LiteLoaderBDS-1.16.40/LiteLoader/Header/third-party/entt/core/utility.hpp
2022-09-21 19:47:03 +08:00

107 lines
2.6 KiB
C++

#ifndef ENTT_CORE_UTILITY_HPP
#define ENTT_CORE_UTILITY_HPP
#include <utility>
#include "../config/config.h"
namespace entt {
/*! @brief Identity function object (waiting for C++20). */
struct identity {
/**
* @brief Returns its argument unchanged.
* @tparam Type Type of the argument.
* @param value The actual argument.
* @return The submitted value as-is.
*/
template<class Type>
[[nodiscard]] constexpr Type && operator()(Type &&value) const ENTT_NOEXCEPT {
return std::forward<Type>(value);
}
};
/**
* @brief Constant utility to disambiguate overloaded members of a class.
* @tparam Type Type of the desired overload.
* @tparam Class Type of class to which the member belongs.
* @param member A valid pointer to a member.
* @return Pointer to the member.
*/
template<typename Type, typename Class>
[[nodiscard]] constexpr auto overload(Type Class:: *member) ENTT_NOEXCEPT { return member; }
/**
* @brief Constant utility to disambiguate overloaded functions.
* @tparam Func Function type of the desired overload.
* @param func A valid pointer to a function.
* @return Pointer to the function.
*/
template<typename Func>
[[nodiscard]] constexpr auto overload(Func *func) ENTT_NOEXCEPT { return func; }
/**
* @brief Helper type for visitors.
* @tparam Func Types of function objects.
*/
template<class... Func>
struct overloaded: Func... {
using Func::operator()...;
};
/**
* @brief Deduction guide.
* @tparam Func Types of function objects.
*/
template<class... Func>
overloaded(Func...)
-> overloaded<Func...>;
/**
* @brief Basic implementation of a y-combinator.
* @tparam Func Type of a potentially recursive function.
*/
template<class Func>
struct y_combinator {
/**
* @brief Constructs a y-combinator from a given function.
* @param recursive A potentially recursive function.
*/
y_combinator(Func recursive):
func{std::move(recursive)}
{}
/**
* @brief Invokes a y-combinator and therefore its underlying function.
* @tparam Args Types of arguments to use to invoke the underlying function.
* @param args Parameters to use to invoke the underlying function.
* @return Return value of the underlying function, if any.
*/
template <class... Args>
decltype(auto) operator()(Args &&... args) const {
return func(*this, std::forward<Args>(args)...);
}
/*! @copydoc operator()() */
template <class... Args>
decltype(auto) operator()(Args &&... args) {
return func(*this, std::forward<Args>(args)...);
}
private:
Func func;
};
}
#endif