1. 개요
# 제약조건2. 설명
3. 예제
==# 모듈 요약 코드 #==
#!syntax cpp
namespace std
{
// language-related concepts
template<class T, class U>
concept same_as = is_same_v<T, U> && is_same_v<U, T>;
template<class Derived, class Base>
concept derived_from = is_base_of_v<Base, Derived> && is_convertible_v<const volatile Derived*, const volatile Base*>;
template<class From, class To>
concept convertible_to = is_convertible_v<From, To>
&& requires(From (&from)())
{
static_cast<To>(from()); // std::declval<From&>()
};
template<class T, class U>
concept common_reference_with = same_as<common_reference_t<T, U>, common_reference_t<U, T>>
&& convertible_to<T, common_reference_t<T, U>>
&& convertible_to<U, common_reference_t<T, U>>;
template<class T, class U>
concept common_with = same_as<common_type_t<T, U>, common_type_t<U, T>>
&& requires
{
static_cast<common_type_t<T, U>>(declval<T>());
static_cast<common_type_t<T, U>>(declval<U>());
}
&& common_reference_with<add_lvalue_reference_t<const T>, add_lvalue_reference_t<const U>>
&& common_reference_with<add_lvalue_reference_t<common_type_t<T, U>>, common_reference_t<add_lvalue_reference_t<const T>, add_lvalue_reference_t<const U>>>;
// arithmetic concepts
template<class T>
concept integral = is_integral_v<T>;
template<class T>
concept signed_integral = integral<T> && is_signed_v<T>;
template<class T>
concept unsigned_integral = integral<T> && !signed_integral<T>;
template<class T>
concept floating_point = is_floating_point_v<T>;
template<class LHS, class RHS>
concept assignable_from = is_lvalue_reference_v<LHS>
&& common_reference_with<const remove_reference_t<LHS>&, const remove_reference_t<RHS>&>
&& requires(LHS lhs, RHS&& rhs)
{
{ lhs = std::forward<RHS>(rhs) } -> same_as<LHS>;
}
namespace ranges
{
inline namespace /* unspecified */
{
inline constexpr /* unspecified */ swap = /* unspecified */;
}
}
template<class T>
concept swappable = requires(T& a, T& b) { ranges::swap(a, b); };
template<class T, class U>
concept swappable_with = common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&>
&& requires(T&& t, U&& u)
{
ranges::swap(std::forward<T>(t), std::forward<T>(t));
ranges::swap(std::forward<U>(u), std::forward<U>(u));
ranges::swap(std::forward<T>(t), std::forward<U>(u));
ranges::swap(std::forward<U>(u), std::forward<T>(t));
};
template<class T>
concept destructible = is_nothrow_destructible_v<T>;
template<class T, class... Args>
concept constructible_from = destructible<T> && is_constructible_v<T, Args...>;
template<class T>
concept default_initializable = /* --- */;
template<class T>
concept move_constructible = constructible_from<T, T> && convertible_to<T, T>;
template<class T>
concept copy_constructible = move_constructible<T>
&& constructible_from<T, T&> && convertible_to<T&, T>
&& constructible_from<T, const T&> && convertible_to<const T&, T>
&& constructible_from<T, const T> && convertible_to<const T, T>;
// comparison concepts
template<class T, class U>
concept __WeaklyEqualityComparableWith = // exposition only
requires(const remove_reference_t<T>& t, const remove_reference_t<U>& u)
{
{ t == u } -> boolean-testable;
{ t != u } -> boolean-testable;
{ u == t } -> boolean-testable;
{ u != t } -> boolean-testable;
};
template<class T>
concept equality_comparable = __WeaklyEqualityComparableWith<T, T>;
template<class T>
concept equality_comparable = /* see description */;
template<class T, class U>
concept equality_comparable_with = equality_comparable<T> && equality_comparable<U>
&& common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&>
&& equality_comparable<common_reference_t<const remove_reference_t<T>&, const remove_reference_t<U>&>>
&& __WeaklyEqualityComparableWith<T, U>;
template<class T>
concept totally_ordered = equality_comparable<T>
&& requires(const remove_reference_t<T>& a, const remove_reference_t<T>& b)
{
{ a < b } -> boolean-testable;
{ a > b } -> boolean-testable;
{ a <= b } -> boolean-testable;
{ a >= b } -> boolean-testable;
};
template<class T, class U>
concept totally_ordered_with = totally_ordered<T> && totally_ordered<U>
&& common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&>
&& totally_ordered<common_reference_t<const remove_reference_t<T>&, const remove_reference_t<U>&>>
&& equality_comparable_with<T, U>
&& requires(const remove_reference_t<T>& t, const remove_reference_t<U>& u)
{
{ t < u } -> boolean-testable;
{ t > u } -> boolean-testable;
{ t <= u } -> boolean-testable;
{ t >= u } -> boolean-testable;
{ u < t } -> boolean-testable;
{ u > t } -> boolean-testable;
{ u <= t } -> boolean-testable;
{ u >= t } -> boolean-testable;
};
// object concepts
template<class T>
concept movable = is_object_v<T> && move_constructible<T>
&& assignable_from<T&, T> && swappable<T>;
template<class T>
concept copyable = copy_constructible<T> && movable<T> && assignable_from<T&, T&>
&& assignable_from<T&, const T&> && assignable_from<T&, const T>;
template<class T>
concept semiregular = copyable<T> && default_initializable<T>;
template<class T>
concept regular = semiregular<T> && equality_comparable<T>;
// callable concepts
template<class F, class... Args>
concept invocable = requires(F&& f, Args&&... args)
{
std::invoke(std::forward<F>(f), std::forward<Args>(args)...);
};
template<class F, class... Args>
concept regular_invocable = invocable<F, Args...>;
template<class F, class... Args>
concept predicate = regular_invocable<F, Args...> && boolean-testable<invoke_result_t<F, Args...>>;
template<class R, class T, class U>
concept relation = predicate<R, T, T> && predicate<R, U, U> && predicate<R, T, U> && predicate<R, U, T>;
template<class R, class T, class U>
concept equivalence_relation = relation<R, T, U>;
template<class R, class T, class U>
concept strict_weak_order = relation<R, T, U>;
}