source: trunk/yat/utility/IteratorPolicy.h @ 1487

#ifndef _theplu_yat_utility_iterator_policy_
#define _theplu_yat_utility_iterator_policy_ 

// $Id: IteratorPolicy.h 1487 2008-09-10 08:41:36Z jari $

/*
  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 "iterator_traits.h"

#include <cstddef>
#include <utility>

namespace theplu {
namespace yat {
namespace utility {

  /**
     \brief Default policy for Iterator
  */
  template<class Container, typename reference, typename weight_t>
  struct IteratorPolicy
  {
    /// type returned from function data
    typedef reference data_type;
    /// type returned from function weight
    typedef weight_t weight_type;
    /**
       returns unweighted_iterator_tag as Policy is intended to be
       used in a unweighted iterator
    */
    typedef unweighted_iterator_tag weighted_iterator_type;

    /**
       \return c(row, column)
     */
    data_type data(const Container& c, size_t row, size_t column) const
    {
      return c(row, column);
    }

    /**
       \return same as data
    */
    reference dereference(const Container& c, size_t row, size_t column) const
    {
      return c(row, column);
    }

    /**
       \return 1.0
    */
    weight_type weight(const Container& c, size_t row, size_t column) const
    {
      return 1.0;
    }
   
  };


  /**
     \brief policy for weighted Iterator
  */
  template<class Container, typename data_t, typename weight_t>
  struct IteratorPolicyWeighted
  {
    /// type returned from function dereference
    typedef std::pair<data_t, weight_t> reference;
    /// type returned from function data
    typedef data_t data_type;
    /// type returned from function weight
    typedef weight_t weight_type;
    /// weighted_iterator_tag as Policy is intended for weighted iterators
    typedef weighted_iterator_tag weighted_iterator_type;

    /**
       \return data
    */
    data_type data(const Container& c, size_t row, size_t column) const
    {
      return c.data(row, column);
    }

    /**
       \return a pair in of <data, weight>.
    */
    reference dereference(const Container& c, size_t row, size_t column) const
    {
      return reference(this->data(c, row, column),this->weight(c, row, column));
    }

    /**
       \return weight
    */
    weight_type weight(const Container& c, size_t row, size_t column) const
    {
      return c.weight(row, column);
    }
   
  };
}}} // of namespace utility, yat, and theplu

#endif