libcxx/include/__iterator/concepts.h - rust-lang/llvm-project - Git at Google

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // 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___ITERATOR_CONCEPTS_H
 #define _LIBCPP___ITERATOR_CONCEPTS_H

 #include <__concepts/arithmetic.h>
 #include <__concepts/assignable.h>
 #include <__concepts/common_reference_with.h>
 #include <__concepts/constructible.h>
 #include <__concepts/copyable.h>
 #include <__concepts/derived_from.h>
 #include <__concepts/equality_comparable.h>
 #include <__concepts/invocable.h>
 #include <__concepts/movable.h>
 #include <__concepts/predicate.h>
 #include <__concepts/regular.h>
 #include <__concepts/relation.h>
 #include <__concepts/same_as.h>
 #include <__concepts/semiregular.h>
 #include <__concepts/totally_ordered.h>
 #include <__config>
 #include <__functional/invoke.h>
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/iter_move.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/readable_traits.h>
 #include <__memory/pointer_traits.h>
 #include <__type_traits/add_pointer.h>
 #include <__type_traits/common_reference.h>
 #include <__type_traits/is_pointer.h>
 #include <__type_traits/is_reference.h>
 #include <__type_traits/remove_cv.h>
 #include <__type_traits/remove_cvref.h>
 #include <__utility/forward.h>

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

 _LIBCPP_BEGIN_NAMESPACE_STD

 #if _LIBCPP_STD_VER >= 20

 // [iterator.concept.readable]
 template<class _In>
 concept __indirectly_readable_impl =
   requires(const _In __i) {
     typename iter_value_t<_In>;
     typename iter_reference_t<_In>;
     typename iter_rvalue_reference_t<_In>;
     { *__i } -> same_as<iter_reference_t<_In>>;
     { ranges::iter_move(__i) } -> same_as<iter_rvalue_reference_t<_In>>;
   } &&
   common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
   common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
   common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;

 template<class _In>
 concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In>>;

 template<indirectly_readable _Tp>
 using iter_common_reference_t = common_reference_t<iter_reference_t<_Tp>, iter_value_t<_Tp>&>;

 // [iterator.concept.writable]
 template<class _Out, class _Tp>
 concept indirectly_writable =
   requires(_Out&& __o, _Tp&& __t) {
     *__o = _VSTD::forward<_Tp>(__t);                        // not required to be equality-preserving
     *_VSTD::forward<_Out>(__o) = _VSTD::forward<_Tp>(__t);  // not required to be equality-preserving
     const_cast<const iter_reference_t<_Out>&&>(*__o) = _VSTD::forward<_Tp>(__t);                       // not required to be equality-preserving
     const_cast<const iter_reference_t<_Out>&&>(*_VSTD::forward<_Out>(__o)) = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
   };

 // [iterator.concept.winc]
 template<class _Tp>
 concept __integer_like = integral<_Tp> && !same_as<_Tp, bool>;

 template<class _Tp>
 concept __signed_integer_like = signed_integral<_Tp>;

 template<class _Ip>
 concept weakly_incrementable =
   // TODO: remove this once the clang bug is fixed (bugs.llvm.org/PR48173).
   !same_as<_Ip, bool> && // Currently, clang does not handle bool correctly.
   movable<_Ip> &&
   requires(_Ip __i) {
     typename iter_difference_t<_Ip>;
     requires __signed_integer_like<iter_difference_t<_Ip>>;
     { ++__i } -> same_as<_Ip&>;   // not required to be equality-preserving
     __i++;                        // not required to be equality-preserving
   };

 // [iterator.concept.inc]
 template<class _Ip>
 concept incrementable =
   regular<_Ip> &&
   weakly_incrementable<_Ip> &&
   requires(_Ip __i) {
     { __i++ } -> same_as<_Ip>;
   };

 // [iterator.concept.iterator]
 template<class _Ip>
 concept input_or_output_iterator =
   requires(_Ip __i) {
     { *__i } -> __can_reference;
   } &&
   weakly_incrementable<_Ip>;

 // [iterator.concept.sentinel]
 template<class _Sp, class _Ip>
 concept sentinel_for =
   semiregular<_Sp> &&
   input_or_output_iterator<_Ip> &&
   __weakly_equality_comparable_with<_Sp, _Ip>;

 template<class, class>
 inline constexpr bool disable_sized_sentinel_for = false;

 template<class _Sp, class _Ip>
 concept sized_sentinel_for =
   sentinel_for<_Sp, _Ip> &&
   !disable_sized_sentinel_for<remove_cv_t<_Sp>, remove_cv_t<_Ip>> &&
   requires(const _Ip& __i, const _Sp& __s) {
     { __s - __i } -> same_as<iter_difference_t<_Ip>>;
     { __i - __s } -> same_as<iter_difference_t<_Ip>>;
   };

 // [iterator.concept.input]
 template<class _Ip>
 concept input_iterator =
   input_or_output_iterator<_Ip> &&
   indirectly_readable<_Ip> &&
   requires { typename _ITER_CONCEPT<_Ip>; } &&
   derived_from<_ITER_CONCEPT<_Ip>, input_iterator_tag>;

 // [iterator.concept.output]
 template<class _Ip, class _Tp>
 concept output_iterator =
   input_or_output_iterator<_Ip> &&
   indirectly_writable<_Ip, _Tp> &&
   requires (_Ip __it, _Tp&& __t) {
     *__it++ = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
   };

 // [iterator.concept.forward]
 template<class _Ip>
 concept forward_iterator =
   input_iterator<_Ip> &&
   derived_from<_ITER_CONCEPT<_Ip>, forward_iterator_tag> &&
   incrementable<_Ip> &&
   sentinel_for<_Ip, _Ip>;

 // [iterator.concept.bidir]
 template<class _Ip>
 concept bidirectional_iterator =
   forward_iterator<_Ip> &&
   derived_from<_ITER_CONCEPT<_Ip>, bidirectional_iterator_tag> &&
   requires(_Ip __i) {
     { --__i } -> same_as<_Ip&>;
     { __i-- } -> same_as<_Ip>;
   };

 template<class _Ip>
 concept random_access_iterator =
   bidirectional_iterator<_Ip> &&
   derived_from<_ITER_CONCEPT<_Ip>, random_access_iterator_tag> &&
   totally_ordered<_Ip> &&
   sized_sentinel_for<_Ip, _Ip> &&
   requires(_Ip __i, const _Ip __j, const iter_difference_t<_Ip> __n) {
     { __i += __n } -> same_as<_Ip&>;
     { __j +  __n } -> same_as<_Ip>;
     { __n +  __j } -> same_as<_Ip>;
     { __i -= __n } -> same_as<_Ip&>;
     { __j -  __n } -> same_as<_Ip>;
     {  __j[__n]  } -> same_as<iter_reference_t<_Ip>>;
   };

 template<class _Ip>
 concept contiguous_iterator =
   random_access_iterator<_Ip> &&
   derived_from<_ITER_CONCEPT<_Ip>, contiguous_iterator_tag> &&
   is_lvalue_reference_v<iter_reference_t<_Ip>> &&
   same_as<iter_value_t<_Ip>, remove_cvref_t<iter_reference_t<_Ip>>> &&
   requires(const _Ip& __i) {
     { _VSTD::to_address(__i) } -> same_as<add_pointer_t<iter_reference_t<_Ip>>>;
   };

 template<class _Ip>
 concept __has_arrow = input_iterator<_Ip> && (is_pointer_v<_Ip> || requires(_Ip __i) { __i.operator->(); });

 // [indirectcallable.indirectinvocable]
 template<class _Fp, class _It>
 concept indirectly_unary_invocable =
   indirectly_readable<_It> &&
   copy_constructible<_Fp> &&
   invocable<_Fp&, iter_value_t<_It>&> &&
   invocable<_Fp&, iter_reference_t<_It>> &&
   invocable<_Fp&, iter_common_reference_t<_It>> &&
   common_reference_with<
     invoke_result_t<_Fp&, iter_value_t<_It>&>,
     invoke_result_t<_Fp&, iter_reference_t<_It>>>;

 template<class _Fp, class _It>
 concept indirectly_regular_unary_invocable =
   indirectly_readable<_It> &&
   copy_constructible<_Fp> &&
   regular_invocable<_Fp&, iter_value_t<_It>&> &&
   regular_invocable<_Fp&, iter_reference_t<_It>> &&
   regular_invocable<_Fp&, iter_common_reference_t<_It>> &&
   common_reference_with<
     invoke_result_t<_Fp&, iter_value_t<_It>&>,
     invoke_result_t<_Fp&, iter_reference_t<_It>>>;

 template<class _Fp, class _It>
 concept indirect_unary_predicate =
   indirectly_readable<_It> &&
   copy_constructible<_Fp> &&
   predicate<_Fp&, iter_value_t<_It>&> &&
   predicate<_Fp&, iter_reference_t<_It>> &&
   predicate<_Fp&, iter_common_reference_t<_It>>;

 template<class _Fp, class _It1, class _It2>
 concept indirect_binary_predicate =
   indirectly_readable<_It1> && indirectly_readable<_It2> &&
   copy_constructible<_Fp> &&
   predicate<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
   predicate<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
   predicate<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
   predicate<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
   predicate<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

 template<class _Fp, class _It1, class _It2 = _It1>
 concept indirect_equivalence_relation =
   indirectly_readable<_It1> && indirectly_readable<_It2> &&
   copy_constructible<_Fp> &&
   equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
   equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
   equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
   equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
   equivalence_relation<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

 template<class _Fp, class _It1, class _It2 = _It1>
 concept indirect_strict_weak_order =
   indirectly_readable<_It1> && indirectly_readable<_It2> &&
   copy_constructible<_Fp> &&
   strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
   strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
   strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
   strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
   strict_weak_order<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

 template<class _Fp, class... _Its>
   requires (indirectly_readable<_Its> && ...) && invocable<_Fp, iter_reference_t<_Its>...>
 using indirect_result_t = invoke_result_t<_Fp, iter_reference_t<_Its>...>;

 template<class _In, class _Out>
 concept indirectly_movable =
   indirectly_readable<_In> &&
   indirectly_writable<_Out, iter_rvalue_reference_t<_In>>;

 template<class _In, class _Out>
 concept indirectly_movable_storable =
   indirectly_movable<_In, _Out> &&
   indirectly_writable<_Out, iter_value_t<_In>> &&
   movable<iter_value_t<_In>> &&
   constructible_from<iter_value_t<_In>, iter_rvalue_reference_t<_In>> &&
   assignable_from<iter_value_t<_In>&, iter_rvalue_reference_t<_In>>;

 template<class _In, class _Out>
 concept indirectly_copyable =
   indirectly_readable<_In> &&
   indirectly_writable<_Out, iter_reference_t<_In>>;

 template<class _In, class _Out>
 concept indirectly_copyable_storable =
   indirectly_copyable<_In, _Out> &&
   indirectly_writable<_Out, iter_value_t<_In>&> &&
   indirectly_writable<_Out, const iter_value_t<_In>&> &&
   indirectly_writable<_Out, iter_value_t<_In>&&> &&
   indirectly_writable<_Out, const iter_value_t<_In>&&> &&
   copyable<iter_value_t<_In>> &&
   constructible_from<iter_value_t<_In>, iter_reference_t<_In>> &&
   assignable_from<iter_value_t<_In>&, iter_reference_t<_In>>;

 // Note: indirectly_swappable is located in iter_swap.h to prevent a dependency cycle
 // (both iter_swap and indirectly_swappable require indirectly_readable).

 #endif // _LIBCPP_STD_VER >= 20

 _LIBCPP_END_NAMESPACE_STD

 #endif // _LIBCPP___ITERATOR_CONCEPTS_H
	// -- C++ --
	//===----------------------------------------------------------------------===//
	//
	// 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___ITERATOR_CONCEPTS_H
	#define _LIBCPP___ITERATOR_CONCEPTS_H

	#include <__concepts/arithmetic.h>
	#include <__concepts/assignable.h>
	#include <__concepts/common_reference_with.h>
	#include <__concepts/constructible.h>
	#include <__concepts/copyable.h>
	#include <__concepts/derived_from.h>
	#include <__concepts/equality_comparable.h>
	#include <__concepts/invocable.h>
	#include <__concepts/movable.h>
	#include <__concepts/predicate.h>
	#include <__concepts/regular.h>
	#include <__concepts/relation.h>
	#include <__concepts/same_as.h>
	#include <__concepts/semiregular.h>
	#include <__concepts/totally_ordered.h>
	#include <__config>
	#include <__functional/invoke.h>
	#include <__iterator/incrementable_traits.h>
	#include <__iterator/iter_move.h>
	#include <__iterator/iterator_traits.h>
	#include <__iterator/readable_traits.h>
	#include <__memory/pointer_traits.h>
	#include <__type_traits/add_pointer.h>
	#include <__type_traits/common_reference.h>
	#include <__type_traits/is_pointer.h>
	#include <__type_traits/is_reference.h>
	#include <__type_traits/remove_cv.h>
	#include <__type_traits/remove_cvref.h>
	#include <__utility/forward.h>

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

	_LIBCPP_BEGIN_NAMESPACE_STD

	#if _LIBCPP_STD_VER >= 20

	// [iterator.concept.readable]
	template<class _In>
	concept __indirectly_readable_impl =
	requires(const _In __i) {
	typename iter_value_t<_In>;
	typename iter_reference_t<_In>;
	typename iter_rvalue_reference_t<_In>;
	{ *__i } -> same_as<iter_reference_t<_In>>;
	{ ranges::iter_move(__i) } -> same_as<iter_rvalue_reference_t<_In>>;
	} &&
	common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
	common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
	common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;

	template<class _In>
	concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In>>;

	template<indirectly_readable _Tp>
	using iter_common_reference_t = common_reference_t<iter_reference_t<_Tp>, iter_value_t<_Tp>&>;

	// [iterator.concept.writable]
	template<class _Out, class _Tp>
	concept indirectly_writable =
	requires(_Out&& __o, _Tp&& __t) {
	*__o = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
	*_VSTD::forward<_Out>(__o) = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
	const_cast<const iter_reference_t<_Out>&&>(*__o) = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
	const_cast<const iter_reference_t<_Out>&&>(*_VSTD::forward<_Out>(__o)) = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
	};

	// [iterator.concept.winc]
	template<class _Tp>
	concept __integer_like = integral<_Tp> && !same_as<_Tp, bool>;

	template<class _Tp>
	concept __signed_integer_like = signed_integral<_Tp>;

	template<class _Ip>
	concept weakly_incrementable =
	// TODO: remove this once the clang bug is fixed (bugs.llvm.org/PR48173).
	!same_as<_Ip, bool> && // Currently, clang does not handle bool correctly.
	movable<_Ip> &&
	requires(_Ip __i) {
	typename iter_difference_t<_Ip>;
	requires __signed_integer_like<iter_difference_t<_Ip>>;
	{ ++__i } -> same_as<_Ip&>; // not required to be equality-preserving
	__i++; // not required to be equality-preserving
	};

	// [iterator.concept.inc]
	template<class _Ip>
	concept incrementable =
	regular<_Ip> &&
	weakly_incrementable<_Ip> &&
	requires(_Ip __i) {
	{ __i++ } -> same_as<_Ip>;
	};

	// [iterator.concept.iterator]
	template<class _Ip>
	concept input_or_output_iterator =
	requires(_Ip __i) {
	{ *__i } -> __can_reference;
	} &&
	weakly_incrementable<_Ip>;

	// [iterator.concept.sentinel]
	template<class _Sp, class _Ip>
	concept sentinel_for =
	semiregular<_Sp> &&
	input_or_output_iterator<_Ip> &&
	__weakly_equality_comparable_with<_Sp, _Ip>;

	template<class, class>
	inline constexpr bool disable_sized_sentinel_for = false;

	template<class _Sp, class _Ip>
	concept sized_sentinel_for =
	sentinel_for<_Sp, _Ip> &&
	!disable_sized_sentinel_for<remove_cv_t<_Sp>, remove_cv_t<_Ip>> &&
	requires(const _Ip& __i, const _Sp& __s) {
	{ __s - __i } -> same_as<iter_difference_t<_Ip>>;
	{ __i - __s } -> same_as<iter_difference_t<_Ip>>;
	};

	// [iterator.concept.input]
	template<class _Ip>
	concept input_iterator =
	input_or_output_iterator<_Ip> &&
	indirectly_readable<_Ip> &&
	requires { typename _ITER_CONCEPT<_Ip>; } &&
	derived_from<_ITER_CONCEPT<_Ip>, input_iterator_tag>;

	// [iterator.concept.output]
	template<class _Ip, class _Tp>
	concept output_iterator =
	input_or_output_iterator<_Ip> &&
	indirectly_writable<_Ip, _Tp> &&
	requires (_Ip __it, _Tp&& __t) {
	*__it++ = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
	};

	// [iterator.concept.forward]
	template<class _Ip>
	concept forward_iterator =
	input_iterator<_Ip> &&
	derived_from<_ITER_CONCEPT<_Ip>, forward_iterator_tag> &&
	incrementable<_Ip> &&
	sentinel_for<_Ip, _Ip>;

	// [iterator.concept.bidir]
	template<class _Ip>
	concept bidirectional_iterator =
	forward_iterator<_Ip> &&
	derived_from<_ITER_CONCEPT<_Ip>, bidirectional_iterator_tag> &&
	requires(_Ip __i) {
	{ --__i } -> same_as<_Ip&>;
	{ __i-- } -> same_as<_Ip>;
	};

	template<class _Ip>
	concept random_access_iterator =
	bidirectional_iterator<_Ip> &&
	derived_from<_ITER_CONCEPT<_Ip>, random_access_iterator_tag> &&
	totally_ordered<_Ip> &&
	sized_sentinel_for<_Ip, _Ip> &&
	requires(_Ip __i, const _Ip __j, const iter_difference_t<_Ip> __n) {
	{ __i += __n } -> same_as<_Ip&>;
	{ __j + __n } -> same_as<_Ip>;
	{ __n + __j } -> same_as<_Ip>;
	{ __i -= __n } -> same_as<_Ip&>;
	{ __j - __n } -> same_as<_Ip>;
	{ __j[__n] } -> same_as<iter_reference_t<_Ip>>;
	};

	template<class _Ip>
	concept contiguous_iterator =
	random_access_iterator<_Ip> &&
	derived_from<_ITER_CONCEPT<_Ip>, contiguous_iterator_tag> &&
	is_lvalue_reference_v<iter_reference_t<_Ip>> &&
	same_as<iter_value_t<_Ip>, remove_cvref_t<iter_reference_t<_Ip>>> &&
	requires(const _Ip& __i) {
	{ _VSTD::to_address(__i) } -> same_as<add_pointer_t<iter_reference_t<_Ip>>>;
	};

	template<class _Ip>
	concept __has_arrow = input_iterator<_Ip> && (is_pointer_v<_Ip> \|\| requires(_Ip __i) { __i.operator->(); });

	// [indirectcallable.indirectinvocable]
	template<class _Fp, class _It>
	concept indirectly_unary_invocable =
	indirectly_readable<_It> &&
	copy_constructible<_Fp> &&
	invocable<_Fp&, iter_value_t<_It>&> &&
	invocable<_Fp&, iter_reference_t<_It>> &&
	invocable<_Fp&, iter_common_reference_t<_It>> &&
	common_reference_with<
	invoke_result_t<_Fp&, iter_value_t<_It>&>,
	invoke_result_t<_Fp&, iter_reference_t<_It>>>;

	template<class _Fp, class _It>
	concept indirectly_regular_unary_invocable =
	indirectly_readable<_It> &&
	copy_constructible<_Fp> &&
	regular_invocable<_Fp&, iter_value_t<_It>&> &&
	regular_invocable<_Fp&, iter_reference_t<_It>> &&
	regular_invocable<_Fp&, iter_common_reference_t<_It>> &&
	common_reference_with<
	invoke_result_t<_Fp&, iter_value_t<_It>&>,
	invoke_result_t<_Fp&, iter_reference_t<_It>>>;

	template<class _Fp, class _It>
	concept indirect_unary_predicate =
	indirectly_readable<_It> &&
	copy_constructible<_Fp> &&
	predicate<_Fp&, iter_value_t<_It>&> &&
	predicate<_Fp&, iter_reference_t<_It>> &&
	predicate<_Fp&, iter_common_reference_t<_It>>;

	template<class _Fp, class _It1, class _It2>
	concept indirect_binary_predicate =
	indirectly_readable<_It1> && indirectly_readable<_It2> &&
	copy_constructible<_Fp> &&
	predicate<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
	predicate<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
	predicate<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
	predicate<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
	predicate<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

	template<class _Fp, class _It1, class _It2 = _It1>
	concept indirect_equivalence_relation =
	indirectly_readable<_It1> && indirectly_readable<_It2> &&
	copy_constructible<_Fp> &&
	equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
	equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
	equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
	equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
	equivalence_relation<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

	template<class _Fp, class _It1, class _It2 = _It1>
	concept indirect_strict_weak_order =
	indirectly_readable<_It1> && indirectly_readable<_It2> &&
	copy_constructible<_Fp> &&
	strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
	strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
	strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
	strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>> &&
	strict_weak_order<_Fp&, iter_common_reference_t<_It1>, iter_common_reference_t<_It2>>;

	template<class _Fp, class... _Its>
	requires (indirectly_readable<_Its> && ...) && invocable<_Fp, iter_reference_t<_Its>...>
	using indirect_result_t = invoke_result_t<_Fp, iter_reference_t<_Its>...>;

	template<class _In, class _Out>
	concept indirectly_movable =
	indirectly_readable<_In> &&
	indirectly_writable<_Out, iter_rvalue_reference_t<_In>>;

	template<class _In, class _Out>
	concept indirectly_movable_storable =
	indirectly_movable<_In, _Out> &&
	indirectly_writable<_Out, iter_value_t<_In>> &&
	movable<iter_value_t<_In>> &&
	constructible_from<iter_value_t<_In>, iter_rvalue_reference_t<_In>> &&
	assignable_from<iter_value_t<_In>&, iter_rvalue_reference_t<_In>>;

	template<class _In, class _Out>
	concept indirectly_copyable =
	indirectly_readable<_In> &&
	indirectly_writable<_Out, iter_reference_t<_In>>;

	template<class _In, class _Out>
	concept indirectly_copyable_storable =
	indirectly_copyable<_In, _Out> &&
	indirectly_writable<_Out, iter_value_t<_In>&> &&
	indirectly_writable<_Out, const iter_value_t<_In>&> &&
	indirectly_writable<_Out, iter_value_t<_In>&&> &&
	indirectly_writable<_Out, const iter_value_t<_In>&&> &&
	copyable<iter_value_t<_In>> &&
	constructible_from<iter_value_t<_In>, iter_reference_t<_In>> &&
	assignable_from<iter_value_t<_In>&, iter_reference_t<_In>>;

	// Note: indirectly_swappable is located in iter_swap.h to prevent a dependency cycle
	// (both iter_swap and indirectly_swappable require indirectly_readable).

	#endif // _LIBCPP_STD_VER >= 20

	_LIBCPP_END_NAMESPACE_STD

	#endif // _LIBCPP___ITERATOR_CONCEPTS_H