boost/graph/two_bit_color_map.hpp
// 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/property_map.hpp>
#include <boost/shared_array.hpp>
#include <algorithm>
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])
{
// Fill to white
std::fill(data.get(), data.get() + (n + 3) / 4, 0);
}
};
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 ((std::size_t)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 ((std::size_t)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
#ifdef BOOST_GRAPH_USE_MPI
# include <boost/graph/distributed/two_bit_color_map.hpp>
#endif