mem_func_const.hpp

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#ifndef EAGINE_MEM_FUNC_CONST_HPP
#define EAGINE_MEM_FUNC_CONST_HPP
 
#include <utility>
 
namespace eagine {
 
template <typename T, T Ptr>
struct member_function_constant;
 
template <typename RV, typename C, typename... P, RV (C::*Ptr)(P...)>
struct member_function_constant<RV (C::*)(P...), Ptr> {
 
    using pointer = RV (C::*)(P...);
 
    using free_pointer = RV (*)(C*, P...);
 
    using result_type = RV;
 
    using scope = C;
 
    using is_const = std::false_type;
 
    static constexpr auto get() noexcept -> pointer {
        return Ptr;
    }
 
    static auto free_func(C* c, P... a) -> RV {
        return (c->*Ptr)(std::forward<P>(a)...);
    }
 
    static auto make_free() noexcept -> free_pointer {
        return &free_func;
    }
};
 
template <typename RV, typename C, typename... P, RV (C::*Ptr)(P...) const>
struct member_function_constant<RV (C::*)(P...) const, Ptr> {
 
    using pointer = RV (C::*)(P...) const;
 
    using free_pointer = RV (*)(const C*, P...);
 
    using result_type = RV;
 
    using scope = C;
 
    using is_const = std::true_type;
 
    static constexpr auto get() noexcept -> pointer {
        return Ptr;
    }
 
    static auto free_func(const C* c, P... a) -> RV {
        return (c->*Ptr)(std::forward<P>(a)...);
    }
 
    static auto make_free() noexcept -> free_pointer {
        return &free_func;
    }
};
 
template <typename RV, typename C, typename... P, RV (C::*Ptr)(P...) noexcept>
struct member_function_constant<RV (C::*)(P...) noexcept, Ptr> {
 
    using pointer = RV (C::*)(P...) noexcept;
 
    using free_pointer = RV (*)(C*, P...) noexcept;
 
    using result_type = RV;
 
    using scope = C;
 
    using is_const = std::false_type;
 
    static constexpr auto get() noexcept -> pointer {
        return Ptr;
    }
 
    static auto free_func(C* c, P... a) noexcept -> RV {
        return (c->*Ptr)(std::forward<P>(a)...);
    }
 
    static auto make_free() noexcept -> free_pointer {
        return &free_func;
    }
};
 
template <typename RV, typename C, typename... P, RV (C::*Ptr)(P...) const noexcept>
struct member_function_constant<RV (C::*)(P...) const noexcept, Ptr> {
 
    using pointer = RV (C::*)(P...) const noexcept;
 
    using free_pointer = RV (*)(const C*, P...) noexcept;
 
    using result_type = RV;
 
    using scope = C;
 
    using is_const = std::true_type;
 
    static constexpr auto get() noexcept -> pointer {
        return Ptr;
    }
 
    static auto free_func(const C* c, P... a) noexcept -> RV {
        return (c->*Ptr)(std::forward<P>(a)...);
    }
 
    static auto make_free() noexcept -> free_pointer {
        return &free_func;
    }
};
 
#define EAGINE_MEM_FUNC_T(CLASS, FUNC) \
    ::eagine::member_function_constant<decltype(&CLASS::FUNC), &CLASS::FUNC>
 
#define EAGINE_MEM_FUNC_C(CLASS, FUNC) \
    EAGINE_MEM_FUNC_T(CLASS, FUNC) {}
 
#define EAGINE_THIS_T() std::remove_cv_t<std::remove_pointer_t<decltype(this)>>
 
#define EAGINE_THIS_MEM_FUNC_T(FUNC)    \
    ::eagine::member_function_constant< \
      decltype(&EAGINE_THIS_T()::FUNC), \
      &EAGINE_THIS_T()::FUNC>
 
#define EAGINE_THIS_MEM_FUNC_C(FUNC) \
    EAGINE_THIS_MEM_FUNC_T(FUNC) {}
 
} // namespace eagine
 
#endif // EAGINE_MEM_FUNC_CONST_HPP