ecs/include/ecs/core/utils/bitset.h

#pragma once

#include <bitset>
#include <ecs/config.h>
#include <ecs/core/mp/list.h>

beg_namespace_ecs_core_utils
{

    template<typename T_settings>
    struct bitset
    {
    private:
        static constexpr decltype(auto) csl() noexcept
            { return (T_settings { }).component_signatures(); }

        static constexpr decltype(auto) all_components() noexcept
            { return csl().all_components(); }

    public:
        static constexpr decltype(auto) component_count() noexcept
            { return hana::size(all_components()); }

        template<typename T_component_tag>
        static constexpr decltype(auto) component_id(T_component_tag ct) noexcept
            { return mp::list::index_of(all_components(), ct); }

        using bitset_type = std::bitset<component_count()>;

    private:
        bitset_type _bitset;

    public:
        inline void clear() noexcept
            { _bitset.reset(); }

        template<typename T_other>
        inline bool contains(const T_other& other) const noexcept
            { return (_bitset & other._bitset) == _bitset; }

        template<typename T_component_tag>
        inline bool has_component(T_component_tag ct) const
            { return _bitset.test(component_id(ct)); }

        template<typename T_component_tag>
        inline void set_component(T_component_tag ct, bool value)
            { _bitset.set(component_id(ct), value); }
    };

}
end_namespace_ecs_core_utils