hash_iterator.h

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/*
 * Copyright (c) 2013-2015:  G-CSC, Goethe University Frankfurt
 * Author: Sebastian Reiter
 * 
 * This file is part of UG4.
 * 
 * UG4 is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 3 (as published by the
 * Free Software Foundation) with the following additional attribution
 * requirements (according to LGPL/GPL v3 §7):
 * 
 * (1) The following notice must be displayed in the Appropriate Legal Notices
 * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (2) The following notice must be displayed at a prominent place in the
 * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (3) The following bibliography is recommended for citation and must be
 * preserved in all covered files:
 * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
 *   parallel geometric multigrid solver on hierarchically distributed grids.
 *   Computing and visualization in science 16, 4 (2013), 151-164"
 * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
 *   flexible software system for simulating pde based models on high performance
 *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 */
 
#ifndef __H__UG__hash_iterator__
#define __H__UG__hash_iterator__
 
#include <cassert>
namespace ug{
 
template <class TKey, class TValue, class TEntry>
class hash_iterator
{
  public:
    typedef hash_iterator         this_type;
    typedef std::forward_iterator_tag   iterator_category;
    typedef size_t              difference_type;
    typedef TValue*             pointer;
    typedef TValue              value_type;
    typedef TValue&             reference;
 
    typedef TKey  key_t;
    typedef TValue  value_t;
    typedef TEntry  entry_t;
 
 
    hash_iterator() : m_entries(NULL), m_entryInd(s_invalidIndex) {}
    hash_iterator(const key_t& key, const entry_t* entries, size_t entryInd) :
      m_key(key), m_entries(entries), m_entryInd(entryInd)  {}
 
    this_type operator ++()             {increment(); return *this;}
    this_type operator ++(int unused)       {this_type i = *this; increment(); return i;}
 
    bool operator ==(const this_type& iter) const {return equal(iter);}
    bool operator !=(const this_type& iter) const {return !equal(iter);}
 
    value_type& operator *()
    {
      assert(m_entryInd != s_invalidIndex);
      return m_entries[m_entryInd].value;
    }
 
  private:
    inline bool equal(const this_type& other) const
    {
      return m_entryInd == other.m_entryInd;
    }
 
    void increment()
    {
      assert(m_entries);
      assert(m_entryInd != s_invalidIndex);
      m_entryInd = m_entries[m_entryInd].next;
      while(m_entryInd != s_invalidIndex){
        if(m_entries[m_entryInd].key == m_key)
          break;
        m_entryInd = m_entries[m_entryInd].next;
      }
    }
 
    static const size_t s_invalidIndex = -1;
 
    key_t     m_key;
    const entry_t*  m_entries;
    size_t      m_entryInd;
};
 
}// end of namespace
 
#endif