_default_constructor)
+    {
+      DataDC data;
+
+      CHECK_EQUAL(data.size(), size_t(0));
+      CHECK(data.empty());
+      CHECK_EQUAL(data.capacity(), SIZE);
+      CHECK_EQUAL(data.max_size(), SIZE);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_constructor_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK(data.size() == SIZE);
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_begin)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.begin(), std::begin(data));
+      CHECK_EQUAL(constData.begin(), std::begin(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_end)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.end(), std::end(data));
+      CHECK_EQUAL(constData.end(), std::end(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_empty)
+    {
+      DataNDC data;
+      data.insert(initial_data.begin(), initial_data.end());
+
+      CHECK(data.full());
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_full)
+    {
+      DataDC data;
+
+      CHECK(!data.full());
+      CHECK(data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_index)
+    {
+      Compare_DataDC compare_data(initial_data_dc.begin(), initial_data_dc.end());
+
+      DataDC data(initial_data_dc.begin(), initial_data_dc.end());
+
+      CHECK_EQUAL(compare_data[0], data[0]);
+      CHECK_EQUAL(compare_data[1], data[1]);
+      CHECK_EQUAL(compare_data[2], data[2]);
+      CHECK_EQUAL(compare_data[3], data[3]);
+      CHECK_EQUAL(compare_data[4], data[4]);
+      CHECK_EQUAL(compare_data[5], data[5]);
+      CHECK_EQUAL(compare_data[6], data[6]);
+      CHECK_EQUAL(compare_data[7], data[7]);
+      CHECK_EQUAL(compare_data[8], data[8]);
+      CHECK_EQUAL(compare_data[9], data[9]);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_index_value_changed)
+    {
+      Compare_DataDC compare_data;
+      DataDC data;
+
+      DataDC::value_type item(0, M0);
+
+      data.insert(item);
+      compare_data[0] = M0;
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      data[0] = M2;
+      compare_data[0] = M2;
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_at)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.at(0), compare_data.at(0));
+      CHECK_EQUAL(data.at(1), compare_data.at(1));
+      CHECK_EQUAL(data.at(2), compare_data.at(2));
+      CHECK_EQUAL(data.at(3), compare_data.at(3));
+      CHECK_EQUAL(data.at(4), compare_data.at(4));
+      CHECK_EQUAL(data.at(5), compare_data.at(5));
+      CHECK_EQUAL(data.at(6), compare_data.at(6));
+      CHECK_EQUAL(data.at(7), compare_data.at(7));
+      CHECK_EQUAL(data.at(8), compare_data.at(8));
+      CHECK_EQUAL(data.at(9), compare_data.at(9));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_at_out_of_bounds)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_THROW(data.at(10), etl::intrusive_flat_map_out_of_bounds);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_at_const)
+    {
+      const Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.at(0), compare_data.at(0));
+      CHECK_EQUAL(data.at(1), compare_data.at(1));
+      CHECK_EQUAL(data.at(2), compare_data.at(2));
+      CHECK_EQUAL(data.at(3), compare_data.at(3));
+      CHECK_EQUAL(data.at(4), compare_data.at(4));
+      CHECK_EQUAL(data.at(5), compare_data.at(5));
+      CHECK_EQUAL(data.at(6), compare_data.at(6));
+      CHECK_EQUAL(data.at(7), compare_data.at(7));
+      CHECK_EQUAL(data.at(8), compare_data.at(8));
+      CHECK_EQUAL(data.at(9), compare_data.at(9));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_at_const_out_of_bounds)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_THROW(data.at(10), etl::intrusive_flat_map_out_of_bounds);
+    }
+
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_assign_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data;
+
+      data.assign(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      std::pair<DataNDC::iterator, bool> result;
+
+      DataNDC::value_type item(0, N0);
+      result = data.insert(item);
+      compare_data.insert(item);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+      
+      CHECK(isEqual);
+      CHECK(result.second);
+      CHECK(*result.first == std::make_pair(0, N0));
+
+      DataNDC::value_type item2(2, N2);
+      result = data.insert(item2);
+      compare_data.insert(item2);
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+      CHECK(result.second);
+      CHECK(*result.first == std::make_pair(2, N2));
+
+      DataNDC::value_type item1(1, N1);
+      result = data.insert(item1);
+      compare_data.insert(item1);
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+      CHECK(result.second);
+      CHECK(*result.first == item1);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_changed)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      std::pair<DataNDC::iterator, bool> result1;
+      std::pair<Compare_DataNDC::iterator, bool> result2;
+
+      DataNDC::value_type item(0, N0);
+      result1 = data.insert(item);
+      result2 = compare_data.insert(item);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+      CHECK(result1.second);
+      CHECK(*result1.first == item);
+
+      DataNDC::value_type item2(0, N2);
+      result1 = data.insert(item2);
+      result2 = compare_data.insert(item2);
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+      CHECK(!result1.second);
+      CHECK(*result1.first != item2);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_multiple)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(std::make_pair(0, N0));
+      compare_data.insert(std::make_pair(0, N0));
+
+      data.insert(std::make_pair(1, N1));
+      compare_data.insert(std::make_pair(1, N1));
+
+      data.insert(std::make_pair(2, N2));
+      compare_data.insert(std::make_pair(2, N2));
+
+      // Do it again.
+      data.insert(std::make_pair(0, N0));
+      compare_data.insert(std::make_pair(0, N0));
+
+      data.insert(std::make_pair(1, N1));
+      compare_data.insert(std::make_pair(1, N1));
+
+      data.insert(std::make_pair(2, N2));
+      compare_data.insert(std::make_pair(2, N2));
+
+      CHECK_EQUAL(compare_data.size(), data.size());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_excess)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_THROW(data.insert(std::make_pair(10, N10)), etl::intrusive_flat_map_full);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(initial_data.begin(), initial_data.end());
+      compare_data.insert(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range_excess)
+    {
+      DataNDC data;
+
+      CHECK_THROW(data.insert(excess_data.begin(), excess_data.end()), etl::intrusive_flat_map_full);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_key)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data = data.begin();
+
+      size_t count_compare = compare_data.erase(5);
+      size_t count         = data.erase(5);
+
+      CHECK_EQUAL(count_compare, count);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_single)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      compare_data.erase(i_compare);
+      data.erase(i_data);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      Compare_DataNDC::iterator i_compare_end = compare_data.begin();
+      DataNDC::iterator i_data_end            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      std::advance(i_compare_end, 4);
+      std::advance(i_data_end,    4);
+
+      compare_data.erase(i_compare, i_compare_end);
+      data.erase(i_data, i_data_end);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_clear)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+      data.clear();
+
+      CHECK_EQUAL(data.size(), size_t(0));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.cbegin(),
+                                 data.cend(),
+                                 compare_data.cbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.rbegin(),
+                                 data.rend(),
+                                 compare_data.rbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.crbegin(),
+                                 data.crend(),
+                                 compare_data.crbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(3);
+      CHECK_EQUAL(N3, it->second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(-1);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(10);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(3);
+      CHECK_EQUAL(N3, it->second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const_not_present)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(-1);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(10);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_lower_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.lower_bound(5);
+      DataNDC::iterator         i_data    = data.lower_bound(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_upper_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.upper_bound(5);
+      DataNDC::iterator         i_data    = data.upper_bound(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> i_compare = compare_data.equal_range(5);
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data = data.equal_range(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.first),  std::distance(data.begin(), i_data.first));
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.second), std::distance(data.begin(), i_data.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range_not_present)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> i_compare;
+
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data;
+      
+      i_data = data.equal_range(-1);
+      CHECK_EQUAL(data.begin(), i_data.first);
+      CHECK_EQUAL(data.begin(), i_data.second);
+
+      i_data = data.equal_range(99);
+      CHECK_EQUAL(data.end(), i_data.first);
+      CHECK_EQUAL(data.end(), i_data.second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(initial1 == initial2);
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(!(initial1 == different));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_not_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(!(initial1 != initial2));
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(initial1 != different);
+    }
+  };
+}

test/test_intrusive_flat_multimap.cpp

@@ -0,0 +1,685 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include <UnitTest++/UnitTest++.h>
+
+#include <map>
+#include <array>
+#include <algorithm>
+#include <utility>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include "data.h"
+
+#include "../src/intrusive_flat_multimap.h"
+
+namespace
+{
+  static const size_t SIZE = 10;
+
+  typedef TestDataDC<std::string>  DC;
+  typedef TestDataNDC<std::string> NDC;
+
+  typedef std::pair<int, DC>  ElementDC;
+  typedef std::pair<int, NDC> ElementNDC;
+
+  typedef etl::intrusive_flat_multimap<int, DC, SIZE>  DataDC;
+  typedef etl::intrusive_flat_multimap<int, NDC, SIZE> DataNDC;
+  typedef etl::iintrusive_flat_multimap<int, DC>       IDataDC;
+  typedef etl::iintrusive_flat_multimap<int, NDC>      IDataNDC;
+
+  typedef std::multimap<int, DC>  Compare_DataDC;
+  typedef std::multimap<int, NDC> Compare_DataNDC;
+
+  NDC N0 = NDC("A");
+  NDC N1 = NDC("B");
+  NDC N2 = NDC("C");
+  NDC N3 = NDC("D");
+  NDC N4 = NDC("E");
+  NDC N5 = NDC("F");
+  NDC N6 = NDC("G");
+  NDC N7 = NDC("H");
+  NDC N8 = NDC("I");
+  NDC N9 = NDC("J");
+  NDC N10 = NDC("K");
+  NDC N11 = NDC("L");
+  NDC N12 = NDC("M");
+  NDC N13 = NDC("N");
+  NDC N14 = NDC("O");
+  NDC N15 = NDC("P");
+  NDC N16 = NDC("Q");
+  NDC N17 = NDC("R");
+  NDC N18 = NDC("S");
+  NDC N19 = NDC("T");
+
+  std::vector<ElementNDC> initial_data;
+  std::vector<ElementNDC> excess_data;
+  std::vector<ElementNDC> different_data;
+  std::vector<ElementNDC> multi_data;
+
+  //*************************************************************************
+  template <typename T1, typename T2>
+  bool Check_Equal(T1 begin1, T1 end1, T2 begin2)
+  {
+    while (begin1 != end1)
+    {
+      if ((begin1->first != begin2->first) || (begin1->second != begin2->second))
+      {
+        return false;
+      }
+
+      ++begin1;
+      ++begin2;
+    }
+
+    return true;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::const_iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::const_iterator& itr)
+  {
+    os << itr->first;
+
+    return os;
+  }
+
+  SUITE(test_intrusive_flat_multimap)
+  {
+    //*************************************************************************
+    struct SetupFixture
+    {
+      SetupFixture()
+      {
+        ElementNDC n[] =
+        {
+          ElementNDC(0, N0), ElementNDC(1, N1), ElementNDC(2, N2), ElementNDC(3, N3), ElementNDC(4, N4),
+          ElementNDC(5, N5), ElementNDC(6, N6), ElementNDC(7, N7), ElementNDC(8, N8), ElementNDC(9, N9)
+        };
+
+        ElementNDC n2[] =
+        {
+          ElementNDC(0, N0), ElementNDC(1, N1), ElementNDC(2, N2), ElementNDC(3, N3), ElementNDC(4, N4),
+          ElementNDC(5, N5), ElementNDC(6, N6), ElementNDC(7, N7), ElementNDC(8, N8), ElementNDC(9, N9),
+          ElementNDC(10, N10)
+        };
+
+        ElementNDC n3[] =
+        {
+          ElementNDC(10, N10), ElementNDC(11, N11), ElementNDC(12, N12), ElementNDC(13, N13), ElementNDC(14, N14),
+          ElementNDC(15, N15), ElementNDC(16, N16), ElementNDC(17, N17), ElementNDC(18, N18), ElementNDC(19, N19)
+        };
+
+        ElementNDC n4[] =
+        {
+          ElementNDC(0, N0), ElementNDC(1, N1), ElementNDC(2, N2), ElementNDC(1, N3), ElementNDC(3, N4),
+          ElementNDC(4, N5), ElementNDC(4, N6), ElementNDC(5, N7), ElementNDC(4, N8), ElementNDC(0, N9)
+        };
+
+        initial_data.assign(std::begin(n), std::end(n));
+        excess_data.assign(std::begin(n2), std::end(n2));
+        different_data.assign(std::begin(n3), std::end(n3));
+        multi_data.assign(std::begin(n4), std::end(n4));
+      }
+    };
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_default_constructor)
+    {
+      DataDC data;
+
+      CHECK_EQUAL(data.size(), size_t(0));
+      CHECK(data.empty());
+      CHECK_EQUAL(data.capacity(), SIZE);
+      CHECK_EQUAL(data.max_size(), SIZE);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_constructor_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK(data.size() == SIZE);
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_begin)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.begin(), std::begin(data));
+      CHECK_EQUAL(constData.begin(), std::begin(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_end)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.end(), std::end(data));
+      CHECK_EQUAL(constData.end(), std::end(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_empty)
+    {
+      DataNDC data;
+      data.insert(initial_data.begin(), initial_data.end());
+
+      CHECK(data.full());
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_full)
+    {
+      DataDC data;
+
+      CHECK(!data.full());
+      CHECK(data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_assign_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data;
+
+      data.assign(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      DataNDC::value_type item0(0, N0);
+      data.insert(item0);
+      compare_data.insert(item0);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      DataNDC::value_type item2(2, N2);
+      data.insert(item2);
+      compare_data.insert(item2);
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+
+      DataNDC::value_type item1(1, N1);
+      data.insert(item1);
+      compare_data.insert(item1);
+
+      isEqual = Check_Equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_multiple)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      DataNDC::value_type item0(0, N0);
+      data.insert(item0);
+      compare_data.insert(item0);
+
+      DataNDC::value_type item1(1, N1);
+      data.insert(item1);
+      compare_data.insert(item1);
+
+      DataNDC::value_type item2(2, N2);
+      data.insert(item2);
+      compare_data.insert(item2);
+
+      // Do it again.
+      data.insert(item0);
+      compare_data.insert(item0);
+
+      data.insert(item1);
+      compare_data.insert(item1);
+
+      data.insert(item2);
+      compare_data.insert(item2);
+
+      CHECK_EQUAL(compare_data.size(), data.size());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_excess)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::value_type item10(10, N10);
+      CHECK_THROW(data.insert(item10), etl::intrusive_flat_multimap_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(initial_data.begin(), initial_data.end());
+      compare_data.insert(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range_excess)
+    {
+      DataNDC data;
+
+      CHECK_THROW(data.insert(excess_data.begin(), excess_data.end()), etl::intrusive_flat_multimap_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_key)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data = data.begin();
+
+      size_t count_compare = compare_data.erase(5);
+      size_t count         = data.erase(5);
+
+      CHECK_EQUAL(count_compare, count);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_single)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      compare_data.erase(i_compare);
+      data.erase(i_data);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      Compare_DataNDC::iterator i_compare_end = compare_data.begin();
+      DataNDC::iterator i_data_end            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      std::advance(i_compare_end, 4);
+      std::advance(i_data_end,    4);
+
+      compare_data.erase(i_compare, i_compare_end);
+      data.erase(i_data, i_data_end);
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_clear)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+      data.clear();
+
+      CHECK_EQUAL(data.size(), size_t(0));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.cbegin(),
+                                 data.cend(),
+                                 compare_data.cbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.rbegin(),
+                                 data.rend(),
+                                 compare_data.rbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = Check_Equal(data.crbegin(),
+                                 data.crend(),
+                                 compare_data.crbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(3);
+      CHECK_EQUAL(N3, it->second);
+
+      it = data.find(19);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(-1);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(10);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(3);
+      CHECK_EQUAL(N3, it->second);
+
+      it = data.find(19);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const_not_present)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(-1);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(10);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_lower_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.lower_bound(5);
+      DataNDC::iterator         i_data    = data.lower_bound(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_upper_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.upper_bound(5);
+      DataNDC::iterator         i_data    = data.upper_bound(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> i_compare = compare_data.equal_range(5);
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data = data.equal_range(5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.first),  std::distance(data.begin(), i_data.first));
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.second), std::distance(data.begin(), i_data.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data;
+      
+      i_data = data.equal_range(-1);
+      CHECK_EQUAL(data.begin(), i_data.first);
+      CHECK_EQUAL(data.begin(), i_data.second);
+
+      i_data = data.equal_range(99);
+      CHECK_EQUAL(data.end(), i_data.first);
+      CHECK_EQUAL(data.end(), i_data.second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(initial1 == initial2);
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(!(initial1 == different));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_not_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(!(initial1 != initial2));
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(initial1 != different);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_multi)
+    {
+      Compare_DataNDC compare_data(multi_data.begin(), multi_data.end());
+      DataNDC data(multi_data.begin(), multi_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> compare_range;
+      std::pair<DataNDC::iterator, DataNDC::iterator> test_range;
+    
+      compare_range = compare_data.equal_range(0);
+      test_range    = data.equal_range(0);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(1);
+      test_range    = data.equal_range(1);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(2);
+      test_range    = data.equal_range(2);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(3);
+      test_range    = data.equal_range(3);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(4);
+      test_range    = data.equal_range(4);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(5);
+      test_range    = data.equal_range(5);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_count)
+    {
+      Compare_DataNDC compare_data(multi_data.begin(), multi_data.end());
+      DataNDC data(multi_data.begin(), multi_data.end());
+
+      CHECK_EQUAL(compare_data.count(0), data.count(0));
+      CHECK_EQUAL(compare_data.count(1), data.count(1));
+      CHECK_EQUAL(compare_data.count(2), data.count(2));
+      CHECK_EQUAL(compare_data.count(3), data.count(3));
+      CHECK_EQUAL(compare_data.count(4), data.count(4));
+      CHECK_EQUAL(compare_data.count(5), data.count(5));
+    }
+  };
+}

test/test_intrusive_flat_multiset.cpp

@@ -0,0 +1,649 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2015 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include <UnitTest++/UnitTest++.h>
+
+#include <set>
+#include <array>
+#include <algorithm>
+#include <utility>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include "data.h"
+
+#include "../src/intrusive_flat_multiset.h"
+
+namespace
+{
+  static const size_t SIZE = 10;
+
+  typedef TestDataDC<std::string>  DC;
+  typedef TestDataNDC<std::string> NDC;
+
+  typedef etl::intrusive_flat_multiset<DC, SIZE>  DataDC;
+  typedef etl::intrusive_flat_multiset<NDC, SIZE> DataNDC;
+  typedef etl::iintrusive_flat_multiset<NDC>      IDataNDC;
+
+  typedef std::multiset<DC>  Compare_DataDC;
+  typedef std::multiset<NDC> Compare_DataNDC;
+
+  NDC NX = NDC("@");
+  NDC NY = NDC("[");
+
+  NDC N0 = NDC("A");
+  NDC N1 = NDC("B");
+  NDC N2 = NDC("C");
+  NDC N3 = NDC("D");
+  NDC N4 = NDC("E");
+  NDC N5 = NDC("F");
+  NDC N6 = NDC("G");
+  NDC N7 = NDC("H");
+  NDC N8 = NDC("I");
+  NDC N9 = NDC("J");
+  NDC N10 = NDC("K");
+  NDC N11 = NDC("L");
+  NDC N12 = NDC("M");
+  NDC N13 = NDC("N");
+  NDC N14 = NDC("O");
+  NDC N15 = NDC("P");
+  NDC N16 = NDC("Q");
+  NDC N17 = NDC("R");
+  NDC N18 = NDC("S");
+  NDC N19 = NDC("T");
+
+  std::vector<NDC> initial_data;
+  std::vector<NDC> excess_data;
+  std::vector<NDC> different_data;
+  std::vector<NDC> multi_data;
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::iterator& itr)
+  {
+    os << itr->value;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataDC::const_iterator& itr)
+  {
+    os << itr->value;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::iterator& itr)
+  {
+    os << itr->value;
+
+    return os;
+  }
+
+  //*************************************************************************
+  std::ostream& operator <<(std::ostream& os, const DataNDC::const_iterator& itr)
+  {
+    os << itr->value;
+
+    return os;
+  }
+
+  SUITE(test_flat_multiset)
+  {
+    //*************************************************************************
+    struct SetupFixture
+    {
+      SetupFixture()
+      {
+        NDC n[] =
+        {
+          N0, N1, N2, N3, N4, N5, N6, N7, N8, N9
+        };
+
+        NDC n2[] =
+        {
+          N0, N1, N2, N3, N4, N5, N6, N7, N8, N9, N10
+        };
+
+        NDC n3[] =
+        {
+          N10, N11, N12, N13, N14, N15, N16, N17, N18, N19
+        };
+
+        NDC n4[] =
+        {
+          N0, N0, N1, N2, N3, N1, N3, N3, N4, N2
+        };
+
+        initial_data.assign(std::begin(n), std::end(n));
+        excess_data.assign(std::begin(n2), std::end(n2));
+        different_data.assign(std::begin(n3), std::end(n3));
+        multi_data.assign(std::begin(n4), std::end(n4));
+      }
+    };
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_default_constructor)
+    {
+      DataDC data;
+
+      CHECK_EQUAL(data.size(), size_t(0));
+      CHECK(data.empty());
+      CHECK_EQUAL(data.capacity(), SIZE);
+      CHECK_EQUAL(data.max_size(), SIZE);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_constructor_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK(data.size() == SIZE);
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_begin)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.begin(), std::begin(data));
+      CHECK_EQUAL(constData.begin(), std::begin(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_end)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.end(), std::end(data));
+      CHECK_EQUAL(constData.end(), std::end(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_empty)
+    {
+      DataNDC data;
+      data.insert(initial_data.begin(), initial_data.end());
+
+      CHECK(data.full());
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_full)
+    {
+      DataNDC data;
+
+      CHECK(!data.full());
+      CHECK(data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_assign_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data;
+
+      data.assign(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      isEqual = std::equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      isEqual = std::equal(data.begin(),
+                            data.end(),
+                            compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_multiple)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      // Do it again.
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      CHECK_EQUAL(compare_data.size(), data.size());
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_excess)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_THROW(data.insert(N10), etl::intrusive_flat_multiset_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(initial_data.begin(), initial_data.end());
+      compare_data.insert(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range_excess)
+    {
+      DataNDC data;
+
+      CHECK_THROW(data.insert(excess_data.begin(), excess_data.end()), etl::intrusive_flat_multiset_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_key)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data = data.begin();
+
+      size_t count_compare = compare_data.erase(N5);
+      size_t count         = data.erase(N5);
+
+      CHECK_EQUAL(count_compare, count);
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_single)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      compare_data.erase(i_compare);
+      data.erase(i_data);
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      Compare_DataNDC::iterator i_compare_end = compare_data.begin();
+      DataNDC::iterator i_data_end            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      std::advance(i_compare_end, 4);
+      std::advance(i_data_end,    4);
+
+      compare_data.erase(i_compare, i_compare_end);
+      data.erase(i_data, i_data_end);
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_clear)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+      data.clear();
+
+      CHECK_EQUAL(data.size(), size_t(0));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.cbegin(),
+                                data.cend(),
+                                compare_data.cbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.rbegin(),
+                                data.rend(),
+                                compare_data.rbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.crbegin(),
+                                data.crend(),
+                                compare_data.crbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(N3);
+      CHECK_EQUAL(N3, *it);
+
+      it = data.find(N19);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(NX);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(NY);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(N3);
+      CHECK_EQUAL(N3, *it);
+
+      it = data.find(N19);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const_not_present)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(NX);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(NY);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_lower_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.lower_bound(N5);
+      DataNDC::iterator         i_data    = data.lower_bound(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_upper_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.upper_bound(N5);
+      DataNDC::iterator         i_data    = data.upper_bound(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> i_compare = compare_data.equal_range(N5);
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data = data.equal_range(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.first),  std::distance(data.begin(), i_data.first));
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.second), std::distance(data.begin(), i_data.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data;
+
+      i_data = data.equal_range(NX);
+      CHECK_EQUAL(data.begin(), i_data.first);
+      CHECK_EQUAL(data.begin(), i_data.second);
+
+      i_data = data.equal_range(NY);
+      CHECK_EQUAL(data.end(), i_data.first);
+      CHECK_EQUAL(data.end(), i_data.second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(initial1 == initial2);
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(!(initial1 == different));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_not_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(!(initial1 != initial2));
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(initial1 != different);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_multi)
+    {
+      Compare_DataNDC compare_data(multi_data.begin(), multi_data.end());
+      DataNDC data(multi_data.begin(), multi_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> compare_range;
+      std::pair<DataNDC::iterator, DataNDC::iterator> test_range;
+
+      compare_range = compare_data.equal_range(N0);
+      test_range = data.equal_range(N0);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(N1);
+      test_range = data.equal_range(N1);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(N2);
+      test_range = data.equal_range(N2);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(N3);
+      test_range = data.equal_range(N3);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+
+      compare_range = compare_data.equal_range(N4);
+      test_range = data.equal_range(N4);
+      CHECK_EQUAL(std::distance(compare_range.first, compare_range.second), std::distance(test_range.first, test_range.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_count)
+    {
+      Compare_DataNDC compare_data(multi_data.begin(), multi_data.end());
+      DataNDC data(multi_data.begin(), multi_data.end());
+
+      CHECK_EQUAL(compare_data.count(N0), data.count(N0));
+      CHECK_EQUAL(compare_data.count(N1), data.count(N1));
+      CHECK_EQUAL(compare_data.count(N2), data.count(N2));
+      CHECK_EQUAL(compare_data.count(N3), data.count(N3));
+      CHECK_EQUAL(compare_data.count(N4), data.count(N4));
+    }
+  };
+}

test/test_intrusive_flat_set.cpp

@@ -0,0 +1,592 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include <UnitTest++/UnitTest++.h>
+
+#include <set>
+#include <array>
+#include <algorithm>
+#include <utility>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include "data.h"
+
+#include "../src/intrusive_flat_set.h"
+
+namespace
+{
+  static const size_t SIZE = 10;
+
+  typedef TestDataDC<std::string>  DC;
+  typedef TestDataNDC<std::string> NDC;
+
+  typedef etl::intrusive_flat_set<DC, SIZE>  DataDC;
+  typedef etl::intrusive_flat_set<NDC, SIZE> DataNDC;
+  typedef etl::iintrusive_flat_set<NDC>      IDataNDC;
+
+  typedef std::set<DC>  Compare_DataDC;
+  typedef std::set<NDC> Compare_DataNDC;
+
+  NDC NX = NDC("@");
+  NDC NY = NDC("[");
+
+  NDC N0 = NDC("A");
+  NDC N1 = NDC("B");
+  NDC N2 = NDC("C");
+  NDC N3 = NDC("D");
+  NDC N4 = NDC("E");
+  NDC N5 = NDC("F");
+  NDC N6 = NDC("G");
+  NDC N7 = NDC("H");
+  NDC N8 = NDC("I");
+  NDC N9 = NDC("J");
+  NDC N10 = NDC("K");
+  NDC N11 = NDC("L");
+  NDC N12 = NDC("M");
+  NDC N13 = NDC("N");
+  NDC N14 = NDC("O");
+  NDC N15 = NDC("P");
+  NDC N16 = NDC("Q");
+  NDC N17 = NDC("R");
+  NDC N18 = NDC("S");
+  NDC N19 = NDC("T");
+
+  std::vector<NDC> initial_data;
+  std::vector<NDC> excess_data;
+  std::vector<NDC> different_data;
+}
+
+//*************************************************************************
+std::ostream& operator <<(std::ostream& os, const DataDC::iterator& itr)
+{
+  os << itr->value;
+
+  return os;
+}
+
+//*************************************************************************
+std::ostream& operator <<(std::ostream& os, const DataDC::const_iterator& itr)
+{
+  os << itr->value;
+
+  return os;
+}
+
+//*************************************************************************
+std::ostream& operator <<(std::ostream& os, const DataNDC::iterator& itr)
+{
+  os << itr->value;
+
+  return os;
+}
+
+//*************************************************************************
+std::ostream& operator <<(std::ostream& os, const DataNDC::const_iterator& itr)
+{
+  os << itr->value;
+
+  return os;
+}
+
+namespace
+{
+  SUITE(test_flat_set)
+  {
+    //*************************************************************************
+    struct SetupFixture
+    {
+      SetupFixture()
+      {
+        NDC n[] =
+        {
+          N0, N1, N2, N3, N4, N5, N6, N7, N8, N9
+        };
+
+        NDC n2[] =
+        {
+          N0, N1, N2, N3, N4, N5, N6, N7, N8, N9, N10
+        };
+
+        NDC n3[] =
+        {
+          N10, N11, N12, N13, N14, N15, N16, N17, N18, N19
+        };
+
+        initial_data.assign(std::begin(n), std::end(n));
+        excess_data.assign(std::begin(n2), std::end(n2));
+        different_data.assign(std::begin(n3), std::end(n3));
+      }
+    };
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_default_constructor)
+    {
+      DataDC data;
+
+      CHECK_EQUAL(data.size(), size_t(0));
+      CHECK(data.empty());
+      CHECK_EQUAL(data.capacity(), SIZE);
+      CHECK_EQUAL(data.max_size(), SIZE);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_constructor_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK(data.size() == SIZE);
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_begin)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.begin(), std::begin(data));
+      CHECK_EQUAL(constData.begin(), std::begin(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_end)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+      const DataNDC constData(initial_data.begin(), initial_data.end());
+
+      CHECK_EQUAL(data.end(), std::end(data));
+      CHECK_EQUAL(constData.end(), std::end(constData));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_empty)
+    {
+      DataNDC data;
+      data.insert(initial_data.begin(), initial_data.end());
+
+      CHECK(data.full());
+      CHECK(!data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_full)
+    {
+      DataNDC data;
+
+      CHECK(!data.full());
+      CHECK(data.empty());
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_assign_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data;
+
+      data.assign(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                 data.end(),
+                                 compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      isEqual = std::equal(data.begin(),
+                           data.end(),
+                           compare_data.begin());
+
+      CHECK(isEqual);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      std::vector<NDC> test(data.begin(), data.end());
+
+      isEqual = std::equal(data.begin(),
+                           data.end(),
+                           compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_multiple)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      // Do it again.
+      data.insert(N0);
+      compare_data.insert(N0);
+
+      data.insert(N1);
+      compare_data.insert(N1);
+
+      data.insert(N2);
+      compare_data.insert(N2);
+
+      CHECK_EQUAL(compare_data.size(), data.size());
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_value_excess)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      CHECK_THROW(data.insert(N10), etl::intrusive_flat_set_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range)
+    {
+      Compare_DataNDC compare_data;
+      DataNDC data;
+
+      data.insert(initial_data.begin(), initial_data.end());
+      compare_data.insert(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_insert_range_excess)
+    {
+      DataNDC data;
+
+      CHECK_THROW(data.insert(excess_data.begin(), excess_data.end()), etl::intrusive_flat_set_full);
+
+      CHECK(std::is_sorted(data.begin(), data.end()));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_key)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data = data.begin();
+
+      size_t count_compare = compare_data.erase(N5);
+      size_t count         = data.erase(N5);
+
+      CHECK_EQUAL(count_compare, count);
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_single)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      compare_data.erase(i_compare);
+      data.erase(i_data);
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_erase_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.begin();
+      DataNDC::iterator i_data            = data.begin();
+
+      Compare_DataNDC::iterator i_compare_end = compare_data.begin();
+      DataNDC::iterator i_data_end            = data.begin();
+
+      std::advance(i_compare, 2);
+      std::advance(i_data,    2);
+
+      std::advance(i_compare_end, 4);
+      std::advance(i_data_end,    4);
+
+      compare_data.erase(i_compare, i_compare_end);
+      data.erase(i_data, i_data_end);
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_clear)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+      data.clear();
+
+      CHECK_EQUAL(data.size(), size_t(0));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.begin(),
+                                data.end(),
+                                compare_data.begin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.cbegin(),
+                                data.cend(),
+                                compare_data.cbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.rbegin(),
+                                data.rend(),
+                                compare_data.rbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_const_reverse_iterator)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      bool isEqual = std::equal(data.crbegin(),
+                                data.crend(),
+                                compare_data.crbegin());
+
+      CHECK(isEqual);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(N3);
+      CHECK_EQUAL(N3, *it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::iterator it = data.find(NX);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(NY);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(N3);
+      CHECK_EQUAL(N3, *it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_find_const_not_present)
+    {
+      const DataNDC data(initial_data.begin(), initial_data.end());
+
+      DataNDC::const_iterator it = data.find(NX);
+      CHECK_EQUAL(data.end(), it);
+
+      it = data.find(NY);
+      CHECK_EQUAL(data.end(), it);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_lower_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.lower_bound(N5);
+      DataNDC::iterator         i_data    = data.lower_bound(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_upper_bound)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      Compare_DataNDC::iterator i_compare = compare_data.upper_bound(N5);
+      DataNDC::iterator         i_data    = data.upper_bound(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare), std::distance(data.begin(), i_data));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range)
+    {
+      Compare_DataNDC compare_data(initial_data.begin(), initial_data.end());
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<Compare_DataNDC::iterator, Compare_DataNDC::iterator> i_compare = compare_data.equal_range(N5);
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data = data.equal_range(N5);
+
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.first),  std::distance(data.begin(), i_data.first));
+      CHECK_EQUAL(std::distance(compare_data.begin(), i_compare.second), std::distance(data.begin(), i_data.second));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal_range_not_present)
+    {
+      DataNDC data(initial_data.begin(), initial_data.end());
+
+      std::pair<DataNDC::iterator, DataNDC::iterator> i_data;
+
+      i_data = data.equal_range(NX);
+      CHECK_EQUAL(data.begin(),   i_data.first);
+      CHECK_EQUAL(data.begin(), i_data.second);
+
+      i_data = data.equal_range(NY);
+      CHECK_EQUAL(data.end(), i_data.first);
+      CHECK_EQUAL(data.end(), i_data.second);
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(initial1 == initial2);
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(!(initial1 == different));
+    }
+
+    //*************************************************************************
+    TEST_FIXTURE(SetupFixture, test_not_equal)
+    {
+      const DataNDC initial1(initial_data.begin(), initial_data.end());
+      const DataNDC initial2(initial_data.begin(), initial_data.end());
+
+      CHECK(!(initial1 != initial2));
+
+      const DataNDC different(different_data.begin(), different_data.end());
+
+      CHECK(initial1 != different);
+    }
+  };
+}