json_std_optional.hpp

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// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#pragma once
 
#include <nlohmann/json.hpp>
#include <optional>
 
namespace nlohmann {
    template<typename T>
    struct adl_serializer<std::optional<T>> {
        static void to_json(json &j, const std::optional<T> &opt) {
            if (opt.has_value()) {
                j = *opt;
            } else {
                j = nullptr;
            }
        }
 
        static void from_json(const json &j, std::optional<T> &opt) {
            if (j.is_null()) {
                opt = std::nullopt;
            } else {
                opt = j.get<T>();
            }
        }
    };
} // namespace nlohmann