BGL adjacency_list<listS, listS>::vertex_descriptor 计算为 void*

Question

boost::graph_traits<graph_type>::vertex_descriptor> vertex_map_type 计算结果为 void* 将boost::listS 用于VertexListS 时

以下代码无法编译。但是使用 vecS 而不是 listS 可以。

#include <iostream>
#include <fstream>
#include <map>
#include <list>
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_io.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/adj_list_serialize.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/serialization/map.hpp>
#include <boost/uuid/uuid_io.hpp>
#include <boost/uuid/uuid_serialize.hpp>

typedef boost::adjacency_list<
    boost::listS,
    boost::listS, // << ------ vecS works but listS or setS doesn't !!
    boost::bidirectionalS> graph_type;
typedef std::map<boost::uuids::uuid, typename boost::graph_traits<graph_type>::vertex_descriptor> vertex_map_type;

int main(){
    graph_type graph;
    vertex_map_type map;
    std::ofstream stream("archive");
    boost::archive::binary_oarchive archive(stream);
    archive << graph;
    archive << map;
    return 0;
}

由于void*而无法编译

$ g++ graph.cpp -o graph -lboost_graph -lboost_serialization
In file included from /usr/include/boost/archive/detail/interface_oarchive.hpp:23:0,
                 from /usr/include/boost/archive/detail/common_oarchive.hpp:22,
                 from /usr/include/boost/archive/basic_binary_oarchive.hpp:34,
                 from /usr/include/boost/archive/binary_oarchive_impl.hpp:23,
                 from /usr/include/boost/archive/binary_oarchive.hpp:21,
                 from graph.cpp:9:
/usr/include/boost/archive/detail/oserializer.hpp: In instantiation of ‘static void boost::archive::detail::save_pointer_type<Archive>::invoke(Archive&, TPtr) [with TPtr = void*; Archive = boost::archive::binary_oarchive]’:
/usr/include/boost/archive/detail/oserializer.hpp:525:24:   required from ‘void boost::archive::save(Archive&, T&) [with Archive = boost::archive::binary_oarchive; T = void* const]’
/usr/include/boost/archive/detail/common_oarchive.hpp:69:40:   required from ‘void boost::archive::detail::common_oarchive<Archive>::save_override(T&, int) [with T = void* const; Archive = boost::archive::binary_oarchive]’
/usr/include/boost/archive/basic_binary_oarchive.hpp:75:7:   required from ‘void boost::archive::basic_binary_oarchive<Archive>::save_override(const T&, int) [with T = void*; Archive = boost::archive::binary_oarchive]’
/usr/include/boost/archive/binary_oarchive_impl.hpp:51:9:   required from ‘void boost::archive::binary_oarchive_impl<Archive, Elem, Tr>::save_override(T&, int) [with T = void* const; Archive = boost::archive::binary_oarchive; Elem = char; Tr = std::char_traits<char>]’
/usr/include/boost/archive/detail/interface_oarchive.hpp:63:9:   required from ‘Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = void* const; Archive = boost::archive::binary_oarchive]’
/usr/include/boost/serialization/nvp.hpp:79:9:   [ skipping 52 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/include/boost/archive/detail/oserializer.hpp:525:24:   required from ‘void boost::archive::save(Archive&, T&) [with Archive = boost::archive::binary_oarchive; T = const std::map<boost::uuids::uuid, void*>]’
/usr/include/boost/archive/detail/common_oarchive.hpp:69:40:   required from ‘void boost::archive::detail::common_oarchive<Archive>::save_override(T&, int) [with T = const std::map<boost::uuids::uuid, void*>; Archive = boost::archive::binary_oarchive]’
/usr/include/boost/archive/basic_binary_oarchive.hpp:75:7:   required from ‘void boost::archive::basic_binary_oarchive<Archive>::save_override(const T&, int) [with T = std::map<boost::uuids::uuid, void*>; Archive = boost::archive::binary_oarchive]’
/usr/include/boost/archive/binary_oarchive_impl.hpp:51:9:   required from ‘void boost::archive::binary_oarchive_impl<Archive, Elem, Tr>::save_override(T&, int) [with T = std::map<boost::uuids::uuid, void*>; Archive = boost::archive::binary_oarchive; Elem = char; Tr = std::char_traits<char>]’
/usr/include/boost/archive/detail/interface_oarchive.hpp:63:9:   required from ‘Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = std::map<boost::uuids::uuid, void*>; Archive = boost::archive::binary_oarchive]’
graph.cpp:27:13:   required from here
/usr/include/boost/archive/detail/oserializer.hpp:465:27: error: ‘void*’ is not a pointer-to-object type
         register_type(ar, * t);
                           ^
/usr/include/boost/archive/detail/oserializer.hpp:473:18: error: ‘void*’ is not a pointer-to-object type
         save(ar, * t);

See it on coliru

Answer 1

没错。它确实评估为不透明的整数类型。这是设计使然，并已记录在案。

vecS 具有连续存储，但 listS 和 setS (etc) 具有迭代器稳定性。您可以选择您的应用所需的内容。

这意味着您需要一个 ID（BGL 算法为此使用 vertex_index_t 属性）。或者，只需使用内置的序列化支持。

#include <boost/archive/binary_oarchive.hpp>
#include <boost/graph/adj_list_serialize.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_serialize.hpp>
#include <fstream>

typedef boost::adjacency_list<
    boost::listS, boost::listS, boost::bidirectionalS,
    boost::property<boost::vertex_index_t, boost::uuids::uuid>
> graph_type;

int main(){
    graph_type graph;

    std::ofstream stream("archive");
    boost::archive::binary_oarchive archive(stream);
    archive << graph;
}