Re: [Boost-users] Creating custom depth first search visitor for Boost graph

Hello, when you are inside the visitor the () operator takes two arguments, a vertex descriptor and a reference to the graph. So I guess you can use this graph variable to access the property map for color. For example I have the following visitor: struct SendMsg : public base_visitor <SendMsg> { typedef on_finish_vertex event_filter; /* here what the visitor must do... */ template void operator()(Vertex u, Graph& g) { Vertex v = g[u].get_parent_node(); typename graph_traits <Graph>::edge_descriptor e = edge(u,v,g).first; g[u].send_message( g[v].get_object(), g[e] ); } }; I guess in that example, you need to use the g variable with the color map in order to do what you want... take a look at "http://www.boost.org/libs/graph/doc/depth_first_search.html" and that should help you. I don't know exactly how to that, because I don't know about property maps, but that would be something like g.color_map[v] = ... (excuse me for the absolutely wrong syntax... you'd have to use put I guess) Jean-Noël On 7-Mar-05, at 10:37 PM, Stephen Torri wrote:

I have a need to have a graph visitor algorithm similar to depth first search. The only difference is that if upon running discover_vertex the intended operation to be done on the vertex is not done I want the graph color value for this position to still be white.

The reason is that the graph I am using the depth first search is a directed graph with no loops in it. A vertex might have two or more vertices providing information. If all the information is not there I want the visitor to try again.

What do I have to do to gain access to the color map inside the visitor when I am in discover_vertex?

Stephen

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