I would like an implementation of a C++ concept for the standard library containers.
Many thanks in advance!
There's the pre-concept Container requirements. As a concept that would look something like
template <class E>
concept default_erasable = requires(E * p) {
std::destroy_at(p);
};
template <class E, class T, class A>
concept allocator_erasable = requires(A m, E * p) {
requires std::same_as<typename T::allocator_type, typename std::allocator_traits<A>::rebind_alloc<E>>;
std::allocator_traits<A>::destroy(m, p);
};
template <class T>
concept allocator_aware = requires (T a) {
{ a.get_allocator() } -> std::same_as<typename T::allocator_type>;
};
template <class T>
struct is_basic_string : std::false_type {};
template <class C, class T, class A>
struct is_basic_string<std::basic_string<C, T, A>> : std::true_type {};
template <class T>
constexpr bool is_basic_string_v = is_basic_string<T>::value;
template <class E, class T>
concept erasable = (is_basic_string_v<T> && default_erasable<E>)
|| (allocator_aware<T> && allocator_erasable<E, T, typename T::allocator_type>)
|| (!allocator_aware<T> && default_erasable<E>);
template <class T>
concept container = requires(T a, const T b)
{
requires std::regular<T>;
requires std::swappable<T>;
requires erasable<typename T::value_type, T>;
requires std::same_as<typename T::reference, typename T::value_type &>;
requires std::same_as<typename T::const_reference, const typename T::value_type &>;
requires std::forward_iterator<typename T::iterator>;
requires std::forward_iterator<typename T::const_iterator>;
requires std::signed_integral<typename T::difference_type>;
requires std::same_as<typename T::difference_type, typename std::iterator_traits<typename T::iterator>::difference_type>;
requires std::same_as<typename T::difference_type, typename std::iterator_traits<typename T::const_iterator>::difference_type>;
{ a.begin() } -> std::same_as<typename T::iterator>;
{ a.end() } -> std::same_as<typename T::iterator>;
{ b.begin() } -> std::same_as<typename T::const_iterator>;
{ b.end() } -> std::same_as<typename T::const_iterator>;
{ a.cbegin() } -> std::same_as<typename T::const_iterator>;
{ a.cend() } -> std::same_as<typename T::const_iterator>;
{ a.size() } -> std::same_as<typename T::size_type>;
{ a.max_size() } -> std::same_as<typename T::size_type>;
{ a.empty() } -> std::convertible_to<bool>;
};
and you probably want to add requires std::ranges::range<T>;
for concept partial ordering.