Chris@16: // Copyright 2004 The Trustees of Indiana University.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software
Chris@16: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: //  Authors: Douglas Gregor
Chris@16: //           Andrew Lumsdaine
Chris@16: 
Chris@16: #ifndef BOOST_GRAPH_PARALLEL_PROPERTIES_HPP
Chris@16: #define BOOST_GRAPH_PARALLEL_PROPERTIES_HPP
Chris@16: 
Chris@16: #ifndef BOOST_GRAPH_USE_MPI
Chris@16: #error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/graph/properties.hpp>
Chris@16: #include <boost/property_map/parallel/distributed_property_map.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16:   /***************************************************************************
Chris@16:    * Property map reduction operations
Chris@16:    ***************************************************************************/
Chris@16:   /**
Chris@16:    * Metafunction that produces a reduction operation for the given
Chris@16:    * property. The default behavior merely forwards to @ref
Chris@16:    * basic_reduce, but it is expected that this class template will be
Chris@16:    * specified for important properties.
Chris@16:    */
Chris@16:   template<typename Property>
Chris@16:   struct property_reduce
Chris@16:   {
Chris@16:     template<typename Value>
Chris@16:     class apply : public parallel::basic_reduce<Value> {};
Chris@16:   };
Chris@16: 
Chris@16:   /**
Chris@16:    * Reduction of vertex colors can only darken, not lighten, the
Chris@16:    * color. Black cannot turn black, grey can only turn black, and
Chris@16:    * white can be changed to either color. The default color is white.
Chris@16:    */ 
Chris@16:   template<> 
Chris@16:   struct property_reduce<vertex_color_t>
Chris@16:   {
Chris@16:     template<typename Color>
Chris@16:     class apply
Chris@16:     {
Chris@16:       typedef color_traits<Color> traits;
Chris@16:       
Chris@16:     public:
Chris@16:       BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
Chris@16: 
Chris@16:       template<typename Key>
Chris@16:       Color operator()(const Key&) const { return traits::white(); }
Chris@16:       
Chris@16:       template<typename Key>
Chris@16:       Color operator()(const Key&, Color local, Color remote) const {
Chris@16:         if (local == traits::white()) return remote;
Chris@16:         else if (remote == traits::black()) return remote;
Chris@16:         else return local;
Chris@16:       }
Chris@16:     };
Chris@16:   };
Chris@16: 
Chris@16:   /**
Chris@16:    * Reduction of a distance always takes the shorter distance. The
Chris@16:    * default distance value is the maximum value for the data type.
Chris@16:    */
Chris@16:   template<> 
Chris@16:   struct property_reduce<vertex_distance_t>
Chris@16:   {
Chris@16:     template<typename T>
Chris@16:     class apply
Chris@16:     {
Chris@16:     public:
Chris@16:       BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
Chris@16: 
Chris@16:       template<typename Key>
Chris@16:       T operator()(const Key&) const { return (std::numeric_limits<T>::max)(); }
Chris@16: 
Chris@16:       template<typename Key>
Chris@16:       T operator()(const Key&, T x, T y) const { return x < y? x : y; }
Chris@16:     };
Chris@16:   };
Chris@16: 
Chris@16:   template<> 
Chris@16:   struct property_reduce<vertex_predecessor_t>
Chris@16:   {
Chris@16:     template<typename T>
Chris@16:     class apply
Chris@16:     {
Chris@16:     public:
Chris@16:       BOOST_STATIC_CONSTANT(bool, non_default_resolver = true);
Chris@16: 
Chris@16:       T operator()(T key) const { return key; }
Chris@16:       T operator()(T key, T, T y) const { return y; }
Chris@16:     };
Chris@16:   };
Chris@16: 
Chris@16:   template<typename Property, typename PropertyMap>
Chris@16:   inline void set_property_map_role(Property p, PropertyMap pm)
Chris@16:   {
Chris@16:     typedef typename property_traits<PropertyMap>::value_type value_type;
Chris@16:     typedef property_reduce<Property> property_red;
Chris@16:     typedef typename property_red::template apply<value_type> reduce;
Chris@16: 
Chris@16:     pm.set_reduce(reduce());
Chris@16:   }
Chris@16: 
Chris@16: } // end namespace boost
Chris@16: #endif // BOOST_GRAPH_PARALLEL_PROPERTIES_HPP