18 Concepts library [concepts]

18.6 Object concepts [concepts.object]

This subclause describes concepts that specify the basis of the value-oriented programming style on which the library is based.

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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>;

[Note 1:

The semiregular concept is modeled by types that behave similarly to fundamental types like int, except that they need not be comparable with ==.

— end note]

[Note 2:

The regular concept is modeled by types that behave similarly to fundamental types like int and that are comparable with ==.

— end note]