//=======================================================================

 // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.

 // Copyright (C) Vladimir Prus 2003

 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek

 //

 // 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)

 //=======================================================================

 #ifndef BOOST_GRAPH_RANDOM_HPP

 #define BOOST_GRAPH_RANDOM_HPP

 #include <boost/graph/graph_traits.hpp>

 #include <boost/random/uniform_int.hpp>

 #include <boost/random/variate_generator.hpp>

 #include <boost/pending/property.hpp>

 #include <boost/graph/properties.hpp>

 #include <boost/graph/adjacency_list.hpp>

 #include <boost/graph/copy.hpp>

 #include <boost/mpl/if.hpp>

 #include <boost/type_traits/is_convertible.hpp>

 #include <iostream>

 namespace boost {

   // grab a random vertex from the graph's vertex set

   template <class Graph, class RandomNumGen>

   typename graph_traits<Graph>::vertex_descriptor

   random_vertex(Graph& g, RandomNumGen& gen)

   {

     if (num_vertices(g) > 1) {

     #if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581))

       std::size_t n = std::random( num_vertices(g) );

     #else

       uniform_int<> distrib(0, num_vertices(g)-1);

       variate_generator<RandomNumGen&, uniform_int<> > rand_gen(gen, distrib);

       std::size_t n = rand_gen();

     #endif

       typename graph_traits<Graph>::vertex_iterator

         i = vertices(g).first;

       while (n-- > 0) ++i; // std::advance not VC++ portable

       return *i;

     } else

       return *vertices(g).first;

   }

   template <class Graph, class RandomNumGen>

   typename graph_traits<Graph>::edge_descriptor

   random_edge(Graph& g, RandomNumGen& gen) {

     if (num_edges(g) > 1) {

     #if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581))

       typename graph_traits<Graph>::edges_size_type

         n = std::random( num_edges(g) );

     #else

       uniform_int<> distrib(0, num_edges(g)-1);

       variate_generator<RandomNumGen&, uniform_int<> > rand_gen(gen, distrib);

       typename graph_traits<Graph>::edges_size_type

         n = rand_gen();

     #endif

       typename graph_traits<Graph>::edge_iterator

         i = edges(g).first;

       while (n-- > 0) ++i; // std::advance not VC++ portable

       return *i;

     } else

       return *edges(g).first;

   }

   namespace detail {

     class dummy_property_copier {

     public:

       template<class V1, class V2>

       void operator()(const V1&, const V2&) const {}

     };

   }

   template <typename MutableGraph, class RandNumGen>

   void generate_random_graph1

     (MutableGraph& g,

      typename graph_traits<MutableGraph>::vertices_size_type V,

      typename graph_traits<MutableGraph>::vertices_size_type E,

      RandNumGen& gen,

      bool allow_parallel = true,

      bool self_edges = false)

   {

     typedef graph_traits<MutableGraph> Traits;

     typedef typename Traits::vertices_size_type v_size_t;

     typedef typename Traits::edges_size_type e_size_t;

     typedef typename Traits::vertex_descriptor vertex_descriptor;

     // When parallel edges are not allowed, we create a new graph which

     // does not allow parallel edges, construct it and copy back.

     // This is not efficient if 'g' already disallow parallel edges,

     // but that's task for later.

     if (!allow_parallel) {

       typedef typename boost::graph_traits<MutableGraph>::directed_category dir;

       typedef typename mpl::if_<is_convertible<dir, directed_tag>,

           directedS, undirectedS>::type select;

       adjacency_list<setS, vecS, select> g2;

       generate_random_graph1(g2, V, E, gen, true, self_edges);

       copy_graph(g2, g, vertex_copy(detail::dummy_property_copier()).

                         edge_copy(detail::dummy_property_copier()));

     } else {

       for (v_size_t i = 0; i < V; ++i)

         add_vertex(g);

       for (e_size_t j = 0; j < E; ++j) {

         vertex_descriptor a = random_vertex(g, gen), b;

         do {

           b = random_vertex(g, gen);

         } while (self_edges == false && a == b);

         add_edge(a, b, g);

       }

     }

   }

   template <typename MutableGraph, class RandNumGen>

   void generate_random_graph

     (MutableGraph& g,

      typename graph_traits<MutableGraph>::vertices_size_type V,

      typename graph_traits<MutableGraph>::vertices_size_type E,

      RandNumGen& gen,

      bool allow_parallel = true,

      bool self_edges = false)

   {

       generate_random_graph1(g, V, E, gen, allow_parallel, self_edges);

   }

   template <typename MutableGraph, typename RandNumGen,

             typename VertexOutputIterator, typename EdgeOutputIterator>

   void generate_random_graph

     (MutableGraph& g,

      typename graph_traits<MutableGraph>::vertices_size_type V,

      typename graph_traits<MutableGraph>::vertices_size_type E,

      RandNumGen& gen,

      VertexOutputIterator vertex_out,

      EdgeOutputIterator edge_out,

      bool self_edges = false)

   {

     typedef graph_traits<MutableGraph> Traits;

     typedef typename Traits::vertices_size_type v_size_t;

     typedef typename Traits::edges_size_type e_size_t;

     typedef typename Traits::vertex_descriptor vertex_t;

     typedef typename Traits::edge_descriptor edge_t;

     for (v_size_t i = 0; i < V; ++i)

       *vertex_out++ = add_vertex(g);

     for (e_size_t j = 0; j < E; ++j) {

       vertex_t a = random_vertex(g, gen), b;

       do {

         b = random_vertex(g, gen);

       } while (self_edges == false && a == b);

       edge_t e; bool inserted;

       tie(e, inserted) = add_edge(a, b, g);

       if (inserted)

         *edge_out++ = std::make_pair(source(e, g), target(e, g));

     }

   }

   namespace detail {

     template<class Property, class G, class RandomGenerator>

     void randomize_property(G& g, RandomGenerator& rg,

                             Property, vertex_property_tag)

     {

       typename property_map<G, Property>::type pm = get(Property(), g);

       typename graph_traits<G>::vertex_iterator vi, ve;

       for (tie(vi, ve) = vertices(g); vi != ve; ++vi) {

         pm[*vi] = rg();

       }

     }

     template<class Property, class G, class RandomGenerator>

     void randomize_property(G& g, RandomGenerator& rg,

                             Property, edge_property_tag)

     {

       typename property_map<G, Property>::type pm = get(Property(), g);

       typename graph_traits<G>::edge_iterator ei, ee;

       for (tie(ei, ee) = edges(g); ei != ee; ++ei) {

         pm[*ei] = rg();

       }

     }

   }

   template<class Property, class G, class RandomGenerator>

   void randomize_property(G& g, RandomGenerator& rg)

   {

     detail::randomize_property

         (g, rg, Property(), typename property_kind<Property>::type());

   }

 }

 #endif