How to traverse graph in boost use BFS

Question

I have problems getting to compile the BFS of a very simple graph. Whatever I do I get various compiler messages about unmatched method calls (I\'ve tried boost::visit

Answer 1

I faced the same problem, but compared to the answer provided by user1252091 my vertex type is a struct that doesn't include an integer that can be used to create a vertex_index_map, therefore the line

breadth_first_search(graph, a, boost::visitor(vis).vertex_index_map(get(boost::vertex_bundle,graph)));

wouldn't work in my case. Eventually I figured out how to create an external vertex_index_map (thanks also to this answer) and pass it to the breadth_first_search function. Here is a working example in case it helps others:

#include 
#include 
#include 
#include 

struct Person
{
    std::string Name;
    unsigned int YearBorn;
};

typedef boost::adjacency_list  FamilyTree;
typedef boost::graph_traits::vertex_descriptor  Vertex;
typedef boost::graph_traits::edge_descriptor    Edge;

template 
class BfsVisitor : public boost::default_bfs_visitor
{
public:
    typedef typename boost::graph_traits::vertex_descriptor VertexDescriptor;
    typedef typename boost::graph_traits::edge_descriptor   EdgeDescriptor;

    BfsVisitor(std::vector& nodesVisited)
    : m_nodesVisited(nodesVisited){}

    void tree_edge(EdgeDescriptor e, const Graph& g) const
    {
        VertexDescriptor u = source(e, g);
        VertexDescriptor v = target(e, g);
        m_nodesVisited.push_back(v);
    }

private:
    std::vector& m_nodesVisited;
};


const Person Abe_Simpson        {"Abe_Simpson", 0};
const Person Mona_Simpson       { "Mona_Simpson", 0};
const Person Herb_Simpson       { "Herb_Simpson", 0};
const Person Homer_Simpson      { "Homer_Simpson", 0};

const Person Clancy_Bouvier     { "Clancy_Bouvier", 0};
const Person Jacqueline_Bouvier { "Jacqueline_Bouvier", 0};
const Person Marge_Bouvier      { "Marge_Bouvier", 0};
const Person Patty_Bouvier      { "Patty_Bouvier", 0};
const Person Selma_Bouvier      { "Selma_Bouvier", 0};

const Person Bart_Simpson       { "Bart_Simpson", 0};
const Person Lisa_Simpson       { "Lisa_Simpson", 0};
const Person Maggie_Simpson     { "Maggie_Simpson", 0};
const Person Ling_Bouvier       { "Ling_Bouvier", 0};





int main(void)
{
    std::cout << __FUNCTION__ << "\n";

    FamilyTree g;


    // nodes
    auto v_Abe_Simpson = boost::add_vertex(Abe_Simpson,g);
    auto v_Mona_Simpson = boost::add_vertex(Mona_Simpson,g);
    auto v_Herb_Simpson = boost::add_vertex(Herb_Simpson,g);
    auto v_Homer_Simpson = boost::add_vertex(Homer_Simpson,g);

    auto v_Clancy_Bouvier = boost::add_vertex(Clancy_Bouvier,g);
    auto v_Jacqueline_Bouvier = boost::add_vertex(Jacqueline_Bouvier,g);
    auto v_Marge_Bouvier = boost::add_vertex(Marge_Bouvier,g);
    auto v_Patty_Bouvier = boost::add_vertex(Patty_Bouvier,g);
    auto v_Selma_Bouvier = boost::add_vertex(Selma_Bouvier,g);

    auto v_Bart_Simpson = boost::add_vertex(Bart_Simpson,g);
    auto v_Lisa_Simpson = boost::add_vertex(Lisa_Simpson,g);
    auto v_Maggie_Simpson = boost::add_vertex(Maggie_Simpson,g);
    auto v_Ling_Bouvier = boost::add_vertex(Ling_Bouvier,g);

    // connections
    boost::add_edge(v_Abe_Simpson, v_Herb_Simpson, g);
    boost::add_edge(v_Abe_Simpson, v_Homer_Simpson, g);
    boost::add_edge(v_Mona_Simpson, v_Herb_Simpson, g);
    boost::add_edge(v_Mona_Simpson, v_Homer_Simpson, g);

    boost::add_edge(v_Clancy_Bouvier, v_Marge_Bouvier, g);
    boost::add_edge(v_Clancy_Bouvier, v_Patty_Bouvier, g);
    boost::add_edge(v_Clancy_Bouvier, v_Selma_Bouvier, g);
    boost::add_edge(v_Jacqueline_Bouvier, v_Marge_Bouvier, g);
    boost::add_edge(v_Jacqueline_Bouvier, v_Patty_Bouvier, g);
    boost::add_edge(v_Jacqueline_Bouvier, v_Selma_Bouvier, g);

    boost::add_edge(v_Homer_Simpson, v_Bart_Simpson, g);
    boost::add_edge(v_Homer_Simpson, v_Lisa_Simpson, g);
    boost::add_edge(v_Homer_Simpson, v_Maggie_Simpson, g);
    boost::add_edge(v_Marge_Bouvier, v_Bart_Simpson, g);
    boost::add_edge(v_Marge_Bouvier, v_Lisa_Simpson, g);
    boost::add_edge(v_Marge_Bouvier, v_Maggie_Simpson, g);

    boost::add_edge(v_Selma_Bouvier, v_Ling_Bouvier, g);


    typedef std::mapIndexMap;
    IndexMap mapIndex;
    boost::associative_property_map propmapIndex(mapIndex);
    size_t i=0;
    FamilyTree::vertex_iterator vi, vi_end;
    for (boost::tie(vi, vi_end) = boost::vertices(g); vi != vi_end; ++vi)
    {
        boost::put(propmapIndex, *vi, i++);
    }


    for (boost::tie(vi, vi_end) = boost::vertices(g); vi != vi_end; ++vi)
    {
        Vertex vParent = *vi;

        std::vector vertexDescriptors;
        BfsVisitor bfsVisitor(vertexDescriptors);
        breadth_first_search(g, vParent, visitor(bfsVisitor).vertex_index_map(propmapIndex));


        std::cout << "\nDecendants of " << g[vParent].Name << ":\n";
        for (auto v : vertexDescriptors)
        {   
            Person p = g[v];
            std::cout << p.Name << "\n";
        }   
    }

    getchar();
    return 0;
}