utility.hpp

#ifndef ENTT_CORE_UTILITY_HPP
#define ENTT_CORE_UTILITY_HPP
 
#include <utility>
#include "../config/config.h"
 
namespace entt {
 
struct identity {
    using is_transparent = void;
 
    template<class Type>
    [[nodiscard]] constexpr Type &&operator()(Type &&value) const ENTT_NOEXCEPT {
        return std::forward<Type>(value);
    }
};
 
template<typename Type, typename Class>
[[nodiscard]] constexpr auto overload(Type Class::*member) ENTT_NOEXCEPT {
    return member;
}
 
template<typename Func>
[[nodiscard]] constexpr auto overload(Func *func) ENTT_NOEXCEPT {
    return func;
}
 
template<class... Func>
struct overloaded: Func... {
    using Func::operator()...;
};
 
template<class... Func>
overloaded(Func...) -> overloaded<Func...>;
 
template<class Func>
struct y_combinator {
    y_combinator(Func recursive)
        : func{std::move(recursive)} {}
 
    template<class... Args>
    decltype(auto) operator()(Args &&...args) const {
        return func(*this, std::forward<Args>(args)...);
    }
 
    template<class... Args>
    decltype(auto) operator()(Args &&...args) {
        return func(*this, std::forward<Args>(args)...);
    }
 
private:
    Func func;
};
 
} // namespace entt
 
#endif