DFS Visitor Adaptor

#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/depth_first_search.hpp>
#include <boost/graph/visitors.hpp>
#include <iostream>
#include <vector>

int main() {
    using namespace boost;
    using Graph = adjacency_list<vecS, vecS, directedS>;

    Graph g(5);
    add_edge(0, 1, g);
    add_edge(0, 2, g);
    add_edge(1, 3, g);
    add_edge(3, 4, g);
    add_edge(4, 0, g);  // back edge

    std::vector<int> dtime(num_vertices(g));
    std::vector<int> ftime(num_vertices(g));
    int t = 0;

    auto vis = make_dfs_visitor(
        std::make_pair(
            stamp_times(dtime.data(), t, on_discover_vertex()),
            stamp_times(ftime.data(), t, on_finish_vertex())
        )
    );
    depth_first_search(g, visitor(vis));

    for (std::size_t v = 0; v < num_vertices(g); ++v) {
        std::cout << "vertex " << v
                  << "  discover=" << dtime[v]
                  << "  finish=" << ftime[v] << "\n";
    }
}

vertex 0  discover=1  finish=10
vertex 1  discover=2  finish=7
vertex 2  discover=8  finish=9
vertex 3  discover=3  finish=6
vertex 4  discover=4  finish=5

template <typename EventVisitorList = null_visitor>
class dfs_visitor;

template <typename EventVisitorList>
dfs_visitor<EventVisitorList>
make_dfs_visitor(EventVisitorList ev_list);