pickle.h

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#pragma once
#include <iosfwd>
#include <vector>
#include <pybind11/pybind11.h>
 
#include "hate/type_list.h"
 
 
namespace haldls::vx {
 
template <typename TL>
struct AddPickle;
 
template <typename... Ts>
struct AddPickle<hate::type_list<Ts...>>
{
    static void apply(pybind11::module& parent, std::vector<std::string> const& container_names)
    {
        apply_impl(parent, container_names, std::make_index_sequence<sizeof...(Ts)>{});
    }
 
private:
    template <size_t I, size_t... Is>
    static void apply_impl(
        pybind11::module& parent,
        std::vector<std::string> const& container_names,
        std::index_sequence<I, Is...>)
    {
        typedef typename hate::index_type_list_by_integer<I, hate::type_list<Ts...>>::type type;
        apply_single<type>(parent, container_names.at(I));
        if constexpr (sizeof...(Is)) {
            apply_impl(parent, container_names, std::index_sequence<Is...>{});
        }
    }
 
    template <typename T>
    static void apply_single(pybind11::module& parent, std::string const& name)
    {
        auto attr = parent.attr(name.c_str());
        auto ism = pybind11::is_method(attr);
        auto const getattr = [](pybind11::object const& self) {
            auto& thing = self.cast<T const&>();
            std::string serialized{haldls::vx::to_portablebinary(thing)};
            if (pybind11::hasattr(self, "__dict__")) {
                return pybind11::make_tuple(pybind11::bytes(serialized), self.attr("__dict__"));
            } else {
                return pybind11::make_tuple(pybind11::bytes(serialized));
            }
        };
 
        auto const setattr = [](pybind11::object& self, pybind11::tuple const& data) {
            auto& thing = self.cast<T&>();
            new (&thing) T();
            haldls::vx::from_portablebinary(thing, data[0].cast<std::string>());
            if (pybind11::hasattr(self, "__dict__")) {
                self.attr("__dict__") = data[1];
            }
        };
 
        attr.attr("__getstate__") = pybind11::cpp_function(getattr, ism);
        attr.attr("__setstate__") = pybind11::cpp_function(setattr, ism);
    }
};
 
} // namespace haldls::vx