// Copyright (C) 2005-2006 The Trustees of Indiana University.

// Distributed under the Boost Software License, Version 1.0.

// (See accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

//  Authors: Jeremiah Willcock

//           Douglas Gregor

//           Andrew Lumsdaine

// Two bit per color property map

#ifndef BOOST_TWO_BIT_COLOR_MAP_HPP

#define BOOST_TWO_BIT_COLOR_MAP_HPP

#include <boost/property_map.hpp>

#include <boost/shared_array.hpp>

namespace boost {

enum two_bit_color_type { 

  two_bit_white = 0, 

  two_bit_gray  = 1, 

  two_bit_green = 2, 

  two_bit_black = 3 

};

template <>

struct color_traits<two_bit_color_type>

{

  static two_bit_color_type white() { return two_bit_white; }

  static two_bit_color_type gray()  { return two_bit_gray; }

  static two_bit_color_type green() { return two_bit_green; }

  static two_bit_color_type black() { return two_bit_black; }

};

template<typename IndexMap = identity_property_map>

struct two_bit_color_map 

{

  std::size_t n;

  IndexMap index;

  shared_array<unsigned char> data;

  typedef typename property_traits<IndexMap>::key_type key_type;

  typedef two_bit_color_type value_type;

  typedef void reference;

  typedef read_write_property_map_tag category;

  explicit two_bit_color_map(std::size_t n, const IndexMap& index = IndexMap())

    : n(n), index(index), data(new unsigned char[(n + 3) / 4])

  {

  }

};

template<typename IndexMap>

inline two_bit_color_type

get(const two_bit_color_map<IndexMap>& pm, 

    typename two_bit_color_map<IndexMap>::key_type key) 

{

  typename property_traits<IndexMap>::value_type i = get(pm.index, key);

  assert (i < pm.n);

  return two_bit_color_type((pm.data.get()[i / 4] >> ((i % 4) * 2)) & 3);

}

template<typename IndexMap>

inline void

put(const two_bit_color_map<IndexMap>& pm, 

    typename two_bit_color_map<IndexMap>::key_type key,

    two_bit_color_type value)

{

  typename property_traits<IndexMap>::value_type i = get(pm.index, key);

  assert (i < pm.n);

  assert (value >= 0 && value < 4);

  std::size_t byte_num = i / 4;

  std::size_t bit_position = ((i % 4) * 2);

    pm.data.get()[byte_num] = (pm.data.get()[byte_num] & ~(3 << bit_position))

      | (value << bit_position);

}

template<typename IndexMap>

inline two_bit_color_map<IndexMap>

make_two_bit_color_map(std::size_t n, const IndexMap& index_map)

{

  return two_bit_color_map<IndexMap>(n, index_map);

}

} // end namespace boost

#endif // BOOST_TWO_BIT_COLOR_MAP_HPP