Boost-graph：当我的图使用 listS 作为 VertexList 时，如何调用 depth-first-search()？

Question

我正在学习如何将 Boost-graph 库用于大学项目。我有一个图表，我需要在其中添加和删除顶点，所以我用 listS 作为顶点列表声明了我的邻接列表。我对 depth_first_search() 函数的调用有一个大问题：因为 listS，我需要提供一个索引属性映射，但我不明白我需要如何处理。代码如下：

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

struct VertexProperties {
    int value;
};


typedef boost::adjacency_list<boost::vecS,            // OutEdgeList
                              boost::listS,            // VertexList
                              boost::bidirectionalS,  // Directed
                              VertexProperties     // VertexProperties
                              >
MyGraph; 

typedef boost::graph_traits<MyGraph>::vertex_descriptor MyVertex;
typedef boost::graph_traits<MyGraph>::edge_descriptor MyEdge;

class dfs_visitor : public boost::default_dfs_visitor {
    public:
        dfs_visitor();
        dfs_visitor(const dfs_visitor& other);
        void initialize_vertex(MyVertex s, MyGraph g);
        void start_vertex(MyVertex s, MyGraph g);
        void discover_vertex(MyVertex s, MyGraph g);
        void finish_vertex(MyVertex s, MyGraph g);
        void examine_edge(MyEdge e, MyGraph g);
        void tree_edge(MyEdge e, MyGraph g);
        void back_edge(MyEdge e, MyGraph g);
        void forward_or_cross_edge(MyEdge e, MyGraph g);
        void finish_edge(MyEdge e, MyGraph g);
};

dfs_visitor::dfs_visitor() {}
dfs_visitor::dfs_visitor(const dfs_visitor& other) {}
void dfs_visitor::initialize_vertex(MyVertex s, MyGraph g){
    std::cout << "Initialize: " << g[s].value << std::endl;
}
void dfs_visitor::start_vertex(MyVertex s, MyGraph g) {
    std::cout << "Start: " << g[s].value << std::endl;   
}
void dfs_visitor::discover_vertex(MyVertex s, MyGraph g) {
    std::cout << "Discover: " << g[s].value << std::endl;   
}
void dfs_visitor::finish_vertex(MyVertex s, MyGraph g) {
    std::cout << "Finished: " << g[s].value << std::endl;   
}
void dfs_visitor::examine_edge(MyEdge e, MyGraph g) {}
void dfs_visitor::tree_edge(MyEdge e, MyGraph g) {}
void dfs_visitor::back_edge(MyEdge e, MyGraph g) {}
void dfs_visitor::forward_or_cross_edge(MyEdge e, MyGraph g) {}
void dfs_visitor::finish_edge(MyEdge e, MyGraph g) {}




int main(){
    MyGraph g{};


    for(int i = 0; i < 10; i++) {
        MyVertex v = boost::add_vertex(g); 
        g[v].value = i;
    }
    MyGraph::vertex_iterator v, v_end;

    std::tie(v, v_end) = boost::vertices(g);
    auto u = v;
    u++;
    while(v != v_end && u != v_end) {
        boost::add_edge(*u, *v, g);
        u++;
        v++;
    }
    /* INDEX MAP CREATION*/
    typedef std::map<MyVertex, size_t> MyIndexMap;
    MyIndexMap i_map;
    auto ipmap = boost::make_assoc_property_map(i_map);
    std::tie(v, v_end) = boost::vertices(g);
    while(v != v_end) {
        i_map[*v] = i_map.size();
        v++; 
    }

    /* COLOR MAP CREATION */
    typedef std::map<size_t, boost::default_color_type> ColorMap;
    ColorMap c_map;
    auto cpmap = boost::make_assoc_property_map(c_map);
    std::tie(v, v_end) = boost::vertices(g);

    while(v != v_end) {
        c_map[ipmap[*v]] = boost::color_traits<boost::default_color_type>::white();
        v++; 
    }

    dfs_visitor vis{};
    boost::depth_first_search(g, 
                              boost::visitor(vis)), 
                              boost::color_map(cpmap);
                              boost::vertex_index_map(ipmap);
}

当我要编译这个时，这是输出：

In file included from /usr/include/boost/graph/adjacency_list.hpp:223,
                 from test.cpp:2:
/usr/include/boost/graph/detail/adjacency_list.hpp: In instantiation of ‘struct boost::adj_list_any_vertex_pa::bind_<boost::vertex_index_t, boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, VertexProperties>’:
/usr/include/boost/graph/detail/adjacency_list.hpp:2618:12:   required from ‘struct boost::detail::adj_list_choose_vertex_pa<boost::vertex_index_t, boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, VertexProperties>’
/usr/include/boost/graph/detail/adjacency_list.hpp:2755:12:   required from ‘struct boost::adj_list_vertex_property_selector::bind_<boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, VertexProperties, boost::vertex_index_t>’
/usr/include/boost/graph/properties.hpp:201:12:   required from ‘struct boost::detail::vertex_property_map<boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, boost::vertex_index_t>’
/usr/include/boost/graph/properties.hpp:212:10:   required from ‘struct boost::property_map<boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, boost::vertex_index_t, void>’
/usr/include/boost/graph/named_function_params.hpp:416:69:   [ skipping 2 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/include/boost/graph/named_function_params.hpp:605:41:   required from ‘struct boost::detail::map_maker<boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>, boost::graph::keywords::tag::color_map, boost::default_color_type>’
/usr/include/boost/graph/named_function_params.hpp:621:7:   required by substitution of ‘template<class Graph, class ArgPack> typename boost::detail::map_maker<Graph, ArgPack, boost::graph::keywords::tag::color_map, boost::default_color_type>::map_type boost::detail::make_property_map_from_arg_pack_gen<boost::graph::keywords::tag::color_map, boost::default_color_type>::operator()<Graph, ArgPack>(const Graph&, const ArgPack&) const [with Graph = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>; ArgPack = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>]’
/usr/include/boost/graph/depth_first_search.hpp:337:80:   required from ‘void boost::graph::detail::depth_first_search_impl<Graph>::operator()(const Graph&, const ArgPack&) const [with ArgPack = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>; Graph = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>]’
/usr/include/boost/graph/depth_first_search.hpp:342:5:   required from ‘typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const ArgPack&)>::type boost::graph::depth_first_search_with_named_params(const Param0&, const ArgPack&) [with Param0 = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>; ArgPack = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>; typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const ArgPack&)>::type = void]’
/usr/include/boost/graph/depth_first_search.hpp:345:3:   required from ‘typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const typename boost::detail::convert_bgl_params_to_boost_parameter<boost::bgl_named_params<T, Tag, Base> >::type&)>::type boost::depth_first_search(const Param0&, const boost::bgl_named_params<T, Tag, Base>&) [with Param0 = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>; P = dfs_visitor; T = boost::graph_visitor_t; R = boost::no_property; typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const typename boost::detail::convert_bgl_params_to_boost_parameter<boost::bgl_named_params<T, Tag, Base> >::type&)>::type = void]’
test.cpp:100:50:   required from here
/usr/include/boost/graph/detail/adjacency_list.hpp:2548:29: error: forming reference to void
 2548 |         typedef value_type& reference;
      |                             ^~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2549:35: error: forming reference to void
 2549 |         typedef const value_type& const_reference;
      |                                   ^~~~~~~~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2552:47: error: forming reference to void
 2552 |           <Graph, value_type, reference, Tag> type;
      |                                               ^~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2554:53: error: forming reference to void
 2554 |           <Graph, value_type, const_reference, Tag> const_type;
      |                                                     ^~~~~~~~~~
In file included from /usr/include/boost/graph/graph_utility.hpp:24,
                 from test.cpp:3:
/usr/include/boost/graph/depth_first_search.hpp: In instantiation of ‘void boost::graph::detail::depth_first_search_impl<Graph>::operator()(const Graph&, const ArgPack&) const [with ArgPack = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>; Graph = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>]’:
/usr/include/boost/graph/depth_first_search.hpp:342:5:   required from ‘typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const ArgPack&)>::type boost::graph::depth_first_search_with_named_params(const Param0&, const ArgPack&) [with Param0 = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>; ArgPack = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>; typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const ArgPack&)>::type = void]’
/usr/include/boost/graph/depth_first_search.hpp:345:3:   required from ‘typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const typename boost::detail::convert_bgl_params_to_boost_parameter<boost::bgl_named_params<T, Tag, Base> >::type&)>::type boost::depth_first_search(const Param0&, const boost::bgl_named_params<T, Tag, Base>&) [with Param0 = boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>; P = dfs_visitor; T = boost::graph_visitor_t; R = boost::no_property; typename boost::result_of<boost::graph::detail::depth_first_search_impl<Param0>(Param0, const typename boost::detail::convert_bgl_params_to_boost_parameter<boost::bgl_named_params<T, Tag, Base> >::type&)>::type = void]’
test.cpp:100:50:   required from here
/usr/include/boost/graph/depth_first_search.hpp:337:80: error: no match for call to ‘(const boost::detail::make_property_map_from_arg_pack_gen<boost::graph::keywords::tag::color_map, boost::default_color_type>) (const boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, VertexProperties>&, const boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, const dfs_visitor>, boost::parameter::aux::empty_arg_list>&)’
  337 |                       boost::detail::make_color_map_from_arg_pack(g, arg_pack),
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~

In file included from /usr/include/boost/graph/depth_first_search.hpp:21,
                 from /usr/include/boost/graph/graph_utility.hpp:24,
                 from test.cpp:3:
/usr/include/boost/graph/named_function_params.hpp:621:7: note: candidate: ‘template<class Graph, class ArgPack> typename boost::detail::map_maker<Graph, ArgPack, MapTag, ValueType>::map_type boost::detail::make_property_map_from_arg_pack_gen<MapTag, ValueType>::operator()(const Graph&, const ArgPack&) const [with Graph = Graph; ArgPack = ArgPack; MapTag = boost::graph::keywords::tag::color_map; ValueType = boost::default_color_type]’
  621 |       operator()(const Graph& g, const ArgPack& ap) const {
      |       ^~~~~~~~
/usr/include/boost/graph/named_function_params.hpp:621:7: note:   substitution of deduced template arguments resulted in errors seen above

我认为这是一种模板错误。谁能解释一下错误在哪里？

Answer 1

命名参数未正确给出。他们使用Fluent Syntax：

boost::depth_first_search(g,
         boost::visitor(vis)
        .vertex_index_map(ipmap)
        .color_map(cpmap));

现在，您可以显着简化其余代码。

• eerything 公开的类，可以是struct
• 尽可能锻炼Rule Of Zero
• 访客成员可以标记为const
• 通过 const 引用获取图表以避免在每个事件中复制图表
• 使用 c++ 类型别名 (using) 而不是旧版 typedef
• 一次添加VertexProperties 和add_vertex
• 更喜欢范围而不是迭代器对（例如boost::make_iterator_range）
• 无需对 default_color_type、std::vector 或 std::map 进行值初始化就可以了

一下子搞定：Live On Coliru

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

struct VertexProperties {
    int value;
};

using MyGraph = boost::adjacency_list<boost::vecS,           // OutEdgeList
        boost::listS,          // VertexList
        boost::bidirectionalS, // Directed
        VertexProperties       // VertexProperties
        >;

using MyVertex = boost::graph_traits<MyGraph>::vertex_descriptor;
using MyEdge = boost::graph_traits<MyGraph>::edge_descriptor;

struct dfs_visitor : boost::default_dfs_visitor {
    void initialize_vertex(MyVertex   s, MyGraph const& g) const { std::cout << "Initialize: " << g[s].value << std::endl; }
    void start_vertex(MyVertex        s, MyGraph const& g) const { std::cout << "Start:      " << g[s].value << std::endl; }
    void discover_vertex(MyVertex     s, MyGraph const& g) const { std::cout << "Discover:   " << g[s].value << std::endl; }
    void finish_vertex(MyVertex       s, MyGraph const& g) const { std::cout << "Finished:   " << g[s].value << std::endl; }
};

int main() {
    MyGraph g{};

    for (int i = 0; i < 10; i++) {
        add_vertex(VertexProperties{i}, g);
    }

    {
        boost::optional<MyVertex> prev;

        for (auto v : boost::make_iterator_range(vertices(g))) {
            if (prev)
                add_edge(v, *prev, g);
            prev = v;
        }
    }

    /* INDEX MAP CREATION*/
    std::map<MyVertex, size_t> i_map;
    for (auto v : boost::make_iterator_range(vertices(g))) {
        i_map.emplace(v, i_map.size());
    }

    auto ipmap = boost::make_assoc_property_map(i_map);

    /* COLOR MAP CREATION */
    std::vector<boost::default_color_type> c_map(num_vertices(g));
    auto cpmap = boost::make_iterator_property_map(c_map.begin(), ipmap);

    dfs_visitor vis{};
    boost::depth_first_search(g,
             boost::visitor(vis)
            .vertex_index_map(ipmap)
            .color_map(cpmap));
}

打印

Initialize: 0
Initialize: 1
Initialize: 2
Initialize: 3
Initialize: 4
Initialize: 5
Initialize: 6
Initialize: 7
Initialize: 8
Initialize: 9
Start:      0
Discover:   0
Finished:   0
Start:      1
Discover:   1
Finished:   1
Start:      2
Discover:   2
Finished:   2
Start:      3
Discover:   3
Finished:   3
Start:      4
Discover:   4
Finished:   4
Start:      5
Discover:   5
Finished:   5
Start:      6
Discover:   6
Finished:   6
Start:      7
Discover:   7
Finished:   7
Start:      8
Discover:   8
Finished:   8
Start:      9
Discover:   9
Finished:   9