1 // <ranges> -*- C++ -*-
3 // Copyright (C) 2019-2021 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
25 /** @file include/ranges
26 * This is a Standard C++ Library header.
30 #ifndef _GLIBCXX_RANGES
31 #define _GLIBCXX_RANGES 1
33 #if __cplusplus > 201703L
35 #pragma GCC system_header
39 #if __cpp_lib_concepts
42 #include <initializer_list>
46 #include <bits/ranges_util.h>
47 #include <bits/refwrap.h>
50 * @defgroup ranges Ranges
52 * Components for dealing with ranges of elements.
55 namespace std _GLIBCXX_VISIBILITY(default)
57 _GLIBCXX_BEGIN_NAMESPACE_VERSION
60 // [range.access] customization point objects
61 // [range.req] range and view concepts
62 // [range.dangling] dangling iterator handling
63 // Defined in <bits/ranges_base.h>
65 // [view.interface] View interface
66 // [range.subrange] Sub-ranges
67 // Defined in <bits/ranges_util.h>
69 // C++20 24.6 [range.factories] Range factories
71 /// A view that contains no elements.
72 template<typename _Tp> requires is_object_v<_Tp>
74 : public view_interface<empty_view<_Tp>>
77 static constexpr _Tp* begin() noexcept { return nullptr; }
78 static constexpr _Tp* end() noexcept { return nullptr; }
79 static constexpr _Tp* data() noexcept { return nullptr; }
80 static constexpr size_t size() noexcept { return 0; }
81 static constexpr bool empty() noexcept { return true; }
84 template<typename _Tp>
85 inline constexpr bool enable_borrowed_range<empty_view<_Tp>> = true;
89 template<typename _Tp>
90 concept __boxable = copy_constructible<_Tp> && is_object_v<_Tp>;
92 template<__boxable _Tp>
93 struct __box : std::optional<_Tp>
95 using std::optional<_Tp>::optional;
99 noexcept(is_nothrow_default_constructible_v<_Tp>)
100 requires default_initializable<_Tp>
101 : std::optional<_Tp>{std::in_place}
104 __box(const __box&) = default;
105 __box(__box&&) = default;
107 using std::optional<_Tp>::operator=;
109 // _GLIBCXX_RESOLVE_LIB_DEFECTS
110 // 3477. Simplify constraints for semiregular-box
112 operator=(const __box& __that)
113 noexcept(is_nothrow_copy_constructible_v<_Tp>)
114 requires (!copyable<_Tp>)
117 this->emplace(*__that);
124 operator=(__box&& __that)
125 noexcept(is_nothrow_move_constructible_v<_Tp>)
126 requires (!movable<_Tp>)
129 this->emplace(std::move(*__that));
136 // For types which are already semiregular, this specialization of the
137 // semiregular wrapper stores the object directly without going through
138 // std::optional. It provides just the subset of the primary template's
139 // API that we currently use.
140 template<__boxable _Tp> requires semiregular<_Tp>
144 [[no_unique_address]] _Tp _M_value = _Tp();
150 __box(const _Tp& __t)
151 noexcept(is_nothrow_copy_constructible_v<_Tp>)
157 noexcept(is_nothrow_move_constructible_v<_Tp>)
158 : _M_value{std::move(__t)}
161 template<typename... _Args>
162 requires constructible_from<_Tp, _Args...>
164 __box(in_place_t, _Args&&... __args)
165 noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
166 : _M_value(std::forward<_Args>(__args)...)
170 has_value() const noexcept
178 operator*() const noexcept
182 operator->() noexcept
183 { return std::__addressof(_M_value); }
186 operator->() const noexcept
187 { return std::__addressof(_M_value); }
189 } // namespace __detail
191 /// A view that contains exactly one element.
192 template<copy_constructible _Tp> requires is_object_v<_Tp>
193 class single_view : public view_interface<single_view<_Tp>>
196 single_view() = default;
199 single_view(const _Tp& __t)
204 single_view(_Tp&& __t)
205 : _M_value(std::move(__t))
208 // _GLIBCXX_RESOLVE_LIB_DEFECTS
209 // 3428. single_view's in place constructor should be explicit
210 template<typename... _Args>
211 requires constructible_from<_Tp, _Args...>
213 single_view(in_place_t, _Args&&... __args)
214 : _M_value{in_place, std::forward<_Args>(__args)...}
222 begin() const noexcept
227 { return data() + 1; }
231 { return data() + 1; }
233 static constexpr size_t
239 { return _M_value.operator->(); }
242 data() const noexcept
243 { return _M_value.operator->(); }
246 [[no_unique_address]] __detail::__box<_Tp> _M_value;
249 template<typename _Tp>
250 single_view(_Tp) -> single_view<_Tp>;
254 template<typename _Wp>
255 constexpr auto __to_signed_like(_Wp __w) noexcept
257 if constexpr (!integral<_Wp>)
258 return iter_difference_t<_Wp>();
259 else if constexpr (sizeof(iter_difference_t<_Wp>) > sizeof(_Wp))
260 return iter_difference_t<_Wp>(__w);
261 else if constexpr (sizeof(ptrdiff_t) > sizeof(_Wp))
262 return ptrdiff_t(__w);
263 else if constexpr (sizeof(long long) > sizeof(_Wp))
264 return (long long)(__w);
265 #ifdef __SIZEOF_INT128__
266 else if constexpr (__SIZEOF_INT128__ > sizeof(_Wp))
267 return __int128(__w);
270 return __max_diff_type(__w);
273 template<typename _Wp>
274 using __iota_diff_t = decltype(__to_signed_like(std::declval<_Wp>()));
276 template<typename _It>
277 concept __decrementable = incrementable<_It>
280 { --__i } -> same_as<_It&>;
281 { __i-- } -> same_as<_It>;
284 template<typename _It>
285 concept __advanceable = __decrementable<_It> && totally_ordered<_It>
286 && requires( _It __i, const _It __j, const __iota_diff_t<_It> __n)
288 { __i += __n } -> same_as<_It&>;
289 { __i -= __n } -> same_as<_It&>;
293 { __j - __j } -> convertible_to<__iota_diff_t<_It>>;
296 template<typename _Winc>
297 struct __iota_view_iter_cat
300 template<incrementable _Winc>
301 struct __iota_view_iter_cat<_Winc>
302 { using iterator_category = input_iterator_tag; };
303 } // namespace __detail
305 template<weakly_incrementable _Winc,
306 semiregular _Bound = unreachable_sentinel_t>
307 requires std::__detail::__weakly_eq_cmp_with<_Winc, _Bound>
308 && semiregular<_Winc>
309 class iota_view : public view_interface<iota_view<_Winc, _Bound>>
314 struct _Iterator : __detail::__iota_view_iter_cat<_Winc>
320 using namespace __detail;
321 if constexpr (__advanceable<_Winc>)
322 return random_access_iterator_tag{};
323 else if constexpr (__decrementable<_Winc>)
324 return bidirectional_iterator_tag{};
325 else if constexpr (incrementable<_Winc>)
326 return forward_iterator_tag{};
328 return input_iterator_tag{};
332 using iterator_concept = decltype(_S_iter_concept());
333 // iterator_category defined in __iota_view_iter_cat
334 using value_type = _Winc;
335 using difference_type = __detail::__iota_diff_t<_Winc>;
337 _Iterator() = default;
340 _Iterator(_Winc __value)
341 : _M_value(__value) { }
344 operator*() const noexcept(is_nothrow_copy_constructible_v<_Winc>)
359 operator++(int) requires incrementable<_Winc>
367 operator--() requires __detail::__decrementable<_Winc>
374 operator--(int) requires __detail::__decrementable<_Winc>
382 operator+=(difference_type __n) requires __detail::__advanceable<_Winc>
384 using __detail::__is_integer_like;
385 using __detail::__is_signed_integer_like;
386 if constexpr (__is_integer_like<_Winc>
387 && !__is_signed_integer_like<_Winc>)
389 if (__n >= difference_type(0))
390 _M_value += static_cast<_Winc>(__n);
392 _M_value -= static_cast<_Winc>(-__n);
400 operator-=(difference_type __n) requires __detail::__advanceable<_Winc>
402 using __detail::__is_integer_like;
403 using __detail::__is_signed_integer_like;
404 if constexpr (__is_integer_like<_Winc>
405 && !__is_signed_integer_like<_Winc>)
407 if (__n >= difference_type(0))
408 _M_value -= static_cast<_Winc>(__n);
410 _M_value += static_cast<_Winc>(-__n);
418 operator[](difference_type __n) const
419 requires __detail::__advanceable<_Winc>
420 { return _Winc(_M_value + __n); }
422 friend constexpr bool
423 operator==(const _Iterator& __x, const _Iterator& __y)
424 requires equality_comparable<_Winc>
425 { return __x._M_value == __y._M_value; }
427 friend constexpr bool
428 operator<(const _Iterator& __x, const _Iterator& __y)
429 requires totally_ordered<_Winc>
430 { return __x._M_value < __y._M_value; }
432 friend constexpr bool
433 operator>(const _Iterator& __x, const _Iterator& __y)
434 requires totally_ordered<_Winc>
435 { return __y < __x; }
437 friend constexpr bool
438 operator<=(const _Iterator& __x, const _Iterator& __y)
439 requires totally_ordered<_Winc>
440 { return !(__y < __x); }
442 friend constexpr bool
443 operator>=(const _Iterator& __x, const _Iterator& __y)
444 requires totally_ordered<_Winc>
445 { return !(__x < __y); }
447 #ifdef __cpp_lib_three_way_comparison
448 friend constexpr auto
449 operator<=>(const _Iterator& __x, const _Iterator& __y)
450 requires totally_ordered<_Winc> && three_way_comparable<_Winc>
451 { return __x._M_value <=> __y._M_value; }
454 friend constexpr _Iterator
455 operator+(_Iterator __i, difference_type __n)
456 requires __detail::__advanceable<_Winc>
457 { return __i += __n; }
459 friend constexpr _Iterator
460 operator+(difference_type __n, _Iterator __i)
461 requires __detail::__advanceable<_Winc>
462 { return __i += __n; }
464 friend constexpr _Iterator
465 operator-(_Iterator __i, difference_type __n)
466 requires __detail::__advanceable<_Winc>
467 { return __i -= __n; }
469 friend constexpr difference_type
470 operator-(const _Iterator& __x, const _Iterator& __y)
471 requires __detail::__advanceable<_Winc>
473 using __detail::__is_integer_like;
474 using __detail::__is_signed_integer_like;
475 using _Dt = difference_type;
476 if constexpr (__is_integer_like<_Winc>)
478 if constexpr (__is_signed_integer_like<_Winc>)
479 return _Dt(_Dt(__x._M_value) - _Dt(__y._M_value));
481 return (__y._M_value > __x._M_value)
482 ? _Dt(-_Dt(__y._M_value - __x._M_value))
483 : _Dt(__x._M_value - __y._M_value);
486 return __x._M_value - __y._M_value;
490 _Winc _M_value = _Winc();
499 _M_equal(const _Iterator& __x) const
500 { return __x._M_value == _M_bound; }
503 _M_distance_from(const _Iterator& __x) const
504 { return _M_bound - __x._M_value; }
506 _Bound _M_bound = _Bound();
509 _Sentinel() = default;
512 _Sentinel(_Bound __bound)
513 : _M_bound(__bound) { }
515 friend constexpr bool
516 operator==(const _Iterator& __x, const _Sentinel& __y)
517 { return __y._M_equal(__x); }
519 friend constexpr iter_difference_t<_Winc>
520 operator-(const _Iterator& __x, const _Sentinel& __y)
521 requires sized_sentinel_for<_Bound, _Winc>
522 { return -__y._M_distance_from(__x); }
524 friend constexpr iter_difference_t<_Winc>
525 operator-(const _Sentinel& __x, const _Iterator& __y)
526 requires sized_sentinel_for<_Bound, _Winc>
527 { return __x._M_distance_from(__y); }
530 _Winc _M_value = _Winc();
531 [[no_unique_address]] _Bound _M_bound = _Bound();
534 iota_view() = default;
537 iota_view(_Winc __value)
542 iota_view(type_identity_t<_Winc> __value,
543 type_identity_t<_Bound> __bound)
544 : _M_value(__value), _M_bound(__bound)
546 if constexpr (totally_ordered_with<_Winc, _Bound>)
547 __glibcxx_assert( bool(__value <= __bound) );
551 begin() const { return _Iterator{_M_value}; }
556 if constexpr (same_as<_Bound, unreachable_sentinel_t>)
557 return unreachable_sentinel;
559 return _Sentinel{_M_bound};
563 end() const requires same_as<_Winc, _Bound>
564 { return _Iterator{_M_bound}; }
568 requires (same_as<_Winc, _Bound> && __detail::__advanceable<_Winc>)
569 || (integral<_Winc> && integral<_Bound>)
570 || sized_sentinel_for<_Bound, _Winc>
572 using __detail::__is_integer_like;
573 using __detail::__to_unsigned_like;
574 if constexpr (integral<_Winc> && integral<_Bound>)
576 using _Up = make_unsigned_t<decltype(_M_bound - _M_value)>;
577 return _Up(_M_bound) - _Up(_M_value);
579 else if constexpr (__is_integer_like<_Winc>)
580 return __to_unsigned_like(_M_bound) - __to_unsigned_like(_M_value);
582 return __to_unsigned_like(_M_bound - _M_value);
586 template<typename _Winc, typename _Bound>
587 requires (!__detail::__is_integer_like<_Winc>
588 || !__detail::__is_integer_like<_Bound>
589 || (__detail::__is_signed_integer_like<_Winc>
590 == __detail::__is_signed_integer_like<_Bound>))
591 iota_view(_Winc, _Bound) -> iota_view<_Winc, _Bound>;
593 template<weakly_incrementable _Winc, semiregular _Bound>
594 inline constexpr bool
595 enable_borrowed_range<iota_view<_Winc, _Bound>> = true;
599 template<typename _Tp>
600 inline constexpr empty_view<_Tp> empty{};
604 template<typename _Tp>
606 operator()(_Tp&& __e) const
607 { return single_view<decay_t<_Tp>>(std::forward<_Tp>(__e)); }
610 inline constexpr _Single single{};
614 template<typename _Tp>
616 operator()(_Tp&& __e) const
617 { return iota_view(std::forward<_Tp>(__e)); }
619 template<typename _Tp, typename _Up>
621 operator()(_Tp&& __e, _Up&& __f) const
622 { return iota_view(std::forward<_Tp>(__e), std::forward<_Up>(__f)); }
625 inline constexpr _Iota iota{};
630 template<typename _Val, typename _CharT, typename _Traits>
631 concept __stream_extractable
632 = requires(basic_istream<_CharT, _Traits>& is, _Val& t) { is >> t; };
633 } // namespace __detail
635 template<movable _Val, typename _CharT,
636 typename _Traits = char_traits<_CharT>>
637 requires default_initializable<_Val>
638 && __detail::__stream_extractable<_Val, _CharT, _Traits>
639 class basic_istream_view
640 : public view_interface<basic_istream_view<_Val, _CharT, _Traits>>
643 basic_istream_view() = default;
646 basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
647 : _M_stream(std::__addressof(__stream))
653 if (_M_stream != nullptr)
654 *_M_stream >> _M_object;
655 return _Iterator{this};
658 constexpr default_sentinel_t
660 { return default_sentinel; }
663 basic_istream<_CharT, _Traits>* _M_stream = nullptr;
664 _Val _M_object = _Val();
669 using iterator_concept = input_iterator_tag;
670 using difference_type = ptrdiff_t;
671 using value_type = _Val;
673 _Iterator() = default;
676 _Iterator(basic_istream_view* __parent) noexcept
677 : _M_parent(__parent)
680 _Iterator(const _Iterator&) = delete;
681 _Iterator(_Iterator&&) = default;
682 _Iterator& operator=(const _Iterator&) = delete;
683 _Iterator& operator=(_Iterator&&) = default;
688 __glibcxx_assert(_M_parent->_M_stream != nullptr);
689 *_M_parent->_M_stream >> _M_parent->_M_object;
700 __glibcxx_assert(_M_parent->_M_stream != nullptr);
701 return _M_parent->_M_object;
705 operator==(const _Iterator& __x, default_sentinel_t)
706 { return __x._M_at_end(); }
709 basic_istream_view* _M_parent = nullptr;
713 { return _M_parent == nullptr || !*_M_parent->_M_stream; }
719 template<typename _Val, typename _CharT, typename _Traits>
720 basic_istream_view<_Val, _CharT, _Traits>
721 istream_view(basic_istream<_CharT, _Traits>& __s)
722 { return basic_istream_view<_Val, _CharT, _Traits>{__s}; }
724 // C++20 24.7 [range.adaptors] Range adaptors
730 // Alias for a type that is conditionally present
731 // (and is an empty type otherwise).
732 // Data members using this alias should use [[no_unique_address]] so that
733 // they take no space when not needed.
734 template<bool _Present, typename _Tp>
735 using __maybe_present_t = conditional_t<_Present, _Tp, _Empty>;
737 // Alias for a type that is conditionally const.
738 template<bool _Const, typename _Tp>
739 using __maybe_const_t = conditional_t<_Const, const _Tp, _Tp>;
741 } // namespace __detail
743 namespace views::__adaptor
745 // True if the range adaptor _Adaptor can be applied with _Args.
746 template<typename _Adaptor, typename... _Args>
747 concept __adaptor_invocable
748 = requires { std::declval<_Adaptor>()(declval<_Args>()...); };
750 // True if the range adaptor non-closure _Adaptor can be partially applied
752 template<typename _Adaptor, typename... _Args>
753 concept __adaptor_partial_app_viable = (_Adaptor::_S_arity > 1)
754 && (sizeof...(_Args) == _Adaptor::_S_arity - 1)
755 && (constructible_from<decay_t<_Args>, _Args> && ...);
757 template<typename _Adaptor, typename... _Args>
760 template<typename _Lhs, typename _Rhs>
763 // The base class of every range adaptor closure.
765 // The derived class should define the optional static data member
766 // _S_has_simple_call_op to true if the behavior of this adaptor is
767 // independent of the constness/value category of the adaptor object.
768 struct _RangeAdaptorClosure
770 // range | adaptor is equivalent to adaptor(range).
771 template<typename _Self, typename _Range>
772 requires derived_from<remove_cvref_t<_Self>, _RangeAdaptorClosure>
773 && __adaptor_invocable<_Self, _Range>
774 friend constexpr auto
775 operator|(_Range&& __r, _Self&& __self)
776 { return std::forward<_Self>(__self)(std::forward<_Range>(__r)); }
778 // Compose the adaptors __lhs and __rhs into a pipeline, returning
779 // another range adaptor closure object.
780 template<typename _Lhs, typename _Rhs>
781 requires derived_from<_Lhs, _RangeAdaptorClosure>
782 && derived_from<_Rhs, _RangeAdaptorClosure>
783 friend constexpr auto
784 operator|(_Lhs __lhs, _Rhs __rhs)
785 { return _Pipe<_Lhs, _Rhs>{std::move(__lhs), std::move(__rhs)}; }
788 // The base class of every range adaptor non-closure.
790 // The static data member _Derived::_S_arity must contain the total number of
791 // arguments that the adaptor takes, and the class _Derived must introduce
792 // _RangeAdaptor::operator() into the class scope via a using-declaration.
794 // The optional static data member _Derived::_S_has_simple_extra_args should
795 // be defined to true if the behavior of this adaptor is independent of the
796 // constness/value category of the extra arguments. This data member could
797 // also be defined as a variable template parameterized by the types of the
799 template<typename _Derived>
802 // Partially apply the arguments __args to the range adaptor _Derived,
803 // returning a range adaptor closure object.
804 template<typename... _Args>
805 requires __adaptor_partial_app_viable<_Derived, _Args...>
807 operator()(_Args&&... __args) const
809 return _Partial<_Derived, decay_t<_Args>...>{std::forward<_Args>(__args)...};
813 // True if the range adaptor closure _Adaptor has a simple operator(), i.e.
814 // one that's not overloaded according to constness or value category of the
816 template<typename _Adaptor>
817 concept __closure_has_simple_call_op = _Adaptor::_S_has_simple_call_op;
819 // True if the behavior of the range adaptor non-closure _Adaptor is
820 // independent of the value category of its extra arguments _Args.
821 template<typename _Adaptor, typename... _Args>
822 concept __adaptor_has_simple_extra_args = _Adaptor::_S_has_simple_extra_args
823 || _Adaptor::template _S_has_simple_extra_args<_Args...>;
825 // A range adaptor closure that represents partial application of
826 // the range adaptor _Adaptor with arguments _Args.
827 template<typename _Adaptor, typename... _Args>
828 struct _Partial : _RangeAdaptorClosure
830 tuple<_Args...> _M_args;
833 _Partial(_Args... __args)
834 : _M_args(std::move(__args)...)
837 // Invoke _Adaptor with arguments __r, _M_args... according to the
838 // value category of this _Partial object.
839 template<typename _Range>
840 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
842 operator()(_Range&& __r) const &
844 auto __forwarder = [&__r] (const auto&... __args) {
845 return _Adaptor{}(std::forward<_Range>(__r), __args...);
847 return std::apply(__forwarder, _M_args);
850 template<typename _Range>
851 requires __adaptor_invocable<_Adaptor, _Range, _Args...>
853 operator()(_Range&& __r) &&
855 auto __forwarder = [&__r] (auto&... __args) {
856 return _Adaptor{}(std::forward<_Range>(__r), std::move(__args)...);
858 return std::apply(__forwarder, _M_args);
861 template<typename _Range>
863 operator()(_Range&& __r) const && = delete;
866 // A lightweight specialization of the above primary template for
867 // the common case where _Adaptor accepts a single extra argument.
868 template<typename _Adaptor, typename _Arg>
869 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
875 : _M_arg(std::move(__arg))
878 template<typename _Range>
879 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
881 operator()(_Range&& __r) const &
882 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
884 template<typename _Range>
885 requires __adaptor_invocable<_Adaptor, _Range, _Arg>
887 operator()(_Range&& __r) &&
888 { return _Adaptor{}(std::forward<_Range>(__r), std::move(_M_arg)); }
890 template<typename _Range>
892 operator()(_Range&& __r) const && = delete;
895 // Partial specialization of the primary template for the case where the extra
896 // arguments of the adaptor can always be safely and efficiently forwarded by
897 // const reference. This lets us get away with a single operator() overload,
898 // which makes overload resolution failure diagnostics more concise.
899 template<typename _Adaptor, typename... _Args>
900 requires __adaptor_has_simple_extra_args<_Adaptor, _Args...>
901 && (is_trivially_copyable_v<_Args> && ...)
902 struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure
904 tuple<_Args...> _M_args;
907 _Partial(_Args... __args)
908 : _M_args(std::move(__args)...)
911 // Invoke _Adaptor with arguments __r, const _M_args&... regardless
912 // of the value category of this _Partial object.
913 template<typename _Range>
914 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
916 operator()(_Range&& __r) const
918 auto __forwarder = [&__r] (const auto&... __args) {
919 return _Adaptor{}(std::forward<_Range>(__r), __args...);
921 return std::apply(__forwarder, _M_args);
924 static constexpr bool _S_has_simple_call_op = true;
927 // A lightweight specialization of the above template for the common case
928 // where _Adaptor accepts a single extra argument.
929 template<typename _Adaptor, typename _Arg>
930 requires __adaptor_has_simple_extra_args<_Adaptor, _Arg>
931 && is_trivially_copyable_v<_Arg>
932 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
938 : _M_arg(std::move(__arg))
941 template<typename _Range>
942 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
944 operator()(_Range&& __r) const
945 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
947 static constexpr bool _S_has_simple_call_op = true;
950 template<typename _Lhs, typename _Rhs, typename _Range>
951 concept __pipe_invocable
952 = requires { std::declval<_Rhs>()(std::declval<_Lhs>()(std::declval<_Range>())); };
954 // A range adaptor closure that represents composition of the range
955 // adaptor closures _Lhs and _Rhs.
956 template<typename _Lhs, typename _Rhs>
957 struct _Pipe : _RangeAdaptorClosure
959 [[no_unique_address]] _Lhs _M_lhs;
960 [[no_unique_address]] _Rhs _M_rhs;
963 _Pipe(_Lhs __lhs, _Rhs __rhs)
964 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
967 // Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
968 // range adaptor closure object.
969 template<typename _Range>
970 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
972 operator()(_Range&& __r) const &
973 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
975 template<typename _Range>
976 requires __pipe_invocable<_Lhs, _Rhs, _Range>
978 operator()(_Range&& __r) &&
979 { return std::move(_M_rhs)(std::move(_M_lhs)(std::forward<_Range>(__r))); }
981 template<typename _Range>
983 operator()(_Range&& __r) const && = delete;
986 // A partial specialization of the above primary template for the case where
987 // both adaptor operands have a simple operator(). This in turn lets us
988 // implement composition using a single simple operator(), which makes
989 // overload resolution failure diagnostics more concise.
990 template<typename _Lhs, typename _Rhs>
991 requires __closure_has_simple_call_op<_Lhs>
992 && __closure_has_simple_call_op<_Rhs>
993 struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure
995 [[no_unique_address]] _Lhs _M_lhs;
996 [[no_unique_address]] _Rhs _M_rhs;
999 _Pipe(_Lhs __lhs, _Rhs __rhs)
1000 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
1003 template<typename _Range>
1004 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
1006 operator()(_Range&& __r) const
1007 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
1009 static constexpr bool _S_has_simple_call_op = true;
1011 } // namespace views::__adaptor
1013 template<range _Range> requires is_object_v<_Range>
1014 class ref_view : public view_interface<ref_view<_Range>>
1017 _Range* _M_r = nullptr;
1019 static void _S_fun(_Range&); // not defined
1020 static void _S_fun(_Range&&) = delete;
1024 ref_view() noexcept = default;
1026 template<__detail::__not_same_as<ref_view> _Tp>
1027 requires convertible_to<_Tp, _Range&>
1028 && requires { _S_fun(declval<_Tp>()); }
1031 : _M_r(std::__addressof(static_cast<_Range&>(std::forward<_Tp>(__t))))
1038 constexpr iterator_t<_Range>
1040 { return ranges::begin(*_M_r); }
1042 constexpr sentinel_t<_Range>
1044 { return ranges::end(*_M_r); }
1047 empty() const requires requires { ranges::empty(*_M_r); }
1048 { return ranges::empty(*_M_r); }
1051 size() const requires sized_range<_Range>
1052 { return ranges::size(*_M_r); }
1055 data() const requires contiguous_range<_Range>
1056 { return ranges::data(*_M_r); }
1059 template<typename _Range>
1060 ref_view(_Range&) -> ref_view<_Range>;
1062 template<typename _Tp>
1063 inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
1069 template<typename _Range>
1070 concept __can_ref_view = requires { ref_view{std::declval<_Range>()}; };
1072 template<typename _Range>
1073 concept __can_subrange = requires { subrange{std::declval<_Range>()}; };
1074 } // namespace __detail
1076 struct _All : __adaptor::_RangeAdaptorClosure
1078 template<viewable_range _Range>
1079 requires view<decay_t<_Range>>
1080 || __detail::__can_ref_view<_Range>
1081 || __detail::__can_subrange<_Range>
1083 operator()(_Range&& __r) const
1085 if constexpr (view<decay_t<_Range>>)
1086 return std::forward<_Range>(__r);
1087 else if constexpr (__detail::__can_ref_view<_Range>)
1088 return ref_view{std::forward<_Range>(__r)};
1090 return subrange{std::forward<_Range>(__r)};
1093 static constexpr bool _S_has_simple_call_op = true;
1096 inline constexpr _All all;
1098 template<viewable_range _Range>
1099 using all_t = decltype(all(std::declval<_Range>()));
1100 } // namespace views
1104 template<typename _Tp>
1105 struct __non_propagating_cache
1107 // When _Tp is not an object type (e.g. is a reference type), we make
1108 // __non_propagating_cache<_Tp> empty rather than ill-formed so that
1109 // users can easily conditionally declare data members with this type
1110 // (such as join_view::_M_inner).
1113 template<typename _Tp>
1114 requires is_object_v<_Tp>
1115 struct __non_propagating_cache<_Tp> : protected _Optional_base<_Tp>
1117 __non_propagating_cache() = default;
1120 __non_propagating_cache(const __non_propagating_cache&) noexcept
1124 __non_propagating_cache(__non_propagating_cache&& __other) noexcept
1125 { __other._M_reset(); }
1127 constexpr __non_propagating_cache&
1128 operator=(const __non_propagating_cache& __other) noexcept
1130 if (std::__addressof(__other) != this)
1135 constexpr __non_propagating_cache&
1136 operator=(__non_propagating_cache&& __other) noexcept
1144 operator*() noexcept
1145 { return this->_M_get(); }
1147 constexpr const _Tp&
1148 operator*() const noexcept
1149 { return this->_M_get(); }
1151 template<typename _Iter>
1153 _M_emplace_deref(const _Iter& __i)
1156 // Using _Optional_base::_M_construct to initialize from '*__i'
1157 // would incur an extra move due to the indirection, so we instead
1158 // use placement new directly.
1159 ::new ((void *) std::__addressof(this->_M_payload._M_payload)) _Tp(*__i);
1160 this->_M_payload._M_engaged = true;
1161 return this->_M_get();
1165 template<range _Range>
1166 struct _CachedPosition
1169 _M_has_value() const
1172 constexpr iterator_t<_Range>
1173 _M_get(const _Range&) const
1175 __glibcxx_assert(false);
1180 _M_set(const _Range&, const iterator_t<_Range>&) const
1184 template<forward_range _Range>
1185 struct _CachedPosition<_Range>
1186 : protected __non_propagating_cache<iterator_t<_Range>>
1189 _M_has_value() const
1190 { return this->_M_is_engaged(); }
1192 constexpr iterator_t<_Range>
1193 _M_get(const _Range&) const
1195 __glibcxx_assert(_M_has_value());
1200 _M_set(const _Range&, const iterator_t<_Range>& __it)
1202 __glibcxx_assert(!_M_has_value());
1203 std::construct_at(std::__addressof(this->_M_payload._M_payload),
1205 this->_M_payload._M_engaged = true;
1209 template<random_access_range _Range>
1210 requires (sizeof(range_difference_t<_Range>)
1211 <= sizeof(iterator_t<_Range>))
1212 struct _CachedPosition<_Range>
1215 range_difference_t<_Range> _M_offset = -1;
1218 _CachedPosition() = default;
1221 _CachedPosition(const _CachedPosition&) = default;
1224 _CachedPosition(_CachedPosition&& __other) noexcept
1225 { *this = std::move(__other); }
1227 constexpr _CachedPosition&
1228 operator=(const _CachedPosition&) = default;
1230 constexpr _CachedPosition&
1231 operator=(_CachedPosition&& __other) noexcept
1233 // Propagate the cached offset, but invalidate the source.
1234 _M_offset = __other._M_offset;
1235 __other._M_offset = -1;
1240 _M_has_value() const
1241 { return _M_offset >= 0; }
1243 constexpr iterator_t<_Range>
1244 _M_get(_Range& __r) const
1246 __glibcxx_assert(_M_has_value());
1247 return ranges::begin(__r) + _M_offset;
1251 _M_set(_Range& __r, const iterator_t<_Range>& __it)
1253 __glibcxx_assert(!_M_has_value());
1254 _M_offset = __it - ranges::begin(__r);
1257 } // namespace __detail
1261 template<typename _Base>
1262 struct __filter_view_iter_cat
1265 template<forward_range _Base>
1266 struct __filter_view_iter_cat<_Base>
1272 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1273 if constexpr (derived_from<_Cat, bidirectional_iterator_tag>)
1274 return bidirectional_iterator_tag{};
1275 else if constexpr (derived_from<_Cat, forward_iterator_tag>)
1276 return forward_iterator_tag{};
1281 using iterator_category = decltype(_S_iter_cat());
1283 } // namespace __detail
1285 template<input_range _Vp,
1286 indirect_unary_predicate<iterator_t<_Vp>> _Pred>
1287 requires view<_Vp> && is_object_v<_Pred>
1288 class filter_view : public view_interface<filter_view<_Vp, _Pred>>
1293 struct _Iterator : __detail::__filter_view_iter_cat<_Vp>
1296 static constexpr auto
1299 if constexpr (bidirectional_range<_Vp>)
1300 return bidirectional_iterator_tag{};
1301 else if constexpr (forward_range<_Vp>)
1302 return forward_iterator_tag{};
1304 return input_iterator_tag{};
1309 using _Vp_iter = iterator_t<_Vp>;
1311 _Vp_iter _M_current = _Vp_iter();
1312 filter_view* _M_parent = nullptr;
1315 using iterator_concept = decltype(_S_iter_concept());
1316 // iterator_category defined in __filter_view_iter_cat
1317 using value_type = range_value_t<_Vp>;
1318 using difference_type = range_difference_t<_Vp>;
1320 _Iterator() = default;
1323 _Iterator(filter_view* __parent, _Vp_iter __current)
1324 : _M_current(std::move(__current)),
1328 constexpr const _Vp_iter&
1329 base() const & noexcept
1330 { return _M_current; }
1334 { return std::move(_M_current); }
1336 constexpr range_reference_t<_Vp>
1338 { return *_M_current; }
1342 requires __detail::__has_arrow<_Vp_iter>
1343 && copyable<_Vp_iter>
1344 { return _M_current; }
1346 constexpr _Iterator&
1349 _M_current = ranges::find_if(std::move(++_M_current),
1350 ranges::end(_M_parent->_M_base),
1351 std::ref(*_M_parent->_M_pred));
1360 operator++(int) requires forward_range<_Vp>
1367 constexpr _Iterator&
1368 operator--() requires bidirectional_range<_Vp>
1372 while (!std::__invoke(*_M_parent->_M_pred, *_M_current));
1377 operator--(int) requires bidirectional_range<_Vp>
1384 friend constexpr bool
1385 operator==(const _Iterator& __x, const _Iterator& __y)
1386 requires equality_comparable<_Vp_iter>
1387 { return __x._M_current == __y._M_current; }
1389 friend constexpr range_rvalue_reference_t<_Vp>
1390 iter_move(const _Iterator& __i)
1391 noexcept(noexcept(ranges::iter_move(__i._M_current)))
1392 { return ranges::iter_move(__i._M_current); }
1394 friend constexpr void
1395 iter_swap(const _Iterator& __x, const _Iterator& __y)
1396 noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
1397 requires indirectly_swappable<_Vp_iter>
1398 { ranges::iter_swap(__x._M_current, __y._M_current); }
1404 sentinel_t<_Vp> _M_end = sentinel_t<_Vp>();
1407 __equal(const _Iterator& __i) const
1408 { return __i._M_current == _M_end; }
1411 _Sentinel() = default;
1414 _Sentinel(filter_view* __parent)
1415 : _M_end(ranges::end(__parent->_M_base))
1418 constexpr sentinel_t<_Vp>
1422 friend constexpr bool
1423 operator==(const _Iterator& __x, const _Sentinel& __y)
1424 { return __y.__equal(__x); }
1427 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
1428 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
1429 _Vp _M_base = _Vp();
1432 filter_view() = default;
1435 filter_view(_Vp __base, _Pred __pred)
1436 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
1440 base() const& requires copy_constructible<_Vp>
1445 { return std::move(_M_base); }
1447 constexpr const _Pred&
1449 { return *_M_pred; }
1454 if (_M_cached_begin._M_has_value())
1455 return {this, _M_cached_begin._M_get(_M_base)};
1457 __glibcxx_assert(_M_pred.has_value());
1458 auto __it = ranges::find_if(ranges::begin(_M_base),
1459 ranges::end(_M_base),
1460 std::ref(*_M_pred));
1461 _M_cached_begin._M_set(_M_base, __it);
1462 return {this, std::move(__it)};
1468 if constexpr (common_range<_Vp>)
1469 return _Iterator{this, ranges::end(_M_base)};
1471 return _Sentinel{this};
1475 template<typename _Range, typename _Pred>
1476 filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
1482 template<typename _Range, typename _Pred>
1483 concept __can_filter_view
1484 = requires { filter_view(std::declval<_Range>(), std::declval<_Pred>()); };
1485 } // namespace __detail
1487 struct _Filter : __adaptor::_RangeAdaptor<_Filter>
1489 template<viewable_range _Range, typename _Pred>
1490 requires __detail::__can_filter_view<_Range, _Pred>
1492 operator()(_Range&& __r, _Pred&& __p) const
1494 return filter_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
1497 using _RangeAdaptor<_Filter>::operator();
1498 static constexpr int _S_arity = 2;
1499 static constexpr bool _S_has_simple_extra_args = true;
1502 inline constexpr _Filter filter;
1503 } // namespace views
1505 template<input_range _Vp, copy_constructible _Fp>
1506 requires view<_Vp> && is_object_v<_Fp>
1507 && regular_invocable<_Fp&, range_reference_t<_Vp>>
1508 && std::__detail::__can_reference<invoke_result_t<_Fp&,
1509 range_reference_t<_Vp>>>
1510 class transform_view : public view_interface<transform_view<_Vp, _Fp>>
1513 template<bool _Const>
1514 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1516 template<bool _Const>
1520 template<bool _Const>
1521 requires forward_range<_Base<_Const>>
1522 struct __iter_cat<_Const>
1528 using _Base = transform_view::_Base<_Const>;
1529 using _Res = invoke_result_t<_Fp&, range_reference_t<_Base>>;
1530 if constexpr (is_lvalue_reference_v<_Res>)
1533 = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1534 if constexpr (derived_from<_Cat, contiguous_iterator_tag>)
1535 return random_access_iterator_tag{};
1540 return input_iterator_tag{};
1543 using iterator_category = decltype(_S_iter_cat());
1546 template<bool _Const>
1549 template<bool _Const>
1550 struct _Iterator : __iter_cat<_Const>
1553 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1554 using _Base = transform_view::_Base<_Const>;
1559 if constexpr (random_access_range<_Base>)
1560 return random_access_iterator_tag{};
1561 else if constexpr (bidirectional_range<_Base>)
1562 return bidirectional_iterator_tag{};
1563 else if constexpr (forward_range<_Base>)
1564 return forward_iterator_tag{};
1566 return input_iterator_tag{};
1569 using _Base_iter = iterator_t<_Base>;
1571 _Base_iter _M_current = _Base_iter();
1572 _Parent* _M_parent = nullptr;
1575 using iterator_concept = decltype(_S_iter_concept());
1576 // iterator_category defined in __transform_view_iter_cat
1578 = remove_cvref_t<invoke_result_t<_Fp&, range_reference_t<_Base>>>;
1579 using difference_type = range_difference_t<_Base>;
1581 _Iterator() = default;
1584 _Iterator(_Parent* __parent, _Base_iter __current)
1585 : _M_current(std::move(__current)),
1590 _Iterator(_Iterator<!_Const> __i)
1592 && convertible_to<iterator_t<_Vp>, _Base_iter>
1593 : _M_current(std::move(__i._M_current)), _M_parent(__i._M_parent)
1596 constexpr const _Base_iter&
1597 base() const & noexcept
1598 { return _M_current; }
1600 constexpr _Base_iter
1602 { return std::move(_M_current); }
1604 constexpr decltype(auto)
1606 noexcept(noexcept(std::__invoke(*_M_parent->_M_fun, *_M_current)))
1607 { return std::__invoke(*_M_parent->_M_fun, *_M_current); }
1609 constexpr _Iterator&
1621 operator++(int) requires forward_range<_Base>
1628 constexpr _Iterator&
1629 operator--() requires bidirectional_range<_Base>
1636 operator--(int) requires bidirectional_range<_Base>
1643 constexpr _Iterator&
1644 operator+=(difference_type __n) requires random_access_range<_Base>
1650 constexpr _Iterator&
1651 operator-=(difference_type __n) requires random_access_range<_Base>
1657 constexpr decltype(auto)
1658 operator[](difference_type __n) const
1659 requires random_access_range<_Base>
1660 { return std::__invoke(*_M_parent->_M_fun, _M_current[__n]); }
1662 friend constexpr bool
1663 operator==(const _Iterator& __x, const _Iterator& __y)
1664 requires equality_comparable<_Base_iter>
1665 { return __x._M_current == __y._M_current; }
1667 friend constexpr bool
1668 operator<(const _Iterator& __x, const _Iterator& __y)
1669 requires random_access_range<_Base>
1670 { return __x._M_current < __y._M_current; }
1672 friend constexpr bool
1673 operator>(const _Iterator& __x, const _Iterator& __y)
1674 requires random_access_range<_Base>
1675 { return __y < __x; }
1677 friend constexpr bool
1678 operator<=(const _Iterator& __x, const _Iterator& __y)
1679 requires random_access_range<_Base>
1680 { return !(__y < __x); }
1682 friend constexpr bool
1683 operator>=(const _Iterator& __x, const _Iterator& __y)
1684 requires random_access_range<_Base>
1685 { return !(__x < __y); }
1687 #ifdef __cpp_lib_three_way_comparison
1688 friend constexpr auto
1689 operator<=>(const _Iterator& __x, const _Iterator& __y)
1690 requires random_access_range<_Base>
1691 && three_way_comparable<_Base_iter>
1692 { return __x._M_current <=> __y._M_current; }
1695 friend constexpr _Iterator
1696 operator+(_Iterator __i, difference_type __n)
1697 requires random_access_range<_Base>
1698 { return {__i._M_parent, __i._M_current + __n}; }
1700 friend constexpr _Iterator
1701 operator+(difference_type __n, _Iterator __i)
1702 requires random_access_range<_Base>
1703 { return {__i._M_parent, __i._M_current + __n}; }
1705 friend constexpr _Iterator
1706 operator-(_Iterator __i, difference_type __n)
1707 requires random_access_range<_Base>
1708 { return {__i._M_parent, __i._M_current - __n}; }
1710 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1711 // 3483. transform_view::iterator's difference is overconstrained
1712 friend constexpr difference_type
1713 operator-(const _Iterator& __x, const _Iterator& __y)
1714 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
1715 { return __x._M_current - __y._M_current; }
1717 friend constexpr decltype(auto)
1718 iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
1720 if constexpr (is_lvalue_reference_v<decltype(*__i)>)
1721 return std::move(*__i);
1726 friend _Iterator<!_Const>;
1727 template<bool> friend struct _Sentinel;
1730 template<bool _Const>
1734 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1735 using _Base = transform_view::_Base<_Const>;
1737 template<bool _Const2>
1739 __distance_from(const _Iterator<_Const2>& __i) const
1740 { return _M_end - __i._M_current; }
1742 template<bool _Const2>
1744 __equal(const _Iterator<_Const2>& __i) const
1745 { return __i._M_current == _M_end; }
1747 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1750 _Sentinel() = default;
1753 _Sentinel(sentinel_t<_Base> __end)
1758 _Sentinel(_Sentinel<!_Const> __i)
1760 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1761 : _M_end(std::move(__i._M_end))
1764 constexpr sentinel_t<_Base>
1768 template<bool _Const2>
1769 requires sentinel_for<sentinel_t<_Base>,
1770 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
1771 friend constexpr bool
1772 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1773 { return __y.__equal(__x); }
1775 template<bool _Const2,
1776 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1777 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1778 friend constexpr range_difference_t<_Base2>
1779 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1780 { return -__y.__distance_from(__x); }
1782 template<bool _Const2,
1783 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1784 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1785 friend constexpr range_difference_t<_Base2>
1786 operator-(const _Sentinel& __y, const _Iterator<_Const2>& __x)
1787 { return __y.__distance_from(__x); }
1789 friend _Sentinel<!_Const>;
1792 [[no_unique_address]] __detail::__box<_Fp> _M_fun;
1793 _Vp _M_base = _Vp();
1796 transform_view() = default;
1799 transform_view(_Vp __base, _Fp __fun)
1800 : _M_fun(std::move(__fun)), _M_base(std::move(__base))
1804 base() const& requires copy_constructible<_Vp>
1805 { return _M_base ; }
1809 { return std::move(_M_base); }
1811 constexpr _Iterator<false>
1813 { return _Iterator<false>{this, ranges::begin(_M_base)}; }
1815 constexpr _Iterator<true>
1817 requires range<const _Vp>
1818 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1819 { return _Iterator<true>{this, ranges::begin(_M_base)}; }
1821 constexpr _Sentinel<false>
1823 { return _Sentinel<false>{ranges::end(_M_base)}; }
1825 constexpr _Iterator<false>
1826 end() requires common_range<_Vp>
1827 { return _Iterator<false>{this, ranges::end(_M_base)}; }
1829 constexpr _Sentinel<true>
1831 requires range<const _Vp>
1832 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1833 { return _Sentinel<true>{ranges::end(_M_base)}; }
1835 constexpr _Iterator<true>
1837 requires common_range<const _Vp>
1838 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1839 { return _Iterator<true>{this, ranges::end(_M_base)}; }
1842 size() requires sized_range<_Vp>
1843 { return ranges::size(_M_base); }
1846 size() const requires sized_range<const _Vp>
1847 { return ranges::size(_M_base); }
1850 template<typename _Range, typename _Fp>
1851 transform_view(_Range&&, _Fp) -> transform_view<views::all_t<_Range>, _Fp>;
1857 template<typename _Range, typename _Fp>
1858 concept __can_transform_view
1859 = requires { transform_view(std::declval<_Range>(), std::declval<_Fp>()); };
1860 } // namespace __detail
1862 struct _Transform : __adaptor::_RangeAdaptor<_Transform>
1864 template<viewable_range _Range, typename _Fp>
1865 requires __detail::__can_transform_view<_Range, _Fp>
1867 operator()(_Range&& __r, _Fp&& __f) const
1869 return transform_view(std::forward<_Range>(__r), std::forward<_Fp>(__f));
1872 using _RangeAdaptor<_Transform>::operator();
1873 static constexpr int _S_arity = 2;
1874 static constexpr bool _S_has_simple_extra_args = true;
1877 inline constexpr _Transform transform;
1878 } // namespace views
1881 class take_view : public view_interface<take_view<_Vp>>
1884 template<bool _Const>
1885 using _CI = counted_iterator<
1886 iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>;
1888 template<bool _Const>
1892 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1893 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1896 _Sentinel() = default;
1899 _Sentinel(sentinel_t<_Base> __end)
1904 _Sentinel(_Sentinel<!_Const> __s)
1905 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1906 : _M_end(std::move(__s._M_end))
1909 constexpr sentinel_t<_Base>
1913 friend constexpr bool
1914 operator==(const _CI<_Const>& __y, const _Sentinel& __x)
1915 { return __y.count() == 0 || __y.base() == __x._M_end; }
1917 template<bool _OtherConst = !_Const,
1918 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
1919 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1920 friend constexpr bool
1921 operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x)
1922 { return __y.count() == 0 || __y.base() == __x._M_end; }
1924 friend _Sentinel<!_Const>;
1927 range_difference_t<_Vp> _M_count = 0;
1928 _Vp _M_base = _Vp();
1931 take_view() = default;
1934 take_view(_Vp base, range_difference_t<_Vp> __count)
1935 : _M_count(std::move(__count)), _M_base(std::move(base))
1939 base() const& requires copy_constructible<_Vp>
1944 { return std::move(_M_base); }
1947 begin() requires (!__detail::__simple_view<_Vp>)
1949 if constexpr (sized_range<_Vp>)
1951 if constexpr (random_access_range<_Vp>)
1952 return ranges::begin(_M_base);
1956 return counted_iterator(ranges::begin(_M_base), __sz);
1960 return counted_iterator(ranges::begin(_M_base), _M_count);
1964 begin() const requires range<const _Vp>
1966 if constexpr (sized_range<const _Vp>)
1968 if constexpr (random_access_range<const _Vp>)
1969 return ranges::begin(_M_base);
1973 return counted_iterator(ranges::begin(_M_base), __sz);
1977 return counted_iterator(ranges::begin(_M_base), _M_count);
1981 end() requires (!__detail::__simple_view<_Vp>)
1983 if constexpr (sized_range<_Vp>)
1985 if constexpr (random_access_range<_Vp>)
1986 return ranges::begin(_M_base) + size();
1988 return default_sentinel;
1991 return _Sentinel<false>{ranges::end(_M_base)};
1995 end() const requires range<const _Vp>
1997 if constexpr (sized_range<const _Vp>)
1999 if constexpr (random_access_range<const _Vp>)
2000 return ranges::begin(_M_base) + size();
2002 return default_sentinel;
2005 return _Sentinel<true>{ranges::end(_M_base)};
2009 size() requires sized_range<_Vp>
2011 auto __n = ranges::size(_M_base);
2012 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2016 size() const requires sized_range<const _Vp>
2018 auto __n = ranges::size(_M_base);
2019 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2023 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2024 // 3447. Deduction guides for take_view and drop_view have different
2026 template<typename _Range>
2027 take_view(_Range&&, range_difference_t<_Range>)
2028 -> take_view<views::all_t<_Range>>;
2030 template<typename _Tp>
2031 inline constexpr bool enable_borrowed_range<take_view<_Tp>>
2032 = enable_borrowed_range<_Tp>;
2038 template<typename _Range, typename _Tp>
2039 concept __can_take_view
2040 = requires { take_view(std::declval<_Range>(), std::declval<_Tp>()); };
2041 } // namespace __detail
2043 struct _Take : __adaptor::_RangeAdaptor<_Take>
2045 template<viewable_range _Range, typename _Tp>
2046 requires __detail::__can_take_view<_Range, _Tp>
2048 operator()(_Range&& __r, _Tp&& __n) const
2050 return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2053 using _RangeAdaptor<_Take>::operator();
2054 static constexpr int _S_arity = 2;
2055 // The count argument of views::take is not always simple -- it can be
2056 // e.g. a move-only class that's implicitly convertible to the difference
2057 // type. But an integer-like count argument is surely simple.
2058 template<typename _Tp>
2059 static constexpr bool _S_has_simple_extra_args
2060 = ranges::__detail::__is_integer_like<_Tp>;
2063 inline constexpr _Take take;
2064 } // namespace views
2066 template<view _Vp, typename _Pred>
2067 requires input_range<_Vp> && is_object_v<_Pred>
2068 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2069 class take_while_view : public view_interface<take_while_view<_Vp, _Pred>>
2071 template<bool _Const>
2075 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2077 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2078 const _Pred* _M_pred = nullptr;
2081 _Sentinel() = default;
2084 _Sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
2085 : _M_end(__end), _M_pred(__pred)
2089 _Sentinel(_Sentinel<!_Const> __s)
2090 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2091 : _M_end(__s._M_end), _M_pred(__s._M_pred)
2094 constexpr sentinel_t<_Base>
2095 base() const { return _M_end; }
2097 friend constexpr bool
2098 operator==(const iterator_t<_Base>& __x, const _Sentinel& __y)
2099 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2101 template<bool _OtherConst = !_Const,
2102 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
2103 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
2104 friend constexpr bool
2105 operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y)
2106 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2108 friend _Sentinel<!_Const>;
2111 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2112 _Vp _M_base = _Vp();
2115 take_while_view() = default;
2118 take_while_view(_Vp base, _Pred __pred)
2119 : _M_pred(std::move(__pred)), _M_base(std::move(base))
2123 base() const& requires copy_constructible<_Vp>
2128 { return std::move(_M_base); }
2130 constexpr const _Pred&
2132 { return *_M_pred; }
2135 begin() requires (!__detail::__simple_view<_Vp>)
2136 { return ranges::begin(_M_base); }
2139 begin() const requires range<const _Vp>
2140 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2141 { return ranges::begin(_M_base); }
2144 end() requires (!__detail::__simple_view<_Vp>)
2145 { return _Sentinel<false>(ranges::end(_M_base),
2146 std::__addressof(*_M_pred)); }
2149 end() const requires range<const _Vp>
2150 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2151 { return _Sentinel<true>(ranges::end(_M_base),
2152 std::__addressof(*_M_pred)); }
2155 template<typename _Range, typename _Pred>
2156 take_while_view(_Range&&, _Pred)
2157 -> take_while_view<views::all_t<_Range>, _Pred>;
2163 template<typename _Range, typename _Pred>
2164 concept __can_take_while_view
2165 = requires { take_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2166 } // namespace __detail
2168 struct _TakeWhile : __adaptor::_RangeAdaptor<_TakeWhile>
2170 template<viewable_range _Range, typename _Pred>
2171 requires __detail::__can_take_while_view<_Range, _Pred>
2173 operator()(_Range&& __r, _Pred&& __p) const
2175 return take_while_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
2178 using _RangeAdaptor<_TakeWhile>::operator();
2179 static constexpr int _S_arity = 2;
2180 static constexpr bool _S_has_simple_extra_args = true;
2183 inline constexpr _TakeWhile take_while;
2184 } // namespace views
2187 class drop_view : public view_interface<drop_view<_Vp>>
2190 range_difference_t<_Vp> _M_count = 0;
2191 _Vp _M_base = _Vp();
2193 // ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
2194 // both random_access_range and sized_range. Otherwise, cache its result.
2195 static constexpr bool _S_needs_cached_begin
2196 = !(random_access_range<const _Vp> && sized_range<const _Vp>);
2197 [[no_unique_address]]
2198 __detail::__maybe_present_t<_S_needs_cached_begin,
2199 __detail::_CachedPosition<_Vp>>
2203 drop_view() = default;
2206 drop_view(_Vp __base, range_difference_t<_Vp> __count)
2207 : _M_count(__count), _M_base(std::move(__base))
2208 { __glibcxx_assert(__count >= 0); }
2211 base() const& requires copy_constructible<_Vp>
2216 { return std::move(_M_base); }
2218 // This overload is disabled for simple views with constant-time begin().
2221 requires (!(__detail::__simple_view<_Vp>
2222 && random_access_range<const _Vp>
2223 && sized_range<const _Vp>))
2225 if constexpr (_S_needs_cached_begin)
2226 if (_M_cached_begin._M_has_value())
2227 return _M_cached_begin._M_get(_M_base);
2229 auto __it = ranges::next(ranges::begin(_M_base),
2230 _M_count, ranges::end(_M_base));
2231 if constexpr (_S_needs_cached_begin)
2232 _M_cached_begin._M_set(_M_base, __it);
2236 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2237 // 3482. drop_view's const begin should additionally require sized_range
2240 requires random_access_range<const _Vp> && sized_range<const _Vp>
2242 return ranges::next(ranges::begin(_M_base), _M_count,
2243 ranges::end(_M_base));
2247 end() requires (!__detail::__simple_view<_Vp>)
2248 { return ranges::end(_M_base); }
2251 end() const requires range<const _Vp>
2252 { return ranges::end(_M_base); }
2255 size() requires sized_range<_Vp>
2257 const auto __s = ranges::size(_M_base);
2258 const auto __c = static_cast<decltype(__s)>(_M_count);
2259 return __s < __c ? 0 : __s - __c;
2263 size() const requires sized_range<const _Vp>
2265 const auto __s = ranges::size(_M_base);
2266 const auto __c = static_cast<decltype(__s)>(_M_count);
2267 return __s < __c ? 0 : __s - __c;
2271 template<typename _Range>
2272 drop_view(_Range&&, range_difference_t<_Range>)
2273 -> drop_view<views::all_t<_Range>>;
2275 template<typename _Tp>
2276 inline constexpr bool enable_borrowed_range<drop_view<_Tp>>
2277 = enable_borrowed_range<_Tp>;
2283 template<typename _Range, typename _Tp>
2284 concept __can_drop_view
2285 = requires { drop_view(std::declval<_Range>(), std::declval<_Tp>()); };
2286 } // namespace __detail
2288 struct _Drop : __adaptor::_RangeAdaptor<_Drop>
2290 template<viewable_range _Range, typename _Tp>
2291 requires __detail::__can_drop_view<_Range, _Tp>
2293 operator()(_Range&& __r, _Tp&& __n) const
2295 return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2298 using _RangeAdaptor<_Drop>::operator();
2299 static constexpr int _S_arity = 2;
2300 template<typename _Tp>
2301 static constexpr bool _S_has_simple_extra_args
2302 = _Take::_S_has_simple_extra_args<_Tp>;
2305 inline constexpr _Drop drop;
2306 } // namespace views
2308 template<view _Vp, typename _Pred>
2309 requires input_range<_Vp> && is_object_v<_Pred>
2310 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2311 class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
2314 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2315 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
2316 _Vp _M_base = _Vp();
2319 drop_while_view() = default;
2322 drop_while_view(_Vp __base, _Pred __pred)
2323 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
2327 base() const& requires copy_constructible<_Vp>
2332 { return std::move(_M_base); }
2334 constexpr const _Pred&
2336 { return *_M_pred; }
2341 if (_M_cached_begin._M_has_value())
2342 return _M_cached_begin._M_get(_M_base);
2344 __glibcxx_assert(_M_pred.has_value());
2345 auto __it = ranges::find_if_not(ranges::begin(_M_base),
2346 ranges::end(_M_base),
2347 std::cref(*_M_pred));
2348 _M_cached_begin._M_set(_M_base, __it);
2354 { return ranges::end(_M_base); }
2357 template<typename _Range, typename _Pred>
2358 drop_while_view(_Range&&, _Pred)
2359 -> drop_while_view<views::all_t<_Range>, _Pred>;
2361 template<typename _Tp, typename _Pred>
2362 inline constexpr bool enable_borrowed_range<drop_while_view<_Tp, _Pred>>
2363 = enable_borrowed_range<_Tp>;
2369 template<typename _Range, typename _Pred>
2370 concept __can_drop_while_view
2371 = requires { drop_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2372 } // namespace __detail
2374 struct _DropWhile : __adaptor::_RangeAdaptor<_DropWhile>
2376 template<viewable_range _Range, typename _Pred>
2377 requires __detail::__can_drop_while_view<_Range, _Pred>
2379 operator()(_Range&& __r, _Pred&& __p) const
2381 return drop_while_view(std::forward<_Range>(__r),
2382 std::forward<_Pred>(__p));
2385 using _RangeAdaptor<_DropWhile>::operator();
2386 static constexpr int _S_arity = 2;
2387 static constexpr bool _S_has_simple_extra_args = true;
2390 inline constexpr _DropWhile drop_while;
2391 } // namespace views
2393 template<input_range _Vp>
2394 requires view<_Vp> && input_range<range_reference_t<_Vp>>
2395 class join_view : public view_interface<join_view<_Vp>>
2398 using _InnerRange = range_reference_t<_Vp>;
2400 template<bool _Const>
2401 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2403 template<bool _Const>
2404 using _Outer_iter = iterator_t<_Base<_Const>>;
2406 template<bool _Const>
2407 using _Inner_iter = iterator_t<range_reference_t<_Base<_Const>>>;
2409 template<bool _Const>
2410 static constexpr bool _S_ref_is_glvalue
2411 = is_reference_v<range_reference_t<_Base<_Const>>>;
2413 template<bool _Const>
2417 template<bool _Const>
2418 requires _S_ref_is_glvalue<_Const>
2419 && forward_range<_Base<_Const>>
2420 && forward_range<range_reference_t<_Base<_Const>>>
2421 struct __iter_cat<_Const>
2424 static constexpr auto
2427 using _Outer_iter = join_view::_Outer_iter<_Const>;
2428 using _Inner_iter = join_view::_Inner_iter<_Const>;
2429 using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
2430 using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
2431 if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
2432 && derived_from<_InnerCat, bidirectional_iterator_tag>)
2433 return bidirectional_iterator_tag{};
2434 else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
2435 && derived_from<_InnerCat, forward_iterator_tag>)
2436 return forward_iterator_tag{};
2438 return input_iterator_tag{};
2441 using iterator_category = decltype(_S_iter_cat());
2444 template<bool _Const>
2447 template<bool _Const>
2448 struct _Iterator : __iter_cat<_Const>
2451 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2452 using _Base = join_view::_Base<_Const>;
2454 static constexpr bool _S_ref_is_glvalue
2455 = join_view::_S_ref_is_glvalue<_Const>;
2460 auto __update_inner = [this] (const iterator_t<_Base>& __x) -> auto&& {
2461 if constexpr (_S_ref_is_glvalue)
2464 return _M_parent->_M_inner._M_emplace_deref(__x);
2467 for (; _M_outer != ranges::end(_M_parent->_M_base); ++_M_outer)
2469 auto&& __inner = __update_inner(_M_outer);
2470 _M_inner = ranges::begin(__inner);
2471 if (_M_inner != ranges::end(__inner))
2475 if constexpr (_S_ref_is_glvalue)
2476 _M_inner = _Inner_iter();
2479 static constexpr auto
2482 if constexpr (_S_ref_is_glvalue
2483 && bidirectional_range<_Base>
2484 && bidirectional_range<range_reference_t<_Base>>)
2485 return bidirectional_iterator_tag{};
2486 else if constexpr (_S_ref_is_glvalue
2487 && forward_range<_Base>
2488 && forward_range<range_reference_t<_Base>>)
2489 return forward_iterator_tag{};
2491 return input_iterator_tag{};
2494 using _Outer_iter = join_view::_Outer_iter<_Const>;
2495 using _Inner_iter = join_view::_Inner_iter<_Const>;
2497 _Outer_iter _M_outer = _Outer_iter();
2498 _Inner_iter _M_inner = _Inner_iter();
2499 _Parent* _M_parent = nullptr;
2502 using iterator_concept = decltype(_S_iter_concept());
2503 // iterator_category defined in __join_view_iter_cat
2504 using value_type = range_value_t<range_reference_t<_Base>>;
2505 using difference_type
2506 = common_type_t<range_difference_t<_Base>,
2507 range_difference_t<range_reference_t<_Base>>>;
2509 _Iterator() = default;
2512 _Iterator(_Parent* __parent, _Outer_iter __outer)
2513 : _M_outer(std::move(__outer)),
2518 _Iterator(_Iterator<!_Const> __i)
2520 && convertible_to<iterator_t<_Vp>, _Outer_iter>
2521 && convertible_to<iterator_t<_InnerRange>, _Inner_iter>
2522 : _M_outer(std::move(__i._M_outer)), _M_inner(std::move(__i._M_inner)),
2523 _M_parent(__i._M_parent)
2526 constexpr decltype(auto)
2528 { return *_M_inner; }
2530 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2531 // 3500. join_view::iterator::operator->() is bogus
2532 constexpr _Inner_iter
2534 requires __detail::__has_arrow<_Inner_iter>
2535 && copyable<_Inner_iter>
2536 { return _M_inner; }
2538 constexpr _Iterator&
2541 auto&& __inner_range = [this] () -> auto&& {
2542 if constexpr (_S_ref_is_glvalue)
2545 return *_M_parent->_M_inner;
2547 if (++_M_inner == ranges::end(__inner_range))
2561 requires _S_ref_is_glvalue && forward_range<_Base>
2562 && forward_range<range_reference_t<_Base>>
2569 constexpr _Iterator&
2571 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2572 && bidirectional_range<range_reference_t<_Base>>
2573 && common_range<range_reference_t<_Base>>
2575 if (_M_outer == ranges::end(_M_parent->_M_base))
2576 _M_inner = ranges::end(*--_M_outer);
2577 while (_M_inner == ranges::begin(*_M_outer))
2578 _M_inner = ranges::end(*--_M_outer);
2585 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2586 && bidirectional_range<range_reference_t<_Base>>
2587 && common_range<range_reference_t<_Base>>
2594 friend constexpr bool
2595 operator==(const _Iterator& __x, const _Iterator& __y)
2596 requires _S_ref_is_glvalue
2597 && equality_comparable<_Outer_iter>
2598 && equality_comparable<_Inner_iter>
2600 return (__x._M_outer == __y._M_outer
2601 && __x._M_inner == __y._M_inner);
2604 friend constexpr decltype(auto)
2605 iter_move(const _Iterator& __i)
2606 noexcept(noexcept(ranges::iter_move(__i._M_inner)))
2607 { return ranges::iter_move(__i._M_inner); }
2609 friend constexpr void
2610 iter_swap(const _Iterator& __x, const _Iterator& __y)
2611 noexcept(noexcept(ranges::iter_swap(__x._M_inner, __y._M_inner)))
2612 requires indirectly_swappable<_Inner_iter>
2613 { return ranges::iter_swap(__x._M_inner, __y._M_inner); }
2615 friend _Iterator<!_Const>;
2616 template<bool> friend struct _Sentinel;
2619 template<bool _Const>
2623 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2624 using _Base = join_view::_Base<_Const>;
2626 template<bool _Const2>
2628 __equal(const _Iterator<_Const2>& __i) const
2629 { return __i._M_outer == _M_end; }
2631 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2634 _Sentinel() = default;
2637 _Sentinel(_Parent* __parent)
2638 : _M_end(ranges::end(__parent->_M_base))
2642 _Sentinel(_Sentinel<!_Const> __s)
2643 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2644 : _M_end(std::move(__s._M_end))
2647 template<bool _Const2>
2648 requires sentinel_for<sentinel_t<_Base>,
2649 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
2650 friend constexpr bool
2651 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
2652 { return __y.__equal(__x); }
2654 friend _Sentinel<!_Const>;
2657 [[no_unique_address]]
2658 __detail::__non_propagating_cache<remove_cv_t<_InnerRange>> _M_inner;
2659 _Vp _M_base = _Vp();
2662 join_view() = default;
2665 join_view(_Vp __base)
2666 : _M_base(std::move(__base))
2670 base() const& requires copy_constructible<_Vp>
2675 { return std::move(_M_base); }
2680 constexpr bool __use_const
2681 = (__detail::__simple_view<_Vp>
2682 && is_reference_v<range_reference_t<_Vp>>);
2683 return _Iterator<__use_const>{this, ranges::begin(_M_base)};
2688 requires input_range<const _Vp>
2689 && is_reference_v<range_reference_t<const _Vp>>
2691 return _Iterator<true>{this, ranges::begin(_M_base)};
2697 if constexpr (forward_range<_Vp> && is_reference_v<_InnerRange>
2698 && forward_range<_InnerRange>
2699 && common_range<_Vp> && common_range<_InnerRange>)
2700 return _Iterator<__detail::__simple_view<_Vp>>{this,
2701 ranges::end(_M_base)};
2703 return _Sentinel<__detail::__simple_view<_Vp>>{this};
2708 requires input_range<const _Vp>
2709 && is_reference_v<range_reference_t<const _Vp>>
2711 if constexpr (forward_range<const _Vp>
2712 && is_reference_v<range_reference_t<const _Vp>>
2713 && forward_range<range_reference_t<const _Vp>>
2714 && common_range<const _Vp>
2715 && common_range<range_reference_t<const _Vp>>)
2716 return _Iterator<true>{this, ranges::end(_M_base)};
2718 return _Sentinel<true>{this};
2722 template<typename _Range>
2723 explicit join_view(_Range&&) -> join_view<views::all_t<_Range>>;
2729 template<typename _Range>
2730 concept __can_join_view
2731 = requires { join_view<all_t<_Range>>{std::declval<_Range>()}; };
2732 } // namespace __detail
2734 struct _Join : __adaptor::_RangeAdaptorClosure
2736 template<viewable_range _Range>
2737 requires __detail::__can_join_view<_Range>
2739 operator()(_Range&& __r) const
2741 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2742 // 3474. Nesting join_views is broken because of CTAD
2743 return join_view<all_t<_Range>>{std::forward<_Range>(__r)};
2746 static constexpr bool _S_has_simple_call_op = true;
2749 inline constexpr _Join join;
2750 } // namespace views
2755 struct __require_constant;
2757 template<typename _Range>
2758 concept __tiny_range = sized_range<_Range>
2760 { typename __require_constant<remove_reference_t<_Range>::size()>; }
2761 && (remove_reference_t<_Range>::size() <= 1);
2763 template<typename _Base>
2764 struct __split_view_outer_iter_cat
2767 template<forward_range _Base>
2768 struct __split_view_outer_iter_cat<_Base>
2769 { using iterator_category = input_iterator_tag; };
2771 template<typename _Base>
2772 struct __split_view_inner_iter_cat
2775 template<forward_range _Base>
2776 struct __split_view_inner_iter_cat<_Base>
2779 static constexpr auto
2782 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
2783 if constexpr (derived_from<_Cat, forward_iterator_tag>)
2784 return forward_iterator_tag{};
2789 using iterator_category = decltype(_S_iter_cat());
2793 template<input_range _Vp, forward_range _Pattern>
2794 requires view<_Vp> && view<_Pattern>
2795 && indirectly_comparable<iterator_t<_Vp>, iterator_t<_Pattern>,
2797 && (forward_range<_Vp> || __detail::__tiny_range<_Pattern>)
2798 class split_view : public view_interface<split_view<_Vp, _Pattern>>
2801 template<bool _Const>
2802 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2804 template<bool _Const>
2807 template<bool _Const>
2809 : __detail::__split_view_outer_iter_cat<_Base<_Const>>
2812 using _Parent = __detail::__maybe_const_t<_Const, split_view>;
2813 using _Base = split_view::_Base<_Const>;
2817 { return __current() == ranges::end(_M_parent->_M_base); }
2819 // [range.split.outer] p1
2820 // Many of the following specifications refer to the notional member
2821 // current of outer-iterator. current is equivalent to current_ if
2822 // V models forward_range, and parent_->current_ otherwise.
2824 __current() noexcept
2826 if constexpr (forward_range<_Vp>)
2829 return _M_parent->_M_current;
2833 __current() const noexcept
2835 if constexpr (forward_range<_Vp>)
2838 return _M_parent->_M_current;
2841 _Parent* _M_parent = nullptr;
2843 // XXX: _M_current is present only if "V models forward_range"
2844 [[no_unique_address]]
2845 __detail::__maybe_present_t<forward_range<_Vp>,
2846 iterator_t<_Base>> _M_current;
2849 using iterator_concept = conditional_t<forward_range<_Base>,
2850 forward_iterator_tag,
2851 input_iterator_tag>;
2852 // iterator_category defined in __split_view_outer_iter_cat
2853 using difference_type = range_difference_t<_Base>;
2855 struct value_type : view_interface<value_type>
2858 _OuterIter _M_i = _OuterIter();
2861 value_type() = default;
2864 value_type(_OuterIter __i)
2865 : _M_i(std::move(__i))
2868 constexpr _InnerIter<_Const>
2870 { return _InnerIter<_Const>{_M_i}; }
2872 constexpr default_sentinel_t
2874 { return default_sentinel; }
2877 _OuterIter() = default;
2880 _OuterIter(_Parent* __parent) requires (!forward_range<_Base>)
2881 : _M_parent(__parent)
2885 _OuterIter(_Parent* __parent, iterator_t<_Base> __current)
2886 requires forward_range<_Base>
2887 : _M_parent(__parent),
2888 _M_current(std::move(__current))
2892 _OuterIter(_OuterIter<!_Const> __i)
2894 && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
2895 : _M_parent(__i._M_parent), _M_current(std::move(__i._M_current))
2898 constexpr value_type
2900 { return value_type{*this}; }
2902 constexpr _OuterIter&
2905 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2906 // 3505. split_view::outer-iterator::operator++ misspecified
2907 const auto __end = ranges::end(_M_parent->_M_base);
2908 if (__current() == __end)
2910 const auto [__pbegin, __pend] = subrange{_M_parent->_M_pattern};
2911 if (__pbegin == __pend)
2913 else if constexpr (__detail::__tiny_range<_Pattern>)
2915 __current() = ranges::find(std::move(__current()), __end,
2917 if (__current() != __end)
2924 = ranges::mismatch(__current(), __end, __pbegin, __pend);
2930 } while (++__current() != __end);
2934 constexpr decltype(auto)
2937 if constexpr (forward_range<_Base>)
2947 friend constexpr bool
2948 operator==(const _OuterIter& __x, const _OuterIter& __y)
2949 requires forward_range<_Base>
2950 { return __x._M_current == __y._M_current; }
2952 friend constexpr bool
2953 operator==(const _OuterIter& __x, default_sentinel_t)
2954 { return __x.__at_end(); };
2956 friend _OuterIter<!_Const>;
2957 friend _InnerIter<_Const>;
2960 template<bool _Const>
2962 : __detail::__split_view_inner_iter_cat<_Base<_Const>>
2965 using _Base = split_view::_Base<_Const>;
2970 auto [__pcur, __pend] = subrange{_M_i._M_parent->_M_pattern};
2971 auto __end = ranges::end(_M_i._M_parent->_M_base);
2972 if constexpr (__detail::__tiny_range<_Pattern>)
2974 const auto& __cur = _M_i_current();
2977 if (__pcur == __pend)
2978 return _M_incremented;
2979 return *__cur == *__pcur;
2983 auto __cur = _M_i_current();
2986 if (__pcur == __pend)
2987 return _M_incremented;
2990 if (*__cur != *__pcur)
2992 if (++__pcur == __pend)
2994 } while (++__cur != __end);
3000 _M_i_current() noexcept
3001 { return _M_i.__current(); }
3004 _M_i_current() const noexcept
3005 { return _M_i.__current(); }
3007 _OuterIter<_Const> _M_i = _OuterIter<_Const>();
3008 bool _M_incremented = false;
3011 using iterator_concept
3012 = typename _OuterIter<_Const>::iterator_concept;
3013 // iterator_category defined in __split_view_inner_iter_cat
3014 using value_type = range_value_t<_Base>;
3015 using difference_type = range_difference_t<_Base>;
3017 _InnerIter() = default;
3020 _InnerIter(_OuterIter<_Const> __i)
3021 : _M_i(std::move(__i))
3024 constexpr const iterator_t<_Base>&
3025 base() const& noexcept
3026 { return _M_i_current(); }
3028 constexpr iterator_t<_Base>
3030 { return std::move(_M_i_current()); }
3032 constexpr decltype(auto)
3034 { return *_M_i_current(); }
3036 constexpr _InnerIter&
3039 _M_incremented = true;
3040 if constexpr (!forward_range<_Base>)
3041 if constexpr (_Pattern::size() == 0)
3047 constexpr decltype(auto)
3050 if constexpr (forward_range<_Base>)
3060 friend constexpr bool
3061 operator==(const _InnerIter& __x, const _InnerIter& __y)
3062 requires forward_range<_Base>
3063 { return __x._M_i == __y._M_i; }
3065 friend constexpr bool
3066 operator==(const _InnerIter& __x, default_sentinel_t)
3067 { return __x.__at_end(); }
3069 friend constexpr decltype(auto)
3070 iter_move(const _InnerIter& __i)
3071 noexcept(noexcept(ranges::iter_move(__i._M_i_current())))
3072 { return ranges::iter_move(__i._M_i_current()); }
3074 friend constexpr void
3075 iter_swap(const _InnerIter& __x, const _InnerIter& __y)
3076 noexcept(noexcept(ranges::iter_swap(__x._M_i_current(),
3077 __y._M_i_current())))
3078 requires indirectly_swappable<iterator_t<_Base>>
3079 { ranges::iter_swap(__x._M_i_current(), __y._M_i_current()); }
3082 _Pattern _M_pattern = _Pattern();
3083 // XXX: _M_current is "present only if !forward_range<V>"
3084 [[no_unique_address]]
3085 __detail::__maybe_present_t<!forward_range<_Vp>,
3086 iterator_t<_Vp>> _M_current;
3087 _Vp _M_base = _Vp();
3091 split_view() = default;
3094 split_view(_Vp __base, _Pattern __pattern)
3095 : _M_pattern(std::move(__pattern)), _M_base(std::move(__base))
3098 template<input_range _Range>
3099 requires constructible_from<_Vp, views::all_t<_Range>>
3100 && constructible_from<_Pattern, single_view<range_value_t<_Range>>>
3102 split_view(_Range&& __r, range_value_t<_Range> __e)
3103 : _M_pattern(views::single(std::move(__e))),
3104 _M_base(views::all(std::forward<_Range>(__r)))
3108 base() const& requires copy_constructible<_Vp>
3113 { return std::move(_M_base); }
3118 if constexpr (forward_range<_Vp>)
3119 return _OuterIter<__detail::__simple_view<_Vp>>{
3120 this, ranges::begin(_M_base)};
3123 _M_current = ranges::begin(_M_base);
3124 return _OuterIter<false>{this};
3129 begin() const requires forward_range<_Vp> && forward_range<const _Vp>
3131 return _OuterIter<true>{this, ranges::begin(_M_base)};
3135 end() requires forward_range<_Vp> && common_range<_Vp>
3137 return _OuterIter<__detail::__simple_view<_Vp>>{
3138 this, ranges::end(_M_base)};
3144 if constexpr (forward_range<_Vp>
3145 && forward_range<const _Vp>
3146 && common_range<const _Vp>)
3147 return _OuterIter<true>{this, ranges::end(_M_base)};
3149 return default_sentinel;
3153 template<typename _Range, typename _Pattern>
3154 split_view(_Range&&, _Pattern&&)
3155 -> split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
3157 template<input_range _Range>
3158 split_view(_Range&&, range_value_t<_Range>)
3159 -> split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
3165 template<typename _Range, typename _Pattern>
3166 concept __can_split_view
3167 = requires { split_view(std::declval<_Range>(), std::declval<_Pattern>()); };
3168 } // namespace __detail
3170 struct _Split : __adaptor::_RangeAdaptor<_Split>
3172 template<viewable_range _Range, typename _Pattern>
3173 requires __detail::__can_split_view<_Range, _Pattern>
3175 operator()(_Range&& __r, _Pattern&& __f) const
3177 return split_view(std::forward<_Range>(__r), std::forward<_Pattern>(__f));
3180 using _RangeAdaptor<_Split>::operator();
3181 static constexpr int _S_arity = 2;
3182 // The pattern argument of views::split is not always simple -- it can be
3183 // a non-view range, the value category of which affects whether the call
3184 // is well-formed. But a scalar or a view pattern argument is surely
3186 template<typename _Pattern>
3187 static constexpr bool _S_has_simple_extra_args
3188 = is_scalar_v<_Pattern> || (view<_Pattern>
3189 && copy_constructible<_Pattern>);
3192 inline constexpr _Split split;
3193 } // namespace views
3199 template<input_or_output_iterator _Iter>
3201 operator()(_Iter __i, iter_difference_t<_Iter> __n) const
3203 if constexpr (random_access_iterator<_Iter>)
3204 return subrange(__i, __i + __n);
3206 return subrange(counted_iterator(std::move(__i), __n),
3211 inline constexpr _Counted counted{};
3212 } // namespace views
3215 requires (!common_range<_Vp>) && copyable<iterator_t<_Vp>>
3216 class common_view : public view_interface<common_view<_Vp>>
3219 _Vp _M_base = _Vp();
3222 common_view() = default;
3225 common_view(_Vp __r)
3226 : _M_base(std::move(__r))
3229 /* XXX: LWG 3280 didn't remove this constructor, but I think it should?
3230 template<viewable_range _Range>
3231 requires (!common_range<_Range>)
3232 && constructible_from<_Vp, views::all_t<_Range>>
3234 common_view(_Range&& __r)
3235 : _M_base(views::all(std::forward<_Range>(__r)))
3240 base() const& requires copy_constructible<_Vp>
3245 { return std::move(_M_base); }
3250 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3251 return ranges::begin(_M_base);
3253 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3254 (ranges::begin(_M_base));
3258 begin() const requires range<const _Vp>
3260 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3261 return ranges::begin(_M_base);
3263 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3264 (ranges::begin(_M_base));
3270 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3271 return ranges::begin(_M_base) + ranges::size(_M_base);
3273 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3274 (ranges::end(_M_base));
3278 end() const requires range<const _Vp>
3280 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3281 return ranges::begin(_M_base) + ranges::size(_M_base);
3283 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3284 (ranges::end(_M_base));
3288 size() requires sized_range<_Vp>
3289 { return ranges::size(_M_base); }
3292 size() const requires sized_range<const _Vp>
3293 { return ranges::size(_M_base); }
3296 template<typename _Range>
3297 common_view(_Range&&) -> common_view<views::all_t<_Range>>;
3299 template<typename _Tp>
3300 inline constexpr bool enable_borrowed_range<common_view<_Tp>>
3301 = enable_borrowed_range<_Tp>;
3307 template<typename _Range>
3308 concept __already_common = common_range<_Range>
3309 && requires { views::all(std::declval<_Range>()); };
3311 template<typename _Range>
3312 concept __can_common_view
3313 = requires { common_view{std::declval<_Range>()}; };
3314 } // namespace __detail
3316 struct _Common : __adaptor::_RangeAdaptorClosure
3318 template<viewable_range _Range>
3319 requires __detail::__already_common<_Range>
3320 || __detail::__can_common_view<_Range>
3322 operator()(_Range&& __r) const
3324 if constexpr (__detail::__already_common<_Range>)
3325 return views::all(std::forward<_Range>(__r));
3327 return common_view{std::forward<_Range>(__r)};
3330 static constexpr bool _S_has_simple_call_op = true;
3333 inline constexpr _Common common;
3334 } // namespace views
3337 requires bidirectional_range<_Vp>
3338 class reverse_view : public view_interface<reverse_view<_Vp>>
3341 static constexpr bool _S_needs_cached_begin
3342 = !common_range<_Vp> && !random_access_range<_Vp>;
3344 [[no_unique_address]]
3345 __detail::__maybe_present_t<_S_needs_cached_begin,
3346 __detail::_CachedPosition<_Vp>>
3348 _Vp _M_base = _Vp();
3351 reverse_view() = default;
3354 reverse_view(_Vp __r)
3355 : _M_base(std::move(__r))
3359 base() const& requires copy_constructible<_Vp>
3364 { return std::move(_M_base); }
3366 constexpr reverse_iterator<iterator_t<_Vp>>
3369 if constexpr (_S_needs_cached_begin)
3370 if (_M_cached_begin._M_has_value())
3371 return std::make_reverse_iterator(_M_cached_begin._M_get(_M_base));
3373 auto __it = ranges::next(ranges::begin(_M_base), ranges::end(_M_base));
3374 if constexpr (_S_needs_cached_begin)
3375 _M_cached_begin._M_set(_M_base, __it);
3376 return std::make_reverse_iterator(std::move(__it));
3380 begin() requires common_range<_Vp>
3381 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3384 begin() const requires common_range<const _Vp>
3385 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3387 constexpr reverse_iterator<iterator_t<_Vp>>
3389 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3392 end() const requires common_range<const _Vp>
3393 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3396 size() requires sized_range<_Vp>
3397 { return ranges::size(_M_base); }
3400 size() const requires sized_range<const _Vp>
3401 { return ranges::size(_M_base); }
3404 template<typename _Range>
3405 reverse_view(_Range&&) -> reverse_view<views::all_t<_Range>>;
3407 template<typename _Tp>
3408 inline constexpr bool enable_borrowed_range<reverse_view<_Tp>>
3409 = enable_borrowed_range<_Tp>;
3416 inline constexpr bool __is_reversible_subrange = false;
3418 template<typename _Iter, subrange_kind _Kind>
3419 inline constexpr bool
3420 __is_reversible_subrange<subrange<reverse_iterator<_Iter>,
3421 reverse_iterator<_Iter>,
3425 inline constexpr bool __is_reverse_view = false;
3427 template<typename _Vp>
3428 inline constexpr bool __is_reverse_view<reverse_view<_Vp>> = true;
3430 template<typename _Range>
3431 concept __can_reverse_view
3432 = requires { reverse_view{std::declval<_Range>()}; };
3433 } // namespace __detail
3435 struct _Reverse : __adaptor::_RangeAdaptorClosure
3437 template<viewable_range _Range>
3438 requires __detail::__is_reverse_view<remove_cvref_t<_Range>>
3439 || __detail::__is_reversible_subrange<remove_cvref_t<_Range>>
3440 || __detail::__can_reverse_view<_Range>
3442 operator()(_Range&& __r) const
3444 using _Tp = remove_cvref_t<_Range>;
3445 if constexpr (__detail::__is_reverse_view<_Tp>)
3446 return std::forward<_Range>(__r).base();
3447 else if constexpr (__detail::__is_reversible_subrange<_Tp>)
3449 using _Iter = decltype(ranges::begin(__r).base());
3450 if constexpr (sized_range<_Tp>)
3451 return subrange<_Iter, _Iter, subrange_kind::sized>
3452 {__r.end().base(), __r.begin().base(), __r.size()};
3454 return subrange<_Iter, _Iter, subrange_kind::unsized>
3455 {__r.end().base(), __r.begin().base()};
3458 return reverse_view{std::forward<_Range>(__r)};
3461 static constexpr bool _S_has_simple_call_op = true;
3464 inline constexpr _Reverse reverse;
3465 } // namespace views
3469 template<typename _Tp, size_t _Nm>
3470 concept __has_tuple_element = requires(_Tp __t)
3472 typename tuple_size<_Tp>::type;
3473 requires _Nm < tuple_size_v<_Tp>;
3474 typename tuple_element_t<_Nm, _Tp>;
3475 { std::get<_Nm>(__t) }
3476 -> convertible_to<const tuple_element_t<_Nm, _Tp>&>;
3479 template<typename _Tp, size_t _Nm>
3480 concept __returnable_element
3481 = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Nm, _Tp>>;
3484 template<input_range _Vp, size_t _Nm>
3486 && __detail::__has_tuple_element<range_value_t<_Vp>, _Nm>
3487 && __detail::__has_tuple_element<remove_reference_t<range_reference_t<_Vp>>,
3489 && __detail::__returnable_element<range_reference_t<_Vp>, _Nm>
3490 class elements_view : public view_interface<elements_view<_Vp, _Nm>>
3493 elements_view() = default;
3496 elements_view(_Vp base)
3497 : _M_base(std::move(base))
3501 base() const& requires copy_constructible<_Vp>
3506 { return std::move(_M_base); }
3509 begin() requires (!__detail::__simple_view<_Vp>)
3510 { return _Iterator<false>(ranges::begin(_M_base)); }
3513 begin() const requires range<const _Vp>
3514 { return _Iterator<true>(ranges::begin(_M_base)); }
3517 end() requires (!__detail::__simple_view<_Vp> && !common_range<_Vp>)
3518 { return _Sentinel<false>{ranges::end(_M_base)}; }
3521 end() requires (!__detail::__simple_view<_Vp> && common_range<_Vp>)
3522 { return _Iterator<false>{ranges::end(_M_base)}; }
3525 end() const requires range<const _Vp>
3526 { return _Sentinel<true>{ranges::end(_M_base)}; }
3529 end() const requires common_range<const _Vp>
3530 { return _Iterator<true>{ranges::end(_M_base)}; }
3533 size() requires sized_range<_Vp>
3534 { return ranges::size(_M_base); }
3537 size() const requires sized_range<const _Vp>
3538 { return ranges::size(_M_base); }
3541 template<bool _Const>
3542 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
3544 template<bool _Const>
3548 template<bool _Const>
3549 requires forward_range<_Base<_Const>>
3550 struct __iter_cat<_Const>
3553 static auto _S_iter_cat()
3555 using _Base = elements_view::_Base<_Const>;
3556 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
3557 using _Res = decltype((std::get<_Nm>(*std::declval<iterator_t<_Base>>())));
3558 if constexpr (!is_lvalue_reference_v<_Res>)
3559 return input_iterator_tag{};
3560 else if constexpr (derived_from<_Cat, random_access_iterator_tag>)
3561 return random_access_iterator_tag{};
3566 using iterator_category = decltype(_S_iter_cat());
3569 template<bool _Const>
3572 template<bool _Const>
3573 struct _Iterator : __iter_cat<_Const>
3576 using _Base = elements_view::_Base<_Const>;
3578 iterator_t<_Base> _M_current = iterator_t<_Base>();
3580 static constexpr decltype(auto)
3581 _S_get_element(const iterator_t<_Base>& __i)
3583 if constexpr (is_reference_v<range_reference_t<_Base>>)
3584 return std::get<_Nm>(*__i);
3587 using _Et = remove_cv_t<tuple_element_t<_Nm, range_reference_t<_Base>>>;
3588 return static_cast<_Et>(std::get<_Nm>(*__i));
3595 if constexpr (random_access_range<_Base>)
3596 return random_access_iterator_tag{};
3597 else if constexpr (bidirectional_range<_Base>)
3598 return bidirectional_iterator_tag{};
3599 else if constexpr (forward_range<_Base>)
3600 return forward_iterator_tag{};
3602 return input_iterator_tag{};
3605 friend _Iterator<!_Const>;
3608 using iterator_concept = decltype(_S_iter_concept());
3609 // iterator_category defined in elements_view::__iter_cat
3611 = remove_cvref_t<tuple_element_t<_Nm, range_value_t<_Base>>>;
3612 using difference_type = range_difference_t<_Base>;
3614 _Iterator() = default;
3617 _Iterator(iterator_t<_Base> current)
3618 : _M_current(std::move(current))
3622 _Iterator(_Iterator<!_Const> i)
3623 requires _Const && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
3624 : _M_current(std::move(i._M_current))
3627 constexpr const iterator_t<_Base>&
3628 base() const& noexcept
3629 { return _M_current; }
3631 constexpr iterator_t<_Base>
3633 { return std::move(_M_current); }
3635 constexpr decltype(auto)
3637 { return _S_get_element(_M_current); }
3639 constexpr _Iterator&
3651 operator++(int) requires forward_range<_Base>
3658 constexpr _Iterator&
3659 operator--() requires bidirectional_range<_Base>
3666 operator--(int) requires bidirectional_range<_Base>
3673 constexpr _Iterator&
3674 operator+=(difference_type __n)
3675 requires random_access_range<_Base>
3681 constexpr _Iterator&
3682 operator-=(difference_type __n)
3683 requires random_access_range<_Base>
3689 constexpr decltype(auto)
3690 operator[](difference_type __n) const
3691 requires random_access_range<_Base>
3692 { return _S_get_element(_M_current + __n); }
3694 friend constexpr bool
3695 operator==(const _Iterator& __x, const _Iterator& __y)
3696 requires equality_comparable<iterator_t<_Base>>
3697 { return __x._M_current == __y._M_current; }
3699 friend constexpr bool
3700 operator<(const _Iterator& __x, const _Iterator& __y)
3701 requires random_access_range<_Base>
3702 { return __x._M_current < __y._M_current; }
3704 friend constexpr bool
3705 operator>(const _Iterator& __x, const _Iterator& __y)
3706 requires random_access_range<_Base>
3707 { return __y._M_current < __x._M_current; }
3709 friend constexpr bool
3710 operator<=(const _Iterator& __x, const _Iterator& __y)
3711 requires random_access_range<_Base>
3712 { return !(__y._M_current > __x._M_current); }
3714 friend constexpr bool
3715 operator>=(const _Iterator& __x, const _Iterator& __y)
3716 requires random_access_range<_Base>
3717 { return !(__x._M_current > __y._M_current); }
3719 #ifdef __cpp_lib_three_way_comparison
3720 friend constexpr auto
3721 operator<=>(const _Iterator& __x, const _Iterator& __y)
3722 requires random_access_range<_Base>
3723 && three_way_comparable<iterator_t<_Base>>
3724 { return __x._M_current <=> __y._M_current; }
3727 friend constexpr _Iterator
3728 operator+(const _Iterator& __x, difference_type __y)
3729 requires random_access_range<_Base>
3730 { return _Iterator{__x} += __y; }
3732 friend constexpr _Iterator
3733 operator+(difference_type __x, const _Iterator& __y)
3734 requires random_access_range<_Base>
3735 { return __y + __x; }
3737 friend constexpr _Iterator
3738 operator-(const _Iterator& __x, difference_type __y)
3739 requires random_access_range<_Base>
3740 { return _Iterator{__x} -= __y; }
3742 // _GLIBCXX_RESOLVE_LIB_DEFECTS
3743 // 3483. transform_view::iterator's difference is overconstrained
3744 friend constexpr difference_type
3745 operator-(const _Iterator& __x, const _Iterator& __y)
3746 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
3747 { return __x._M_current - __y._M_current; }
3749 template <bool> friend struct _Sentinel;
3752 template<bool _Const>
3756 template<bool _Const2>
3758 _M_equal(const _Iterator<_Const2>& __x) const
3759 { return __x._M_current == _M_end; }
3761 template<bool _Const2>
3763 _M_distance_from(const _Iterator<_Const2>& __i) const
3764 { return _M_end - __i._M_current; }
3766 using _Base = elements_view::_Base<_Const>;
3767 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
3770 _Sentinel() = default;
3773 _Sentinel(sentinel_t<_Base> __end)
3774 : _M_end(std::move(__end))
3778 _Sentinel(_Sentinel<!_Const> __other)
3780 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
3781 : _M_end(std::move(__other._M_end))
3784 constexpr sentinel_t<_Base>
3788 template<bool _Const2>
3789 requires sentinel_for<sentinel_t<_Base>,
3790 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
3791 friend constexpr bool
3792 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3793 { return __y._M_equal(__x); }
3795 template<bool _Const2,
3796 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3797 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3798 friend constexpr range_difference_t<_Base2>
3799 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3800 { return -__y._M_distance_from(__x); }
3802 template<bool _Const2,
3803 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3804 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3805 friend constexpr range_difference_t<_Base2>
3806 operator-(const _Sentinel& __x, const _Iterator<_Const2>& __y)
3807 { return __x._M_distance_from(__y); }
3809 friend _Sentinel<!_Const>;
3812 _Vp _M_base = _Vp();
3815 template<typename _Tp, size_t _Nm>
3816 inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Nm>>
3817 = enable_borrowed_range<_Tp>;
3819 template<typename _Range>
3820 using keys_view = elements_view<views::all_t<_Range>, 0>;
3822 template<typename _Range>
3823 using values_view = elements_view<views::all_t<_Range>, 1>;
3829 template<size_t _Nm, typename _Range>
3830 concept __can_elements_view
3831 = requires { elements_view<all_t<_Range>, _Nm>{std::declval<_Range>()}; };
3832 } // namespace __detail
3834 template<size_t _Nm>
3835 struct _Elements : __adaptor::_RangeAdaptorClosure
3837 template<viewable_range _Range>
3838 requires __detail::__can_elements_view<_Nm, _Range>
3840 operator()(_Range&& __r) const
3842 return elements_view<all_t<_Range>, _Nm>{std::forward<_Range>(__r)};
3845 static constexpr bool _S_has_simple_call_op = true;
3848 template<size_t _Nm>
3849 inline constexpr _Elements<_Nm> elements;
3850 inline constexpr auto keys = elements<0>;
3851 inline constexpr auto values = elements<1>;
3852 } // namespace views
3854 } // namespace ranges
3856 namespace views = ranges::views;
3858 _GLIBCXX_END_NAMESPACE_VERSION
3860 #endif // library concepts
3862 #endif /* _GLIBCXX_RANGES */