cereal
A C++11 library for serialization
variant.hpp
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1 
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:
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15  * Neither the name of cereal nor the
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24  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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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  {
42  template <class Archive>
44  {
45  variant_save_visitor(Archive & ar_) : ar(ar_) {}
46 
47  template<class T>
48  void operator()(T const & value) const
49  {
50  ar( CEREAL_NVP_("data", value) );
51  }
52 
53  Archive & ar;
54  };
55 
57  template<int N, class Variant, class ... Args, class Archive>
58  typename std::enable_if<N == std::variant_size_v<Variant>, void>::type
59  load_variant(Archive & /*ar*/, int /*target*/, Variant & /*variant*/)
60  {
61  throw ::cereal::Exception("Error traversing variant during load");
62  }
64  template<int N, class Variant, class H, class ... T, class Archive>
65  typename std::enable_if<N < std::variant_size_v<Variant>, void>::type
66  load_variant(Archive & ar, int target, Variant & variant)
67  {
68  if(N == target)
69  {
70  H value;
71  ar( CEREAL_NVP_("data", value) );
72  variant = std::move(value);
73  }
74  else
75  load_variant<N+1, Variant, T...>(ar, target, variant);
76  }
77 
78  } // namespace variant_detail
79 
81  template <class Archive, typename VariantType1, typename... VariantTypes> inline
82  void CEREAL_SAVE_FUNCTION_NAME( Archive & ar, std::variant<VariantType1, VariantTypes...> const & variant )
83  {
84  std::int32_t index = static_cast<std::int32_t>(variant.index());
85  ar( CEREAL_NVP_("index", index) );
87  std::visit(visitor, variant);
88  }
89 
91  template <class Archive, typename... VariantTypes> inline
92  void CEREAL_LOAD_FUNCTION_NAME( Archive & ar, std::variant<VariantTypes...> & variant )
93  {
94  using variant_t = typename std::variant<VariantTypes...>;
95 
96  std::int32_t index;
97  ar( CEREAL_NVP_("index", index) );
98  if(index >= static_cast<std::int32_t>(std::variant_size_v<variant_t>))
99  throw Exception("Invalid 'index' selector when deserializing std::variant");
100 
101  variant_detail::load_variant<0, variant_t, VariantTypes...>(ar, index, variant);
102  }
103 
105  template <class Archive>
106  void CEREAL_SERIALIZE_FUNCTION_NAME( Archive &, std::monostate const & ) {}
107 } // namespace cereal
108 
109 #endif // CEREAL_TYPES_STD_VARIANT_HPP_
Main cereal functionality.
#define CEREAL_NVP_(name, value)
Convenience for creating a templated NVP.
Definition: helpers.hpp:201
#define CEREAL_LOAD_FUNCTION_NAME
The deserialization (load) function name to search for.
Definition: macros.hpp:85
#define CEREAL_SAVE_FUNCTION_NAME
The serialization (save) function name to search for.
Definition: macros.hpp:92
#define CEREAL_SERIALIZE_FUNCTION_NAME
The serialization/deserialization function name to search for.
Definition: macros.hpp:78
An exception class thrown when things go wrong at runtime.
Definition: helpers.hpp:49