I mean traverse when i said parse. So the problem is i can't traverse in depth-first order my graph and modify  node (or edge) properties. I wrote a basic case which doesn't work.

-----------------------------------------

// Begin main.cpp

#include <boost/graph/adjacency_list.hpp>

#include <boost/graph/depth_first_search.hpp>

#include <vector>

// Node properties

struct MyNode

{

int node_id;

MyNode() : node_id() {}

MyNode(int id) : node_id(id) {}

};

//Edge Properties

struct MyEdge

{

int edge_id;

MyEdge() : edge_id() {}

MyEdge(int id) : edge_id(id) {}

};

// Graph definition

typedef boost::adjacency_list<

boost::vecS, boost::vecS, boost::directedS,

MyNode, MyEdge

> MyGraph;

typedef boost::graph_traits<MyGraph>::vertex_descriptor MyGraphVD;

//My idiot visitor

class my_dfs_visitor : public boost::default_dfs_visitor

{

public:

template < typename Vertex, typename Graph > void discover_vertex(Vertex u, Graph & g)

{

                // here i cant assign 0 to m node_id. however g is not cont.. I didn't find a code with a depth-first traversal and assign

ment.

g[u].node_id = 0;

}

};

int main()

{

MyGraph g;

MyGraphVD vd0 = boost::add_vertex(MyNode(0), g);

MyGraphVD vd1 = boost::add_vertex(MyNode(1), g);

boost::add_edge(vd0, vd1, MyEdge(), g);

boost::add_edge(vd1, vd0, MyEdge(), g);

my_dfs_visitor visitor;

boost::depth_first_search(g, boost::visitor(visitor));

return 0;

}

// end

------------------------------------------

This code doesn't work. I have the following error : ../main.cpp:35:3: erreur: assignment of member ‘MyNode::node_id’ in read-only object. 

I didn't find any example on the web.. 

Thanks for spending time on my problem. It is very nice of you.

Best regards.

Orianne Siret