Merge pull request #148 from sdebionne/add-std-variant-support

Add support for C++17 std::variant

CMake/CMakeLists.txt

@@ -335,6 +335,7 @@ archive_test(test_unregistered)
 archive_test(test_unique_ptr)
 archive_test(test_valarray)
 archive_test(test_variant A)
+archive_test(test_std_variant A)
 archive_test(test_vector A)
 
 polymorphic_archive_test(test_dll_exported polymorphic_derived1)

doc/serialization.html

@@ -919,6 +919,7 @@ As of this writing, the library contains serialization of the following boost cl
   <li>shared_ptr
   <li>auto_ptr (demo)
 </ul>
+C++17 <code style="white-space: normal">std::variant is supported as well</code>.
 Others are being added to the list so check the boost files section and headers for
 new implementations!
 <hr>

include/boost/serialization/std_variant.hpp

@@ -0,0 +1,204 @@
+#ifndef BOOST_SERIALIZATION_STD_VARIANT_HPP
+#define BOOST_SERIALIZATION_STD_VARIANT_HPP
+
+// MS compatible compilers support #pragma once
+#if defined(_MSC_VER)
+# pragma once
+#endif
+
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// variant.hpp - non-intrusive serialization of variant types
+//
+// copyright (c) 2019 Samuel Debionne, ESRF
+//
+// Use, modification and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org for updates, documentation, and revision history.
+//
+// Widely inspired form boost::variant serialization
+//
+
+#include <boost/serialization/throw_exception.hpp>
+
+#include <variant>
+
+#include <boost/archive/archive_exception.hpp>
+
+#include <boost/serialization/split_free.hpp>
+#include <boost/serialization/serialization.hpp>
+#include <boost/serialization/nvp.hpp>
+
+namespace boost {
+namespace serialization {
+
+template<class Archive>
+struct std_variant_save_visitor
+{
+    std_variant_save_visitor(Archive& ar) :
+        m_ar(ar)
+    {}
+    template<class T>
+    void operator()(T const & value) const
+    {
+        m_ar << BOOST_SERIALIZATION_NVP(value);
+    }
+private:
+    Archive & m_ar;
+};
+
+
+template<class Archive>
+struct std_variant_load_visitor
+{
+    std_variant_load_visitor(Archive& ar) :
+        m_ar(ar)
+    {}
+    template<class T>
+    void operator()(T & value) const
+    {
+        m_ar >> BOOST_SERIALIZATION_NVP(value);
+    }
+private:
+    Archive & m_ar;
+};
+
+template<class Archive, class ...Types>
+void save(
+    Archive & ar,
+    std::variant<Types...> const & v,
+    unsigned int /*version*/
+){
+    const std::size_t which = v.index();
+    ar << BOOST_SERIALIZATION_NVP(which);
+    std_variant_save_visitor<Archive> visitor(ar);
+    std::visit(visitor, v);
+}
+
+// Minimalist metaprogramming for handling parameter pack
+namespace mp {
+    namespace detail {
+    template <typename Seq>
+    struct front_impl;
+
+    template <template <typename...> class Seq, typename T, typename... Ts>
+    struct front_impl<Seq<T, Ts...>> {
+        using type = T;
+    };
+
+    template <typename Seq>
+    struct pop_front_impl;
+
+    template <template <typename...> class Seq, typename T, typename... Ts>
+    struct pop_front_impl<Seq<T, Ts...>> {
+        using type = Seq<Ts...>;
+    };
+    } //namespace detail
+
+    template <typename... Ts>
+    struct typelist {};
+
+    template <typename Seq>
+    using front = typename detail::front_impl<Seq>::type;
+
+    template <typename Seq>
+    using pop_front = typename detail::pop_front_impl<Seq>::type;
+}  // namespace mp
+
+template<std::size_t N, class Seq>
+struct variant_impl
+{
+    template<class Archive, class V>
+    static void load (
+        Archive & ar,
+        std::size_t which,
+        V & v,
+        const unsigned int version
+    ){
+        if(which == 0){
+            // note: A non-intrusive implementation (such as this one)
+            // necessary has to copy the value.  This wouldn't be necessary
+            // with an implementation that de-serialized to the address of the
+            // aligned storage included in the variant.
+            using type = mp::front<Seq>;
+            type value;
+            ar >> BOOST_SERIALIZATION_NVP(value);
+            v = std::move(value);
+            type * new_address = & std::get<type>(v);
+            ar.reset_object_address(new_address, & value);
+            return;
+        }
+        //typedef typename mpl::pop_front<S>::type type;
+        using types = mp::pop_front<Seq>;
+        variant_impl<N - 1, types>::load(ar, which - 1, v, version);
+    }
+};
+
+template<class Seq>
+struct variant_impl<0, Seq>
+{
+    template<class Archive, class V>
+    static void load (
+        Archive & /*ar*/,
+        std::size_t /*which*/,
+        V & /*v*/,
+        const unsigned int /*version*/
+    ){}
+};
+
+template<class Archive, class... Types>
+void load(
+    Archive & ar, 
+    std::variant<Types...>& v,
+    const unsigned int version
+){
+    std::size_t which;
+    ar >> BOOST_SERIALIZATION_NVP(which);
+    if(which >=  sizeof...(Types))
+        // this might happen if a type was removed from the list of variant types
+        boost::serialization::throw_exception(
+            boost::archive::archive_exception(
+                boost::archive::archive_exception::unsupported_version
+            )
+        );
+    variant_impl<sizeof...(Types), mp::typelist<Types...>>::load(ar, which, v, version);
+}
+
+template<class Archive,class... Types>
+inline void serialize(
+    Archive & ar,
+    std::variant<Types...> & v,
+    const unsigned int file_version
+){
+    split_free(ar,v,file_version);
+}
+
+// Specialization for std::monostate
+template<class Archive>
+void serialize(Archive &ar, std::monostate &, const unsigned int /*version*/)
+{}
+
+} // namespace serialization
+} // namespace boost
+
+//template<typename T0_, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T)>
+
+#include <boost/serialization/tracking.hpp>
+
+namespace boost {
+    namespace serialization {
+        
+template<class... Types>
+struct tracking_level<
+    std::variant<Types...>
+>{
+    typedef mpl::integral_c_tag tag;
+    typedef mpl::int_< ::boost::serialization::track_always> type;
+    BOOST_STATIC_CONSTANT(int, value = type::value);
+};
+
+} // namespace serialization
+} // namespace boost
+
+#endif //BOOST_SERIALIZATION_VARIANT_HPP

include/boost/serialization/variant2.hpp

@@ -0,0 +1,176 @@
+#ifndef BOOST_SERIALIZATION_VARIANT2_HPP
+#define BOOST_SERIALIZATION_VARIANT2_HPP
+
+// MS compatible compilers support #pragma once
+#if defined(_MSC_VER)
+# pragma once
+#endif
+
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// variant.hpp - non-intrusive serialization of variant types
+//
+// copyright (c) 2019 Samuel Debionne, ESRF
+//
+// Use, modification and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org for updates, documentation, and revision history.
+//
+// Widely inspired form boost::variant serialization
+//
+
+#include <boost/serialization/throw_exception.hpp>
+
+#include <variant>
+
+#include <boost/archive/archive_exception.hpp>
+
+#include <boost/mp11/list.hpp>
+
+#include <boost/serialization/split_free.hpp>
+#include <boost/serialization/serialization.hpp>
+#include <boost/serialization/nvp.hpp>
+
+namespace boost {
+namespace serialization {
+
+template<class Archive>
+struct variant2_save_visitor
+{
+    variant2_save_visitor(Archive& ar) :
+        m_ar(ar)
+    {}
+    template<class T>
+    void operator()(T const & value) const
+    {
+        m_ar << BOOST_SERIALIZATION_NVP(value);
+    }
+private:
+    Archive & m_ar;
+};
+
+
+template<class Archive>
+struct variant2_load_visitor
+{
+    variant2_load_visitor(Archive& ar) :
+        m_ar(ar)
+    {}
+    template<class T>
+    void operator()(T & value) const
+    {
+        m_ar >> BOOST_SERIALIZATION_NVP(value);
+    }
+private:
+    Archive & m_ar;
+};
+
+template<class Archive, class ...Types>
+void save(
+    Archive & ar,
+    variant2::variant<Types...> const & v,
+    unsigned int /*version*/
+){
+    const std::size_t which = v.index();
+    ar << BOOST_SERIALIZATION_NVP(which);
+    variant2_save_visitor<Archive> visitor(ar);
+    std::visit(visitor, v);
+}
+
+template<std::size_t N, class Seq>
+struct variant_impl
+{
+    template<class Archive, class V>
+    static void load (
+        Archive & ar,
+        std::size_t which,
+        V & v,
+        const unsigned int version
+    ){
+        if(which == 0){
+            // note: A non-intrusive implementation (such as this one)
+            // necessary has to copy the value.  This wouldn't be necessary
+            // with an implementation that de-serialized to the address of the
+            // aligned storage included in the variant.
+            using type = mp11::mp_front<Seq>;
+            type value;
+            ar >> BOOST_SERIALIZATION_NVP(value);
+            v = std::move(value);
+            type * new_address = & variant2::get<type>(v);
+            ar.reset_object_address(new_address, & value);
+            return;
+        }
+        //typedef typename mpl::pop_front<S>::type type;
+        using types = mp11::mp_pop_front<Seq>;
+        variant_impl<N - 1, types>::load(ar, which - 1, v, version);
+    }
+};
+
+template<class Seq>
+struct variant_impl<0, Seq>
+{
+    template<class Archive, class V>
+    static void load (
+        Archive & /*ar*/,
+        std::size_t /*which*/,
+        V & /*v*/,
+        const unsigned int /*version*/
+    ){}
+};
+
+template<class Archive, class... Types>
+void load(
+    Archive & ar, 
+    variant2::variant<Types...> & v,
+    const unsigned int version
+){
+    std::size_t which;
+    ar >> BOOST_SERIALIZATION_NVP(which);
+    if(which >=  sizeof...(Types))
+        // this might happen if a type was removed from the list of variant types
+        boost::serialization::throw_exception(
+            boost::archive::archive_exception(
+                boost::archive::archive_exception::unsupported_version
+            )
+        );
+    variant_impl<sizeof...(Types), mp11::mp_list<Types...>>::load(ar, which, v, version);
+}
+
+template<class Archive,class... Types>
+inline void serialize(
+    Archive & ar,
+    variant2::variant<Types...> & v,
+    const unsigned int file_version
+){
+    split_free(ar,v,file_version);
+}
+
+// Specialization for std::monostate
+template<class Archive>
+void serialize(Archive &ar, variant2::monostate &, const unsigned int /*version*/)
+{}
+
+} // namespace serialization
+} // namespace boost
+
+//template<typename T0_, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T)>
+
+#include <boost/serialization/tracking.hpp>
+
+namespace boost {
+    namespace serialization {
+        
+template<class... Types>
+struct tracking_level<
+    variant2::variant<Types...>
+>{
+    typedef mpl::integral_c_tag tag;
+    typedef mpl::int_< ::boost::serialization::track_always> type;
+    BOOST_STATIC_CONSTANT(int, value = type::value);
+};
+
+} // namespace serialization
+} // namespace boost
+
+#endif //BOOST_SERIALIZATION_VARIANT2_HPP

test/Jamfile.v2

@@ -112,6 +112,7 @@ test-suite "serialization" :
      [ test-bsl-run_files test_unique_ptr ]
      [ test-bsl-run_files test_valarray ]
      [ test-bsl-run_files test_variant : A ]
+     [ test-bsl-run_files test_std_variant : A : : [ requires cxx17_hdr_variant ] ] # BOOST_NO_CXX17_HDR_VARIANT
      [ test-bsl-run_files test_vector : A ]
      [ test-bsl-run_files test_shared_ptr ]
      [ test-bsl-run_files test_shared_ptr_multi_base ]
@@ -188,4 +189,3 @@ if ! $(BOOST_ARCHIVE_LIST) {
         [ compile test_const_pass.cpp ]
     ;
 }
-

test/test_std_variant.cpp

@@ -0,0 +1,256 @@
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// test_variant.cpp
+// test of non-intrusive serialization of variant types
+//
+// copyright (c) 2005   
+// troy d. straszheim <troy@resophonic.com>
+// http://www.resophonic.com
+//
+// Use, modification and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org for updates, documentation, and revision history.
+//
+// thanks to Robert Ramey and Peter Dimov.
+//
+
+#include <cstddef> // NULL
+#include <cstdio> // remove
+#include <fstream>
+#include <boost/config.hpp>
+#include <boost/math/special_functions/next.hpp> // float_distance
+#if defined(BOOST_NO_STDC_NAMESPACE)
+namespace std{ 
+    using ::remove;
+}
+#endif
+
+#include <boost/type_traits/is_same.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/serialization/throw_exception.hpp>
+
+#if defined(_MSC_VER) && (_MSC_VER <= 1020)
+#  pragma warning (disable : 4786) // too long name, harmless warning
+#endif
+
+#include "test_tools.hpp"
+
+#include <boost/archive/archive_exception.hpp>
+
+#include <boost/serialization/nvp.hpp>
+#include <boost/serialization/std_variant.hpp>
+
+#include "A.hpp"
+#include "A.ipp"
+
+
+template <class T>
+void test_type(const T& gets_written){
+   const char * testfile = boost::archive::tmpnam(NULL);
+   BOOST_REQUIRE(testfile != NULL);
+   {
+      test_ostream os(testfile, TEST_STREAM_FLAGS);
+      test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
+      oa << boost::serialization::make_nvp("written", gets_written);
+   }
+
+   T got_read;
+   {
+      test_istream is(testfile, TEST_STREAM_FLAGS);
+      test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
+      ia >> boost::serialization::make_nvp("written", got_read);
+   }
+   BOOST_CHECK_EQUAL(gets_written, got_read);
+
+   std::remove(testfile);
+}
+
+// this verifies that if you try to read in a variant from a file
+// whose "which" is illegal for the one in memory (that is, you're
+// reading in to a different variant than you wrote out to) the load()
+// operation will throw.  One could concievably add checking for
+// sequence length as well, but this would add size to the archive for
+// dubious benefit.
+//
+void do_bad_read()
+{
+    std::variant<bool, float, int, std::string> big_variant;
+    big_variant = std::string("adrenochrome");
+
+    const char * testfile = boost::archive::tmpnam(NULL);
+    BOOST_REQUIRE(testfile != NULL);
+    {
+        test_ostream os(testfile, TEST_STREAM_FLAGS);
+        test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
+        oa << BOOST_SERIALIZATION_NVP(big_variant);
+    }
+    std::variant<bool, float, int> little_variant;
+    {
+        test_istream is(testfile, TEST_STREAM_FLAGS);
+        test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
+        bool exception_invoked = false;
+        BOOST_TRY {
+            ia >> BOOST_SERIALIZATION_NVP(little_variant);
+        } BOOST_CATCH (boost::archive::archive_exception const& e) {
+            BOOST_CHECK(boost::archive::archive_exception::unsupported_version == e.code);
+            exception_invoked = true;
+        }
+        BOOST_CATCH_END
+        BOOST_CHECK(exception_invoked);
+    }
+}
+
+struct H {
+    int i;
+};
+
+namespace boost {
+namespace serialization {
+        
+template<class Archive>
+void serialize(Archive &ar, H & h, const unsigned int /*file_version*/){
+    ar & boost::serialization::make_nvp("h", h.i);
+}
+
+} // namespace serialization
+} // namespace boost
+
+inline bool operator==(H const & lhs, H const & rhs) {
+    return lhs.i == rhs.i;
+}
+
+inline bool operator!=(H const & lhs, H const & rhs) {
+    return !(lhs == rhs);
+}
+
+inline bool operator<(H const & lhs, H const & rhs) {
+    return lhs.i < rhs.i;
+}
+
+inline std::size_t hash_value(H const & val) {
+    return val.i;
+}
+
+void test_pointer(){
+    const char * testfile = boost::archive::tmpnam(NULL);
+    BOOST_REQUIRE(testfile != NULL);
+    typedef std::variant<H, int> variant_t;
+    H const h = {5};
+    variant_t v(h);
+    {
+        test_ostream os(testfile, TEST_STREAM_FLAGS);
+        test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
+        oa << boost::serialization::make_nvp("written", v);
+        const H * h_ptr = & std::get<H>(v);
+        oa << boost::serialization::make_nvp("written", h_ptr);
+    }
+    variant_t v2;
+    {
+        test_istream is(testfile, TEST_STREAM_FLAGS);
+        test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
+        ia >> boost::serialization::make_nvp("written", v2);
+        H * h2_ptr;
+        ia >> boost::serialization::make_nvp("written", h2_ptr);
+        BOOST_CHECK_EQUAL(h, std::get<H>(v2));
+        BOOST_CHECK_EQUAL(h2_ptr, & std::get<H>(v2));
+    }
+    BOOST_CHECK_EQUAL(v, v2);
+}
+
+#include <boost/serialization/map.hpp>
+#include <boost/serialization/set.hpp>
+
+// test a pointer to an object contained into a variant that is an
+// element of a set
+void test_variant_set()
+{
+    const char * testfile = boost::archive::tmpnam(NULL);
+    BOOST_REQUIRE(testfile != NULL);
+    typedef std::variant<H, int> variant_t;
+    typedef std::set<variant_t> uset_t;
+    uset_t set;
+    {
+        test_ostream os(testfile, TEST_STREAM_FLAGS);
+        test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
+        H const h = {5};
+        variant_t v(h);
+        set.insert(v);
+        oa << boost::serialization::make_nvp("written", set);
+        H const * const h_ptr = & std::get<H>(*set.begin());
+        oa << boost::serialization::make_nvp("written", h_ptr);
+    }
+    uset_t set2;
+    {
+        test_istream is(testfile, TEST_STREAM_FLAGS);
+        test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
+        ia >> boost::serialization::make_nvp("written", set2);
+        H * h_ptr;
+        ia >> boost::serialization::make_nvp("written", h_ptr);
+        const H * h_ptr2 = & std::get<H>(*set2.begin());
+        BOOST_CHECK_EQUAL(h_ptr, h_ptr2);
+    }
+    BOOST_CHECK_EQUAL(set, set2);
+}
+
+// test a pointer to an object contained into a variant that is an
+// element of a map
+void test_variant_map()
+{
+    const char * testfile = boost::archive::tmpnam(NULL);
+    BOOST_REQUIRE(testfile != NULL);
+    typedef std::variant<H, int> variant_t;
+    typedef std::map<int, variant_t> map_t;
+    map_t map;
+    {
+        test_ostream os(testfile, TEST_STREAM_FLAGS);
+        test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
+        H const h = {5};
+        variant_t v(h);
+        map[0] = v;
+        BOOST_ASSERT(1 == map.size());
+        oa << boost::serialization::make_nvp("written", map);
+        H const * const h_ptr = std::get_if<H>(&map[0]);
+        BOOST_CHECK_EQUAL(h_ptr, std::get_if<H>(&map[0]));
+        oa << boost::serialization::make_nvp("written", h_ptr);
+    }
+    map_t map2;
+    {
+        test_istream is(testfile, TEST_STREAM_FLAGS);
+        test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
+        ia >> boost::serialization::make_nvp("written", map2);
+        BOOST_ASSERT(1 == map2.size());
+        H * h_ptr;
+        ia >> boost::serialization::make_nvp("written", h_ptr);
+        H const * const h_ptr2 = std::get_if<H>(&map2[0]);
+        BOOST_CHECK_EQUAL(h_ptr, h_ptr2);
+    }
+    BOOST_CHECK_EQUAL(map, map2);
+}
+
+int test_main( int /* argc */, char* /* argv */[] )
+{
+    {
+        std::variant<bool, int, float, double, A, std::string> v;
+        v = false;
+        test_type(v);
+        v = 1;
+        test_type(v);
+        v = (float) 2.3;
+        test_type(v);
+        v = (double) 6.4;
+        test_type(v);
+        v = std::string("we can't stop here, this is Bat Country");
+        test_type(v);
+        v = A();
+        test_type(v);
+    }
+    test_pointer();
+    test_variant_set();
+    test_variant_map();
+    do_bad_read();
+    return EXIT_SUCCESS;
+}
+
+// EOF