Line data    Source code

       1             : /*! \file variant.hpp
       2             :     \brief Support for std::variant
       3             :     \ingroup STLSupport */
       4             : /*
       5             :   Copyright (c) 2014, 2017, Randolph Voorhies, Shane Grant, Juan Pedro
       6             :   Bolivar Puente. All rights reserved.
       7             : 
       8             :   Redistribution and use in source and binary forms, with or without
       9             :   modification, are permitted provided that the following conditions are met:
      10             :       * Redistributions of source code must retain the above copyright
      11             :         notice, this list of conditions and the following disclaimer.
      12             :       * Redistributions in binary form must reproduce the above copyright
      13             :         notice, this list of conditions and the following disclaimer in the
      14             :         documentation and/or other materials provided with the distribution.
      15             :       * Neither the name of the copyright holder nor the
      16             :         names of its contributors may be used to endorse or promote products
      17             :         derived from this software without specific prior written permission.
      18             : 
      19             :   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
      20             :   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
      21             :   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
      22             :   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
      23             :   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
      24             :   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
      25             :   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
      26             :   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      27             :   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
      28             :   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      29             : */
      30             : #ifndef CEREAL_TYPES_STD_VARIANT_HPP_
      31             : #define CEREAL_TYPES_STD_VARIANT_HPP_
      32             : 
      33             : #include "cereal/cereal.hpp"
      34             : #include <variant>
      35             : #include <cstdint>
      36             : 
      37             : namespace cereal
      38             : {
      39             :   namespace variant_detail
      40             :   {
      41             :     //! @internal
      42             :     template <class Archive>
      43             :     struct variant_save_visitor
      44             :     {
      45          12 :       variant_save_visitor(Archive & ar_) : ar(ar_) {}
      46             : 
      47             :       template<class T>
      48          12 :         void operator()(T const & value) const
      49             :         {
      50          12 :           ar( CEREAL_NVP_("data", value) );
      51          12 :         }
      52             : 
      53             :       Archive & ar;
      54             :     };
      55             : 
      56             :     //! @internal
      57             :     template<int N, class Variant, class Archive>
      58             :     typename std::enable_if<N == std::variant_size_v<Variant>, void>::type
      59           0 :     load_variant(Archive & /*ar*/, int /*target*/, Variant & /*variant*/)
      60             :     {
      61           0 :       throw ::cereal::Exception("Error traversing variant during load");
      62             :     }
      63             :     //! @internal
      64             :     template<int N, class Variant, class Archive>
      65             :     typename std::enable_if<N < std::variant_size_v<Variant>, void>::type
      66          24 :     load_variant(Archive & ar, int target, Variant & variant)
      67             :     {
      68          24 :       if(N == target)
      69             :       {
      70          12 :         variant.template emplace<N>();
      71          12 :         ar( CEREAL_NVP_("data", std::get<N>(variant)) );
      72             :       }
      73             :       else
      74          12 :         load_variant<N+1>(ar, target, variant);
      75          24 :     }
      76             : 
      77             :   } // namespace variant_detail
      78             : 
      79             :   //! Saving for std::variant
      80             :   template <class Archive, typename VariantType1, typename... VariantTypes> inline
      81          12 :   void CEREAL_SAVE_FUNCTION_NAME( Archive & ar, std::variant<VariantType1, VariantTypes...> const & variant )
      82             :   {
      83          12 :     std::int32_t index = static_cast<std::int32_t>(variant.index());
      84          12 :     ar( CEREAL_NVP_("index", index) );
      85          12 :     variant_detail::variant_save_visitor<Archive> visitor(ar);
      86          12 :     std::visit(visitor, variant);
      87          12 :   }
      88             : 
      89             :   //! Loading for std::variant
      90             :   template <class Archive, typename... VariantTypes> inline
      91          12 :   void CEREAL_LOAD_FUNCTION_NAME( Archive & ar, std::variant<VariantTypes...> & variant )
      92             :   {
      93             :     using variant_t = typename std::variant<VariantTypes...>;
      94             : 
      95             :     std::int32_t index;
      96          12 :     ar( CEREAL_NVP_("index", index) );
      97          12 :     if(index >= static_cast<std::int32_t>(std::variant_size_v<variant_t>))
      98           0 :       throw Exception("Invalid 'index' selector when deserializing std::variant");
      99             : 
     100          12 :     variant_detail::load_variant<0>(ar, index, variant);
     101          12 :   }
     102             : 
     103             :   //! Serializing a std::monostate
     104             :   template <class Archive>
     105             :   void CEREAL_SERIALIZE_FUNCTION_NAME( Archive &, std::monostate const & ) {}
     106             : } // namespace cereal
     107             : 
     108             : #endif // CEREAL_TYPES_STD_VARIANT_HPP_