etl/iunordered_map.h

///\file

/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
http://www.etlcpp.com

Copyright(c) 2016 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
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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******************************************************************************/

#ifndef __ETL_IUNORDERED_MAP__
#define __ETL_IUNORDERED_MAP__

#include <iterator>
#include <algorithm>
#include <functional>
#include <utility>
#include <stddef.h>

#include "type_traits.h"
#include "parameter_type.h"
#include "hash.h"
#include "nullptr.h"
#include "ipool.h"
#include "ivector.h"
#include "error_handler.h"
#include "intrusive_forward_list.h"
#include "exception.h"
#include "error_handler.h"

#undef ETL_FILE
#define ETL_FILE "16"

namespace etl
{
  //***************************************************************************
  /// Exception for the unordered_map.
  ///\ingroup unordered_map
  //***************************************************************************
  class unordered_map_exception : public exception
  {
  public:

    unordered_map_exception(string_type what, string_type file_name, numeric_type line_number)
      : exception(what, file_name, line_number)
    {
    }
  };

  //***************************************************************************
  /// Full exception for the unordered_map.
  ///\ingroup unordered_map
  //***************************************************************************
  class unordered_map_full : public unordered_map_exception
  {
  public:

    unordered_map_full(string_type file_name, numeric_type line_number)
      : unordered_map_exception(ETL_ERROR_TEXT("unordered_map:full", ETL_FILE"A"), file_name, line_number)
    {
    }
  };

  //***************************************************************************
  /// Out of range exception for the unordered_map.
  ///\ingroup unordered_map
  //***************************************************************************
  class unordered_map_out_of_range : public unordered_map_exception
  {
  public:

    unordered_map_out_of_range(string_type file_name, numeric_type line_number)
      : unordered_map_exception(ETL_ERROR_TEXT("unordered_map:range", ETL_FILE"B"), file_name, line_number)
    {}
  };

  //***************************************************************************
  /// Iterator exception for the unordered_map.
  ///\ingroup unordered_map
  //***************************************************************************
  class unordered_map_iterator : public unordered_map_exception
  {
  public:

    unordered_map_iterator(string_type file_name, numeric_type line_number)
      : unordered_map_exception(ETL_ERROR_TEXT("unordered_map:iterator", ETL_FILE"C"), file_name, line_number)
    {
    }
  };

  //***************************************************************************
  /// The base class for specifically sized unordered_map.
  /// Can be used as a reference type for all unordered_map containing a specific type.
  ///\ingroup unordered_map
  //***************************************************************************
  template <typename TKey, typename T, typename THash = etl::hash<TKey>, typename TKeyEqual = std::equal_to<TKey> >
  class iunordered_map
  {
  public:

    typedef std::pair<const TKey, T> value_type;

    typedef TKey              key_type;
    typedef T                 mapped_type;
    typedef THash             hasher;
    typedef TKeyEqual         key_equal;
    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;


    typedef typename parameter_type<TKey>::type key_value_parameter_t;

    typedef etl::forward_link<> link_t; // Default link.

    // The nodes that store the elements.
    struct node_t : public link_t
    {
      node_t(const value_type& key_value_pair)
        : key_value_pair(key_value_pair)
      {
      }

      value_type key_value_pair;
    };

  private:

    typedef etl::intrusive_forward_list<node_t, link_t> bucket_t;
    typedef etl::ipool<node_t>                          pool_t;
    typedef etl::ivector<bucket_t>                      bucket_list_t;

    typedef typename bucket_list_t::iterator  bucket_list_iterator;

  public:

    // Local iterators iterate over one bucket.
    typedef typename bucket_t::iterator       local_iterator;
    typedef typename bucket_t::const_iterator local_const_iterator;

    //*********************************************************************
    class iterator : public std::iterator<std::forward_iterator_tag, T>
    {
    public:

      typedef typename iunordered_map::value_type      value_type;
      typedef typename iunordered_map::key_type        key_type;
      typedef typename iunordered_map::mapped_type     mapped_type;
      typedef typename iunordered_map::hasher          hasher;
      typedef typename iunordered_map::key_equal       key_equal;
      typedef typename iunordered_map::reference       reference;
      typedef typename iunordered_map::const_reference const_reference;
      typedef typename iunordered_map::pointer         pointer;
      typedef typename iunordered_map::const_pointer   const_pointer;
      typedef typename iunordered_map::size_type       size_type;

      friend class iunordered_map;

      //*********************************
      iterator()
      {
      }

      //*********************************
      iterator(const iterator& other)
        : ibuckets_end(other.ibuckets_end),
          ibucket(other.ibucket),
          inode(other.inode)
      {
      }

      //*********************************
      iterator& operator ++()
      {
        ++inode;

        // The end of this node list?
        if (inode == ibucket->end())
        {
          // Search for the next non-empty bucket.
          ++ibucket;
          while ((ibucket != ibuckets_end) && (ibucket->empty()))
          {
            ++ibucket;
          }

          // If not past the end, get the first node in the bucket.
          if (ibucket != ibuckets_end)
          {
            inode = ibucket->begin();
          }
        }

        return *this;
      }

      //*********************************
      iterator operator ++(int)
      {
        iterator temp(*this);
        operator++();
        return temp;
      }

      //*********************************
      iterator operator =(const iterator& other)
      {
        ibuckets_end = other.ibuckets_end;
        ibucket      = other.ibucket;
        inode        = other.inode;
        return *this;
      }

      //*********************************
      std::pair<const TKey, T> operator *()
      {
        return inode->key_value_pair;
      }

      //*********************************
      const_reference operator *() const
      {
        return inode->key_value_pair;
      }

      //*********************************
      pointer operator &()
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      const_pointer operator &() const
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      pointer operator ->()
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      const_pointer operator ->() const
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      friend bool operator == (const iterator& lhs, const iterator& rhs)
      {
        return lhs.compare(rhs);
      }

      //*********************************
      friend bool operator != (const iterator& lhs, const iterator& rhs)
      {
        return !(lhs == rhs);
      }

    private:

      //*********************************
      iterator(bucket_list_iterator ibuckets_end, bucket_list_iterator ibucket, local_iterator inode)
        : ibuckets_end(ibuckets_end),
          ibucket(ibucket),
          inode(inode)
      {
      }

      //*********************************
      bool compare(const iterator& rhs) const
      {
        return rhs.inode == inode;
      }

      //*********************************
      bucket_t& get_bucket()
      {
        return *ibucket;
      }

      //*********************************
      bucket_list_iterator& get_bucket_list_iterator()
      {
        return ibucket;
      }

      //*********************************
      local_iterator get_local_iterator()
      {
        return inode;
      }

      bucket_list_iterator ibuckets_end;
      bucket_list_iterator ibucket;
      local_iterator       inode;
    };

    //*********************************************************************
    class const_iterator : public std::iterator<std::forward_iterator_tag, const T>
    {
    public:

      typedef typename iunordered_map::value_type      value_type;
      typedef typename iunordered_map::key_type        key_type;
      typedef typename iunordered_map::mapped_type     mapped_type;
      typedef typename iunordered_map::hasher          hasher;
      typedef typename iunordered_map::key_equal       key_equal;
      typedef typename iunordered_map::reference       reference;
      typedef typename iunordered_map::const_reference const_reference;
      typedef typename iunordered_map::pointer         pointer;
      typedef typename iunordered_map::const_pointer   const_pointer;
      typedef typename iunordered_map::size_type       size_type;

      friend class iunordered_map;
      friend class iterator;

      //*********************************
      const_iterator()
      {
      }

      //*********************************
      const_iterator(const typename iunordered_map::iterator& other)
        : ibuckets_end(other.ibuckets_end),
          ibucket(other.ibucket),
          inode(other.inode)
      {
      }

      //*********************************
      const_iterator(const const_iterator& other)
        : ibuckets_end(other.ibuckets_end),
          ibucket(other.ibucket),
          inode(other.inode)
      {
      }

      //*********************************
      const_iterator& operator ++()
      {
        ++inode;

        // The end of this node list?
        if (inode == ibucket->end())
        {
          // Search for the next non-empty bucket.

          ++ibucket;
          while ((ibucket != ibuckets_end) && (ibucket->empty()))
          {
            ++ibucket;
          }

          // If not past the end, get the first node in the bucket.
          if (ibucket != ibuckets_end)
          {
            inode = ibucket->begin();
          }
        }

        return *this;
      }

      //*********************************
      const_iterator operator ++(int)
      {
        const_iterator temp(*this);
        operator++();
        return temp;
      }

      //*********************************
      const_iterator operator =(const const_iterator& other)
      {
        ibuckets_end = other.ibuckets_end;
        ibucket      = other.ibucket;
        inode        = other.inode;
        return *this;
      }

      //*********************************
      const_reference operator *() const
      {
        return inode->key_value_pair;
      }

      //*********************************
      const_pointer operator &() const
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      const_pointer operator ->() const
      {
        return &(inode->key_value_pair);
      }

      //*********************************
      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
      {
        return lhs.compare(rhs);
      }

      //*********************************
      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
      {
        return !(lhs == rhs);
      }

    private:

      //*********************************
      const_iterator(bucket_list_iterator ibuckets_end, bucket_list_iterator ibucket, local_iterator inode)
        : ibuckets_end(ibuckets_end),
          ibucket(ibucket),
          inode(inode)
      {
      }

      //*********************************
      bool compare(const const_iterator& rhs) const
      {
        return rhs.inode == inode;
      }

      //*********************************
      bucket_t& get_bucket()
      {
        return *ibucket;
      }

      //*********************************
      bucket_list_iterator& get_bucket_list_iterator()
      {
        return ibucket;
      }

      //*********************************
      local_iterator get_local_iterator()
      {
        return inode;
      }

      bucket_list_iterator ibuckets_end;
      bucket_list_iterator ibucket;
      local_iterator       inode;
    };

    typedef typename std::iterator_traits<iterator>::difference_type difference_type;

    //*********************************************************************
    /// Returns an iterator to the beginning of the unordered_map.
    ///\return An iterator to the beginning of the unordered_map.
    //*********************************************************************
    iterator begin()
    {
      return iterator(pbuckets->end(), first, first->begin());
    }

    //*********************************************************************
    /// Returns a const_iterator to the beginning of the unordered_map.
    ///\return A const iterator to the beginning of the unordered_map.
    //*********************************************************************
    const_iterator begin() const
    {
      return const_iterator(pbuckets->end(), first, first->begin());
    }

    //*********************************************************************
    /// Returns a const_iterator to the beginning of the unordered_map.
    ///\return A const iterator to the beginning of the unordered_map.
    //*********************************************************************
    const_iterator cbegin() const
    {
      return const_iterator(pbuckets->end(), first, first->begin());
    }

    //*********************************************************************
    /// Returns an iterator to the beginning of the unordered_map bucket.
    ///\return An iterator to the beginning of the unordered_map bucket.
    //*********************************************************************
    local_iterator begin(size_t i)
    {
      return (*pbuckets)[i].begin();
    }

    //*********************************************************************
    /// Returns a const_iterator to the beginning of the unordered_map bucket.
    ///\return A const iterator to the beginning of the unordered_map bucket.
    //*********************************************************************
    local_const_iterator begin(size_t i) const
    {
      return (*pbuckets)[i].cbegin();
    }

    //*********************************************************************
    /// Returns a const_iterator to the beginning of the unordered_map bucket.
    ///\return A const iterator to the beginning of the unordered_map bucket.
    //*********************************************************************
    local_const_iterator cbegin(size_t i) const
    {
      return (*pbuckets)[i].cbegin();
    }

    //*********************************************************************
    /// Returns an iterator to the end of the unordered_map.
    ///\return An iterator to the end of the unordered_map.
    //*********************************************************************
    iterator end()
    {
      return iterator(pbuckets->end(), last, last->end());
    }

    //*********************************************************************
    /// Returns a const_iterator to the end of the unordered_map.
    ///\return A const iterator to the end of the unordered_map.
    //*********************************************************************
    const_iterator end() const
    {
      return const_iterator(pbuckets->end(), last, last->end());
    }

    //*********************************************************************
    /// Returns a const_iterator to the end of the unordered_map.
    ///\return A const iterator to the end of the unordered_map.
    //*********************************************************************
    const_iterator cend() const
    {
      return const_iterator(pbuckets->end(), last, last->end());
    }

    //*********************************************************************
    /// Returns an iterator to the end of the unordered_map bucket.
    ///\return An iterator to the end of the unordered_map bucket.
    //*********************************************************************
    local_iterator end(size_t i)
    {
      return (*pbuckets)[i].end();
    }

    //*********************************************************************
    /// Returns a const_iterator to the end of the unordered_map bucket.
    ///\return A const iterator to the end of the unordered_map bucket.
    //*********************************************************************
    local_const_iterator end(size_t i) const
    {
      return (*pbuckets)[i].cend();
    }

    //*********************************************************************
    /// Returns a const_iterator to the end of the unordered_map bucket.
    ///\return A const iterator to the end of the unordered_map bucket.
    //*********************************************************************
    local_const_iterator cend(size_t i) const
    {
      return (*pbuckets)[i].cend();
    }

    //*********************************************************************
    /// Returns the bucket index for the key.
    ///\return The bucket index for the key.
    //*********************************************************************
    size_type bucket(key_value_parameter_t key) const
    {
      return key_hash_function(key) % pbuckets->size();
    }

    //*********************************************************************
    /// Returns the size of the bucket key.
    ///\return The bucket size of the bucket key.
    //*********************************************************************
    size_type bucket_size(key_value_parameter_t key) const
    {
      size_t index = bucket(key);

      return std::distance((*pbuckets)[index].begin(), (*pbuckets)[index].end());
    }

    //*********************************************************************
    /// Returns the maximum number of the buckets the container can hold.
    ///\return The maximum number of the buckets the container can hold.
    //*********************************************************************
    size_type max_bucket_count() const
    {
      return max_size();
    }

    //*********************************************************************
    /// Returns the number of the buckets the container holds.
    ///\return The number of the buckets the container holds.
    //*********************************************************************
    size_type bucket_count() const
    {
      return max_size();
    }

    //*********************************************************************
    /// Returns a reference to the value at index 'key'
    ///\param key The key.
    ///\return A reference to the value at index 'key'
    //*********************************************************************
    mapped_type& operator [](key_value_parameter_t key)
    {
      // Find the bucket.
      bucket_list_iterator ibucket = pbuckets->begin() + bucket(key);

      // Find the first node in the bucket.
      local_iterator inode = ibucket->begin();

      // Walk the list looking for the right one.
      while (inode != ibucket->end())
      {
        // Equal keys?
        if (key_equal_function(key, inode->key_value_pair.first))
        {
          // Found a match.
          return inode->key_value_pair.second;
        }
        else
        {
          ++inode;
        }
      }

      // Doesn't exist, so add a new one.
      // Get a new node.
      node_t& node = *pnodepool->allocate(node_t(value_type(key, T())));
      ibucket->insert_after(ibucket->before_begin(), node);

      return ibucket->begin()->key_value_pair.second;
    }

    //*********************************************************************
    /// Returns a reference to the value at index 'key'
    /// If asserts or exceptions are enabled, emits an etl::unordered_map_out_of_range if the key is not in the range.
    ///\param key The key.
    ///\return A reference to the value at index 'key'
    //*********************************************************************
    mapped_type& at(key_value_parameter_t key)
    {
      // Find the bucket.
      bucket_list_iterator ibucket = pbuckets->begin() + bucket(key);

      // Find the first node in the bucket.
      local_iterator inode = ibucket->begin();

      // Walk the list looking for the right one.
      while (inode != ibucket->end())
      {
        // Equal keys?
        if (key_equal_function(key, inode->key_value_pair.first))
        {
          // Found a match.
          return inode->key_value_pair.second;
        }
        else
        {
          ++inode;
        }
      }

      // Doesn't exist.
      ETL_ASSERT(false, ETL_ERROR(unordered_map_out_of_range));

      return begin()->second;
    }

    //*********************************************************************
    /// Returns a const reference to the value at index 'key'
    /// If asserts or exceptions are enabled, emits an etl::unordered_map_out_of_range if the key is not in the range.
    ///\param key The key.
    ///\return A const reference to the value at index 'key'
    //*********************************************************************
    const mapped_type& at(key_value_parameter_t key) const
    {
      // Find the bucket.
      bucket_list_t::const_iterator ibucket = pbuckets->begin() + bucket(key);

      // Find the first node in the bucket.
      bucket_t::const_iterator inode = ibucket->begin();

      // Walk the list looking for the right one.
      while (inode != ibucket->end())
      {
        // Equal keys?
        if (key_equal_function(key, inode->key_value_pair.first))
        {
          // Found a match.
          return inode->key_value_pair.second;
        }
        else
        {
          ++inode;
        }
      }

      // Doesn't exist.
      ETL_ASSERT(false, ETL_ERROR(unordered_map_out_of_range));

      return begin()->second;
    }

    //*********************************************************************
    /// Assigns values to the unordered_map.
    /// If asserts or exceptions are enabled, emits unordered_map_full if the unordered_map does not have enough free space.
    /// If asserts or exceptions are enabled, emits unordered_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)
    {
#ifdef _DEBUG
      difference_type count = std::distance(first, last);
      ETL_ASSERT(count >= 0, ETL_ERROR(unordered_map_iterator));
      ETL_ASSERT(size_t(count) <= max_size() , ETL_ERROR(unordered_map_full));
#endif

      clear();

      while (first != last)
      {
        insert(*first++);
      }
    }

    //*********************************************************************
    /// Inserts a value to the unordered_map.
    /// If asserts or exceptions are enabled, emits unordered_map_full if the unordered_map is already full.
    ///\param value The value to insert.
    //*********************************************************************
    std::pair<iterator, bool> insert(const value_type& key_value_pair)
    {
      std::pair<iterator, bool> result(end(), false);

      ETL_ASSERT(!full(), ETL_ERROR(unordered_map_full));

      const key_type&    key    = key_value_pair.first;
      const mapped_type& mapped = key_value_pair.second;

      // Get the hash index.
      size_t index = bucket(key);

      // Get the bucket & bucket iterator.
      bucket_list_iterator ibucket = pbuckets->begin() + index;
      bucket_t& bucket = *ibucket;

      // The first one in the bucket?
      if (bucket.empty())
      {
        // Get a new node.
        node_t& node = *pnodepool->allocate(node_t(key_value_pair));

        // Just add the pointer to the bucket;
        bucket.insert_after(bucket.before_begin(), node);

        result.first  = iterator(pbuckets->end(), ibucket, ibucket->begin());
        result.second = true;

        adjust_first_last_markers(ibucket);
      }
      else
      {
        // Step though the bucket looking for a place to insert.
        local_iterator inode_previous = bucket.before_begin();
        local_iterator inode = bucket.begin();

        while (inode != bucket.end())
        {
          // Do we already have this key?
          if (inode->key_value_pair.first == key)
          {
            break;
          }

          ++inode_previous;
          ++inode;
        }

        // Not already there?
        if (inode == bucket.end())
        {
          // Get a new node.
          node_t& node = *pnodepool->allocate(node_t(key_value_pair));

          // Add the node to the end of the bucket;
          bucket.insert_after(inode_previous, node);
          ++inode_previous;

          result.first  = iterator(pbuckets->end(), ibucket, inode_previous);
          result.second = true;
        }
      }

      return result;
    }

    //*********************************************************************
    /// Inserts a value to the unordered_map.
    /// If asserts or exceptions are enabled, emits unordered_map_full if the unordered_map is already full.
    ///\param position The position to insert at.
    ///\param value    The value to insert.
    //*********************************************************************
    iterator insert(const_iterator position, const value_type& key_value_pair)
    {
      return insert(key_value_pair).first;
    }

    //*********************************************************************
    /// Inserts a range of values to the unordered_map.
    /// If asserts or exceptions are enabled, emits unordered_map_full if the unordered_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)
    {
      size_t count = 0;
      size_t bucket_id = bucket(key);

      bucket_t& bucket = (*pbuckets)[bucket_id];

      local_iterator iprevious = bucket.before_begin();
      local_iterator icurrent  = bucket.begin();

      while ((icurrent != bucket.end()) && (icurrent->key_value_pair.first != key))
      {
        ++iprevious;
        ++icurrent;
      }

      if (icurrent != bucket.end())
      {
        bucket.erase_after(iprevious);
        count = 1;
      }

      return count;
    }

    //*********************************************************************
    /// Erases an element.
    ///\param ielement Iterator to the element.
    //*********************************************************************
    iterator erase(const_iterator ielement)
    {
      // Make a note of the next one.
      iterator inext(pbuckets->end(), ielement.get_bucket_list_iterator(), ielement.get_local_iterator());
      ++inext;

      bucket_t&      bucket    = ielement.get_bucket();
      local_iterator icurrent  = ielement.get_local_iterator();
      local_iterator iprevious = bucket.before_begin();

      // Find the node we're interested in.
      while (iprevious->etl_next != &*icurrent)
      {
        ++iprevious;
      }

      bucket.erase_after(iprevious);

      return inext;
    }

    //*********************************************************************
    /// 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 to by last.
    ///\param first Iterator to the first element.
    ///\param last  Iterator to the last element.
    //*********************************************************************
    iterator erase(const_iterator first, const_iterator last)
    {
      // Make a note of the last.
      iterator result(pbuckets->end(), last.get_bucket_list_iterator(), last.get_local_iterator());

      // Get the starting point.
      bucket_list_iterator ibucket   = first.get_bucket_list_iterator();
      local_iterator       ifirst    = first.get_local_iterator();
      local_iterator       iprevious = ibucket->before_begin();
      local_iterator       iend;

      // Find the first node we're interested in.
      while (iprevious->etl_next != &*ifirst)
      {
        ++iprevious;
      }

      iend = iprevious;
      iend++;

      while (first != last)
      {
        // Find how far we can go in this bucket.
        while ((first != last) && (iend != ibucket->end()))
        {
          ++first;
          ++iend;
        }

        // Erase the range.
        ibucket->erase_after(iprevious, iend);

        // At the end of this bucket?
        if (iend == ibucket->end())
        {
          // Move on to the next bucket.
          ++ibucket;
          iprevious = ibucket->before_begin();
          iend = iprevious;
          ++iend;
        }
        else
        {
          // Still in the same bucket.
          iprevious = iend;
        }
      }

      return result;
    }

    //*************************************************************************
    /// Clears the unordered_map.
    //*************************************************************************
    void clear()
    {
      initialise();
    }

    //*********************************************************************
    /// 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 an element.
    ///\param key The key to search for.
    ///\return An iterator to the element if the key exists, otherwise end().
    //*********************************************************************
    iterator find(key_value_parameter_t key)
    {
      size_t index = bucket(key);

      bucket_list_iterator ibucket = pbuckets->begin() + index;
      bucket_t&            bucket  = *ibucket;

      // Is the bucket not empty?
      if (!bucket.empty())
      {
        // Step though the list until we find the end or an equivalent key.
        local_iterator inode = bucket.begin();
        local_iterator iend  = bucket.end();

        while (inode != iend)
        {
          // Do we have this one?
          if (key_equal_function(key, inode->key_value_pair.first))
          {
            return iterator(pbuckets->end(), ibucket, inode);
          }

          ++inode;
        }
      }

      return end();
    }

    //*********************************************************************
    /// Finds an element.
    ///\param key The key to search for.
    ///\return An iterator to the element if the key exists, otherwise end().
    //*********************************************************************
    const_iterator find(key_value_parameter_t key) const
    {
      size_t index = bucket(key);

      bucket_list_iterator ibucket = pbuckets->begin() + index;
      bucket_t&            bucket  = *ibucket;

      // Is the bucket not empty?
      if (!bucket.empty())
      {
        // Step though the list until we find the end or an equivalent key.
        local_iterator inode = bucket.begin();
        local_iterator iend = bucket.end();

        while (inode != iend)
        {
          // Do we have this one?
          if (key_equal_function(key, inode->key_value_pair.first))
          {
            return iterator(pbuckets->end(), ibucket, inode);
          }

          ++inode;
        }
      }

      return end();
    }

    //*********************************************************************
    /// Returns a range containing all elements with key key in the container.
    /// The range is defined by two iterators, the first pointing to the first 
    /// element of the wanted range and the second pointing past the last 
    /// element of the range.
    ///\param key The key to search for.
    ///\return An iterator pair to the range of elements if the key exists, otherwise end().
    //*********************************************************************
    std::pair<iterator, iterator> equal_range(const key_value_parameter_t& key)
    {
      iterator first = find(key);
      iterator last  = first;

      if (last != end())
      {
        ++last;
      }

      return std::pair<iterator, iterator>(first, last);
    }

    //*********************************************************************
    /// Returns a range containing all elements with key key in the container.
    /// The range is defined by two iterators, the first pointing to the first 
    /// element of the wanted range and the second pointing past the last 
    /// element of the range.
    ///\param key The key to search for.
    ///\return A const iterator pair to the range of elements if the key exists, otherwise end().
    //*********************************************************************
    std::pair<const_iterator, const_iterator> equal_range(const key_value_parameter_t& key) const
    {
      const_iterator first = find(key);
      const_iterator last  = first;

      if (last != end())
      {
        ++last;
      }

      return std::pair<const_iterator, const_iterator>(first, last);
    }

    //*************************************************************************
    /// Gets the size of the unordered_map.
    //*************************************************************************
    size_type size() const
    {
      return pnodepool->size();
    }

    //*************************************************************************
    /// Gets the maximum possible size of the unordered_map.
    //*************************************************************************
    size_type max_size() const
    {
      return pnodepool->max_size();
    }

    //*************************************************************************
    /// Checks to see if the unordered_map is empty.
    //*************************************************************************
    bool empty() const
    {
      return pnodepool->empty();
    }

    //*************************************************************************
    /// Checks to see if the unordered_map is full.
    //*************************************************************************
    bool full() const
    {
      return pnodepool->full();
    }

    //*************************************************************************
    /// Returns the remaining capacity.
    ///\return The remaining capacity.
    //*************************************************************************
    size_t available() const
    {
      return pnodepool->available();
    }

    //*************************************************************************
    /// Returns the load factor = size / bucket_count.
    ///\return The load factor = size / bucket_count.
    //*************************************************************************
    float load_factor() const
    {
      return static_cast<float>(size()) / static_cast<float>(bucket_count());
    }

    //*************************************************************************
    /// Returns the function that hashes the keys.
    ///\return The function that hashes the keys..
    //*************************************************************************
    hasher hash_function() const
    {
      return key_hash_function;
    }

    //*************************************************************************
    /// Returns the function that compares the keys.
    ///\return The function that compares the keys..
    //*************************************************************************
    key_equal key_eq() const
    {
      return key_equal_function;
    }

    //*************************************************************************
    /// Assignment operator.
    //*************************************************************************
    iunordered_map& operator = (const iunordered_map& rhs)
    {
      // Skip if doing self assignment
      if (this != &rhs)
      {
        assign(rhs.cbegin(), rhs.cend());
      }

      return *this;
    }

  protected:

    //*********************************************************************
    /// Constructor.
    //*********************************************************************
    iunordered_map(pool_t& node_pool, bucket_list_t& buckets)
      : pnodepool(&node_pool),
        pbuckets(&buckets)
    {
    }

    //*********************************************************************
    /// Initialise the unordered_map.
    //*********************************************************************
    void initialise()
    {
      pbuckets->resize(pnodepool->max_size());

      if (!empty())
      {
        pnodepool->release_all();

        for (size_t i = 0; i < pbuckets->size(); ++i)
        {
          (*pbuckets)[i].clear();
        }
      }

      first = pbuckets->begin();
      last  = first;
    }

  private:

    //*********************************************************************
    /// Adjust the first and last markers according to the new entry.
    //*********************************************************************
    void adjust_first_last_markers(bucket_list_iterator ibucket)
    {
      if (ibucket < first)
      {
        first = ibucket;
      }
      else if (ibucket > last)
      {
        last = ibucket;
      }
    }

    // Disable copy construction.
    iunordered_map(const iunordered_map&);

    /// The pool of data nodes used in the list.
    pool_t* pnodepool;

    /// The bucket list.
    bucket_list_t* pbuckets;

    /// The first and last iterators to buckets with values.
    bucket_list_iterator first;
    bucket_list_iterator last;

    /// The function that creates the hashes.
    hasher key_hash_function;

    /// The function that compares the keys for equality.
    key_equal key_equal_function;
  };

  //***************************************************************************
  /// Equal operator.
  ///\param lhs Reference to the first unordered_map.
  ///\param rhs Reference to the second unordered_map.
  ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
  ///\ingroup unordered_map
  //***************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  bool operator ==(const etl::iunordered_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iunordered_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 unordered_map.
  ///\param rhs Reference to the second unordered_map.
  ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
  ///\ingroup unordered_map
  //***************************************************************************
  template <typename TKey, typename TMapped, typename TKeyCompare>
  bool operator !=(const etl::iunordered_map<TKey, TMapped, TKeyCompare>& lhs, const etl::iunordered_map<TKey, TMapped, TKeyCompare>& rhs)
  {
    return !(lhs == rhs);
  }
}

#undef ETL_FILE
#endif