cpp-reflection-examples-std26/include/case_3.h at main · Dimitrius-dev/cpp-reflection-examples-std26 · GitHub

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//
// Created by belov on 14.07.2026.
//


#pragma once


namespace case_3 {
    struct [[nodiscard]] Save   {};
    struct [[nodiscard]] NoSave {};
    struct [[nodiscard]] Author {
        char name[10];
        std::uint16_t age;
    };

    struct [[=Save{}]] GameState {
        [[=Save{}]]
        int level = 1;

        [[=Save{}]]
        int score = 0;

        [[=Save{}]]
        float health = 100.f;

        [[=Author{.name="Ivan", .age=18}]]
        int personAge = 18;

        [[=NoSave{}]]
        int temp = 0;

        bool loading = false;
    };

    template <typename A>
    consteval bool has_annotation(std::meta::info info) {
        return not std::meta::annotations_of_with_type(info, ^^A).empty();
    }

    consteval bool has_annotation_set(std::meta::info info, std::initializer_list<std::meta::info> annotationList) {
        for (auto a : std::meta::annotations_of(info)) {
            for (auto cA : annotationList) {
                if (std::meta::dealias(std::meta::remove_cvref(std::meta::type_of(a))) != std::meta::dealias(cA))
                    return false;
            }
        }
        return true;
    }

    void case_3() {
        static_assert(has_annotation_set(^^GameState, {^^Save}));
        static_assert(not has_annotation_set(^^GameState, {^^Save, ^^NoSave}));

        static_assert(has_annotation<Save>(^^GameState));
        static_assert(not has_annotation<NoSave>(^^GameState));

        static_assert(has_annotation<Save>(^^GameState::level));
        static_assert(not has_annotation<NoSave>(^^GameState::level));

        static_assert(has_annotation<Author>(^^GameState::personAge));
        {
            static constexpr auto annotationList = std::define_static_array(std::meta::annotations_of_with_type(^^GameState::personAge, ^^Author));
            static_assert(annotationList.size() == 1);
            static constexpr auto author = annotationList[0];

            static_assert(std::string_view(std::meta::extract<Author>(author).name) != "SomeName");
            static_assert(std::string_view(std::meta::extract<Author>(author).name) == "Ivan");
            static_assert(std::meta::extract<Author>(author).age == 18);
        }

        static constexpr std::array<std::meta::info, 2> types{^^Save, ^^NoSave};

        template for (constexpr auto t : types) {
            static_assert(not has_annotation<typename[:t:]>(^^GameState::loading));
        }
    }
}