编译期间boost xml序列化失败

Question

我正在使用boost::icl::interval_map，以维护区间搜索树的城市和它的高，低温。我想将interval_map序列化为一个文件。

代码适用于文本和二进制序列化，但是xml序列化无法编译。这是我所犯的错误

root@ubuntu16:~/workspace/CPPCodes/interval-tree/city# make
g++ -o main  -std=c++14 -g -ggdb -O0 main.cpp -lboost_serialization
In file included from /usr/include/boost/mpl/aux_/na_assert.hpp:23:0,
                 from /usr/include/boost/mpl/arg.hpp:25,
                 from /usr/include/boost/mpl/placeholders.hpp:24,
                 from /usr/include/boost/archive/basic_binary_iprimitive.hpp:52,
                 from /usr/include/boost/archive/binary_iarchive_impl.hpp:21,
                 from /usr/include/boost/archive/binary_iarchive.hpp:20,
                 from main.cpp:4:
/usr/include/boost/archive/basic_xml_oarchive.hpp: In instantiation of ‘void boost::archive::basic_xml_oarchive<Archive>::save_override(T&, int) [with T = const boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> >; Archive = boost::archive::xml_oarchive]’:
/usr/include/boost/archive/detail/interface_oarchive.hpp:63:9:   required from ‘Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = const boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> >; Archive = boost::archive::xml_oarchive]’
main.cpp:186:8:   required from here
/usr/include/boost/archive/basic_xml_oarchive.hpp:99:9: error: no matching function for call to ‘assertion_failed(mpl_::failed************ boost::serialization::is_wrapper<const boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > >::************)’
         BOOST_MPL_ASSERT((serialization::is_wrapper< T >));
         ^
/usr/include/boost/mpl/assert.hpp:83:5: note: candidate: template<bool C> int mpl_::assertion_failed(typename mpl_::assert<C>::type)
 int assertion_failed( typename assert<C>::type );
     ^
/usr/include/boost/mpl/assert.hpp:83:5: note:   template argument deduction/substitution failed:
/usr/include/boost/archive/basic_xml_oarchive.hpp:99:9: note:   cannot convert ‘mpl_::assert_arg<boost::serialization::is_wrapper<const boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > > >(0u, 1)’ (type ‘mpl_::failed************ boost::serialization::is_wrapper<const boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > >::************’) to type ‘mpl_::assert<false>::type {aka mpl_::assert<false>}’
         BOOST_MPL_ASSERT((serialization::is_wrapper< T >));
         ^
/usr/include/boost/archive/basic_xml_iarchive.hpp: In instantiation of ‘void boost::archive::basic_xml_iarchive<Archive>::load_override(T&, int) [with T = boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> >; Archive = boost::archive::xml_iarchive]’:
/usr/include/boost/archive/xml_iarchive.hpp:103:51:   required from ‘void boost::archive::xml_iarchive_impl<Archive>::load_override(T&, int) [with T = boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> >; Archive = boost::archive::xml_iarchive]’
/usr/include/boost/archive/detail/interface_iarchive.hpp:60:9:   required from ‘Archive& boost::archive::detail::interface_iarchive<Archive>::operator>>(T&) [with T = boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> >; Archive = boost::archive::xml_iarchive]’
main.cpp:194:8:   required from here
/usr/include/boost/archive/basic_xml_iarchive.hpp:76:9: error: no matching function for call to ‘assertion_failed(mpl_::failed************ boost::serialization::is_wrapper<boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > >::************)’
         BOOST_MPL_ASSERT((serialization::is_wrapper< T >));
         ^
/usr/include/boost/mpl/assert.hpp:83:5: note: candidate: template<bool C> int mpl_::assertion_failed(typename mpl_::assert<C>::type)
 int assertion_failed( typename assert<C>::type );
     ^
/usr/include/boost/mpl/assert.hpp:83:5: note:   template argument deduction/substitution failed:
/usr/include/boost/archive/basic_xml_iarchive.hpp:76:9: note:   cannot convert ‘mpl_::assert_arg<boost::serialization::is_wrapper<boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > > >(0u, 1)’ (type ‘mpl_::failed************ boost::serialization::is_wrapper<boost::icl::interval_map<long unsigned int, boost::container::flat_set<City> > >::************’) to type ‘mpl_::assert<false>::type {aka mpl_::assert<false>}’
         BOOST_MPL_ASSERT((serialization::is_wrapper< T >));
         ^
Makefile:7: recipe for target 'main' failed
make: *** [main] Error 1

在编译过程中，以下BOOST_MPL_ASSERT失败

// Anything not an attribute and not a name-value pair is an
// error and should be trapped here.
template<class T>
void save_override(T & t, BOOST_PFTO int)
{
    // If your program fails to compile here, its most likely due to
    // not specifying an nvp wrapper around the variable to
    // be serialized.
    BOOST_MPL_ASSERT((serialization::is_wrapper< T >));
    this->detail_common_oarchive::save_override(t, 0);
}

该评论建议，我没有使用NVP包装周围的成员被序列化。但是，我认为，对于所有成员变量，我都使用了BOOST_SERIALIZATION_NVP或boost::serialization::make_nvp。不知道发生了什么。

代码被推到这里：failure/interval-tree/city

Answer 1

我认为，你的问题在一定程度上是对oarchive的重复。通过将oa << tree更改为oa << BOOST_SERIALIZATION_NVP(tree)来修正编译错误。我得到的结果输出存档是有意义的：

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="14">
<tree class_id="0" tracking_level="0" version="0">
    <sz>1</sz>
    <INTERVAL class_id="1" tracking_level="0" version="0">
        <bb>2</bb>
        <l>28</l>
        <u>39</u>
    </INTERVAL>
    <SET class_id="2" tracking_level="0" version="0">
        <count>1</count>
        <item_version>0</item_version>
        <item class_id="3" tracking_level="0" version="0">
            <city_>cpur</city_>
            <low_>28</low_>
            <high_>39</high_>
        </item>
    </SET>
</tree>