include/concepts

// -*- C++ -*-
//===-------------------------- concepts ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_CONCEPTS
#define _LIBCPP_CONCEPTS

/*
    concepts synopsis
namespace std {
  // [concepts.lang], language-related concepts
  // [concept.same], concept same_as
  template<class T, class U>
    concept same_as = see below;

  // [concept.derived], concept derived_from
  template<class Derived, class Base>
    concept derived_from = see below;

  // [concept.convertible], concept convertible_to
  template<class From, class To>
    concept convertible_to = see below;

  // [concept.commonref], concept common_reference_with
  template<class T, class U>
    concept common_reference_with = see below;

  // [concept.common], concept common_with
  template<class T, class U>
    concept common_with = see below;

  // [concepts.arithmetic], arithmetic concepts
  template<class T>
    concept integral = see below;
  template<class T>
    concept signed_integral = see below;
  template<class T>
    concept unsigned_integral = see below;
  template<class T>
    concept floating_point = see below;

  // [concept.assignable], concept assignable_from
  template<class LHS, class RHS>
    concept assignable_from = see below;

  // [concept.swappable], concept swappable
  namespace ranges {
    inline namespace unspecified {
      inline constexpr unspecified swap = unspecified;
    }
  }
  template<class T>
    concept swappable = see below;
  template<class T, class U>
    concept swappable_with = see below;

  // [concept.destructible], concept destructible
  template<class T>
    concept destructible = see below;

  // [concept.constructible], concept constructible_from
  template<class T, class... Args>
    concept constructible_from = see below;

  // [concept.defaultconstructible], concept default_constructible
  template<class T>
    concept default_constructible = see below;

  // [concept.moveconstructible], concept move_constructible
  template<class T>
    concept move_constructible = see below;

  // [concept.copyconstructible], concept copy_constructible
  template<class T>
    concept copy_constructible = see below;

  // [concepts.compare], comparison concepts
  // [concept.boolean], concept boolean
  template<class B>
    concept boolean = see below;

  // [concept.equalitycomparable], concept equality_comparable
  template<class T>
    concept equality_comparable = see below;
  template<class T, class U>
    concept equality_comparable_with = see below;

  // [concept.totallyordered], concept totally_ordered
  template<class T>
    concept totally_ordered = see below;
  template<class T, class U>
    concept totally_ordered_with = see below;

  // [concepts.object], object concepts
  template<class T>
    concept movable = see below;
  template<class T>
    concept copyable = see below;
  template<class T>
    concept semiregular = see below;
  template<class T>
    concept regular = see below;

  // [concepts.callable], callable concepts
  // [concept.invocable], concept invocable
  template<class F, class... Args>
    concept invocable = see below;

  // [concept.regularinvocable], concept regular_invocable
  template<class F, class... Args>
    concept regular_invocable = see below;

  // [concept.predicate], concept predicate
  template<class F, class... Args>
    concept predicate = see below;

  // [concept.relation], concept relation
  template<class R, class T, class U>
    concept relation = see below;

  // [concept.equiv], concept equivalence_relation
  template<class R, class T, class U>
    concept equivalence_relation = see below;

  // [concept.strictweakorder], concept strict_weak_order
  template<class R, class T, class U>
    concept strict_weak_order = see below;
}

*/

#include <__config>
#include <__functional_base>
#include <type_traits>
#include <utility>
#include <version>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)

// [concept.same]

template<class _Tp, class _Up>
concept __same_as_impl = _VSTD::_IsSame<_Tp, _Up>::value;

template<class _Tp, class _Up>
concept same_as = __same_as_impl<_Tp, _Up> && __same_as_impl<_Up, _Tp>;

// [concept.derived]
template<class _Dp, class _Bp>
concept derived_from =
  is_base_of_v<_Bp, _Dp> &&
  is_convertible_v<const volatile _Dp*, const volatile _Bp*>;

// [concept.convertible]
template<class _From, class _To>
concept convertible_to =
  is_convertible_v<_From, _To> &&
  requires(add_rvalue_reference_t<_From> (&__f)()) {
    static_cast<_To>(__f());
  };

// [concept.commonref]
template<class _Tp, class _Up>
concept common_reference_with =
  same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> &&
  convertible_to<_Tp, common_reference_t<_Tp, _Up>> &&
  convertible_to<_Up, common_reference_t<_Tp, _Up>>;

// [concept.common]
template<class _Tp, class _Up>
concept common_with =
  same_as<common_type_t<_Tp, _Up>, common_type_t<_Up, _Tp>> &&
  requires {
    static_cast<common_type_t<_Tp, _Up>>(_VSTD::declval<_Tp>());
    static_cast<common_type_t<_Tp, _Up>>(_VSTD::declval<_Up>());
  } &&
  common_reference_with<
    add_lvalue_reference_t<const _Tp>,
    add_lvalue_reference_t<const _Up>> &&
  common_reference_with<
    add_lvalue_reference_t<common_type_t<_Tp, _Up>>,
    common_reference_t<
      add_lvalue_reference_t<const _Tp>,
      add_lvalue_reference_t<const _Up>>>;

// [concepts.arithmetic], arithmetic concepts
template<class _Tp>
concept integral = is_integral_v<_Tp>;

template<class _Tp>
concept signed_integral = integral<_Tp> && is_signed_v<_Tp>;

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

template<class _Tp>
concept floating_point = is_floating_point_v<_Tp>;

// [concept.assignable]
template<class _Lhs, class _Rhs>
concept assignable_from =
  is_lvalue_reference_v<_Lhs> &&
  common_reference_with<__make_const_lvalue_ref<_Lhs>, __make_const_lvalue_ref<_Rhs>> &&
  requires (_Lhs __lhs, _Rhs&& __rhs) {
    { __lhs = _VSTD::forward<_Rhs>(__rhs) } -> same_as<_Lhs>;
  };

// [concept.destructible]

template<class _Tp>
concept destructible = _VSTD::is_nothrow_destructible_v<_Tp>;

// [concept.constructible]
template<class _Tp, class... _Args>
concept constructible_from =
    destructible<_Tp> && _VSTD::is_constructible_v<_Tp, _Args...>;

// [concept.default.init]

template<class _Tp>
concept __default_initializable = requires { ::new _Tp; };

template<class _Tp>
concept default_initializable = constructible_from<_Tp> &&
    requires { _Tp{}; } && __default_initializable<_Tp>;

// [concept.moveconstructible]
template<class _Tp>
concept move_constructible =
  constructible_from<_Tp, _Tp> && convertible_to<_Tp, _Tp>;

// [concept.copyconstructible]
template<class _Tp>
concept copy_constructible =
  move_constructible<_Tp> &&
  constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp> &&
  constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp> &&
  constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;

// [concept.swappable]
namespace ranges::__swap {
  // Deleted to inhibit ADL
  template<class _Tp>
  void swap(_Tp&, _Tp&) = delete;

  template<class _Tp>
  concept __class_or_enum = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;

  // [1]
  template<class _Tp, class _Up>
  concept __unqualified_swappable_with =
    (__class_or_enum<remove_cvref_t<_Tp>> || __class_or_enum<remove_cvref_t<_Up>>) &&
    requires(_Tp&& __t, _Up&& __u) {
      swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
    };

  struct __fn;

  template<class _Tp, class _Up, size_t _Size>
  concept __swappable_arrays =
    !__unqualified_swappable_with<_Tp(&)[_Size], _Up(&)[_Size]> &&
    extent_v<_Tp> == extent_v<_Up> &&
    requires(_Tp(& __t)[_Size], _Up(& __u)[_Size], const __fn& __swap) {
      __swap(__t[0], __u[0]);
    };

  template<class _Tp>
  concept __exchangeable =
    !__unqualified_swappable_with<_Tp&, _Tp&> &&
    move_constructible<_Tp> &&
    assignable_from<_Tp&, _Tp>;

  struct __fn {
    // 2.1   `S` is `(void)swap(E1, E2)`* if `E1` or `E2` has class or enumeration type and...
    // *The name `swap` is used here unqualified.
    template<class _Tp, class _Up>
    requires __unqualified_swappable_with<_Tp, _Up>
    constexpr void operator()(_Tp&& __t, _Up&& __u) const
    noexcept(noexcept(swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
    {
      swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
    }

    // 2.2   Otherwise, if `E1` and `E2` are lvalues of array types with equal extent and...
    template<class _Tp, class _Up, size_t _Size>
    requires __swappable_arrays<_Tp, _Up, _Size>
    constexpr void operator()(_Tp(& __t)[_Size], _Up(& __u)[_Size]) const
    noexcept(noexcept((*this)(*__t, *__u)))
    {
      // TODO(cjdb): replace with `ranges::swap_ranges`.
      for (size_t __i = 0; __i < _Size; ++__i) {
        (*this)(__t[__i], __u[__i]);
      }
    }

    // 2.3   Otherwise, if `E1` and `E2` are lvalues of the same type `T` that models...
    template<__exchangeable _Tp>
    constexpr void operator()(_Tp& __x, _Tp& __y) const
    noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_move_assignable_v<_Tp>)
    {
      __y = _VSTD::exchange(__x, _VSTD::move(__y));
    }
  };
} // namespace ranges::__swap

namespace ranges::inline __cpo {
  inline constexpr auto swap = __swap::__fn{};
} // namespace ranges::__cpo

template<class _Tp>
concept swappable = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); };

template<class _Tp, class _Up>
concept swappable_with =
  common_reference_with<_Tp&, _Up&> &&
  requires(_Tp&& __t, _Up&& __u) {
    ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Tp>(__t));
    ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Up>(__u));
    ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
    ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Tp>(__t));
  };

// [concept.booleantestable]
template<class _Tp>
concept __boolean_testable_impl = convertible_to<_Tp, bool>;

template<class _Tp>
concept __boolean_testable = __boolean_testable_impl<_Tp> && requires(_Tp&& __t) {
  { !std::forward<_Tp>(__t) } -> __boolean_testable_impl;
};

// [concept.equalitycomparable]
template<class _Tp, class _Up>
concept __weakly_equality_comparable_with =
  requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __u) {
    { __t == __u } -> __boolean_testable;
    { __t != __u } -> __boolean_testable;
    { __u == __t } -> __boolean_testable;
    { __u != __t } -> __boolean_testable;
  };

template<class _Tp>
concept equality_comparable = __weakly_equality_comparable_with<_Tp, _Tp>;

template<class _Tp, class _Up>
concept equality_comparable_with =
  equality_comparable<_Tp> && equality_comparable<_Up> &&
  common_reference_with<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>> &&
  equality_comparable<
    common_reference_t<
      __make_const_lvalue_ref<_Tp>,
      __make_const_lvalue_ref<_Up>>> &&
  __weakly_equality_comparable_with<_Tp, _Up>;

// [concept.totallyordered]

template<class _Tp, class _Up>
concept __partially_ordered_with =
  requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __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;
  };

template<class _Tp>
concept totally_ordered = equality_comparable<_Tp> && __partially_ordered_with<_Tp, _Tp>;

template<class _Tp, class _Up>
concept totally_ordered_with =
  totally_ordered<_Tp> && totally_ordered<_Up> &&
  equality_comparable_with<_Tp, _Up> &&
  totally_ordered<
    common_reference_t<
      __make_const_lvalue_ref<_Tp>,
      __make_const_lvalue_ref<_Up>>> &&
  __partially_ordered_with<_Tp, _Up>;

// [concepts.object]
template<class _Tp>
concept movable =
  is_object_v<_Tp> &&
  move_constructible<_Tp> &&
  assignable_from<_Tp&, _Tp> &&
  swappable<_Tp>;

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

template<class _Tp>
concept semiregular = copyable<_Tp> && default_initializable<_Tp>;

template<class _Tp>
concept regular = semiregular<_Tp> && equality_comparable<_Tp>;

// [concept.invocable]
template<class _Fn, class... _Args>
concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
  _VSTD::invoke(_VSTD::forward<_Fn>(__fn), _VSTD::forward<_Args>(__args)...); // not required to be equality preserving
};

// [concept.regular.invocable]
template<class _Fn, class... _Args>
concept regular_invocable = invocable<_Fn, _Args...>;

#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP_CONCEPTS