STL/stl/inc/concepts

// concepts standard header (core)

// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#ifndef _CONCEPTS_
#define _CONCEPTS_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR

#if !_HAS_CXX20
_EMIT_STL_WARNING(STL4038, "The contents of <concepts> are available only with C++20 or later.");
#else // ^^^ !_HAS_CXX20 / _HAS_CXX20 vvv
#include <type_traits>
#include <vcruntime_new.h>

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
_STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new

_STD_BEGIN
// clang-format off
template <class _Ty1, class _Ty2>
concept _Same_impl = // Must be a distinct concept to provide symmetric subsumption for same_as
#ifdef __clang__
    __is_same(_Ty1, _Ty2);
#else // ^^^ use intrinsic / no intrinsic vvv
    is_same_v<_Ty1, _Ty2>;
#endif // ^^^ no intrinsic ^^^

_EXPORT_STD template <class _Ty1, class _Ty2>
concept same_as = _Same_impl<_Ty1, _Ty2> && _Same_impl<_Ty2, _Ty1>;

_EXPORT_STD template <class _Derived, class _Base>
concept derived_from = __is_base_of(_Base, _Derived)
    && __is_convertible_to(const volatile _Derived*, const volatile _Base*);

template <class _From, class _To>
concept _Implicitly_convertible_to = is_convertible_v<_From, _To>;

_EXPORT_STD template <class _Ty1, class _Ty2>
concept common_reference_with =
    requires {
        typename common_reference_t<_Ty1, _Ty2>;
        typename common_reference_t<_Ty2, _Ty1>;
    }
    && same_as<common_reference_t<_Ty1, _Ty2>, common_reference_t<_Ty2, _Ty1>>
    && convertible_to<_Ty1, common_reference_t<_Ty1, _Ty2>>
    && convertible_to<_Ty2, common_reference_t<_Ty1, _Ty2>>;

_EXPORT_STD template <class _Ty1, class _Ty2>
concept common_with =
    requires {
        typename common_type_t<_Ty1, _Ty2>;
        typename common_type_t<_Ty2, _Ty1>;
    }
    && same_as<common_type_t<_Ty1, _Ty2>, common_type_t<_Ty2, _Ty1>>
    && requires {
        static_cast<common_type_t<_Ty1, _Ty2>>(_STD declval<_Ty1>());
        static_cast<common_type_t<_Ty1, _Ty2>>(_STD declval<_Ty2>());
    }
    && common_reference_with<add_lvalue_reference_t<const _Ty1>, add_lvalue_reference_t<const _Ty2>>
    && common_reference_with<add_lvalue_reference_t<common_type_t<_Ty1, _Ty2>>,
        common_reference_t<add_lvalue_reference_t<const _Ty1>, add_lvalue_reference_t<const _Ty2>>>;

_EXPORT_STD template <class _Ty>
concept integral = is_integral_v<_Ty>;

_EXPORT_STD template <class _Ty>
concept signed_integral = integral<_Ty> && static_cast<_Ty>(-1) < static_cast<_Ty>(0);

_EXPORT_STD template <class _Ty>
concept unsigned_integral = integral<_Ty> && !signed_integral<_Ty>;

_EXPORT_STD template <class _Ty>
concept floating_point = is_floating_point_v<_Ty>;

_EXPORT_STD template <class _LTy, class _RTy>
concept assignable_from = is_lvalue_reference_v<_LTy>
    && common_reference_with<const remove_reference_t<_LTy>&, const remove_reference_t<_RTy>&>
    && requires(_LTy _Left, _RTy&& _Right) {
        { _Left = static_cast<_RTy&&>(_Right) } -> same_as<_LTy>;
    };

// swappable and swappable_with are defined below, since they depend on move_constructible.

_EXPORT_STD template <class _Ty>
concept destructible = __is_nothrow_destructible(_Ty);

_EXPORT_STD template <class _Ty, class... _ArgTys>
concept constructible_from = destructible<_Ty>
    && __is_constructible(_Ty, _ArgTys...);

_EXPORT_STD template <class _Ty>
concept default_initializable = constructible_from<_Ty>
    && requires {
        _Ty{};
        ::new (static_cast<void*>(nullptr)) _Ty; // is-default-initializable<_Ty>
    };

_EXPORT_STD template <class _Ty>
concept move_constructible = constructible_from<_Ty, _Ty> && convertible_to<_Ty, _Ty>;

template <class _Ty>
concept _Has_class_or_enum_type = __is_class(remove_reference_t<_Ty>) || __is_enum(remove_reference_t<_Ty>)
    || __is_union(remove_reference_t<_Ty>);

namespace ranges {
    namespace _Swap {
        template <class _Ty>
        void swap(_Ty&, _Ty&) = delete;

        template <class _Ty1, class _Ty2>
        concept _Use_ADL_swap = (_Has_class_or_enum_type<_Ty1> || _Has_class_or_enum_type<_Ty2>)
            && requires(_Ty1&& __t, _Ty2&& __u) {
                swap(static_cast<_Ty1&&>(__t), static_cast<_Ty2&&>(__u)); // intentional ADL
            };

        struct _Cpo {
            template <class _Ty1, class _Ty2>
                requires _Use_ADL_swap<_Ty1, _Ty2>
            _STATIC_CALL_OPERATOR constexpr void operator()(_Ty1&& __t, _Ty2&& __u) _CONST_CALL_OPERATOR
                noexcept(noexcept(swap(static_cast<_Ty1&&>(__t), static_cast<_Ty2&&>(__u)))) { // intentional ADL
                swap(static_cast<_Ty1&&>(__t), static_cast<_Ty2&&>(__u)); // intentional ADL
            }

            template <class _Ty>
                requires (!_Use_ADL_swap<_Ty&, _Ty&> && move_constructible<_Ty> && assignable_from<_Ty&, _Ty>)
            _STATIC_CALL_OPERATOR constexpr void operator()(_Ty& __x, _Ty& __y) _CONST_CALL_OPERATOR
                noexcept(is_nothrow_move_constructible_v<_Ty> && is_nothrow_move_assignable_v<_Ty>) {
                _Ty __tmp(static_cast<_Ty&&>(__x));
                __x = static_cast<_Ty&&>(__y);
                __y = static_cast<_Ty&&>(__tmp);
            }

            template <class _Ty1, class _Ty2, size_t _Size>
            _STATIC_CALL_OPERATOR constexpr void operator()(_Ty1 (&__t)[_Size], _Ty2 (&__u)[_Size]) _CONST_CALL_OPERATOR
                noexcept(noexcept(operator()(__t[0], __u[0])))
                requires requires(_Cpo __fn) { __fn(__t[0], __u[0]); } {
                for (size_t __i = 0; __i < _Size; ++__i) {
                    operator()(__t[__i], __u[__i]);
                }
            }
        };
    } // namespace _Swap

    inline namespace _Cpos {
        _EXPORT_STD inline constexpr _Swap::_Cpo swap;
    }
} // namespace ranges

_EXPORT_STD template <class _Ty>
concept swappable = requires(_Ty& __x, _Ty& __y) {
    _RANGES swap(__x, __y);
};

_EXPORT_STD template <class _Ty1, class _Ty2>
concept swappable_with = common_reference_with<_Ty1, _Ty2>
    && requires(_Ty1&& __t, _Ty2&& __u) {
        _RANGES swap(static_cast<_Ty1&&>(__t), static_cast<_Ty1&&>(__t));
        _RANGES swap(static_cast<_Ty2&&>(__u), static_cast<_Ty2&&>(__u));
        _RANGES swap(static_cast<_Ty1&&>(__t), static_cast<_Ty2&&>(__u));
        _RANGES swap(static_cast<_Ty2&&>(__u), static_cast<_Ty1&&>(__t));
    };

_EXPORT_STD template <class _Ty>
concept copy_constructible = move_constructible<_Ty>
    && constructible_from<_Ty, _Ty&> && convertible_to<_Ty&, _Ty>
    && constructible_from<_Ty, const _Ty&> && convertible_to<const _Ty&, _Ty>
    && constructible_from<_Ty, const _Ty> && convertible_to<const _Ty, _Ty>;

template <class _Ty>
concept _Boolean_testable_impl = convertible_to<_Ty, bool>;

template <class _Ty>
concept _Boolean_testable = _Boolean_testable_impl<_Ty>
    && requires(_Ty&& __t) {
        { !static_cast<_Ty&&>(__t) } -> _Boolean_testable_impl;
    };

template <class _Ty1, class _Ty2>
concept _Half_equality_comparable =
    requires(const remove_reference_t<_Ty1>& __x, const remove_reference_t<_Ty2>& __y) {
        { __x == __y } -> _Boolean_testable;
        { __x != __y } -> _Boolean_testable;
    };

template <class _Ty1, class _Ty2>
concept _Weakly_equality_comparable_with =
    _Half_equality_comparable<_Ty1, _Ty2> && _Half_equality_comparable<_Ty2, _Ty1>;

_EXPORT_STD template <class _Ty>
concept equality_comparable = _Half_equality_comparable<_Ty, _Ty>;

#if _HAS_CXX23
template <class _Ty1, class _Ty2, class _Ref = common_reference_t<const _Ty1&, const _Ty2&>>
concept _Comparison_common_type_with_impl =
    same_as<_Ref, common_reference_t<const _Ty2&, const _Ty1&>>
    && requires {
           requires convertible_to<const _Ty1&, const _Ref&> || convertible_to<_Ty1, const _Ref&>;
           requires convertible_to<const _Ty2&, const _Ref&> || convertible_to<_Ty2, const _Ref&>;
       };

template <class _Ty1, class _Ty2>
concept _Comparison_common_type_with = _Comparison_common_type_with_impl<remove_cvref_t<_Ty1>, remove_cvref_t<_Ty2>>;
#endif // _HAS_CXX23

_EXPORT_STD template <class _Ty1, class _Ty2>
concept equality_comparable_with = equality_comparable<_Ty1> && equality_comparable<_Ty2>
#if _HAS_CXX23
    && _Comparison_common_type_with<_Ty1, _Ty2>
#else // ^^^ _HAS_CXX23 / !_HAS_CXX23 vvv
    && common_reference_with<const remove_reference_t<_Ty1>&, const remove_reference_t<_Ty2>&>
#endif // ^^^ !_HAS_CXX23 ^^^
    && equality_comparable<common_reference_t<const remove_reference_t<_Ty1>&, const remove_reference_t<_Ty2>&>>
    && _Weakly_equality_comparable_with<_Ty1, _Ty2>;

template <class _Ty1, class _Ty2>
concept _Half_ordered = requires(const remove_reference_t<_Ty1>& __t, const remove_reference_t<_Ty2>& __u) {
    { __t <  __u } -> _Boolean_testable;
    { __t >  __u } -> _Boolean_testable;
    { __t <= __u } -> _Boolean_testable;
    { __t >= __u } -> _Boolean_testable;
};

template <class _Ty1, class _Ty2>
concept _Partially_ordered_with = _Half_ordered<_Ty1, _Ty2> && _Half_ordered<_Ty2, _Ty1>;

_EXPORT_STD template <class _Ty>
concept totally_ordered = equality_comparable<_Ty> && _Half_ordered<_Ty, _Ty>;

_EXPORT_STD template <class _Ty1, class _Ty2>
concept totally_ordered_with = totally_ordered<_Ty1> && totally_ordered<_Ty2>
    && equality_comparable_with<_Ty1, _Ty2>
    && totally_ordered<common_reference_t<const remove_reference_t<_Ty1>&, const remove_reference_t<_Ty2>&>>
    && _Partially_ordered_with<_Ty1, _Ty2>;

_EXPORT_STD template <class _Ty>
concept movable = is_object_v<_Ty>
    && move_constructible<_Ty>
    && assignable_from<_Ty&, _Ty>
    && swappable<_Ty>;

_EXPORT_STD template <class _Ty>
concept copyable = copy_constructible<_Ty>
    && movable<_Ty>
    && assignable_from<_Ty&, _Ty&>
    && assignable_from<_Ty&, const _Ty&>
    && assignable_from<_Ty&, const _Ty>;

_EXPORT_STD template <class _Ty>
concept semiregular = copyable<_Ty> && default_initializable<_Ty>;

_EXPORT_STD template <class _Ty>
concept regular = semiregular<_Ty> && equality_comparable<_Ty>;

_EXPORT_STD template <class _FTy, class... _ArgTys>
concept invocable = requires(_FTy&& _Fn, _ArgTys&&... _Args) {
    _STD invoke(static_cast<_FTy&&>(_Fn), static_cast<_ArgTys&&>(_Args)...);
};

_EXPORT_STD template <class _FTy, class... _ArgTys>
concept regular_invocable = invocable<_FTy, _ArgTys...>;

_EXPORT_STD template <class _FTy, class... _ArgTys>
concept predicate = regular_invocable<_FTy, _ArgTys...>
    && _Boolean_testable<invoke_result_t<_FTy, _ArgTys...>>;

_EXPORT_STD template <class _FTy, class _Ty1, class _Ty2>
concept relation =
       predicate<_FTy, _Ty1, _Ty1>
    && predicate<_FTy, _Ty2, _Ty2>
    && predicate<_FTy, _Ty1, _Ty2>
    && predicate<_FTy, _Ty2, _Ty1>;

_EXPORT_STD template <class _FTy, class _Ty1, class _Ty2>
concept equivalence_relation = relation<_FTy, _Ty1, _Ty2>;

_EXPORT_STD template <class _FTy, class _Ty1, class _Ty2>
concept strict_weak_order = relation<_FTy, _Ty1, _Ty2>;

// clang-format on

template <class _Ty>
struct _Choice_t {
    _Ty _Strategy  = _Ty{};
    bool _No_throw = false;
};

_STD_END

#pragma pop_macro("new")
_STL_RESTORE_CLANG_WARNINGS
#pragma warning(pop)
#pragma pack(pop)
#endif // _HAS_CXX20
#endif // _STL_COMPILER_PREPROCESSOR
#endif // _CONCEPTS_