WeightedIterator.h

#ifndef _theplu_yat_utility_weighted_iterator_
#define _theplu_yat_utility_weighted_iterator_

// $Id: WeightedIterator.h 3461 2016-01-22 01:29:13Z peter $

/*
  Copyright (C) 2008, 2009, 2010, 2016 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 "DataWeight.h"
#include "DataWeightProxy.h"

#include <boost/iterator/is_readable_iterator.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/utility/enable_if.hpp>

#include <iterator>

namespace theplu {
namespace yat {
namespace utility {

  namespace detail {
    namespace weighted_iterator {

      template<typename DataIterator, typename WeightIterator>
      class Traversal
      {
        typedef typename boost::iterator_traversal<DataIterator>::type T1;
        typedef typename boost::iterator_traversal<WeightIterator>::type T2;
      public:
        typedef typename boost::mpl::if_<
          boost::is_convertible<T1, T2>, T2, T1>::type type;
      };

    } // end of weighted_iterator namespace
  } // end of detail namespace

  template<typename DataIterator, typename WeightIterator>
  class WeightedIterator
    : public boost::iterator_facade<
    WeightedIterator<DataIterator, WeightIterator>,
    DataWeight,
    typename
    detail::weighted_iterator::Traversal<DataIterator, WeightIterator>::type,
    DataWeightProxy<DataIterator, WeightIterator> >

  {
  public:
    typedef DataIterator data_iterator;

    typedef WeightIterator weight_iterator;

    WeightedIterator(void)
    {}

    WeightedIterator(DataIterator d, WeightIterator w)
      : d_iter_(d), w_iter_(w)
    {}

    const DataIterator& data_base(void) const { return d_iter_; }

    const WeightIterator& weight_base(void) const { return w_iter_; }

    DataWeightProxy<DataIterator, WeightIterator> operator[](int n) const
    {
      return DataWeightProxy<DataIterator, WeightIterator>(d_iter_+n,
                                                           w_iter_+n);
    }


    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)
      : d_iter_(other.data_base()), w_iter_(other.weight_base()) {}


  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_); }

    utility::DataWeightProxy<DataIterator, WeightIterator>
    dereference(void) const
    { return DataWeightProxy<DataIterator, WeightIterator>(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_; }

  };

  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