//=======================================================================
// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
#include <boost/config.hpp>
#include <iostream>
#include <boost/graph/copy.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/filtered_graph.hpp>
#include <boost/graph/graph_utility.hpp>

template < typename Graph > struct non_zero_degree
{
    non_zero_degree() {} // has to have a default constructor!

    non_zero_degree(const Graph& g) : g(&g) {}

    bool operator()(
        typename boost::graph_traits< Graph >::vertex_descriptor v) const
    {
        return degree(v, *g) != 0;
    }
    const Graph* g;
};

int main()
{
    using namespace boost;
    typedef adjacency_list< vecS, vecS, bidirectionalS,
        property< vertex_name_t, char > >
        graph_t;

    enum
    {
        a,
        b,
        c,
        d,
        e,
        f,
        g,
        N
    };
    graph_t G(N);
    property_map< graph_t, vertex_name_t >::type name_map = get(vertex_name, G);
    char name = 'a';
    graph_traits< graph_t >::vertex_iterator v, v_end;
    for (boost::tie(v, v_end) = vertices(G); v != v_end; ++v, ++name)
        name_map[*v] = name;

    typedef std::pair< int, int > E;
    E edges[] = { E(a, c), E(a, d), E(b, a), E(b, d), E(c, f), E(d, c), E(d, e),
        E(d, f), E(e, b), E(e, g), E(f, e), E(f, g) };
    for (int i = 0; i < 12; ++i)
        add_edge(edges[i].first, edges[i].second, G);

    print_graph(G, name_map);
    std::cout << std::endl;

    clear_vertex(b, G);
    clear_vertex(d, G);

    graph_t G_copy;
    copy_graph(
        make_filtered_graph(G, keep_all(), non_zero_degree< graph_t >(G)),
        G_copy);

    print_graph(G_copy, get(vertex_name, G_copy));

    return 0;
}