source: trunk/yat/utility/WeightedIterator.h @ 1532

#ifndef _theplu_yat_utility_weighted_iterator_
#define _theplu_yat_utility_weighted_iterator_

// $Id: WeightedIterator.h 1532 2008-09-24 22:06:47Z peter $

/*
  Copyright (C) 2008 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 3 of the
  License, or (at your option) any later version.

  The yat library 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
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include <boost/iterator/iterator_facade.hpp>

#include <iterator>

namespace theplu {
namespace yat {
namespace utility {

  /**
     @brief WeightedIterator
  */
  template<typename DataIterator, typename WeightIterator>
  class WeightedIterator
    : public boost::iterator_facade<
    WeightedIterator<DataIterator, WeightIterator>,
    DataWeight,
    std::random_access_iterator_tag,
    DataWeight>
    
  {
  public:
    /**
       \brief Constructor
     */
    WeightedIterator(DataIterator d, WeightIterator w)
      : d_iter_(d), w_iter_(w)
    {}

    /**
       \brief Conversion constructor. 

       Create a WeightIterator<Base> from a
       WeightIterator<B2>. Possible if B2 is convertible to a
       Base. Constructor allows implicit conversions such as iterator
       to const_iterator.
     */
    /*
    template<typename D2, typename W2>
    WeightedIterator(WeightedIterator<D2, W2> other,
            typename boost::enable_if_convertible<D2,DataIterator>::type* = 0,
            typename boost::enable_if_convertible<W2,WeightIterator>::type* = 0)
    {}
    */

  private:
    friend class boost::iterator_core_access;

    DataIterator d_iter_;
    WeightIterator w_iter_;

    void advance(size_t n)
    { std::advance(d_iter_, n); std::advance(w_iter_, n); }

    void decrement(void) { --d_iter_; --w_iter_; }

    typename std::iterator_traits<DataIterator>::difference_type 
    distance_to(const WeightedIterator& other) const
    { return std::distance(d_iter_, other.d_iter_); }

    DataWeight dereference(void) const 
    { return DataWeight(*d_iter_, *w_iter_); }

    bool equal(const WeightedIterator& other) const
    { return d_iter_==other.d_iter_ && w_iter_==other.w_iter_; }

    void increment(void) { ++d_iter_; ++w_iter_; }

  };

  /**
     \brief convenient function to create WeightedIterator

     Convenient function in same fashion as std::make_pair.
   */
  template<typename DataIterator, typename WeightIterator>
  WeightedIterator<DataIterator, WeightIterator> 
  weighted_iterator(DataIterator data, WeightIterator weight)
  {
    return WeightedIterator<DataIterator, WeightIterator>(data, weight);
  }
  


}}} // of namespace utility, yat, and theplu

#endif