/usr/include/boost/histogram/detail
Edit: /usr/include/boost/histogram/detail/variant_proxy.hpp (2430B)
// Copyright 2019 Hans Dembinski
//
// Distributed under 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)
#ifndef BOOST_HISTOGRAM_DETAIL_VARIANT_PROXY_HPP
#define BOOST_HISTOGRAM_DETAIL_VARIANT_PROXY_HPP
#include
#include // variant_access
#include
#include // mp_with_index, mp_find, mp_at
#include // mp_size
#include
#include
namespace boost {
namespace histogram {
namespace detail {
// This is a workaround to remain backward compatible in the serialization format. The
// proxy uses only the public interface of axis::variant for serialization and works
// independently of the underlying variant implementation.
template
struct variant_proxy {
Variant& variant;
template
void serialize(Archive& ar, unsigned /* version */) {
detail::static_if_c(
[this](auto& ar) { // loading
int which = 0;
ar >> make_nvp("which", which);
constexpr unsigned N = mp11::mp_size::value;
if (which < 0 || static_cast(which) >= N)
// throw if which >= N, can happen if type was removed from variant
BOOST_THROW_EXCEPTION(
std::runtime_error("variant has fewer types than stored version"));
mp11::mp_with_index(static_cast(which), [&ar, this](auto i) {
using T = mp11::mp_at_c;
T value;
ar >> make_nvp("value", value);
this->variant = std::move(value);
T* new_address = variant_access::template get_if(&this->variant);
ar.reset_object_address(new_address, &value);
});
},
[this](auto& ar) { // saving
visit(
[&ar](const auto& value) {
using T = std::decay_t;
const int which = static_cast(mp11::mp_find::value);
ar << make_nvp("which", which);
ar << make_nvp("value", value);
},
this->variant);
},
ar);
}
};
} // namespace detail
} // namespace histogram
} // namespace boost
#endif