unique_class_id/unique_class_id.hpp at main · LimiNode/unique_class_id · GitHub

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#pragma once
#ifndef _UNIQUE_CLASS_ID_HPP_INCLUDED
#define _UNIQUE_CLASS_ID_HPP_INCLUDED

#include <typeinfo>
#include <cstdint>

namespace unique_class_id {
    using class_id_t = std::uint32_t;

    namespace detail  {
        class_id_t djb2_hash(const char *str) {
            std::uint32_t hash  = 5381;
            int c = 0;
            while ((c = *str++)) {
                hash = ((hash  << 5) + hash) + c;
            }
            return static_cast<class_id_t>(hash);
        }
    }

    template<class T>
    class_id_t get_class_id() {
        static const class_id_t id = detail::djb2_hash(typeid(T).name());
        return id;
    }

    template<class T1, class T2>
    bool is_same_class(T2 *second) {
        static const class_id_t id1 = get_class_id<T1>();
        class_id_t id2 = second->id();
        return id1 == id2;
    }
}

#define DEFINE_UNIQUE_CLASS_ID(T)                       \
public:                                                 \
virtual unique_class_id::class_id_t id() const {        \
    static const unique_class_id::class_id_t id =       \
        unique_class_id::get_class_id<T>();             \
    return id;                                          \
}

#define DEFINE_FINAL_UNIQUE_CLASS_ID(T)                 \
public:                                                 \
unique_class_id::class_id_t id() const override final { \
    static const unique_class_id::class_id_t id =       \
        unique_class_id::get_class_id<T>();             \
    return id;                                          \
}

#endif // _UNIQUE_CLASS_ID_HPP_INCLUDED