boost/libs/graph/test/bfs.cpp

//=======================================================================
// Copyright 2001 University of Notre Dame.
// Author: Andrew Janiszewski, 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)
//=======================================================================

#include <boost/core/lightweight_test.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/random.hpp>
#include <boost/graph/graph_utility.hpp>
#include <boost/graph/graph_archetypes.hpp>
#include <boost/graph/breadth_first_search.hpp>

#include <boost/random/mersenne_twister.hpp>

#ifdef BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP
using namespace boost;
#endif

template < typename DistanceMap, typename ParentMap, typename Graph,
    typename ColorMap >
class bfs_testing_visitor
{
    typedef typename boost::graph_traits< Graph >::vertex_descriptor Vertex;
    typedef typename boost::graph_traits< Graph >::edge_descriptor Edge;
    typedef typename boost::color_traits<
        typename boost::property_traits< ColorMap >::value_type >
        Color;

public:
    bfs_testing_visitor(Vertex s, DistanceMap d, ParentMap p, ColorMap c)
    : current_distance(0), distance(d), parent(p), color(c), src(s)
    {
    }

    void initialize_vertex(const Vertex& u, const Graph&) const
    {
        BOOST_TEST(get(color, u) == Color::white());
    }
    void examine_vertex(const Vertex& u, const Graph&) const
    {
        current_vertex = u;
        // Ensure that the distances monotonically increase.
        BOOST_TEST(distance[u] == current_distance
            || distance[u] == current_distance + 1);
        if (distance[u] == current_distance + 1) // new level
            ++current_distance;
    }
    void discover_vertex(const Vertex& u, const Graph&) const
    {
        BOOST_TEST(get(color, u) == Color::gray());
        if (u == src)
        {
            current_vertex = src;
        }
        else
        {
            BOOST_TEST(parent[u] == current_vertex);
            BOOST_TEST(distance[u] == current_distance + 1);
            BOOST_TEST(distance[u] == distance[parent[u]] + 1);
        }
    }
    void examine_edge(const Edge& e, const Graph& g) const
    {
        BOOST_TEST(source(e, g) == current_vertex);
    }
    void tree_edge(const Edge& e, const Graph& g) const
    {
        BOOST_TEST(get(color, target(e, g)) == Color::white());
        Vertex u = source(e, g), v = target(e, g);
        BOOST_TEST(distance[u] == current_distance);
        parent[v] = u;
        distance[v] = distance[u] + 1;
    }
    void non_tree_edge(const Edge& e, const Graph& g) const
    {
        BOOST_TEST(color[target(e, g)] != Color::white());

        if (boost::is_directed(g))
            // cross or back edge
            BOOST_TEST(distance[target(e, g)] <= distance[source(e, g)] + 1);
        else
        {
            // cross edge (or going backwards on a tree edge)
            BOOST_TEST(distance[target(e, g)] == distance[source(e, g)]
                || distance[target(e, g)] == distance[source(e, g)] + 1
                || distance[target(e, g)] == distance[source(e, g)] - 1);
        }
    }

    void gray_target(const Edge& e, const Graph& g) const
    {
        BOOST_TEST(color[target(e, g)] == Color::gray());
    }

    void black_target(const Edge& e, const Graph& g) const
    {
        BOOST_TEST(color[target(e, g)] == Color::black());

        // All vertices adjacent to a black vertex must already be discovered
        typename boost::graph_traits< Graph >::adjacency_iterator ai, ai_end;
        for (boost::tie(ai, ai_end) = adjacent_vertices(target(e, g), g);
             ai != ai_end; ++ai)
            BOOST_TEST(color[*ai] != Color::white());
    }
    void finish_vertex(const Vertex& u, const Graph&) const
    {
        BOOST_TEST(color[u] == Color::black());
    }

private:
    mutable Vertex current_vertex;
    mutable typename boost::property_traits< DistanceMap >::value_type
        current_distance;
    DistanceMap distance;
    ParentMap parent;
    ColorMap color;
    Vertex src;
};

template < class Graph > struct bfs_test
{
    typedef boost::graph_traits< Graph > Traits;
    typedef typename Traits::vertices_size_type vertices_size_type;
    static void go(vertices_size_type max_V)
    {
        typedef typename Traits::vertex_descriptor vertex_descriptor;
        typedef boost::color_traits< boost::default_color_type > Color;

        vertices_size_type i;
        typename Traits::edges_size_type j;
        typename Traits::vertex_iterator ui, ui_end;

        boost::mt19937 gen;

        for (i = 0; i < max_V; ++i)
            for (j = 0; j < i * i; ++j)
            {
                Graph g;
                boost::generate_random_graph(g, i, j, gen);

                // declare the "start" variable
                vertex_descriptor start = boost::random_vertex(g, gen);

                // vertex properties
                std::vector< int > distance(
                    i, (std::numeric_limits< int >::max)());
                distance[start] = 0;
                std::vector< vertex_descriptor > parent(i);
                for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
                    parent[*ui] = *ui;
                std::vector< boost::default_color_type > color(i);

                // Get vertex index map
                typedef typename boost::property_map< Graph,
                    boost::vertex_index_t >::const_type idx_type;
                idx_type idx = get(boost::vertex_index, g);

                // Make property maps from vectors
                typedef boost::iterator_property_map<
                    std::vector< int >::iterator, idx_type >
                    distance_pm_type;
                distance_pm_type distance_pm(distance.begin(), idx);
                typedef boost::iterator_property_map<
                    typename std::vector< vertex_descriptor >::iterator,
                    idx_type >
                    parent_pm_type;
                parent_pm_type parent_pm(parent.begin(), idx);
                typedef boost::iterator_property_map<
                    std::vector< boost::default_color_type >::iterator,
                    idx_type >
                    color_pm_type;
                color_pm_type color_pm(color.begin(), idx);

                // Create the testing visitor.
                bfs_testing_visitor< distance_pm_type, parent_pm_type, Graph,
                    color_pm_type >
                    vis(start, distance_pm, parent_pm, color_pm);

                boost::breadth_first_search(
                    g, start, visitor(vis).color_map(color_pm));

                // All white vertices should be unreachable from the source.
                for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
                    if (color[*ui] == Color::white())
                    {
                        std::vector< boost::default_color_type > color2(
                            i, Color::white());
                        BOOST_TEST(!boost::is_reachable(
                            start, *ui, g, color_pm_type(color2.begin(), idx)));
                    }

                // The shortest path to a child should be one longer than
                // shortest path to the parent.
                for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
                    if (parent[*ui] != *ui) // *ui not the root of the bfs tree
                        BOOST_TEST(distance[*ui] == distance[parent[*ui]] + 1);
            }
    }
};

int main(int argc, char* argv[])
{
    using namespace boost;
    int max_V = 7;
    if (argc > 1)
        max_V = atoi(argv[1]);

    bfs_test< adjacency_list< vecS, vecS, directedS > >::go(max_V);
    bfs_test< adjacency_list< vecS, vecS, undirectedS > >::go(max_V);
    return boost::report_errors();
}