boost/serialization/variant.hpp

   1 #ifndef BOOST_SERIALIZATION_VARIANT_HPP
   2 #define BOOST_SERIALIZATION_VARIANT_HPP
   3
   4 // MS compatible compilers support #pragma once
   5 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   6 # pragma once
   7 #endif
   8
   9 #if defined(_MSC_VER) && (_MSC_VER <= 1020)
  10 #  pragma warning (disable : 4786) // too long name, harmless warning
  11 #endif
  12
  13 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
  14 // variant.hpp - non-intrusive serialization of variant types
  15 //
  16 // copyright (c) 2005
  17 // troy d. straszheim <troy@resophonic.com>
  18 // http://www.resophonic.com
  19 //
  20 // Use, modification and distribution is subject to the Boost Software
  21 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  22 // http://www.boost.org/LICENSE_1_0.txt)
  23 //
  24 // See http://www.boost.org for updates, documentation, and revision history.
  25 //
  26 // thanks to Robert Ramey, Peter Dimov, and Richard Crossley.
  27 //
  28
  29 #include <boost/mpl/front.hpp>
  30 #include <boost/mpl/pop_front.hpp>
  31 #include <boost/mpl/eval_if.hpp>
  32 #include <boost/mpl/identity.hpp>
  33 #include <boost/mpl/size.hpp>
  34 #include <boost/mpl/empty.hpp>
  35
  36 #include <boost/serialization/throw_exception.hpp>
  37
  38 #include <boost/variant.hpp>
  39
  40 #include <boost/archive/archive_exception.hpp>
  41
  42 #include <boost/serialization/split_free.hpp>
  43 #include <boost/serialization/serialization.hpp>
  44
  45 namespace boost {
  46 namespace serialization {
  47
  48 template<class Archive>
  49 struct variant_save_visitor : boost::static_visitor<> {
  50     variant_save_visitor(Archive& ar) :
  51         m_ar(ar)
  52     {}
  53     template<class T>
  54     void operator()(T const & value) const
  55     {
  56         m_ar << BOOST_SERIALIZATION_NVP(value);
  57     }
  58 private:
  59     Archive & m_ar;
  60 };
  61
  62 template<class Archive, BOOST_VARIANT_ENUM_PARAMS(/* typename */ class T)>
  63 void save(
  64     Archive & ar,
  65     boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const & v,
  66     unsigned int /*version*/
  67 ){
  68     int which = v.which();
  69     ar << BOOST_SERIALIZATION_NVP(which);
  70     typedef BOOST_DEDUCED_TYPENAME  boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types types;
  71     variant_save_visitor<Archive> visitor(ar);
  72     v.apply_visitor(visitor);
  73 }
  74
  75 template<class S>
  76 struct variant_impl {
  77
  78     struct load_null {
  79         template<class Archive, class V>
  80         static void invoke(
  81             Archive & /*ar*/,
  82             int /*which*/,
  83             V & /*v*/,
  84             const unsigned int /*version*/
  85         ){}
  86     };
  87
  88     struct load_impl {
  89         template<class Archive, class V>
  90         static void invoke(
  91             Archive & ar,
  92             int which,
  93             V & v,
  94             const unsigned int version
  95         ){
  96             if(which == 0){
  97                 // note: A non-intrusive implementation (such as this one)
  98                 // necessary has to copy the value.  This wouldn't be necessary
  99                 // with an implementation that de-serialized to the address of the
 100                 // aligned storage included in the variant.
 101                 typedef BOOST_DEDUCED_TYPENAME mpl::front<S>::type head_type;
 102                 head_type value;
 103                 ar >> BOOST_SERIALIZATION_NVP(value);
 104                 v = value;
 105                 ar.reset_object_address(& boost::get<head_type>(v), & value);
 106                 return;
 107             }
 108             typedef BOOST_DEDUCED_TYPENAME mpl::pop_front<S>::type type;
 109             variant_impl<type>::load(ar, which - 1, v, version);
 110         }
 111     };
 112
 113     template<class Archive, class V>
 114     static void load(
 115         Archive & ar,
 116         int which,
 117         V & v,
 118         const unsigned int version
 119     ){
 120         typedef BOOST_DEDUCED_TYPENAME mpl::eval_if<mpl::empty<S>,
 121             mpl::identity<load_null>,
 122             mpl::identity<load_impl>
 123         >::type typex;
 124         typex::invoke(ar, which, v, version);
 125     }
 126
 127 };
 128
 129 template<class Archive, BOOST_VARIANT_ENUM_PARAMS(/* typename */ class T)>
 130 void load(
 131     Archive & ar,
 132     boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& v,
 133     const unsigned int version
 134 ){
 135     int which;
 136     typedef BOOST_DEDUCED_TYPENAME boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types types;
 137     ar >> BOOST_SERIALIZATION_NVP(which);
 138     if(which >=  mpl::size<types>::value)
 139         // this might happen if a type was removed from the list of variant types
 140         boost::serialization::throw_exception(
 141             boost::archive::archive_exception(
 142                 boost::archive::archive_exception::unsupported_version
 143             )
 144         );
 145     variant_impl<types>::load(ar, which, v, version);
 146 }
 147
 148 template<class Archive,BOOST_VARIANT_ENUM_PARAMS(/* typename */ class T)>
 149 inline void serialize(
 150     Archive & ar,
 151     boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> & v,
 152     const unsigned int file_version
 153 ){
 154     split_free(ar,v,file_version);
 155 }
 156
 157 } // namespace serialization
 158 } // namespace boost
 159
 160 #endif //BOOST_SERIALIZATION_VARIANT_HPP