Modifying vertex properties in a Boost::Graph

Question

I am trying to figure out how to use boost::graph to store some information. However, there is information I want tied to each vertex. Staring at the documentation for the l

Answer 1

I don't like the nested-template property approach of boost::graph, so I wrote a small wrapper around everything, that basically allows to put any struct/class as a vertex/edge property. One can access properties accessing the struct members.

To keep it flexible these structs are defined as template parameter.

Here the Code:

/* definition of basic boost::graph properties */
enum vertex_properties_t { vertex_properties };
enum edge_properties_t { edge_properties };
namespace boost {
    BOOST_INSTALL_PROPERTY(vertex, properties);
    BOOST_INSTALL_PROPERTY(edge, properties);
}


/* the graph base class template */
template < typename VERTEXPROPERTIES, typename EDGEPROPERTIES >
class Graph
{
public:

    /* an adjacency_list like we need it */
    typedef adjacency_list<
        setS, // disallow parallel edges
        listS, // vertex container
        bidirectionalS, // directed graph
        property,
        property
    > GraphContainer;


    /* a bunch of graph-specific typedefs */
    typedef typename graph_traits::vertex_descriptor Vertex;
    typedef typename graph_traits::edge_descriptor Edge;
    typedef std::pair EdgePair;

    typedef typename graph_traits::vertex_iterator vertex_iter;
    typedef typename graph_traits::edge_iterator edge_iter;
    typedef typename graph_traits::adjacency_iterator adjacency_iter;
    typedef typename graph_traits::out_edge_iterator out_edge_iter;

    typedef typename graph_traits::degree_size_type degree_t;

    typedef std::pair adjacency_vertex_range_t;
    typedef std::pair out_edge_range_t;
    typedef std::pair vertex_range_t;
    typedef std::pair edge_range_t;


    /* constructors etc. */
    Graph()
    {}

    Graph(const Graph& g) :
        graph(g.graph)
    {}

    virtual ~Graph()
    {}


    /* structure modification methods */
    void Clear()
    {
        graph.clear();
    }

    Vertex AddVertex(const VERTEXPROPERTIES& prop)
    {
        Vertex v = add_vertex(graph);
        properties(v) = prop;
        return v;
    }

    void RemoveVertex(const Vertex& v)
    {
        clear_vertex(v, graph);
        remove_vertex(v, graph);
    }

    EdgePair AddEdge(const Vertex& v1, const Vertex& v2, const EDGEPROPERTIES& prop_12, const EDGEPROPERTIES& prop_21)
    {
        /* TODO: maybe one wants to check if this edge could be inserted */
        Edge addedEdge1 = add_edge(v1, v2, graph).first;
        Edge addedEdge2 = add_edge(v2, v1, graph).first;

        properties(addedEdge1) = prop_12;
        properties(addedEdge2) = prop_21;

        return EdgePair(addedEdge1, addedEdge2);
    }


    /* property access */
    VERTEXPROPERTIES& properties(const Vertex& v)
    {
        typename property_map::type param = get(vertex_properties, graph);
        return param[v];
    }

    const VERTEXPROPERTIES& properties(const Vertex& v) const
    {
        typename property_map::const_type param = get(vertex_properties, graph);
        return param[v];
    }

    EDGEPROPERTIES& properties(const Edge& v)
    {
        typename property_map::type param = get(edge_properties, graph);
        return param[v];
    }

    const EDGEPROPERTIES& properties(const Edge& v) const
    {
        typename property_map::const_type param = get(edge_properties, graph);
        return param[v];
    }


    /* selectors and properties */
    const GraphContainer& getGraph() const
    {
        return graph;
    }

    vertex_range_t getVertices() const
    {
        return vertices(graph);
    }

    adjacency_vertex_range_t getAdjacentVertices(const Vertex& v) const
    {
        return adjacent_vertices(v, graph);
    }

    int getVertexCount() const
    {
        return num_vertices(graph);
    }

    int getVertexDegree(const Vertex& v) const
    {
        return out_degree(v, graph);
    }


    /* operators */
    Graph& operator=(const Graph &rhs)
    {
        graph = rhs.graph;
        return *this;
    }

protected:
    GraphContainer graph;
};

Using this you can access properties like this:

struct VertexProperties {
    int i;
};

struct EdgeProperties {
};

typedef Graph MyGraph;

MyGraph g;

VertexProperties vp;
vp.i = 42;

MyGraph::Vertex v = g.AddVertex(vp);

g.properties(v).i = 23;

Of course you may have other needs for your graph's structure, but modification of the code above should be pretty easy.