ecency-mobile/ios/Pods/boost-for-react-native/boost/graph/parallel/properties.hpp

114 lines
3.5 KiB
C++

// Copyright 2004 The Trustees of Indiana University.
// Use, modification and distribution is subject to 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: Douglas Gregor
// Andrew Lumsdaine
#ifndef BOOST_GRAPH_PARALLEL_PROPERTIES_HPP
#define BOOST_GRAPH_PARALLEL_PROPERTIES_HPP
#ifndef BOOST_GRAPH_USE_MPI
#error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
#endif
#include <boost/graph/properties.hpp>
#include <boost/property_map/parallel/distributed_property_map.hpp>
namespace boost {
/***************************************************************************
* Property map reduction operations
***************************************************************************/
/**
* Metafunction that produces a reduction operation for the given
* property. The default behavior merely forwards to @ref
* basic_reduce, but it is expected that this class template will be
* specified for important properties.
*/
template<typename Property>
struct property_reduce
{
template<typename Value>
class apply : public parallel::basic_reduce<Value> {};
};
/**
* Reduction of vertex colors can only darken, not lighten, the
* color. Black cannot turn black, grey can only turn black, and
* white can be changed to either color. The default color is white.
*/
template<>
struct property_reduce<vertex_color_t>
{
template<typename Color>
class apply
{
typedef color_traits<Color> traits;
public:
BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
template<typename Key>
Color operator()(const Key&) const { return traits::white(); }
template<typename Key>
Color operator()(const Key&, Color local, Color remote) const {
if (local == traits::white()) return remote;
else if (remote == traits::black()) return remote;
else return local;
}
};
};
/**
* Reduction of a distance always takes the shorter distance. The
* default distance value is the maximum value for the data type.
*/
template<>
struct property_reduce<vertex_distance_t>
{
template<typename T>
class apply
{
public:
BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
template<typename Key>
T operator()(const Key&) const { return (std::numeric_limits<T>::max)(); }
template<typename Key>
T operator()(const Key&, T x, T y) const { return x < y? x : y; }
};
};
template<>
struct property_reduce<vertex_predecessor_t>
{
template<typename T>
class apply
{
public:
BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
template<typename Key>
T operator()(Key key) const { return key; }
template<typename Key>
T operator()(Key key, T, T y) const { return y; }
};
};
template<typename Property, typename PropertyMap>
inline void set_property_map_role(Property p, PropertyMap pm)
{
typedef typename property_traits<PropertyMap>::value_type value_type;
typedef property_reduce<Property> property_red;
typedef typename property_red::template apply<value_type> reduce;
pm.set_reduce(reduce());
}
} // end namespace boost
#endif // BOOST_GRAPH_PARALLEL_PROPERTIES_HPP