DepthGuide/src/object_manager.h

#ifndef DEPTHGUIDE_OBJECT_MANAGER_H
#define DEPTHGUIDE_OBJECT_MANAGER_H

#include <cassert>
#include <cstdint>
#include <functional>
#include <memory>
#include <typeindex>
#include <typeinfo>

class object_manager {
public:

    using name_type = uint16_t;

    object_manager();

    ~object_manager();

    template<typename T>
    void save(name_type obj_name, T &&ptr) {
        using RT = std::remove_cvref_t<T>;
        auto pl_ptr = query_placeholder(obj_name, typeid(RT));
        if (pl_ptr == nullptr) {
            static_assert(std::is_default_constructible_v<RT>);
            create_placeholder(obj_name, typeid(RT),
                               new RT{}, [](void *ptr) { delete (RT *) ptr; });
            pl_ptr = query_placeholder(obj_name, typeid(RT));
        }
        assert(pl_ptr != nullptr);

        static_assert(std::is_copy_assignable_v<RT>);
        *(RT *) pl_ptr = ptr;
        notify_signal(obj_name);
    }

    template<typename T>
    T query(name_type obj_name) {
        auto pl_ptr = query_placeholder(obj_name, typeid(T));
        assert(pl_ptr != nullptr);

        static_assert(std::is_copy_constructible_v<T>);
        return *(T *) pl_ptr;
    }

    std::type_index query_type(name_type obj_name);

    using priority_type = int;
    using ob_type = std::function<void(name_type)>;
    using de_ob_func_type = std::function<void()>;

    de_ob_func_type observe(name_type obj_name, const ob_type &cb_func, priority_type pri = 0);

private:

    using del_func_type = void (*)(void *);

    void *query_placeholder(name_type obj_name, std::type_index obj_type);

    void create_placeholder(name_type obj_name, std::type_index obj_type,
                            void *ptr, del_func_type del_func);

    void notify_signal(name_type obj_name);

    struct impl;
    std::unique_ptr<impl> pimpl;
};

using obj_name_type = object_manager::name_type;

static constexpr obj_name_type invalid_obj_name = -1;

extern object_manager main_ob;

#define OBJ_QUERY(type, name) \
    main_ob.query<type>(name)

#define OBJ_TYPE(name) \
    main_ob.query_type(name)

#define OBJ_SAVE(name, val) \
    main_ob.save(name, val)

#define OBJ_OBSERVE(name, func) \
    main_ob.observe(name, func)

#define OBJ_OBSERVE_PRI(name, func, pri) \
    main_ob.observe(name, func, pri)

#endif //DEPTHGUIDE_OBJECT_MANAGER_H