Containers (STL-compatible) StateMachines MessageBus and more for Embedded Systems. See www.etlcpp.com

Revision:
0:b47c2a7920c2
diff -r 000000000000 -r b47c2a7920c2 multiset.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/multiset.h	Fri Mar 16 16:34:18 2018 +0000
@@ -0,0 +1,2025 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2014 jwellbelove, rlindeman
+
+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_MULTISET__
+#define __ETL_MULTISET__
+
+#include <stddef.h>
+#include <iterator>
+#include <algorithm>
+#include <functional>
+
+#include "platform.h"
+#include "parameter_type.h"
+#include "container.h"
+#include "pool.h"
+#include "exception.h"
+#include "error_handler.h"
+#include "debug_count.h"
+#include "nullptr.h"
+#include "type_traits.h"
+
+#ifdef ETL_COMPILER_MICROSOFT
+#undef min
+#endif
+
+#undef ETL_FILE
+#define ETL_FILE "10"
+
+//*****************************************************************************
+/// A multiset with the capacity defined at compile time.
+///\ingroup containers
+//*****************************************************************************
+
+namespace etl
+{
+  //***************************************************************************
+  /// Exception for the set.
+  ///\ingroup set
+  //***************************************************************************
+  class multiset_exception : public etl::exception
+  {
+  public:
+
+    multiset_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
+      : etl::exception(reason_, file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Full exception for the set.
+  ///\ingroup set
+  //***************************************************************************
+  class multiset_full : public etl::multiset_exception
+  {
+  public:
+
+    multiset_full(string_type file_name_, numeric_type line_number_)
+      : etl::multiset_exception(ETL_ERROR_TEXT("multiset:full", ETL_FILE"A"), file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Map out of bounds exception.
+  ///\ingroup set
+  //***************************************************************************
+  class multiset_out_of_bounds : public etl::multiset_exception
+  {
+  public:
+
+    multiset_out_of_bounds(string_type file_name_, numeric_type line_number_)
+      : etl::multiset_exception(ETL_ERROR_TEXT("multiset:bounds", ETL_FILE"B"), file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Iterator exception for the set.
+  ///\ingroup set
+  //***************************************************************************
+  class multiset_iterator : public etl::multiset_exception
+  {
+  public:
+
+    multiset_iterator(string_type file_name_, numeric_type line_number_)
+      : etl::multiset_exception(ETL_ERROR_TEXT("multiset:iterator", ETL_FILE"C"), file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// The base class for all sets.
+  ///\ingroup set
+  //***************************************************************************
+  class multiset_base
+  {
+  public:
+
+    typedef size_t size_type; ///< The type used for determining the size of set.
+
+    //*************************************************************************
+    /// Gets the size of the set.
+    //*************************************************************************
+    size_type size() const
+    {
+      return current_size;
+    }
+
+    //*************************************************************************
+    /// Gets the maximum possible size of the set.
+    //*************************************************************************
+    size_type max_size() const
+    {
+      return CAPACITY;
+    }
+
+    //*************************************************************************
+    /// Checks to see if the set is empty.
+    //*************************************************************************
+    bool empty() const
+    {
+      return current_size == 0;
+    }
+
+    //*************************************************************************
+    /// Checks to see if the set is full.
+    //*************************************************************************
+    bool full() const
+    {
+      return current_size == CAPACITY;
+    }
+
+    //*************************************************************************
+    /// Returns the capacity of the vector.
+    ///\return The capacity of the vector.
+    //*************************************************************************
+    size_type capacity() const
+    {
+      return CAPACITY;
+    }
+
+    //*************************************************************************
+    /// Returns the remaining capacity.
+    ///\return The remaining capacity.
+    //*************************************************************************
+    size_t available() const
+    {
+      return max_size() - size();
+    }
+
+  protected:
+
+    enum
+    {
+      kLeft,
+      kRight,
+      kNeither
+    };
+
+    //*************************************************************************
+    /// The node element in the multiset.
+    //*************************************************************************
+    struct Node
+    {
+      //***********************************************************************
+      /// Constructor
+      //***********************************************************************
+      Node() :
+        weight(kNeither),
+        dir(kNeither)
+      {
+      }
+
+      //***********************************************************************
+      /// Marks the node as a leaf.
+      //***********************************************************************
+      void mark_as_leaf()
+      {
+        weight = kNeither;
+        dir = kNeither;
+        parent = std::nullptr;
+        children[0] = std::nullptr;
+        children[1] = std::nullptr;
+      }
+
+      Node* parent;
+      Node* children[2];
+      uint_least8_t weight;
+      uint_least8_t dir;
+    };
+
+    //*************************************************************************
+    /// The constructor that is called from derived classes.
+    //*************************************************************************
+    multiset_base(size_type max_size_)
+      : current_size(0)
+      , CAPACITY(max_size_)
+      , root_node(std::nullptr)
+    {
+    }
+
+    //*************************************************************************
+    /// Attach the provided node to the position provided
+    //*************************************************************************
+    void attach_node(Node* parent, Node*& position, Node& node)
+    {
+      // Mark new node as leaf on attach to tree at position provided
+      node.mark_as_leaf();
+
+      // Keep track of this node's parent
+      node.parent = parent;
+
+      // Add the node here
+      position = &node;
+
+      // One more.
+      ++current_size;
+    }
+
+    //*************************************************************************
+    /// Detach the node at the position provided
+    //*************************************************************************
+    void detach_node(Node*& position, Node*& replacement)
+    {
+      // Make temporary copy of actual nodes involved because we might lose
+      // their references in the process (e.g. position is the same as
+      // replacement or replacement is a child of position)
+      Node* detached = position;
+      Node* swap = replacement;
+
+      // Update current position to point to swap (replacement) node first
+      position = swap;
+
+      // Update replacement node to point to child in opposite direction
+      // otherwise we might lose the other child of the swap node
+      replacement = swap->children[1 - swap->dir];
+
+      // Point swap node to detached node's parent, children and weight
+      swap->parent = detached->parent;
+      swap->children[kLeft] = detached->children[kLeft];
+      swap->children[kRight] = detached->children[kRight];
+      if (swap->children[kLeft])
+      {
+        swap->children[kLeft]->parent = swap;
+      }
+      if (swap->children[kRight])
+      {
+        swap->children[kRight]->parent = swap;
+      }
+      swap->weight = detached->weight;
+    }
+
+    //*************************************************************************
+    /// Balance the critical node at the position provided as needed
+    //*************************************************************************
+    void balance_node(Node*& critical_node)
+    {
+      // Step 1: Update weights for all children of the critical node up to the
+      // newly inserted node. This step is costly (in terms of traversing nodes
+      // multiple times during insertion) but doesn't require as much recursion
+      Node* weight_node = critical_node->children[critical_node->dir];
+      while (weight_node)
+      {
+        // Keep going until we reach a terminal node (dir == kNeither)
+        if (kNeither != weight_node->dir)
+        {
+          // Does this insert balance the previous weight factor value?
+          if (weight_node->weight == 1 - weight_node->dir)
+          {
+            weight_node->weight = kNeither;
+          }
+          else
+          {
+            weight_node->weight = weight_node->dir;
+          }
+
+          // Update weight factor node to point to next node
+          weight_node = weight_node->children[weight_node->dir];
+        }
+        else
+        {
+          // Stop loop, terminal node found
+          break;
+        }
+      } // while(weight_node)
+
+        // Step 2: Update weight for critical_node or rotate tree to balance node
+      if (kNeither == critical_node->weight)
+      {
+        critical_node->weight = critical_node->dir;
+      }
+      // If direction is different than weight, then it will now be balanced
+      else if (critical_node->dir != critical_node->weight)
+      {
+        critical_node->weight = kNeither;
+      }
+      // Rotate is required to balance the tree at the critical node
+      else
+      {
+        // If critical node matches child node direction then perform a two
+        // node rotate in the direction of the critical node
+        if (critical_node->weight == critical_node->children[critical_node->dir]->dir)
+        {
+          rotate_2node(critical_node, critical_node->dir);
+        }
+        // Otherwise perform a three node rotation in the direction of the
+        // critical node
+        else
+        {
+          rotate_3node(critical_node, critical_node->dir,
+            critical_node->children[critical_node->dir]->children[1 - critical_node->dir]->dir);
+        }
+      }
+    }
+
+    //*************************************************************************
+    /// Find the node whose key would go before all the other keys from the
+    /// position provided
+    //*************************************************************************
+    Node* find_limit_node(Node* position, const int8_t dir) const
+    {
+      // Something at this position and in the direction specified? keep going
+      Node* limit_node = position;
+      while (limit_node && limit_node->children[dir])
+      {
+        limit_node = limit_node->children[dir];
+      }
+
+      // Return the limit node position found
+      return limit_node;
+    }
+
+    //*************************************************************************
+    /// Find the next node in sequence from the node provided
+    //*************************************************************************
+    void next_node(Node*& position) const
+    {
+      if (position)
+      {
+        // Is there a tree on the right? then find the minimum of that tree
+        if (position->children[kRight])
+        {
+          // Return minimum node found
+          position = find_limit_node(position->children[kRight], kLeft);
+        }
+        // Otherwise find the parent of this node
+        else
+        {
+          // Start with current position as parent
+          Node* parent = position;
+          do {
+            // Update current position as previous parent
+            position = parent;
+            // Find parent of current position
+            parent = position->parent; // find_parent_node(root_node, position);
+                                       // Repeat while previous position was on right side of parent tree
+          } while (parent && parent->children[kRight] == position);
+
+          // Set parent node as the next position
+          position = parent;
+        }
+      }
+    }
+
+    //*************************************************************************
+    /// Find the next node in sequence from the node provided
+    //*************************************************************************
+    void next_node(const Node*& position) const
+    {
+      if (position)
+      {
+        // Is there a tree on the right? then find the minimum of that tree
+        if (position->children[kRight])
+        {
+          // Return minimum node found
+          position = find_limit_node(position->children[kRight], kLeft);
+        }
+        // Otherwise find the parent of this node
+        else
+        {
+          // Start with current position as parent
+          const Node* parent = position;
+          do {
+            // Update current position as previous parent
+            position = parent;
+            // Find parent of current position
+            parent = position->parent;
+            // Repeat while previous position was on right side of parent tree
+          } while (parent && parent->children[kRight] == position);
+
+          // Set parent node as the next position
+          position = parent;
+        }
+      }
+    }
+
+    //*************************************************************************
+    /// Find the previous node in sequence from the node provided
+    //*************************************************************************
+    void prev_node(Node*& position) const
+    {
+      // If starting at the terminal end, the previous node is the maximum node
+      // from the root
+      if (!position)
+      {
+        position = find_limit_node(root_node, kRight);
+      }
+      else
+      {
+        // Is there a tree on the left? then find the maximum of that tree
+        if (position->children[kLeft])
+        {
+          // Return maximum node found
+          position = find_limit_node(position->children[kLeft], kRight);
+        }
+        // Otherwise find the parent of this node
+        else
+        {
+          // Start with current position as parent
+          Node* parent = position;
+          do {
+            // Update current position as previous parent
+            position = parent;
+            // Find parent of current position
+            parent = position->parent;
+            // Repeat while previous position was on left side of parent tree
+          } while (parent && parent->children[kLeft] == position);
+
+          // Set parent node as the next position
+          position = parent;
+        }
+      }
+    }
+
+    //*************************************************************************
+    /// Find the previous node in sequence from the node provided
+    //*************************************************************************
+    void prev_node(const Node*& position) const
+    {
+      // If starting at the terminal end, the previous node is the maximum node
+      // from the root
+      if (!position)
+      {
+        position = find_limit_node(root_node, kRight);
+      }
+      else
+      {
+        // Is there a tree on the left? then find the maximum of that tree
+        if (position->children[kLeft])
+        {
+          // Return maximum node found
+          position = find_limit_node(position->children[kLeft], kRight);
+        }
+        // Otherwise find the parent of this node
+        else
+        {
+          // Start with current position as parent
+          const Node* parent = position;
+          do {
+            // Update current position as previous parent
+            position = parent;
+            // Find parent of current position
+            parent = position->parent;
+            // Repeat while previous position was on left side of parent tree
+          } while (parent && parent->children[kLeft] == position);
+
+          // Set parent node as the next position
+          position = parent;
+        }
+      }
+    }
+
+    //*************************************************************************
+    /// Rotate two nodes at the position provided the to balance the tree
+    //*************************************************************************
+    void rotate_2node(Node*& position, uint_least8_t dir)
+    {
+      //     A            C             A          B
+      //   B   C   ->   A   E   OR    B   C  ->  D   A
+      //      D E      B D           D E            E C
+      // C (new position) becomes the root
+      // A (position) takes ownership of D as its children[kRight] child
+      // C (new position) takes ownership of A as its left child
+      //                 OR
+      // B (new position) becomes the root
+      // A (position) takes ownership of E as its left child
+      // B (new position) takes ownership of A as its right child
+
+      // Capture new root (either B or C depending on dir) and its parent
+      Node* new_root = position->children[dir];
+
+      // Replace position's previous child with new root's other child
+      position->children[dir] = new_root->children[1 - dir];
+      // Update new root's other child parent pointer
+      if (position->children[dir])
+      {
+        position->children[dir]->parent = position;
+      }
+
+      // New root's parent becomes current position's parent
+      new_root->parent = position->parent;
+      new_root->children[1 - dir] = position;
+      new_root->dir = 1 - dir;
+
+      // Clear weight factor from current position
+      position->weight = kNeither;
+      // Position's parent becomes new_root
+      position->parent = new_root;
+      position = new_root;
+      // Clear weight factor from new root
+      position->weight = kNeither;
+    }
+
+    //*************************************************************************
+    /// Rotate three nodes at the position provided the to balance the tree
+    //*************************************************************************
+    void rotate_3node(Node*& position, uint_least8_t dir, uint_least8_t third)
+    {
+      //        __A__             __E__            __A__             __D__
+      //      _B_    C    ->     B     A    OR    B    _C_   ->     A     C
+      //     D   E              D F   G C             D   E        B F   G E
+      //        F G                                  F G
+      // E (new position) becomes the root
+      // B (position) takes ownership of F as its left child
+      // A takes ownership of G as its right child
+      //                  OR
+      // D (new position) becomes the root
+      // A (position) takes ownership of F as its right child
+      // C takes ownership of G as its left child
+
+      // Capture new root (either E or D depending on dir)
+      Node* new_root = position->children[dir]->children[1 - dir];
+      // Set weight factor for B or C based on F or G existing and being a different than dir
+      position->children[dir]->weight = third != kNeither && third != dir ? dir : kNeither;
+
+      // Detach new root from its tree (replace with new roots child)
+      position->children[dir]->children[1 - dir] = new_root->children[dir];
+      // Update new roots child parent pointer
+      if (new_root->children[dir])
+      {
+        new_root->children[dir]->parent = position->children[dir];
+      }
+
+      // Attach current left tree to new root and update its parent
+      new_root->children[dir] = position->children[dir];
+      position->children[dir]->parent = new_root;
+
+      // Set weight factor for A based on F or G
+      position->weight = third != kNeither && third == dir ? 1 - dir : kNeither;
+
+      // Move new root's right tree to current roots left tree
+      position->children[dir] = new_root->children[1 - dir];
+      if (new_root->children[1 - dir])
+      {
+        new_root->children[1 - dir]->parent = position;
+      }
+
+      // Attach current root to new roots right tree and assume its parent
+      new_root->parent = position->parent;
+      new_root->children[1 - dir] = position;
+      new_root->dir = 1 - dir;
+
+      // Update current position's parent and replace with new root
+      position->parent = new_root;
+      position = new_root;
+      // Clear weight factor for new current position
+      position->weight = kNeither;
+    }
+
+    size_type current_size;   ///< The number of the used nodes.
+    const size_type CAPACITY; ///< The maximum size of the set.
+    Node* root_node;          ///< The node that acts as the multiset root.
+    etl::debug_count construct_count;
+  };
+
+  //***************************************************************************
+  /// A templated base for all etl::multiset types.
+  ///\ingroup set
+  //***************************************************************************
+  template <typename T, typename TCompare>
+  class imultiset : public etl::multiset_base
+  {
+  public:
+
+    typedef const T                        key_type;
+    typedef const T                        value_type;
+    typedef TCompare                       key_compare;
+    typedef TCompare                       value_compare;
+    typedef value_type&                    const_reference;
+    typedef value_type*                    const_pointer;
+    typedef size_t                         size_type;
+
+    //*************************************************************************
+    /// How to compare two key elements.
+    //*************************************************************************
+    struct key_comp
+    {
+      bool operator ()(key_type& key1, key_type& key2) const
+      {
+        return key_compare()(key1, key2);
+      }
+    };
+
+    //*************************************************************************
+    /// How to compare two value elements.
+    //*************************************************************************
+    struct value_comp
+    {
+      bool operator ()(value_type& value1, value_type& value2) const
+      {
+        return value_compare()(value1, value2);
+      }
+    };
+
+  protected:
+
+    //*************************************************************************
+    /// The data node element in the multiset.
+    //*************************************************************************
+    struct Data_Node : public Node
+    {
+      explicit Data_Node(value_type value_)
+        : value(value_)
+      {
+      }
+
+      value_type value;
+    };
+
+    /// Defines the key value parameter type
+    typedef typename etl::parameter_type<T>::type key_parameter_t;
+
+    //*************************************************************************
+    /// How to compare node elements.
+    //*************************************************************************
+    bool node_comp(const Data_Node& node1, const Data_Node& node2) const
+    {
+      return key_compare()(node1.value, node2.value);
+    }
+    bool node_comp(const Data_Node& node, key_parameter_t key) const
+    {
+      return key_compare()(node.value, key);
+    }
+    bool node_comp(key_parameter_t key, const Data_Node& node) const
+    {
+      return key_compare()(key, node.value);
+    }
+
+  private:
+
+    /// The pool of data nodes used in the multiset.
+    ipool* p_node_pool;
+
+    //*************************************************************************
+    /// Downcast a Node* to a Data_Node*
+    //*************************************************************************
+    static Data_Node* data_cast(Node* p_node)
+    {
+      return static_cast<Data_Node*>(p_node);
+    }
+
+    //*************************************************************************
+    /// Downcast a Node& to a Data_Node&
+    //*************************************************************************
+    static Data_Node& data_cast(Node& node)
+    {
+      return static_cast<Data_Node&>(node);
+    }
+
+    //*************************************************************************
+    /// Downcast a const Node* to a const Data_Node*
+    //*************************************************************************
+    static const Data_Node* data_cast(const Node* p_node)
+    {
+      return static_cast<const Data_Node*>(p_node);
+    }
+
+    //*************************************************************************
+    /// Downcast a const Node& to a const Data_Node&
+    //*************************************************************************
+    static const Data_Node& data_cast(const Node& node)
+    {
+      return static_cast<const Data_Node&>(node);
+    }
+
+  public:
+    //*************************************************************************
+    /// iterator.
+    //*************************************************************************
+    class iterator : public std::iterator<std::bidirectional_iterator_tag, value_type>
+    {
+    public:
+
+      friend class imultiset;
+
+      iterator()
+        : p_multiset(std::nullptr)
+        , p_node(std::nullptr)
+      {
+      }
+
+      iterator(imultiset& multiset)
+        : p_multiset(&multiset)
+        , p_node(std::nullptr)
+      {
+      }
+
+      iterator(imultiset& multiset, Node* node)
+        : p_multiset(&multiset)
+        , p_node(node)
+      {
+      }
+
+      iterator(const iterator& other)
+        : p_multiset(other.p_multiset)
+        , p_node(other.p_node)
+      {
+      }
+
+      ~iterator()
+      {
+      }
+
+      iterator& operator ++()
+      {
+        p_multiset->next_node(p_node);
+        return *this;
+      }
+
+      iterator operator ++(int)
+      {
+        iterator temp(*this);
+        p_multiset->next_node(p_node);
+        return temp;
+      }
+
+      iterator& operator --()
+      {
+        p_multiset->prev_node(p_node);
+        return *this;
+      }
+
+      iterator operator --(int)
+      {
+        iterator temp(*this);
+        p_multiset->prev_node(p_node);
+        return temp;
+      }
+
+      iterator operator =(const iterator& other)
+      {
+        p_multiset = other.p_multiset;
+        p_node = other.p_node;
+        return *this;
+      }
+
+      const_reference operator *() const
+      {
+        return imultiset::data_cast(p_node)->value;
+      }
+
+      const_pointer operator &() const
+      {
+        return &(imultiset::data_cast(p_node)->value);
+      }
+
+      const_pointer operator ->() const
+      {
+        return &(imultiset::data_cast(p_node)->value);
+      }
+
+      friend bool operator == (const iterator& lhs, const iterator& rhs)
+      {
+        return lhs.p_multiset == rhs.p_multiset && lhs.p_node == rhs.p_node;
+      }
+
+      friend bool operator != (const iterator& lhs, const iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+
+      // Pointer to multiset associated with this iterator
+      imultiset* p_multiset;
+
+      // Pointer to the current node for this iterator
+      Node* p_node;
+    };
+    friend class iterator;
+
+    //*************************************************************************
+    /// const_iterator
+    //*************************************************************************
+    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const value_type>
+    {
+    public:
+
+      friend class imultiset;
+
+      const_iterator()
+        : p_multiset(std::nullptr)
+        , p_node(std::nullptr)
+      {
+      }
+
+      const_iterator(const imultiset& multiset)
+        : p_multiset(&multiset)
+        , p_node(std::nullptr)
+      {
+      }
+
+      const_iterator(const imultiset& multiset, const Node* node)
+        : p_multiset(&multiset)
+        , p_node(node)
+      {
+      }
+
+      const_iterator(const typename imultiset::iterator& other)
+        : p_multiset(other.p_multiset)
+        , p_node(other.p_node)
+      {
+      }
+
+      const_iterator(const const_iterator& other)
+        : p_multiset(other.p_multiset)
+        , p_node(other.p_node)
+      {
+      }
+
+      ~const_iterator()
+      {
+      }
+
+      const_iterator& operator ++()
+      {
+        p_multiset->next_node(p_node);
+        return *this;
+      }
+
+      const_iterator operator ++(int)
+      {
+        const_iterator temp(*this);
+        p_multiset->next_node(p_node);
+        return temp;
+      }
+
+      const_iterator& operator --()
+      {
+        p_multiset->prev_node(p_node);
+        return *this;
+      }
+
+      const_iterator operator --(int)
+      {
+        const_iterator temp(*this);
+        p_multiset->prev_node(p_node);
+        return temp;
+      }
+
+      const_iterator operator =(const const_iterator& other)
+      {
+        p_multiset = other.p_multiset;
+        p_node = other.p_node;
+        return *this;
+      }
+
+      const_reference operator *() const
+      {
+        return imultiset::data_cast(p_node)->value;
+      }
+
+      const_pointer operator &() const
+      {
+        return imultiset::data_cast(p_node)->value;
+      }
+
+      const_pointer operator ->() const
+      {
+        return &(imultiset::data_cast(p_node)->value);
+      }
+
+      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return lhs.p_multiset == rhs.p_multiset && lhs.p_node == rhs.p_node;
+      }
+
+      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
+      {
+        return !(lhs == rhs);
+      }
+
+    private:
+      // Pointer to multiset associated with this iterator
+      const imultiset* p_multiset;
+
+      // Pointer to the current node for this iterator
+      const Node* p_node;
+    };
+    friend class const_iterator;
+
+    typedef typename std::iterator_traits<iterator>::difference_type difference_type;
+
+    typedef std::reverse_iterator<iterator>       reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+
+
+    //*************************************************************************
+    /// Gets the beginning of the multiset.
+    //*************************************************************************
+    iterator begin()
+    {
+      return iterator(*this, find_limit_node(root_node, kLeft));
+    }
+
+    //*************************************************************************
+    /// Gets the beginning of the multiset.
+    //*************************************************************************
+    const_iterator begin() const
+    {
+      return const_iterator(*this, find_limit_node(root_node, kLeft));
+    }
+
+    //*************************************************************************
+    /// Gets the end of the multiset.
+    //*************************************************************************
+    iterator end()
+    {
+      return iterator(*this);
+    }
+
+    //*************************************************************************
+    /// Gets the end of the multiset.
+    //*************************************************************************
+    const_iterator end() const
+    {
+      return const_iterator(*this);
+    }
+
+    //*************************************************************************
+    /// Gets the beginning of the multiset.
+    //*************************************************************************
+    const_iterator cbegin() const
+    {
+      return const_iterator(*this, find_limit_node(root_node, kLeft));
+    }
+
+    //*************************************************************************
+    /// Gets the end of the multiset.
+    //*************************************************************************
+    const_iterator cend() const
+    {
+      return const_iterator(*this);
+    }
+
+    //*************************************************************************
+    /// Gets the reverse beginning of the list.
+    //*************************************************************************
+    reverse_iterator rbegin()
+    {
+      return reverse_iterator(iterator(*this));
+    }
+
+    //*************************************************************************
+    /// Gets the reverse beginning of the list.
+    //*************************************************************************
+    const_reverse_iterator rbegin() const
+    {
+      return const_reverse_iterator(const_iterator(*this));
+    }
+
+    //*************************************************************************
+    /// Gets the reverse end of the list.
+    //*************************************************************************
+    reverse_iterator rend()
+    {
+      return reverse_iterator(iterator(*this, find_limit_node(root_node, kLeft)));
+    }
+
+    //*************************************************************************
+    /// Gets the reverse end of the list.
+    //*************************************************************************
+    const_reverse_iterator rend() const
+    {
+      return const_reverse_iterator(iterator(*this, find_limit_node(root_node, kLeft)));
+    }
+
+    //*************************************************************************
+    /// Gets the reverse beginning of the list.
+    //*************************************************************************
+    const_reverse_iterator crbegin() const
+    {
+      return const_reverse_iterator(const_iterator(*this));
+    }
+
+    //*************************************************************************
+    /// Gets the reverse end of the list.
+    //*************************************************************************
+    const_reverse_iterator crend() const
+    {
+      return const_reverse_iterator(const_iterator(*this, find_limit_node(root_node, kLeft)));
+    }
+
+    //*********************************************************************
+    /// Assigns values to the multiset.
+    /// If asserts or exceptions are enabled, emits set_full if the multiset does not have enough free space.
+    /// If asserts or exceptions are enabled, emits 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)
+    {
+      initialise();
+      insert(first, last);
+    }
+
+    //*************************************************************************
+    /// Clears the multiset.
+    //*************************************************************************
+    void clear()
+    {
+      initialise();
+    }
+
+    //*********************************************************************
+    /// Counts the number of elements that contain the key specified.
+    ///\param key The key to search for.
+    ///\return 1 if element was found, 0 otherwise.
+    //*********************************************************************
+    size_type count(key_parameter_t key) const
+    {
+      return count_nodes(key);
+    }
+
+    //*************************************************************************
+    /// Returns two iterators with bounding (lower bound, upper bound) the key
+    /// provided
+    //*************************************************************************
+    std::pair<iterator, iterator> equal_range(const value_type& key)
+    {
+      return std::make_pair<iterator, iterator>(
+        iterator(*this, find_lower_node(root_node, key)),
+        iterator(*this, find_upper_node(root_node, key)));
+    }
+
+    //*************************************************************************
+    /// Returns two const iterators with bounding (lower bound, upper bound)
+    /// the key provided.
+    //*************************************************************************
+    std::pair<const_iterator, const_iterator> equal_range(const value_type& key) const
+    {
+      return std::make_pair<const_iterator, const_iterator>(
+        const_iterator(*this, find_lower_node(root_node, key)),
+        const_iterator(*this, find_upper_node(root_node, key)));
+    }
+
+    //*************************************************************************
+    /// Erases the value at the specified position.
+    //*************************************************************************
+    void erase(iterator position)
+    {
+      // Remove the node by its node specified in iterator position
+      (void)erase(const_iterator(position));
+    }
+
+    //*************************************************************************
+    /// Erases the value at the specified position.
+    //*************************************************************************
+    iterator erase(const_iterator position)
+    {
+      // Cast const away from node to be removed. This is necessary because the
+      // STL definition of this method requires we provide the next node in the
+      // sequence as an iterator.
+      Node* node = const_cast<Node*>(position.p_node);
+      iterator next(*this, node);
+      ++next;
+
+      // Remove the non-const node provided
+      remove_node(node);
+
+      return next;
+    }
+
+    //*************************************************************************
+    // Erase the key specified.
+    //*************************************************************************
+    size_type erase(key_parameter_t key_value)
+    {
+      // Number of nodes removed
+      size_type d = 0;
+      const_iterator lower(*this, find_lower_node(root_node, key_value));
+      const_iterator upper(*this, find_upper_node(root_node, key_value));
+      while (lower != upper)
+      {
+        // Increment count for each node removed
+        ++d;
+        // Remove node using the other erase method
+        (void)erase(lower++);
+      }
+
+      // Return the total count erased
+      return d;
+    }
+
+    //*************************************************************************
+    /// Erases a range of elements.
+    //*************************************************************************
+    iterator erase(iterator first, iterator last)
+    {
+      iterator next;
+      while (first != last)
+      {
+        next = erase(const_iterator(first++));
+      }
+
+      return next;
+    }
+
+    //*************************************************************************
+    /// Erases a range of elements.
+    //*************************************************************************
+    iterator erase(const_iterator first, const_iterator last)
+    {
+      iterator next;
+      while (first != last)
+      {
+        next = erase(first++);
+      }
+
+      return next;
+    }
+
+    //*********************************************************************
+    /// 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_parameter_t key_value)
+    {
+      return iterator(*this, find_node(root_node, key_value));
+    }
+
+    //*********************************************************************
+    /// 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_parameter_t key_value) const
+    {
+      return const_iterator(*this, find_node(root_node, key_value));
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the multiset.
+    /// If asserts or exceptions are enabled, emits set_full if the multiset is already full.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(const value_type& value)
+    {
+      // Default to no inserted node
+      Node* inserted_node = std::nullptr;
+
+      ETL_ASSERT(!full(), ETL_ERROR(multiset_full));
+
+      // Get next available free node
+      Data_Node& node = allocate_data_node(value);
+
+      // Obtain the inserted node (might be std::nullptr if node was a duplicate)
+      inserted_node = insert_node(root_node, node);
+
+      // Insert node into tree and return iterator to new node location in tree
+      return iterator(*this, inserted_node);
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the multiset starting at the position recommended.
+    /// If asserts or exceptions are enabled, emits set_full if the multiset is already full.
+    ///\param position The position that would precede the value to insert.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(iterator /*position*/, const value_type& value)
+    {
+      // Ignore position provided and just do a normal insert
+      return insert(value);
+    }
+
+    //*********************************************************************
+    /// Inserts a value to the multiset starting at the position recommended.
+    /// If asserts or exceptions are enabled, emits set_full if the multiset is already full.
+    ///\param position The position that would precede the value to insert.
+    ///\param value    The value to insert.
+    //*********************************************************************
+    iterator insert(const_iterator /*position*/, const value_type& value)
+    {
+      // Ignore position provided and just do a normal insert
+      return insert(value);
+    }
+
+    //*********************************************************************
+    /// Inserts a range of values to the multiset.
+    /// If asserts or exceptions are enabled, emits set_full if the 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++);
+      }
+    }
+
+    //*********************************************************************
+    /// Returns an iterator pointing to the first element in the container
+    /// whose key is not considered to go before the key provided or end()
+    /// if all keys are considered to go before the key provided.
+    ///\return An iterator pointing to the element not before key or end()
+    //*********************************************************************
+    iterator lower_bound(key_parameter_t key)
+    {
+      return iterator(*this, find_lower_node(root_node, key));
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator pointing to the first element in the
+    /// container whose key is not considered to go before the key provided
+    /// or end() if all keys are considered to go before the key provided.
+    ///\return An const_iterator pointing to the element not before key or end()
+    //*********************************************************************
+    const_iterator lower_bound(key_parameter_t key) const
+    {
+      return const_iterator(*this, find_lower_node(root_node, key));
+    }
+
+    //*********************************************************************
+    /// Returns an iterator pointing to the first element in the container
+    /// whose key is not considered to go after the key provided or end()
+    /// if all keys are considered to go after the key provided.
+    ///\return An iterator pointing to the element after key or end()
+    //*********************************************************************
+    iterator upper_bound(key_parameter_t key)
+    {
+      return iterator(*this, find_upper_node(root_node, key));
+    }
+
+    //*********************************************************************
+    /// Returns a const_iterator pointing to the first element in the
+    /// container whose key is not considered to go after the key provided
+    /// or end() if all keys are considered to go after the key provided.
+    ///\return An const_iterator pointing to the element after key or end()
+    //*********************************************************************
+    const_iterator upper_bound(key_parameter_t key) const
+    {
+      return const_iterator(*this, find_upper_node(root_node, key));
+    }
+
+    //*************************************************************************
+    /// Assignment operator.
+    //*************************************************************************
+    imultiset& operator = (const imultiset& rhs)
+    {
+      // Skip if doing self assignment
+      if (this != &rhs)
+      {
+        assign(rhs.cbegin(), rhs.cend());
+      }
+
+      return *this;
+    }
+
+  protected:
+
+    //*************************************************************************
+    /// Constructor.
+    //*************************************************************************
+    imultiset(etl::ipool& node_pool, size_t max_size_)
+      : etl::multiset_base(max_size_)
+      , p_node_pool(&node_pool)
+    {
+    }
+
+    //*************************************************************************
+    /// Initialise the multiset.
+    //*************************************************************************
+    void initialise()
+    {
+      erase(begin(), end());
+    }
+
+  private:
+
+    //*************************************************************************
+    /// Allocate a Data_Node.
+    //*************************************************************************
+    Data_Node& allocate_data_node(value_type value)
+    {
+      Data_Node& node = *p_node_pool->allocate<Data_Node>();
+      ::new ((void*)&node.value) value_type(value);
+      ++construct_count;
+      return node;
+    }
+
+    //*************************************************************************
+    /// Destroy a Data_Node.
+    //*************************************************************************
+    void destroy_data_node(Data_Node& node)
+    {
+      node.value.~value_type();
+      p_node_pool->release(&node);
+      --construct_count;
+    }
+
+    //*************************************************************************
+    /// Count the nodes that match the key provided
+    //*************************************************************************
+    size_type count_nodes(key_parameter_t key) const
+    {
+      // Number of nodes that match the key provided result
+      size_type result = 0;
+
+      // Find lower and upper nodes for the key provided
+      const Node* lower = find_lower_node(root_node, key);
+      const Node* upper = find_upper_node(root_node, key);
+
+      // Loop from lower node to upper node and find nodes that match
+      while (lower != upper)
+      {
+        // Downcast found to Data_Node class for comparison and other operations
+        const Data_Node& data_node = imultiset::data_cast(*lower);
+
+        if (!node_comp(key, data_node) && !node_comp(data_node, key))
+        {
+          // This node matches the key provided
+          ++result;
+        }
+
+        // Move on to the next node
+        next_node(lower);
+      }
+
+      // Return the number of nodes that match
+      return result;
+    }
+
+    //*************************************************************************
+    /// Find the value matching the node provided
+    //*************************************************************************
+    Node* find_node(Node* position, key_parameter_t key) const
+    {
+      Node* found = std::nullptr;
+      while (position)
+      {
+        // Downcast found to Data_Node class for comparison and other operations
+        Data_Node& data_node = imultiset::data_cast(*position);
+        // Compare the node value to the current position value
+        if (node_comp(key, data_node))
+        {
+          // Keep searching for the node on the left
+          position = position->children[kLeft];
+        }
+        else if (node_comp(data_node, key))
+        {
+          // Keep searching for the node on the right
+          position = position->children[kRight];
+        }
+        else
+        {
+          // We found one, keep looking for more on the left
+          found = position;
+          position = position->children[kLeft];
+        }
+      }
+
+      // Return the node found (might be std::nullptr)
+      return found;
+    }
+
+    //*************************************************************************
+    /// Find the value matching the node provided
+    //*************************************************************************
+    const Node* find_node(const Node* position, key_parameter_t key) const
+    {
+      const Node* found = std::nullptr;
+      while (position)
+      {
+        // Downcast found to Data_Node class for comparison and other operations
+        const Data_Node& data_node = imultiset::data_cast(*position);
+        // Compare the node value to the current position value
+        if (node_comp(key, data_node))
+        {
+          // Keep searching for the node on the left
+          position = position->children[kLeft];
+        }
+        else if (node_comp(data_node, key))
+        {
+          // Keep searching for the node on the right
+          position = position->children[kRight];
+        }
+        else
+        {
+          // We found one, keep looking for more on the left
+          found = position;
+          position = position->children[kLeft];
+        }
+      }
+
+      // Return the node found (might be std::nullptr)
+      return found;
+    }
+
+    //*************************************************************************
+    /// Find the node whose key is not considered to go before the key provided
+    //*************************************************************************
+    Node* find_lower_node(Node* position, key_parameter_t key) const
+    {
+      // Something at this position? keep going
+      Node* lower_node = std::nullptr;
+      while (position)
+      {
+        // Downcast lower node to Data_Node reference for key comparisons
+        Data_Node& data_node = imultiset::data_cast(*position);
+        // Compare the key value to the current lower node key value
+        if (node_comp(key, data_node))
+        {
+          lower_node = position;
+          if (position->children[kLeft])
+          {
+            position = position->children[kLeft];
+          }
+          else
+          {
+            // Found lowest node
+            break;
+          }
+        }
+        else if (node_comp(data_node, key))
+        {
+          position = position->children[kRight];
+        }
+        else
+        {
+          // Make note of current position, but keep looking to left for more
+          lower_node = position;
+          position = position->children[kLeft];
+        }
+      }
+
+      // Return the lower_node position found
+      return lower_node;
+    }
+
+    //*************************************************************************
+    /// Find the node whose key is considered to go after the key provided
+    //*************************************************************************
+    Node* find_upper_node(Node* position, key_parameter_t key) const
+    {
+      // Keep track of parent of last upper node
+      Node* upper_node = std::nullptr;
+      // Has an equal node been found? start with no
+      bool found = false;
+      while (position)
+      {
+        // Downcast position to Data_Node reference for key comparisons
+        Data_Node& data_node = imultiset::data_cast(*position);
+        // Compare the key value to the current upper node key value
+        if (node_comp(data_node, key))
+        {
+          position = position->children[kRight];
+        }
+        else if (node_comp(key, data_node))
+        {
+          upper_node = position;
+          // If a node equal to key hasn't been found go left
+          if (!found && position->children[kLeft])
+          {
+            position = position->children[kLeft];
+          }
+          else
+          {
+            break;
+          }
+        }
+        else
+        {
+          // We found an equal item, break on next bigger item
+          found = true;
+          next_node(position);
+        }
+      }
+
+      // Return the upper node position found (might be std::nullptr)
+      return upper_node;
+    }
+
+    //*************************************************************************
+    /// Insert a node.
+    //*************************************************************************
+    Node* insert_node(Node*& position, Data_Node& node)
+    {
+      // Find the location where the node belongs
+      Node* found = position;
+
+      // Was position provided not empty? then find where the node belongs
+      if (position)
+      {
+        // Find the critical parent node (default to std::nullptr)
+        Node* critical_parent_node = std::nullptr;
+        Node* critical_node = root_node;
+
+        while (found)
+        {
+          // Search for critical weight node (all nodes whose weight factor
+          // is set to kNeither (balanced)
+          if (kNeither != found->weight)
+          {
+            critical_node = found;
+          }
+
+          // Downcast found to Data_Node class for comparison and other operations
+          Data_Node& found_data_node = imultiset::data_cast(*found);
+
+          // Is the node provided to the left of the current position?
+          if (node_comp(node, found_data_node))
+          {
+            // Update direction taken to insert new node in parent node
+            found->dir = kLeft;
+          }
+          // Is the node provided to the right of the current position?
+          else if (node_comp(found_data_node, node))
+          {
+            // Update direction taken to insert new node in parent node
+            found->dir = kRight;
+          }
+          else
+          {
+            // Update direction taken to insert new node in parent (and
+            // duplicate) node to the right.
+            found->dir = kRight;
+          }
+
+          // Is there a child of this parent node?
+          if (found->children[found->dir])
+          {
+            // Will this node be the parent of the next critical node whose
+            // weight factor is set to kNeither (balanced)?
+            if (kNeither != found->children[found->dir]->weight)
+            {
+              critical_parent_node = found;
+            }
+
+            // Keep looking for empty spot to insert new node
+            found = found->children[found->dir];
+          }
+          else
+          {
+            // Attach node as a child of the parent node found
+            attach_node(found, found->children[found->dir], node);
+
+            // Return newly added node
+            found = found->children[found->dir];
+
+            // Exit loop
+            break;
+          }
+        }
+
+        // Was a critical node found that should be checked for balance?
+        if (critical_node)
+        {
+          if (critical_parent_node == std::nullptr && critical_node == root_node)
+          {
+            balance_node(root_node);
+          }
+          else if (critical_parent_node == std::nullptr && critical_node == position)
+          {
+            balance_node(position);
+          }
+          else
+          {
+            balance_node(critical_parent_node->children[critical_parent_node->dir]);
+          }
+        }
+      }
+      else
+      {
+        // Attatch node to current position (which is assumed to be root)
+        attach_node(std::nullptr, position, node);
+
+        // Return newly added node at current position
+        found = position;
+      }
+
+      // Return the node found (might be std::nullptr)
+      return found;
+    }
+
+    //*************************************************************************
+    /// Remove the node specified from somewhere starting at the position
+    /// provided
+    //*************************************************************************
+    void remove_node(Node* node)
+    {
+      // If valid found node was provided then proceed with steps 1 through 5
+      if (node)
+      {
+        // Downcast found node provided to Data_Node class
+        Data_Node& data_node = imultiset::data_cast(*node);
+
+        // Keep track of node as found node
+        Node* found = node;
+
+        // Step 1: Mark path from node provided back to the root node using the
+        // internal temporary dir member value and using the parent pointer. This
+        // will allow us to avoid recursion in finding the node in a tree that
+        //might contain duplicate keys to be found.
+        while (node)
+        {
+          if (node->parent)
+          {
+            // Which direction does parent use to get to this node?
+            node->parent->dir =
+              node->parent->children[kLeft] == node ? kLeft : kRight;
+
+            // Make this nodes parent the next node
+            node = node->parent;
+          }
+          else
+          {
+            // Root node found - break loop
+            break;
+          }
+        }
+
+        // Step 2: Follow the path provided above until we reach the node
+        // provided and look for the balance node to start rebalancing the tree
+        // from (up to the replacement node that will be found in step 3)
+        Node* balance = root_node;
+        while (node)
+        {
+          // Did we reach the node provided originally (found) then go to step 3
+          if (node == found)
+          {
+            // Update the direction towards a replacement node at the found node
+            node->dir = node->children[kLeft] ? kLeft : kRight;
+
+            // Exit loop and proceed with step 3
+            break;
+          }
+          else
+          {
+            // If this nodes weight is kNeither or we are taking the shorter path
+            // to the next node and our sibling (on longer path) is balanced then
+            // we need to update the balance node to this node but all our
+            // ancestors will not require rebalancing
+            if ((node->weight == kNeither) ||
+              (node->weight == (1 - node->dir) &&
+                node->children[1 - node->dir]->weight == kNeither))
+            {
+              // Update balance node to this node
+              balance = node;
+            }
+
+            // Keep searching for found in the direction provided in step 1
+            node = node->children[node->dir];
+          }
+        }
+        // The value for node should not be std::nullptr at this point otherwise
+        // step 1 failed to provide the correct path to found. Step 5 will fail
+        // (probably subtly) if node should be std::nullptr at this point
+
+        // Step 3: Find the node (node should be equal to found at this point)
+        // to replace found with (might end up equal to found) while also
+        // continuing to update balance the same as in step 2 above.
+        while (node)
+        {
+          // Replacement node found if its missing a child in the replace->dir
+          // value set at the end of step 2 above
+          if (node->children[node->dir] == std::nullptr)
+          {
+            // Exit loop once node to replace found is determined
+            break;
+          }
+
+          // If this nodes weight is kNeither or we are taking the shorter path
+          // to the next node and our sibling (on longer path) is balanced then
+          // we need to update the balance node to this node but all our
+          // ancestors will not require rebalancing
+          if ((node->weight == kNeither) ||
+            (node->weight == (1 - node->dir) &&
+              node->children[1 - node->dir]->weight == kNeither))
+          {
+            // Update balance node to this node
+            balance = node;
+          }
+
+          // Keep searching for replacement node in the direction specified above
+          node = node->children[node->dir];
+
+          // Downcast node to Data_Node class for comparison operations
+          Data_Node& replace_data_node = imultiset::data_cast(*node);
+
+          // Compare the key provided to the replace data node key
+          if (node_comp(data_node, replace_data_node))
+          {
+            // Update the direction to the replace node
+            node->dir = kLeft;
+          }
+          else if (node_comp(replace_data_node, data_node))
+          {
+            // Update the direction to the replace node
+            node->dir = kRight;
+          }
+          else
+          {
+            // Update the direction to the replace node
+            node->dir = node->children[kLeft] ? kLeft : kRight;
+          }
+        } // while(node)
+
+          // Step 4: Update weights from balance to parent of node determined
+          // in step 3 above rotating (2 or 3 node rotations) as needed.
+        while (balance)
+        {
+          // Break when balance node reaches the parent of replacement node
+          if (balance->children[balance->dir] == std::nullptr)
+          {
+            break;
+          }
+
+          // If balance node is balanced already (kNeither) then just imbalance
+          // the node in the opposite direction of the node being removed
+          if (balance->weight == kNeither)
+          {
+            balance->weight = 1 - balance->dir;
+          }
+          // If balance node is imbalanced in the opposite direction of the
+          // node being removed then the node now becomes balanced
+          else if (balance->weight == balance->dir)
+          {
+            balance->weight = kNeither;
+          }
+          // Otherwise a rotation is required at this node
+          else
+          {
+            int weight = balance->children[1 - balance->dir]->weight;
+            // Perform a 3 node rotation if weight is same as balance->dir
+            if (weight == balance->dir)
+            {
+              // Is the root node being rebalanced (no parent)
+              if (balance->parent == std::nullptr)
+              {
+                rotate_3node(root_node, 1 - balance->dir,
+                  balance->children[1 - balance->dir]->children[balance->dir]->weight);
+              }
+              else
+              {
+                rotate_3node(balance->parent->children[balance->parent->dir], 1 - balance->dir,
+                  balance->children[1 - balance->dir]->children[balance->dir]->weight);
+              }
+            }
+            // Already balanced, rebalance and make it heavy in opposite
+            // direction of the node being removed
+            else if (weight == kNeither)
+            {
+              // Is the root node being rebalanced (no parent)
+              if (balance->parent == std::nullptr)
+              {
+                rotate_2node(root_node, 1 - balance->dir);
+                root_node->weight = balance->dir;
+              }
+              else
+              {
+                // Balance parent might change during rotate, keep local copy
+                // to old parent so its weight can be updated after the 2 node
+                // rotate is completed
+                Node* old_parent = balance->parent;
+                rotate_2node(balance->parent->children[balance->parent->dir], 1 - balance->dir);
+                old_parent->children[old_parent->dir]->weight = balance->dir;
+              }
+              // Update balance node weight in opposite direction of node removed
+              balance->weight = 1 - balance->dir;
+            }
+            // Rebalance and leave it balanced
+            else
+            {
+              // Is the root node being rebalanced (no parent)
+              if (balance->parent == std::nullptr)
+              {
+                rotate_2node(root_node, 1 - balance->dir);
+              }
+              else
+              {
+                rotate_2node(balance->parent->children[balance->parent->dir], 1 - balance->dir);
+              }
+            }
+          }
+
+          // Next balance node to consider
+          balance = balance->children[balance->dir];
+        } // while(balance)
+
+          // Step 5: Swap found with node (replacement)
+        if (found->parent)
+        {
+          // Handle traditional case
+          detach_node(found->parent->children[found->parent->dir],
+            node->parent->children[node->parent->dir]);
+        }
+        // Handle root node removal
+        else
+        {
+          // Valid replacement node for root node being removed?
+          if (node->parent)
+          {
+            detach_node(root_node, node->parent->children[node->parent->dir]);
+          }
+          else
+          {
+            // Found node and replacement node are both root node
+            detach_node(root_node, root_node);
+          }
+        }
+
+        // One less.
+        --current_size;
+
+        // Destroy the node detached above
+        destroy_data_node(data_node);
+      } // if(found)
+    }
+
+    // Disable copy construction.
+    imultiset(const imultiset&);
+  };
+
+  //*************************************************************************
+  /// A templated multiset implementation that uses a fixed size buffer.
+  //*************************************************************************
+  template <typename T, const size_t MAX_SIZE_, typename TCompare = std::less<T> >
+  class multiset : public etl::imultiset<T, TCompare>
+  {
+  public:
+
+    static const size_t MAX_SIZE = MAX_SIZE_;
+
+    //*************************************************************************
+    /// Default constructor.
+    //*************************************************************************
+    multiset()
+      : etl::imultiset<T, TCompare>(node_pool, MAX_SIZE)
+    {
+      etl::imultiset<T, TCompare>::initialise();
+    }
+
+    //*************************************************************************
+    /// Copy constructor.
+    //*************************************************************************
+    multiset(const multiset& other)
+      : etl::imultiset<T, TCompare>(node_pool, MAX_SIZE)
+    {
+      etl::imultiset<T, 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>
+    multiset(TIterator first, TIterator last)
+      : etl::imultiset<T, TCompare>(node_pool, MAX_SIZE)
+    {
+      etl::imultiset<T, TCompare>::assign(first, last);
+    }
+
+    //*************************************************************************
+    /// Destructor.
+    //*************************************************************************
+    ~multiset()
+    {
+      etl::imultiset<T, TCompare>::initialise();
+    }
+
+    //*************************************************************************
+    /// Assignment operator.
+    //*************************************************************************
+    multiset& operator = (const multiset& rhs)
+    {
+      // Skip if doing self assignment
+      if (this != &rhs)
+      {
+        etl::imultiset<T, TCompare>::assign(rhs.cbegin(), rhs.cend());
+      }
+
+      return *this;
+    }
+
+  private:
+
+    /// The pool of data nodes used for the multiset.
+    etl::pool<typename etl::imultiset<T, TCompare>::Data_Node, MAX_SIZE> node_pool;
+  };
+}
+
+//***************************************************************************
+/// Equal operator.
+///\param lhs Reference to the first lookup.
+///\param rhs Reference to the second lookup.
+///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
+///\ingroup lookup
+//***************************************************************************
+template <typename T, typename TCompare>
+bool operator ==(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return (lhs.size() == rhs.size()) && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+}
+
+//***************************************************************************
+/// Not equal operator.
+///\param lhs Reference to the first lookup.
+///\param rhs Reference to the second lookup.
+///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
+///\ingroup lookup
+//***************************************************************************
+template <typename T, typename TCompare>
+bool operator !=(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return !(lhs == rhs);
+}
+
+//*************************************************************************
+/// Less than operator.
+///\param lhs Reference to the first list.
+///\param rhs Reference to the second list.
+///\return <b>true</b> if the first list is lexicographically less than the
+/// second, otherwise <b>false</b>.
+//*************************************************************************
+template <typename T, typename TCompare>
+bool operator <(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return std::lexicographical_compare(lhs.begin(),
+    lhs.end(),
+    rhs.begin(),
+    rhs.end());
+}
+
+//*************************************************************************
+/// Greater than operator.
+///\param lhs Reference to the first list.
+///\param rhs Reference to the second list.
+///\return <b>true</b> if the first list is lexicographically greater than the
+/// second, otherwise <b>false</b>.
+//*************************************************************************
+template <typename T, typename TCompare>
+bool operator >(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return (rhs < lhs);
+}
+
+//*************************************************************************
+/// Less than or equal operator.
+///\param lhs Reference to the first list.
+///\param rhs Reference to the second list.
+///\return <b>true</b> if the first list is lexicographically less than or equal
+/// to the second, otherwise <b>false</b>.
+//*************************************************************************
+template <typename T, typename TCompare>
+bool operator <=(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return !(lhs > rhs);
+}
+
+//*************************************************************************
+/// Greater than or equal operator.
+///\param lhs Reference to the first list.
+///\param rhs Reference to the second list.
+///\return <b>true</b> if the first list is lexicographically greater than or
+/// equal to the second, otherwise <b>false</b>.
+//*************************************************************************
+template <typename T, typename TCompare>
+bool operator >=(const etl::imultiset<T, TCompare>& lhs, const etl::imultiset<T, TCompare>& rhs)
+{
+  return !(lhs < rhs);
+}
+
+#ifdef ETL_COMPILER_MICROSOFT
+#define min(a,b) (((a) < (b)) ? (a) : (b))
+#endif
+
+#undef ETL_FILE
+
+#endif
+