Using Boost Graph Library (BGL) in Fortran program

Question

Is there anyway, I can use the graph data structure using the Boost Graph Library (BGL) inside my FORTRAN program.

Could anyone help me or give me a hint. I want to do parallel graph structure on several processors in my MPI-FORTRAN code. Is it possible to use Boost Graph Library (BGL) for this purpose!

Kind regards, Ziv

Answer 1

You would have to construct an intermediate layer, written in C++, that does all the templating in some special case useful for you and then call it from Fortran. bind(C) and iso_c_binding module are your friends. I successfully use Boost based library CGAL in Fortran using this approach.

Something along the lines of:

my_bgl.cc:

  #include <boost/graph/graph_traits.hpp>
  #include <boost/graph/adjacency_list.hpp>

  using namespace boost;
extern "C"{  
  void* make_graph(int num_vertices, int num_edges, int *edge_array)
  {

    // create a typedef for the Graph type
    typedef adjacency_list<vecS, vecS, bidirectionalS> Graph;

    Graph *g = new Graph(num_vertices);

    // add the edges to the graph object
    for (int i = 0; i < num_edges; ++i)
      add_edge(edge_array[2*i], edge_array[2*i+1], *g);

    return g;
  }
}

my_bgl.f90:

module my_bgl
  use iso_c_binding

  interface
    type(c_ptr) function make_graph(num_vertices, num_edges, edge_array) bind(C,name="make_graph")
      import
      integer(c_int), value :: num_vertices
      integer(c_int), value :: num_edges
      integer(c_int) :: edge_array(2, num_edges)
    end function
  end interface

end module

The function make_graph returns an opaque pointer to a Graph from the points entered.