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<typename _Winc, typename _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, typename _Traits>
636 requires default_initializable<_Val>
637 && __detail::__stream_extractable<_Val, _CharT, _Traits>
638 class basic_istream_view
639 : public view_interface<basic_istream_view<_Val, _CharT, _Traits>>
642 basic_istream_view() = default;
645 basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
646 : _M_stream(std::__addressof(__stream))
652 if (_M_stream != nullptr)
653 *_M_stream >> _M_object;
654 return _Iterator{this};
657 constexpr default_sentinel_t
659 { return default_sentinel; }
662 basic_istream<_CharT, _Traits>* _M_stream = nullptr;
663 _Val _M_object = _Val();
668 using iterator_concept = input_iterator_tag;
669 using difference_type = ptrdiff_t;
670 using value_type = _Val;
672 _Iterator() = default;
675 _Iterator(basic_istream_view* __parent) noexcept
676 : _M_parent(__parent)
679 _Iterator(const _Iterator&) = delete;
680 _Iterator(_Iterator&&) = default;
681 _Iterator& operator=(const _Iterator&) = delete;
682 _Iterator& operator=(_Iterator&&) = default;
687 __glibcxx_assert(_M_parent->_M_stream != nullptr);
688 *_M_parent->_M_stream >> _M_parent->_M_object;
699 __glibcxx_assert(_M_parent->_M_stream != nullptr);
700 return _M_parent->_M_object;
704 operator==(const _Iterator& __x, default_sentinel_t)
705 { return __x._M_at_end(); }
708 basic_istream_view* _M_parent = nullptr;
712 { return _M_parent == nullptr || !*_M_parent->_M_stream; }
718 template<typename _Val, typename _CharT, typename _Traits>
719 basic_istream_view<_Val, _CharT, _Traits>
720 istream_view(basic_istream<_CharT, _Traits>& __s)
721 { return basic_istream_view<_Val, _CharT, _Traits>{__s}; }
723 // C++20 24.7 [range.adaptors] Range adaptors
729 // Alias for a type that is conditionally present
730 // (and is an empty type otherwise).
731 // Data members using this alias should use [[no_unique_address]] so that
732 // they take no space when not needed.
733 template<bool _Present, typename _Tp>
734 using __maybe_present_t = conditional_t<_Present, _Tp, _Empty>;
736 // Alias for a type that is conditionally const.
737 template<bool _Const, typename _Tp>
738 using __maybe_const_t = conditional_t<_Const, const _Tp, _Tp>;
740 } // namespace __detail
742 namespace views::__adaptor
744 // True if the range adaptor _Adaptor can be applied with _Args.
745 template<typename _Adaptor, typename... _Args>
746 concept __adaptor_invocable
747 = requires { std::declval<_Adaptor>()(declval<_Args>()...); };
749 // True if the range adaptor non-closure _Adaptor can be partially applied
751 template<typename _Adaptor, typename... _Args>
752 concept __adaptor_partial_app_viable = (_Adaptor::_S_arity > 1)
753 && (sizeof...(_Args) == _Adaptor::_S_arity - 1)
754 && (constructible_from<decay_t<_Args>, _Args> && ...);
756 template<typename _Adaptor, typename... _Args>
759 template<typename _Lhs, typename _Rhs>
762 // The base class of every range adaptor closure.
764 // The derived class should define the optional static data member
765 // _S_has_simple_call_op to true if the behavior of this adaptor is
766 // independent of the constness/value category of the adaptor object.
767 struct _RangeAdaptorClosure
769 // range | adaptor is equivalent to adaptor(range).
770 template<typename _Self, typename _Range>
771 requires derived_from<remove_cvref_t<_Self>, _RangeAdaptorClosure>
772 && __adaptor_invocable<_Self, _Range>
773 friend constexpr auto
774 operator|(_Range&& __r, _Self&& __self)
775 { return std::forward<_Self>(__self)(std::forward<_Range>(__r)); }
777 // Compose the adaptors __lhs and __rhs into a pipeline, returning
778 // another range adaptor closure object.
779 template<typename _Lhs, typename _Rhs>
780 requires derived_from<_Lhs, _RangeAdaptorClosure>
781 && derived_from<_Rhs, _RangeAdaptorClosure>
782 friend constexpr auto
783 operator|(_Lhs __lhs, _Rhs __rhs)
784 { return _Pipe<_Lhs, _Rhs>{std::move(__lhs), std::move(__rhs)}; }
787 // The base class of every range adaptor non-closure.
789 // The static data member _Derived::_S_arity must contain the total number of
790 // arguments that the adaptor takes, and the class _Derived must introduce
791 // _RangeAdaptor::operator() into the class scope via a using-declaration.
793 // The optional static data member _Derived::_S_has_simple_extra_args should
794 // be defined to true if the behavior of this adaptor is independent of the
795 // constness/value category of the extra arguments.
796 template<typename _Derived>
799 // Partially apply the arguments __args to the range adaptor _Derived,
800 // returning a range adaptor closure object.
801 template<typename... _Args>
802 requires __adaptor_partial_app_viable<_Derived, _Args...>
804 operator()(_Args&&... __args) const
806 return _Partial<_Derived, decay_t<_Args>...>{std::forward<_Args>(__args)...};
810 // True if the range adaptor closure _Adaptor has a simple operator(), i.e.
811 // one that's not overloaded according to constness or value category of the
813 template<typename _Adaptor>
814 concept __closure_has_simple_call_op = _Adaptor::_S_has_simple_call_op;
816 // True if the behavior of the range adaptor non-closure _Adaptor is
817 // independent of the value category of its extra arguments.
818 template<typename _Adaptor>
819 concept __adaptor_has_simple_extra_args = _Adaptor::_S_has_simple_extra_args;
821 // A range adaptor closure that represents partial application of
822 // the range adaptor _Adaptor with arguments _Args.
823 template<typename _Adaptor, typename... _Args>
824 struct _Partial : _RangeAdaptorClosure
826 tuple<_Args...> _M_args;
829 _Partial(_Args... __args)
830 : _M_args(std::move(__args)...)
833 // Invoke _Adaptor with arguments __r, _M_args... according to the
834 // value category of this _Partial object.
835 template<typename _Range>
836 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
838 operator()(_Range&& __r) const &
840 auto __forwarder = [&__r] (const auto&... __args) {
841 return _Adaptor{}(std::forward<_Range>(__r), __args...);
843 return std::apply(__forwarder, _M_args);
846 template<typename _Range>
847 requires __adaptor_invocable<_Adaptor, _Range, _Args...>
849 operator()(_Range&& __r) &&
851 auto __forwarder = [&__r] (auto&... __args) {
852 return _Adaptor{}(std::forward<_Range>(__r), std::move(__args)...);
854 return std::apply(__forwarder, _M_args);
857 template<typename _Range>
859 operator()(_Range&& __r) const && = delete;
862 // A lightweight specialization of the above primary template for
863 // the common case where _Adaptor accepts a single extra argument.
864 template<typename _Adaptor, typename _Arg>
865 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
871 : _M_arg(std::move(__arg))
874 template<typename _Range>
875 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
877 operator()(_Range&& __r) const &
878 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
880 template<typename _Range>
881 requires __adaptor_invocable<_Adaptor, _Range, _Arg>
883 operator()(_Range&& __r) &&
884 { return _Adaptor{}(std::forward<_Range>(__r), std::move(_M_arg)); }
886 template<typename _Range>
888 operator()(_Range&& __r) const && = delete;
891 // Partial specialization of the primary template for the case where the extra
892 // arguments of the adaptor can always be safely forwarded by const reference.
893 // This lets us get away with a single operator() overload, which makes
894 // overload resolution failure diagnostics more concise.
895 template<typename _Adaptor, typename... _Args>
896 requires __adaptor_has_simple_extra_args<_Adaptor>
897 struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure
899 tuple<_Args...> _M_args;
902 _Partial(_Args... __args)
903 : _M_args(std::move(__args)...)
906 // Invoke _Adaptor with arguments __r, const _M_args&... regardless
907 // of the value category of this _Partial object.
908 template<typename _Range>
909 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
911 operator()(_Range&& __r) const
913 auto __forwarder = [&__r] (const auto&... __args) {
914 return _Adaptor{}(std::forward<_Range>(__r), __args...);
916 return std::apply(__forwarder, _M_args);
919 static constexpr bool _S_has_simple_call_op = true;
922 // A lightweight specialization of the above template for the common case
923 // where _Adaptor accepts a single extra argument.
924 template<typename _Adaptor, typename _Arg>
925 requires __adaptor_has_simple_extra_args<_Adaptor>
926 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
932 : _M_arg(std::move(__arg))
935 template<typename _Range>
936 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
938 operator()(_Range&& __r) const
939 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
941 static constexpr bool _S_has_simple_call_op = true;
944 template<typename _Lhs, typename _Rhs, typename _Range>
945 concept __pipe_invocable
946 = requires { std::declval<_Rhs>()(std::declval<_Lhs>()(std::declval<_Range>())); };
948 // A range adaptor closure that represents composition of the range
949 // adaptor closures _Lhs and _Rhs.
950 template<typename _Lhs, typename _Rhs>
951 struct _Pipe : _RangeAdaptorClosure
953 [[no_unique_address]] _Lhs _M_lhs;
954 [[no_unique_address]] _Rhs _M_rhs;
957 _Pipe(_Lhs __lhs, _Rhs __rhs)
958 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
961 // Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
962 // range adaptor closure object.
963 template<typename _Range>
964 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
966 operator()(_Range&& __r) const &
967 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
969 template<typename _Range>
970 requires __pipe_invocable<_Lhs, _Rhs, _Range>
972 operator()(_Range&& __r) &&
973 { return std::move(_M_rhs)(std::move(_M_lhs)(std::forward<_Range>(__r))); }
975 template<typename _Range>
977 operator()(_Range&& __r) const && = delete;
980 // A partial specialization of the above primary template for the case where
981 // both adaptor operands have a simple operator(). This in turn lets us
982 // implement composition using a single simple operator(), which makes
983 // overload resolution failure diagnostics more concise.
984 template<typename _Lhs, typename _Rhs>
985 requires __closure_has_simple_call_op<_Lhs>
986 && __closure_has_simple_call_op<_Rhs>
987 struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure
989 [[no_unique_address]] _Lhs _M_lhs;
990 [[no_unique_address]] _Rhs _M_rhs;
993 _Pipe(_Lhs __lhs, _Rhs __rhs)
994 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
997 template<typename _Range>
998 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
1000 operator()(_Range&& __r) const
1001 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
1003 static constexpr bool _S_has_simple_call_op = true;
1005 } // namespace views::__adaptor
1007 template<range _Range> requires is_object_v<_Range>
1008 class ref_view : public view_interface<ref_view<_Range>>
1011 _Range* _M_r = nullptr;
1013 static void _S_fun(_Range&); // not defined
1014 static void _S_fun(_Range&&) = delete;
1018 ref_view() noexcept = default;
1020 template<__detail::__not_same_as<ref_view> _Tp>
1021 requires convertible_to<_Tp, _Range&>
1022 && requires { _S_fun(declval<_Tp>()); }
1025 : _M_r(std::__addressof(static_cast<_Range&>(std::forward<_Tp>(__t))))
1032 constexpr iterator_t<_Range>
1034 { return ranges::begin(*_M_r); }
1036 constexpr sentinel_t<_Range>
1038 { return ranges::end(*_M_r); }
1041 empty() const requires requires { ranges::empty(*_M_r); }
1042 { return ranges::empty(*_M_r); }
1045 size() const requires sized_range<_Range>
1046 { return ranges::size(*_M_r); }
1049 data() const requires contiguous_range<_Range>
1050 { return ranges::data(*_M_r); }
1053 template<typename _Range>
1054 ref_view(_Range&) -> ref_view<_Range>;
1056 template<typename _Tp>
1057 inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
1063 template<typename _Range>
1064 concept __can_ref_view = requires { ref_view{std::declval<_Range>()}; };
1066 template<typename _Range>
1067 concept __can_subrange = requires { subrange{std::declval<_Range>()}; };
1068 } // namespace __detail
1070 struct _All : __adaptor::_RangeAdaptorClosure
1072 template<viewable_range _Range>
1073 requires view<decay_t<_Range>>
1074 || __detail::__can_ref_view<_Range>
1075 || __detail::__can_subrange<_Range>
1077 operator()(_Range&& __r) const
1079 if constexpr (view<decay_t<_Range>>)
1080 return std::forward<_Range>(__r);
1081 else if constexpr (__detail::__can_ref_view<_Range>)
1082 return ref_view{std::forward<_Range>(__r)};
1084 return subrange{std::forward<_Range>(__r)};
1087 static constexpr bool _S_has_simple_call_op = true;
1090 inline constexpr _All all;
1092 template<viewable_range _Range>
1093 using all_t = decltype(all(std::declval<_Range>()));
1094 } // namespace views
1096 // The following simple algos are transcribed from ranges_algo.h to avoid
1097 // having to include that entire header.
1100 template<typename _Iter, typename _Sent, typename _Tp>
1102 find(_Iter __first, _Sent __last, const _Tp& __value)
1104 while (__first != __last
1105 && !(bool)(*__first == __value))
1110 template<typename _Iter, typename _Sent, typename _Pred>
1112 find_if(_Iter __first, _Sent __last, _Pred __pred)
1114 while (__first != __last
1115 && !(bool)std::__invoke(__pred, *__first))
1120 template<typename _Iter, typename _Sent, typename _Pred>
1122 find_if_not(_Iter __first, _Sent __last, _Pred __pred)
1124 while (__first != __last
1125 && (bool)std::__invoke(__pred, *__first))
1130 template<typename _Iter1, typename _Sent1, typename _Iter2, typename _Sent2>
1131 constexpr pair<_Iter1, _Iter2>
1132 mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2)
1134 while (__first1 != __last1 && __first2 != __last2
1135 && (bool)ranges::equal_to{}(*__first1, *__first2))
1140 return { std::move(__first1), std::move(__first2) };
1142 } // namespace __detail
1146 template<typename _Tp>
1147 struct __non_propagating_cache
1149 // When _Tp is not an object type (e.g. is a reference type), we make
1150 // __non_propagating_cache<_Tp> empty rather than ill-formed so that
1151 // users can easily conditionally declare data members with this type
1152 // (such as join_view::_M_inner).
1155 template<typename _Tp>
1156 requires is_object_v<_Tp>
1157 struct __non_propagating_cache<_Tp> : protected _Optional_base<_Tp>
1159 __non_propagating_cache() = default;
1162 __non_propagating_cache(const __non_propagating_cache&) noexcept
1166 __non_propagating_cache(__non_propagating_cache&& __other) noexcept
1167 { __other._M_reset(); }
1169 constexpr __non_propagating_cache&
1170 operator=(const __non_propagating_cache& __other) noexcept
1172 if (std::__addressof(__other) != this)
1177 constexpr __non_propagating_cache&
1178 operator=(__non_propagating_cache&& __other) noexcept
1186 operator*() noexcept
1187 { return this->_M_get(); }
1189 constexpr const _Tp&
1190 operator*() const noexcept
1191 { return this->_M_get(); }
1193 template<typename _Iter>
1195 _M_emplace_deref(const _Iter& __i)
1198 // Using _Optional_base::_M_construct to initialize from '*__i'
1199 // would incur an extra move due to the indirection, so we instead
1200 // use placement new directly.
1201 ::new ((void *) std::__addressof(this->_M_payload._M_payload)) _Tp(*__i);
1202 this->_M_payload._M_engaged = true;
1203 return this->_M_get();
1207 template<range _Range>
1208 struct _CachedPosition
1211 _M_has_value() const
1214 constexpr iterator_t<_Range>
1215 _M_get(const _Range&) const
1217 __glibcxx_assert(false);
1222 _M_set(const _Range&, const iterator_t<_Range>&) const
1226 template<forward_range _Range>
1227 struct _CachedPosition<_Range>
1228 : protected __non_propagating_cache<iterator_t<_Range>>
1231 _M_has_value() const
1232 { return this->_M_is_engaged(); }
1234 constexpr iterator_t<_Range>
1235 _M_get(const _Range&) const
1237 __glibcxx_assert(_M_has_value());
1242 _M_set(const _Range&, const iterator_t<_Range>& __it)
1244 __glibcxx_assert(!_M_has_value());
1245 std::construct_at(std::__addressof(this->_M_payload._M_payload),
1247 this->_M_payload._M_engaged = true;
1251 template<random_access_range _Range>
1252 requires (sizeof(range_difference_t<_Range>)
1253 <= sizeof(iterator_t<_Range>))
1254 struct _CachedPosition<_Range>
1257 range_difference_t<_Range> _M_offset = -1;
1260 _CachedPosition() = default;
1263 _CachedPosition(const _CachedPosition&) = default;
1266 _CachedPosition(_CachedPosition&& __other) noexcept
1267 { *this = std::move(__other); }
1269 constexpr _CachedPosition&
1270 operator=(const _CachedPosition&) = default;
1272 constexpr _CachedPosition&
1273 operator=(_CachedPosition&& __other) noexcept
1275 // Propagate the cached offset, but invalidate the source.
1276 _M_offset = __other._M_offset;
1277 __other._M_offset = -1;
1282 _M_has_value() const
1283 { return _M_offset >= 0; }
1285 constexpr iterator_t<_Range>
1286 _M_get(_Range& __r) const
1288 __glibcxx_assert(_M_has_value());
1289 return ranges::begin(__r) + _M_offset;
1293 _M_set(_Range& __r, const iterator_t<_Range>& __it)
1295 __glibcxx_assert(!_M_has_value());
1296 _M_offset = __it - ranges::begin(__r);
1299 } // namespace __detail
1303 template<typename _Base>
1304 struct __filter_view_iter_cat
1307 template<forward_range _Base>
1308 struct __filter_view_iter_cat<_Base>
1314 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1315 if constexpr (derived_from<_Cat, bidirectional_iterator_tag>)
1316 return bidirectional_iterator_tag{};
1317 else if constexpr (derived_from<_Cat, forward_iterator_tag>)
1318 return forward_iterator_tag{};
1323 using iterator_category = decltype(_S_iter_cat());
1325 } // namespace __detail
1327 template<input_range _Vp,
1328 indirect_unary_predicate<iterator_t<_Vp>> _Pred>
1329 requires view<_Vp> && is_object_v<_Pred>
1330 class filter_view : public view_interface<filter_view<_Vp, _Pred>>
1335 struct _Iterator : __detail::__filter_view_iter_cat<_Vp>
1338 static constexpr auto
1341 if constexpr (bidirectional_range<_Vp>)
1342 return bidirectional_iterator_tag{};
1343 else if constexpr (forward_range<_Vp>)
1344 return forward_iterator_tag{};
1346 return input_iterator_tag{};
1351 using _Vp_iter = iterator_t<_Vp>;
1353 _Vp_iter _M_current = _Vp_iter();
1354 filter_view* _M_parent = nullptr;
1357 using iterator_concept = decltype(_S_iter_concept());
1358 // iterator_category defined in __filter_view_iter_cat
1359 using value_type = range_value_t<_Vp>;
1360 using difference_type = range_difference_t<_Vp>;
1362 _Iterator() = default;
1365 _Iterator(filter_view* __parent, _Vp_iter __current)
1366 : _M_current(std::move(__current)),
1370 constexpr const _Vp_iter&
1371 base() const & noexcept
1372 { return _M_current; }
1376 { return std::move(_M_current); }
1378 constexpr range_reference_t<_Vp>
1380 { return *_M_current; }
1384 requires __detail::__has_arrow<_Vp_iter>
1385 && copyable<_Vp_iter>
1386 { return _M_current; }
1388 constexpr _Iterator&
1391 _M_current = __detail::find_if(std::move(++_M_current),
1392 ranges::end(_M_parent->_M_base),
1393 std::ref(*_M_parent->_M_pred));
1402 operator++(int) requires forward_range<_Vp>
1409 constexpr _Iterator&
1410 operator--() requires bidirectional_range<_Vp>
1414 while (!std::__invoke(*_M_parent->_M_pred, *_M_current));
1419 operator--(int) requires bidirectional_range<_Vp>
1426 friend constexpr bool
1427 operator==(const _Iterator& __x, const _Iterator& __y)
1428 requires equality_comparable<_Vp_iter>
1429 { return __x._M_current == __y._M_current; }
1431 friend constexpr range_rvalue_reference_t<_Vp>
1432 iter_move(const _Iterator& __i)
1433 noexcept(noexcept(ranges::iter_move(__i._M_current)))
1434 { return ranges::iter_move(__i._M_current); }
1436 friend constexpr void
1437 iter_swap(const _Iterator& __x, const _Iterator& __y)
1438 noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
1439 requires indirectly_swappable<_Vp_iter>
1440 { ranges::iter_swap(__x._M_current, __y._M_current); }
1446 sentinel_t<_Vp> _M_end = sentinel_t<_Vp>();
1449 __equal(const _Iterator& __i) const
1450 { return __i._M_current == _M_end; }
1453 _Sentinel() = default;
1456 _Sentinel(filter_view* __parent)
1457 : _M_end(ranges::end(__parent->_M_base))
1460 constexpr sentinel_t<_Vp>
1464 friend constexpr bool
1465 operator==(const _Iterator& __x, const _Sentinel& __y)
1466 { return __y.__equal(__x); }
1469 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
1470 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
1471 _Vp _M_base = _Vp();
1474 filter_view() = default;
1477 filter_view(_Vp __base, _Pred __pred)
1478 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
1482 base() const& requires copy_constructible<_Vp>
1487 { return std::move(_M_base); }
1489 constexpr const _Pred&
1491 { return *_M_pred; }
1496 if (_M_cached_begin._M_has_value())
1497 return {this, _M_cached_begin._M_get(_M_base)};
1499 __glibcxx_assert(_M_pred.has_value());
1500 auto __it = __detail::find_if(ranges::begin(_M_base),
1501 ranges::end(_M_base),
1502 std::ref(*_M_pred));
1503 _M_cached_begin._M_set(_M_base, __it);
1504 return {this, std::move(__it)};
1510 if constexpr (common_range<_Vp>)
1511 return _Iterator{this, ranges::end(_M_base)};
1513 return _Sentinel{this};
1517 template<typename _Range, typename _Pred>
1518 filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
1524 template<typename _Range, typename _Pred>
1525 concept __can_filter_view
1526 = requires { filter_view(std::declval<_Range>(), std::declval<_Pred>()); };
1527 } // namespace __detail
1529 struct _Filter : __adaptor::_RangeAdaptor<_Filter>
1531 template<viewable_range _Range, typename _Pred>
1532 requires __detail::__can_filter_view<_Range, _Pred>
1534 operator()(_Range&& __r, _Pred&& __p) const
1536 return filter_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
1539 using _RangeAdaptor<_Filter>::operator();
1540 static constexpr int _S_arity = 2;
1541 static constexpr bool _S_has_simple_extra_args = true;
1544 inline constexpr _Filter filter;
1545 } // namespace views
1547 template<input_range _Vp, copy_constructible _Fp>
1548 requires view<_Vp> && is_object_v<_Fp>
1549 && regular_invocable<_Fp&, range_reference_t<_Vp>>
1550 && std::__detail::__can_reference<invoke_result_t<_Fp&,
1551 range_reference_t<_Vp>>>
1552 class transform_view : public view_interface<transform_view<_Vp, _Fp>>
1555 template<bool _Const>
1556 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1558 template<bool _Const>
1562 template<bool _Const>
1563 requires forward_range<_Base<_Const>>
1564 struct __iter_cat<_Const>
1570 using _Base = transform_view::_Base<_Const>;
1571 using _Res = invoke_result_t<_Fp&, range_reference_t<_Base>>;
1572 if constexpr (is_lvalue_reference_v<_Res>)
1575 = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1576 if constexpr (derived_from<_Cat, contiguous_iterator_tag>)
1577 return random_access_iterator_tag{};
1582 return input_iterator_tag{};
1585 using iterator_category = decltype(_S_iter_cat());
1588 template<bool _Const>
1591 template<bool _Const>
1592 struct _Iterator : __iter_cat<_Const>
1595 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1596 using _Base = transform_view::_Base<_Const>;
1601 if constexpr (random_access_range<_Vp>)
1602 return random_access_iterator_tag{};
1603 else if constexpr (bidirectional_range<_Vp>)
1604 return bidirectional_iterator_tag{};
1605 else if constexpr (forward_range<_Vp>)
1606 return forward_iterator_tag{};
1608 return input_iterator_tag{};
1611 using _Base_iter = iterator_t<_Base>;
1613 _Base_iter _M_current = _Base_iter();
1614 _Parent* _M_parent = nullptr;
1617 using iterator_concept = decltype(_S_iter_concept());
1618 // iterator_category defined in __transform_view_iter_cat
1620 = remove_cvref_t<invoke_result_t<_Fp&, range_reference_t<_Base>>>;
1621 using difference_type = range_difference_t<_Base>;
1623 _Iterator() = default;
1626 _Iterator(_Parent* __parent, _Base_iter __current)
1627 : _M_current(std::move(__current)),
1632 _Iterator(_Iterator<!_Const> __i)
1634 && convertible_to<iterator_t<_Vp>, _Base_iter>
1635 : _M_current(std::move(__i._M_current)), _M_parent(__i._M_parent)
1638 constexpr const _Base_iter&
1639 base() const & noexcept
1640 { return _M_current; }
1642 constexpr _Base_iter
1644 { return std::move(_M_current); }
1646 constexpr decltype(auto)
1648 noexcept(noexcept(std::__invoke(*_M_parent->_M_fun, *_M_current)))
1649 { return std::__invoke(*_M_parent->_M_fun, *_M_current); }
1651 constexpr _Iterator&
1663 operator++(int) requires forward_range<_Base>
1670 constexpr _Iterator&
1671 operator--() requires bidirectional_range<_Base>
1678 operator--(int) requires bidirectional_range<_Base>
1685 constexpr _Iterator&
1686 operator+=(difference_type __n) requires random_access_range<_Base>
1692 constexpr _Iterator&
1693 operator-=(difference_type __n) requires random_access_range<_Base>
1699 constexpr decltype(auto)
1700 operator[](difference_type __n) const
1701 requires random_access_range<_Base>
1702 { return std::__invoke(*_M_parent->_M_fun, _M_current[__n]); }
1704 friend constexpr bool
1705 operator==(const _Iterator& __x, const _Iterator& __y)
1706 requires equality_comparable<_Base_iter>
1707 { return __x._M_current == __y._M_current; }
1709 friend constexpr bool
1710 operator<(const _Iterator& __x, const _Iterator& __y)
1711 requires random_access_range<_Base>
1712 { return __x._M_current < __y._M_current; }
1714 friend constexpr bool
1715 operator>(const _Iterator& __x, const _Iterator& __y)
1716 requires random_access_range<_Base>
1717 { return __y < __x; }
1719 friend constexpr bool
1720 operator<=(const _Iterator& __x, const _Iterator& __y)
1721 requires random_access_range<_Base>
1722 { return !(__y < __x); }
1724 friend constexpr bool
1725 operator>=(const _Iterator& __x, const _Iterator& __y)
1726 requires random_access_range<_Base>
1727 { return !(__x < __y); }
1729 #ifdef __cpp_lib_three_way_comparison
1730 friend constexpr auto
1731 operator<=>(const _Iterator& __x, const _Iterator& __y)
1732 requires random_access_range<_Base>
1733 && three_way_comparable<_Base_iter>
1734 { return __x._M_current <=> __y._M_current; }
1737 friend constexpr _Iterator
1738 operator+(_Iterator __i, difference_type __n)
1739 requires random_access_range<_Base>
1740 { return {__i._M_parent, __i._M_current + __n}; }
1742 friend constexpr _Iterator
1743 operator+(difference_type __n, _Iterator __i)
1744 requires random_access_range<_Base>
1745 { return {__i._M_parent, __i._M_current + __n}; }
1747 friend constexpr _Iterator
1748 operator-(_Iterator __i, difference_type __n)
1749 requires random_access_range<_Base>
1750 { return {__i._M_parent, __i._M_current - __n}; }
1752 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1753 // 3483. transform_view::iterator's difference is overconstrained
1754 friend constexpr difference_type
1755 operator-(const _Iterator& __x, const _Iterator& __y)
1756 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
1757 { return __x._M_current - __y._M_current; }
1759 friend constexpr decltype(auto)
1760 iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
1762 if constexpr (is_lvalue_reference_v<decltype(*__i)>)
1763 return std::move(*__i);
1768 friend _Iterator<!_Const>;
1769 template<bool> friend struct _Sentinel;
1772 template<bool _Const>
1776 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1777 using _Base = transform_view::_Base<_Const>;
1779 template<bool _Const2>
1781 __distance_from(const _Iterator<_Const2>& __i) const
1782 { return _M_end - __i._M_current; }
1784 template<bool _Const2>
1786 __equal(const _Iterator<_Const2>& __i) const
1787 { return __i._M_current == _M_end; }
1789 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1792 _Sentinel() = default;
1795 _Sentinel(sentinel_t<_Base> __end)
1800 _Sentinel(_Sentinel<!_Const> __i)
1802 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1803 : _M_end(std::move(__i._M_end))
1806 constexpr sentinel_t<_Base>
1810 template<bool _Const2>
1811 requires sentinel_for<sentinel_t<_Base>,
1812 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
1813 friend constexpr bool
1814 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1815 { return __y.__equal(__x); }
1817 template<bool _Const2,
1818 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1819 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1820 friend constexpr range_difference_t<_Base2>
1821 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1822 { return -__y.__distance_from(__x); }
1824 template<bool _Const2,
1825 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1826 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1827 friend constexpr range_difference_t<_Base2>
1828 operator-(const _Sentinel& __y, const _Iterator<_Const2>& __x)
1829 { return __y.__distance_from(__x); }
1831 friend _Sentinel<!_Const>;
1834 [[no_unique_address]] __detail::__box<_Fp> _M_fun;
1835 _Vp _M_base = _Vp();
1838 transform_view() = default;
1841 transform_view(_Vp __base, _Fp __fun)
1842 : _M_fun(std::move(__fun)), _M_base(std::move(__base))
1846 base() const& requires copy_constructible<_Vp>
1847 { return _M_base ; }
1851 { return std::move(_M_base); }
1853 constexpr _Iterator<false>
1855 { return _Iterator<false>{this, ranges::begin(_M_base)}; }
1857 constexpr _Iterator<true>
1859 requires range<const _Vp>
1860 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1861 { return _Iterator<true>{this, ranges::begin(_M_base)}; }
1863 constexpr _Sentinel<false>
1865 { return _Sentinel<false>{ranges::end(_M_base)}; }
1867 constexpr _Iterator<false>
1868 end() requires common_range<_Vp>
1869 { return _Iterator<false>{this, ranges::end(_M_base)}; }
1871 constexpr _Sentinel<true>
1873 requires range<const _Vp>
1874 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1875 { return _Sentinel<true>{ranges::end(_M_base)}; }
1877 constexpr _Iterator<true>
1879 requires common_range<const _Vp>
1880 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1881 { return _Iterator<true>{this, ranges::end(_M_base)}; }
1884 size() requires sized_range<_Vp>
1885 { return ranges::size(_M_base); }
1888 size() const requires sized_range<const _Vp>
1889 { return ranges::size(_M_base); }
1892 template<typename _Range, typename _Fp>
1893 transform_view(_Range&&, _Fp) -> transform_view<views::all_t<_Range>, _Fp>;
1899 template<typename _Range, typename _Fp>
1900 concept __can_transform_view
1901 = requires { transform_view(std::declval<_Range>(), std::declval<_Fp>()); };
1902 } // namespace __detail
1904 struct _Transform : __adaptor::_RangeAdaptor<_Transform>
1906 template<viewable_range _Range, typename _Fp>
1907 requires __detail::__can_transform_view<_Range, _Fp>
1909 operator()(_Range&& __r, _Fp&& __f) const
1911 return transform_view(std::forward<_Range>(__r), std::forward<_Fp>(__f));
1914 using _RangeAdaptor<_Transform>::operator();
1915 static constexpr int _S_arity = 2;
1916 static constexpr bool _S_has_simple_extra_args = true;
1919 inline constexpr _Transform transform;
1920 } // namespace views
1923 class take_view : public view_interface<take_view<_Vp>>
1926 template<bool _Const>
1927 using _CI = counted_iterator<
1928 iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>;
1930 template<bool _Const>
1934 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1935 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1938 _Sentinel() = default;
1941 _Sentinel(sentinel_t<_Base> __end)
1946 _Sentinel(_Sentinel<!_Const> __s)
1947 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1948 : _M_end(std::move(__s._M_end))
1951 constexpr sentinel_t<_Base>
1955 friend constexpr bool
1956 operator==(const _CI<_Const>& __y, const _Sentinel& __x)
1957 { return __y.count() == 0 || __y.base() == __x._M_end; }
1959 template<bool _OtherConst = !_Const,
1960 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
1961 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1962 friend constexpr bool
1963 operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x)
1964 { return __y.count() == 0 || __y.base() == __x._M_end; }
1966 friend _Sentinel<!_Const>;
1969 range_difference_t<_Vp> _M_count = 0;
1970 _Vp _M_base = _Vp();
1973 take_view() = default;
1976 take_view(_Vp base, range_difference_t<_Vp> __count)
1977 : _M_count(std::move(__count)), _M_base(std::move(base))
1981 base() const& requires copy_constructible<_Vp>
1986 { return std::move(_M_base); }
1989 begin() requires (!__detail::__simple_view<_Vp>)
1991 if constexpr (sized_range<_Vp>)
1993 if constexpr (random_access_range<_Vp>)
1994 return ranges::begin(_M_base);
1998 return counted_iterator(ranges::begin(_M_base), __sz);
2002 return counted_iterator(ranges::begin(_M_base), _M_count);
2006 begin() const requires range<const _Vp>
2008 if constexpr (sized_range<const _Vp>)
2010 if constexpr (random_access_range<const _Vp>)
2011 return ranges::begin(_M_base);
2015 return counted_iterator(ranges::begin(_M_base), __sz);
2019 return counted_iterator(ranges::begin(_M_base), _M_count);
2023 end() requires (!__detail::__simple_view<_Vp>)
2025 if constexpr (sized_range<_Vp>)
2027 if constexpr (random_access_range<_Vp>)
2028 return ranges::begin(_M_base) + size();
2030 return default_sentinel;
2033 return _Sentinel<false>{ranges::end(_M_base)};
2037 end() const requires range<const _Vp>
2039 if constexpr (sized_range<const _Vp>)
2041 if constexpr (random_access_range<const _Vp>)
2042 return ranges::begin(_M_base) + size();
2044 return default_sentinel;
2047 return _Sentinel<true>{ranges::end(_M_base)};
2051 size() requires sized_range<_Vp>
2053 auto __n = ranges::size(_M_base);
2054 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2058 size() const requires sized_range<const _Vp>
2060 auto __n = ranges::size(_M_base);
2061 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2065 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2066 // 3447. Deduction guides for take_view and drop_view have different
2068 template<typename _Range>
2069 take_view(_Range&&, range_difference_t<_Range>)
2070 -> take_view<views::all_t<_Range>>;
2072 template<typename _Tp>
2073 inline constexpr bool enable_borrowed_range<take_view<_Tp>>
2074 = enable_borrowed_range<_Tp>;
2080 template<typename _Range, typename _Tp>
2081 concept __can_take_view
2082 = requires { take_view(std::declval<_Range>(), std::declval<_Tp>()); };
2083 } // namespace __detail
2085 struct _Take : __adaptor::_RangeAdaptor<_Take>
2087 template<viewable_range _Range, typename _Tp>
2088 requires __detail::__can_take_view<_Range, _Tp>
2090 operator()(_Range&& __r, _Tp&& __n) const
2092 return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2095 using _RangeAdaptor<_Take>::operator();
2096 static constexpr int _S_arity = 2;
2097 static constexpr bool _S_has_simple_extra_args = true;
2100 inline constexpr _Take take;
2101 } // namespace views
2103 template<view _Vp, typename _Pred>
2104 requires input_range<_Vp> && is_object_v<_Pred>
2105 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2106 class take_while_view : public view_interface<take_while_view<_Vp, _Pred>>
2108 template<bool _Const>
2112 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2114 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2115 const _Pred* _M_pred = nullptr;
2118 _Sentinel() = default;
2121 _Sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
2122 : _M_end(__end), _M_pred(__pred)
2126 _Sentinel(_Sentinel<!_Const> __s)
2127 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2128 : _M_end(__s._M_end), _M_pred(__s._M_pred)
2131 constexpr sentinel_t<_Base>
2132 base() const { return _M_end; }
2134 friend constexpr bool
2135 operator==(const iterator_t<_Base>& __x, const _Sentinel& __y)
2136 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2138 template<bool _OtherConst = !_Const,
2139 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
2140 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
2141 friend constexpr bool
2142 operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y)
2143 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2145 friend _Sentinel<!_Const>;
2148 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2149 _Vp _M_base = _Vp();
2152 take_while_view() = default;
2155 take_while_view(_Vp base, _Pred __pred)
2156 : _M_pred(std::move(__pred)), _M_base(std::move(base))
2160 base() const& requires copy_constructible<_Vp>
2165 { return std::move(_M_base); }
2167 constexpr const _Pred&
2169 { return *_M_pred; }
2172 begin() requires (!__detail::__simple_view<_Vp>)
2173 { return ranges::begin(_M_base); }
2176 begin() const requires range<const _Vp>
2177 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2178 { return ranges::begin(_M_base); }
2181 end() requires (!__detail::__simple_view<_Vp>)
2182 { return _Sentinel<false>(ranges::end(_M_base),
2183 std::__addressof(*_M_pred)); }
2186 end() const requires range<const _Vp>
2187 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2188 { return _Sentinel<true>(ranges::end(_M_base),
2189 std::__addressof(*_M_pred)); }
2192 template<typename _Range, typename _Pred>
2193 take_while_view(_Range&&, _Pred)
2194 -> take_while_view<views::all_t<_Range>, _Pred>;
2200 template<typename _Range, typename _Pred>
2201 concept __can_take_while_view
2202 = requires { take_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2203 } // namespace __detail
2205 struct _TakeWhile : __adaptor::_RangeAdaptor<_TakeWhile>
2207 template<viewable_range _Range, typename _Pred>
2208 requires __detail::__can_take_while_view<_Range, _Pred>
2210 operator()(_Range&& __r, _Pred&& __p) const
2212 return take_while_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
2215 using _RangeAdaptor<_TakeWhile>::operator();
2216 static constexpr int _S_arity = 2;
2217 static constexpr bool _S_has_simple_extra_args = true;
2220 inline constexpr _TakeWhile take_while;
2221 } // namespace views
2224 class drop_view : public view_interface<drop_view<_Vp>>
2227 range_difference_t<_Vp> _M_count = 0;
2228 _Vp _M_base = _Vp();
2230 // ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
2231 // both random_access_range and sized_range. Otherwise, cache its result.
2232 static constexpr bool _S_needs_cached_begin
2233 = !(random_access_range<const _Vp> && sized_range<const _Vp>);
2234 [[no_unique_address]]
2235 __detail::__maybe_present_t<_S_needs_cached_begin,
2236 __detail::_CachedPosition<_Vp>>
2240 drop_view() = default;
2243 drop_view(_Vp __base, range_difference_t<_Vp> __count)
2244 : _M_count(__count), _M_base(std::move(__base))
2245 { __glibcxx_assert(__count >= 0); }
2248 base() const& requires copy_constructible<_Vp>
2253 { return std::move(_M_base); }
2255 // This overload is disabled for simple views with constant-time begin().
2258 requires (!(__detail::__simple_view<_Vp>
2259 && random_access_range<const _Vp>
2260 && sized_range<const _Vp>))
2262 if constexpr (_S_needs_cached_begin)
2263 if (_M_cached_begin._M_has_value())
2264 return _M_cached_begin._M_get(_M_base);
2266 auto __it = ranges::next(ranges::begin(_M_base),
2267 _M_count, ranges::end(_M_base));
2268 if constexpr (_S_needs_cached_begin)
2269 _M_cached_begin._M_set(_M_base, __it);
2273 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2274 // 3482. drop_view's const begin should additionally require sized_range
2277 requires random_access_range<const _Vp> && sized_range<const _Vp>
2279 return ranges::next(ranges::begin(_M_base), _M_count,
2280 ranges::end(_M_base));
2284 end() requires (!__detail::__simple_view<_Vp>)
2285 { return ranges::end(_M_base); }
2288 end() const requires range<const _Vp>
2289 { return ranges::end(_M_base); }
2292 size() requires sized_range<_Vp>
2294 const auto __s = ranges::size(_M_base);
2295 const auto __c = static_cast<decltype(__s)>(_M_count);
2296 return __s < __c ? 0 : __s - __c;
2300 size() const requires sized_range<const _Vp>
2302 const auto __s = ranges::size(_M_base);
2303 const auto __c = static_cast<decltype(__s)>(_M_count);
2304 return __s < __c ? 0 : __s - __c;
2308 template<typename _Range>
2309 drop_view(_Range&&, range_difference_t<_Range>)
2310 -> drop_view<views::all_t<_Range>>;
2312 template<typename _Tp>
2313 inline constexpr bool enable_borrowed_range<drop_view<_Tp>>
2314 = enable_borrowed_range<_Tp>;
2320 template<typename _Range, typename _Tp>
2321 concept __can_drop_view
2322 = requires { drop_view(std::declval<_Range>(), std::declval<_Tp>()); };
2323 } // namespace __detail
2325 struct _Drop : __adaptor::_RangeAdaptor<_Drop>
2327 template<viewable_range _Range, typename _Tp>
2328 requires __detail::__can_drop_view<_Range, _Tp>
2330 operator()(_Range&& __r, _Tp&& __n) const
2332 return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2335 using _RangeAdaptor<_Drop>::operator();
2336 static constexpr int _S_arity = 2;
2337 static constexpr bool _S_has_simple_extra_args = true;
2340 inline constexpr _Drop drop;
2341 } // namespace views
2343 template<view _Vp, typename _Pred>
2344 requires input_range<_Vp> && is_object_v<_Pred>
2345 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2346 class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
2349 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2350 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
2351 _Vp _M_base = _Vp();
2354 drop_while_view() = default;
2357 drop_while_view(_Vp __base, _Pred __pred)
2358 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
2362 base() const& requires copy_constructible<_Vp>
2367 { return std::move(_M_base); }
2369 constexpr const _Pred&
2371 { return *_M_pred; }
2376 if (_M_cached_begin._M_has_value())
2377 return _M_cached_begin._M_get(_M_base);
2379 __glibcxx_assert(_M_pred.has_value());
2380 auto __it = __detail::find_if_not(ranges::begin(_M_base),
2381 ranges::end(_M_base),
2382 std::cref(*_M_pred));
2383 _M_cached_begin._M_set(_M_base, __it);
2389 { return ranges::end(_M_base); }
2392 template<typename _Range, typename _Pred>
2393 drop_while_view(_Range&&, _Pred)
2394 -> drop_while_view<views::all_t<_Range>, _Pred>;
2396 template<typename _Tp, typename _Pred>
2397 inline constexpr bool enable_borrowed_range<drop_while_view<_Tp, _Pred>>
2398 = enable_borrowed_range<_Tp>;
2404 template<typename _Range, typename _Pred>
2405 concept __can_drop_while_view
2406 = requires { drop_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2407 } // namespace __detail
2409 struct _DropWhile : __adaptor::_RangeAdaptor<_DropWhile>
2411 template<viewable_range _Range, typename _Pred>
2412 requires __detail::__can_drop_while_view<_Range, _Pred>
2414 operator()(_Range&& __r, _Pred&& __p) const
2416 return drop_while_view(std::forward<_Range>(__r),
2417 std::forward<_Pred>(__p));
2420 using _RangeAdaptor<_DropWhile>::operator();
2421 static constexpr int _S_arity = 2;
2422 static constexpr bool _S_has_simple_extra_args = true;
2425 inline constexpr _DropWhile drop_while;
2426 } // namespace views
2428 template<input_range _Vp>
2429 requires view<_Vp> && input_range<range_reference_t<_Vp>>
2430 class join_view : public view_interface<join_view<_Vp>>
2433 using _InnerRange = range_reference_t<_Vp>;
2435 template<bool _Const>
2436 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2438 template<bool _Const>
2439 using _Outer_iter = iterator_t<_Base<_Const>>;
2441 template<bool _Const>
2442 using _Inner_iter = iterator_t<range_reference_t<_Base<_Const>>>;
2444 template<bool _Const>
2445 static constexpr bool _S_ref_is_glvalue
2446 = is_reference_v<range_reference_t<_Base<_Const>>>;
2448 template<bool _Const>
2452 template<bool _Const>
2453 requires _S_ref_is_glvalue<_Const>
2454 && forward_range<_Base<_Const>>
2455 && forward_range<range_reference_t<_Base<_Const>>>
2456 struct __iter_cat<_Const>
2459 static constexpr auto
2462 using _Outer_iter = join_view::_Outer_iter<_Const>;
2463 using _Inner_iter = join_view::_Inner_iter<_Const>;
2464 using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
2465 using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
2466 if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
2467 && derived_from<_InnerCat, bidirectional_iterator_tag>)
2468 return bidirectional_iterator_tag{};
2469 else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
2470 && derived_from<_InnerCat, forward_iterator_tag>)
2471 return forward_iterator_tag{};
2473 return input_iterator_tag{};
2476 using iterator_category = decltype(_S_iter_cat());
2479 template<bool _Const>
2482 template<bool _Const>
2483 struct _Iterator : __iter_cat<_Const>
2486 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2487 using _Base = join_view::_Base<_Const>;
2489 static constexpr bool _S_ref_is_glvalue
2490 = join_view::_S_ref_is_glvalue<_Const>;
2495 auto __update_inner = [this] (const iterator_t<_Base>& __x) -> auto&& {
2496 if constexpr (_S_ref_is_glvalue)
2499 return _M_parent->_M_inner._M_emplace_deref(__x);
2502 for (; _M_outer != ranges::end(_M_parent->_M_base); ++_M_outer)
2504 auto&& __inner = __update_inner(_M_outer);
2505 _M_inner = ranges::begin(__inner);
2506 if (_M_inner != ranges::end(__inner))
2510 if constexpr (_S_ref_is_glvalue)
2511 _M_inner = _Inner_iter();
2514 static constexpr auto
2517 if constexpr (_S_ref_is_glvalue
2518 && bidirectional_range<_Base>
2519 && bidirectional_range<range_reference_t<_Base>>)
2520 return bidirectional_iterator_tag{};
2521 else if constexpr (_S_ref_is_glvalue
2522 && forward_range<_Base>
2523 && forward_range<range_reference_t<_Base>>)
2524 return forward_iterator_tag{};
2526 return input_iterator_tag{};
2529 using _Outer_iter = join_view::_Outer_iter<_Const>;
2530 using _Inner_iter = join_view::_Inner_iter<_Const>;
2532 _Outer_iter _M_outer = _Outer_iter();
2533 _Inner_iter _M_inner = _Inner_iter();
2534 _Parent* _M_parent = nullptr;
2537 using iterator_concept = decltype(_S_iter_concept());
2538 // iterator_category defined in __join_view_iter_cat
2539 using value_type = range_value_t<range_reference_t<_Base>>;
2540 using difference_type
2541 = common_type_t<range_difference_t<_Base>,
2542 range_difference_t<range_reference_t<_Base>>>;
2544 _Iterator() = default;
2547 _Iterator(_Parent* __parent, _Outer_iter __outer)
2548 : _M_outer(std::move(__outer)),
2553 _Iterator(_Iterator<!_Const> __i)
2555 && convertible_to<iterator_t<_Vp>, _Outer_iter>
2556 && convertible_to<iterator_t<_InnerRange>, _Inner_iter>
2557 : _M_outer(std::move(__i._M_outer)), _M_inner(__i._M_inner),
2558 _M_parent(__i._M_parent)
2561 constexpr decltype(auto)
2563 { return *_M_inner; }
2565 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2566 // 3500. join_view::iterator::operator->() is bogus
2567 constexpr _Inner_iter
2569 requires __detail::__has_arrow<_Inner_iter>
2570 && copyable<_Inner_iter>
2571 { return _M_inner; }
2573 constexpr _Iterator&
2576 auto&& __inner_range = [this] () -> auto&& {
2577 if constexpr (_S_ref_is_glvalue)
2580 return *_M_parent->_M_inner;
2582 if (++_M_inner == ranges::end(__inner_range))
2596 requires _S_ref_is_glvalue && forward_range<_Base>
2597 && forward_range<range_reference_t<_Base>>
2604 constexpr _Iterator&
2606 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2607 && bidirectional_range<range_reference_t<_Base>>
2608 && common_range<range_reference_t<_Base>>
2610 if (_M_outer == ranges::end(_M_parent->_M_base))
2611 _M_inner = ranges::end(*--_M_outer);
2612 while (_M_inner == ranges::begin(*_M_outer))
2613 _M_inner = ranges::end(*--_M_outer);
2620 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2621 && bidirectional_range<range_reference_t<_Base>>
2622 && common_range<range_reference_t<_Base>>
2629 friend constexpr bool
2630 operator==(const _Iterator& __x, const _Iterator& __y)
2631 requires _S_ref_is_glvalue
2632 && equality_comparable<_Outer_iter>
2633 && equality_comparable<_Inner_iter>
2635 return (__x._M_outer == __y._M_outer
2636 && __x._M_inner == __y._M_inner);
2639 friend constexpr decltype(auto)
2640 iter_move(const _Iterator& __i)
2641 noexcept(noexcept(ranges::iter_move(__i._M_inner)))
2642 { return ranges::iter_move(__i._M_inner); }
2644 friend constexpr void
2645 iter_swap(const _Iterator& __x, const _Iterator& __y)
2646 noexcept(noexcept(ranges::iter_swap(__x._M_inner, __y._M_inner)))
2647 requires indirectly_swappable<_Inner_iter>
2648 { return ranges::iter_swap(__x._M_inner, __y._M_inner); }
2650 friend _Iterator<!_Const>;
2651 template<bool> friend struct _Sentinel;
2654 template<bool _Const>
2658 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2659 using _Base = join_view::_Base<_Const>;
2661 template<bool _Const2>
2663 __equal(const _Iterator<_Const2>& __i) const
2664 { return __i._M_outer == _M_end; }
2666 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2669 _Sentinel() = default;
2672 _Sentinel(_Parent* __parent)
2673 : _M_end(ranges::end(__parent->_M_base))
2677 _Sentinel(_Sentinel<!_Const> __s)
2678 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2679 : _M_end(std::move(__s._M_end))
2682 template<bool _Const2>
2683 requires sentinel_for<sentinel_t<_Base>,
2684 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
2685 friend constexpr bool
2686 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
2687 { return __y.__equal(__x); }
2689 friend _Sentinel<!_Const>;
2692 [[no_unique_address]]
2693 __detail::__non_propagating_cache<remove_cv_t<_InnerRange>> _M_inner;
2694 _Vp _M_base = _Vp();
2697 join_view() = default;
2700 join_view(_Vp __base)
2701 : _M_base(std::move(__base))
2705 base() const& requires copy_constructible<_Vp>
2710 { return std::move(_M_base); }
2715 constexpr bool __use_const
2716 = (__detail::__simple_view<_Vp>
2717 && is_reference_v<range_reference_t<_Vp>>);
2718 return _Iterator<__use_const>{this, ranges::begin(_M_base)};
2723 requires input_range<const _Vp>
2724 && is_reference_v<range_reference_t<const _Vp>>
2726 return _Iterator<true>{this, ranges::begin(_M_base)};
2732 if constexpr (forward_range<_Vp> && is_reference_v<_InnerRange>
2733 && forward_range<_InnerRange>
2734 && common_range<_Vp> && common_range<_InnerRange>)
2735 return _Iterator<__detail::__simple_view<_Vp>>{this,
2736 ranges::end(_M_base)};
2738 return _Sentinel<__detail::__simple_view<_Vp>>{this};
2743 requires input_range<const _Vp>
2744 && is_reference_v<range_reference_t<const _Vp>>
2746 if constexpr (forward_range<const _Vp>
2747 && is_reference_v<range_reference_t<const _Vp>>
2748 && forward_range<range_reference_t<const _Vp>>
2749 && common_range<const _Vp>
2750 && common_range<range_reference_t<const _Vp>>)
2751 return _Iterator<true>{this, ranges::end(_M_base)};
2753 return _Sentinel<true>{this};
2757 template<typename _Range>
2758 explicit join_view(_Range&&) -> join_view<views::all_t<_Range>>;
2764 template<typename _Range>
2765 concept __can_join_view
2766 = requires { join_view<all_t<_Range>>{std::declval<_Range>()}; };
2767 } // namespace __detail
2769 struct _Join : __adaptor::_RangeAdaptorClosure
2771 template<viewable_range _Range>
2772 requires __detail::__can_join_view<_Range>
2774 operator()(_Range&& __r) const
2776 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2777 // 3474. Nesting join_views is broken because of CTAD
2778 return join_view<all_t<_Range>>{std::forward<_Range>(__r)};
2781 static constexpr bool _S_has_simple_call_op = true;
2784 inline constexpr _Join join;
2785 } // namespace views
2790 struct __require_constant;
2792 template<typename _Range>
2793 concept __tiny_range = sized_range<_Range>
2795 { typename __require_constant<remove_reference_t<_Range>::size()>; }
2796 && (remove_reference_t<_Range>::size() <= 1);
2798 template<typename _Base>
2799 struct __split_view_outer_iter_cat
2802 template<forward_range _Base>
2803 struct __split_view_outer_iter_cat<_Base>
2804 { using iterator_category = input_iterator_tag; };
2806 template<typename _Base>
2807 struct __split_view_inner_iter_cat
2810 template<forward_range _Base>
2811 struct __split_view_inner_iter_cat<_Base>
2814 static constexpr auto
2817 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
2818 if constexpr (derived_from<_Cat, forward_iterator_tag>)
2819 return forward_iterator_tag{};
2824 using iterator_category = decltype(_S_iter_cat());
2828 template<input_range _Vp, forward_range _Pattern>
2829 requires view<_Vp> && view<_Pattern>
2830 && indirectly_comparable<iterator_t<_Vp>, iterator_t<_Pattern>,
2832 && (forward_range<_Vp> || __detail::__tiny_range<_Pattern>)
2833 class split_view : public view_interface<split_view<_Vp, _Pattern>>
2836 template<bool _Const>
2837 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2839 template<bool _Const>
2842 template<bool _Const>
2844 : __detail::__split_view_outer_iter_cat<_Base<_Const>>
2847 using _Parent = __detail::__maybe_const_t<_Const, split_view>;
2848 using _Base = split_view::_Base<_Const>;
2852 { return __current() == ranges::end(_M_parent->_M_base); }
2854 // [range.split.outer] p1
2855 // Many of the following specifications refer to the notional member
2856 // current of outer-iterator. current is equivalent to current_ if
2857 // V models forward_range, and parent_->current_ otherwise.
2859 __current() noexcept
2861 if constexpr (forward_range<_Vp>)
2864 return _M_parent->_M_current;
2868 __current() const noexcept
2870 if constexpr (forward_range<_Vp>)
2873 return _M_parent->_M_current;
2876 _Parent* _M_parent = nullptr;
2878 // XXX: _M_current is present only if "V models forward_range"
2879 [[no_unique_address]]
2880 __detail::__maybe_present_t<forward_range<_Vp>,
2881 iterator_t<_Base>> _M_current;
2884 using iterator_concept = conditional_t<forward_range<_Base>,
2885 forward_iterator_tag,
2886 input_iterator_tag>;
2887 // iterator_category defined in __split_view_outer_iter_cat
2888 using difference_type = range_difference_t<_Base>;
2890 struct value_type : view_interface<value_type>
2893 _OuterIter _M_i = _OuterIter();
2896 value_type() = default;
2899 value_type(_OuterIter __i)
2900 : _M_i(std::move(__i))
2903 constexpr _InnerIter<_Const>
2905 requires copyable<_OuterIter>
2906 { return _InnerIter<_Const>{_M_i}; }
2908 constexpr _InnerIter<_Const>
2910 requires (!copyable<_OuterIter>)
2911 { return _InnerIter<_Const>{std::move(_M_i)}; }
2913 constexpr default_sentinel_t
2915 { return default_sentinel; }
2918 _OuterIter() = default;
2921 _OuterIter(_Parent* __parent) requires (!forward_range<_Base>)
2922 : _M_parent(__parent)
2926 _OuterIter(_Parent* __parent, iterator_t<_Base> __current)
2927 requires forward_range<_Base>
2928 : _M_parent(__parent),
2929 _M_current(std::move(__current))
2933 _OuterIter(_OuterIter<!_Const> __i)
2935 && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
2936 : _M_parent(__i._M_parent), _M_current(std::move(__i._M_current))
2939 constexpr value_type
2941 { return value_type{*this}; }
2943 constexpr _OuterIter&
2946 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2947 // 3505. split_view::outer-iterator::operator++ misspecified
2948 const auto __end = ranges::end(_M_parent->_M_base);
2949 if (__current() == __end)
2951 const auto [__pbegin, __pend] = subrange{_M_parent->_M_pattern};
2952 if (__pbegin == __pend)
2954 else if constexpr (__detail::__tiny_range<_Pattern>)
2956 __current() = __detail::find(std::move(__current()), __end,
2958 if (__current() != __end)
2965 = __detail::mismatch(__current(), __end, __pbegin, __pend);
2971 } while (++__current() != __end);
2975 constexpr decltype(auto)
2978 if constexpr (forward_range<_Base>)
2988 friend constexpr bool
2989 operator==(const _OuterIter& __x, const _OuterIter& __y)
2990 requires forward_range<_Base>
2991 { return __x._M_current == __y._M_current; }
2993 friend constexpr bool
2994 operator==(const _OuterIter& __x, default_sentinel_t)
2995 { return __x.__at_end(); };
2997 friend _OuterIter<!_Const>;
2998 friend _InnerIter<_Const>;
3001 template<bool _Const>
3003 : __detail::__split_view_inner_iter_cat<_Base<_Const>>
3006 using _Base = split_view::_Base<_Const>;
3011 auto [__pcur, __pend] = subrange{_M_i._M_parent->_M_pattern};
3012 auto __end = ranges::end(_M_i._M_parent->_M_base);
3013 if constexpr (__detail::__tiny_range<_Pattern>)
3015 const auto& __cur = _M_i_current();
3018 if (__pcur == __pend)
3019 return _M_incremented;
3020 return *__cur == *__pcur;
3024 auto __cur = _M_i_current();
3027 if (__pcur == __pend)
3028 return _M_incremented;
3031 if (*__cur != *__pcur)
3033 if (++__pcur == __pend)
3035 } while (++__cur != __end);
3041 _M_i_current() noexcept
3042 { return _M_i.__current(); }
3045 _M_i_current() const noexcept
3046 { return _M_i.__current(); }
3048 _OuterIter<_Const> _M_i = _OuterIter<_Const>();
3049 bool _M_incremented = false;
3052 using iterator_concept
3053 = typename _OuterIter<_Const>::iterator_concept;
3054 // iterator_category defined in __split_view_inner_iter_cat
3055 using value_type = range_value_t<_Base>;
3056 using difference_type = range_difference_t<_Base>;
3058 _InnerIter() = default;
3061 _InnerIter(_OuterIter<_Const> __i)
3062 : _M_i(std::move(__i))
3065 constexpr decltype(auto)
3067 { return *_M_i_current(); }
3069 constexpr _InnerIter&
3072 _M_incremented = true;
3073 if constexpr (!forward_range<_Base>)
3074 if constexpr (_Pattern::size() == 0)
3080 constexpr decltype(auto)
3083 if constexpr (forward_range<_Base>)
3093 friend constexpr bool
3094 operator==(const _InnerIter& __x, const _InnerIter& __y)
3095 requires forward_range<_Base>
3096 { return __x._M_i == __y._M_i; }
3098 friend constexpr bool
3099 operator==(const _InnerIter& __x, default_sentinel_t)
3100 { return __x.__at_end(); }
3102 friend constexpr decltype(auto)
3103 iter_move(const _InnerIter& __i)
3104 noexcept(noexcept(ranges::iter_move(__i._M_i_current())))
3105 { return ranges::iter_move(__i._M_i_current()); }
3107 friend constexpr void
3108 iter_swap(const _InnerIter& __x, const _InnerIter& __y)
3109 noexcept(noexcept(ranges::iter_swap(__x._M_i_current(),
3110 __y._M_i_current())))
3111 requires indirectly_swappable<iterator_t<_Base>>
3112 { ranges::iter_swap(__x._M_i_current(), __y._M_i_current()); }
3115 _Pattern _M_pattern = _Pattern();
3116 // XXX: _M_current is "present only if !forward_range<V>"
3117 [[no_unique_address]]
3118 __detail::__maybe_present_t<!forward_range<_Vp>,
3119 iterator_t<_Vp>> _M_current;
3120 _Vp _M_base = _Vp();
3124 split_view() = default;
3127 split_view(_Vp __base, _Pattern __pattern)
3128 : _M_pattern(std::move(__pattern)), _M_base(std::move(__base))
3131 template<input_range _Range>
3132 requires constructible_from<_Vp, views::all_t<_Range>>
3133 && constructible_from<_Pattern, single_view<range_value_t<_Range>>>
3135 split_view(_Range&& __r, range_value_t<_Range> __e)
3136 : _M_pattern(views::single(std::move(__e))),
3137 _M_base(views::all(std::forward<_Range>(__r)))
3141 base() const& requires copy_constructible<_Vp>
3146 { return std::move(_M_base); }
3151 if constexpr (forward_range<_Vp>)
3152 return _OuterIter<__detail::__simple_view<_Vp>>{
3153 this, ranges::begin(_M_base)};
3156 _M_current = ranges::begin(_M_base);
3157 return _OuterIter<false>{this};
3162 begin() const requires forward_range<_Vp> && forward_range<const _Vp>
3164 return _OuterIter<true>{this, ranges::begin(_M_base)};
3168 end() requires forward_range<_Vp> && common_range<_Vp>
3170 return _OuterIter<__detail::__simple_view<_Vp>>{
3171 this, ranges::end(_M_base)};
3177 if constexpr (forward_range<_Vp>
3178 && forward_range<const _Vp>
3179 && common_range<const _Vp>)
3180 return _OuterIter<true>{this, ranges::end(_M_base)};
3182 return default_sentinel;
3186 template<typename _Range, typename _Pattern>
3187 split_view(_Range&&, _Pattern&&)
3188 -> split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
3190 template<input_range _Range>
3191 split_view(_Range&&, range_value_t<_Range>)
3192 -> split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
3198 template<typename _Range, typename _Pattern>
3199 concept __can_split_view
3200 = requires { split_view(std::declval<_Range>(), std::declval<_Pattern>()); };
3201 } // namespace __detail
3203 struct _Split : __adaptor::_RangeAdaptor<_Split>
3205 template<viewable_range _Range, typename _Pattern>
3206 requires __detail::__can_split_view<_Range, _Pattern>
3208 operator()(_Range&& __r, _Pattern&& __f) const
3210 return split_view(std::forward<_Range>(__r), std::forward<_Pattern>(__f));
3213 using _RangeAdaptor<_Split>::operator();
3214 static constexpr int _S_arity = 2;
3215 // The second argument of views::split is _not_ simple -- it can be a
3216 // non-view range, the value category of which affects whether the call is
3217 // well-formed. So we must not define _S_has_simple_extra_args to true.
3220 inline constexpr _Split split;
3221 } // namespace views
3227 template<input_or_output_iterator _Iter>
3229 operator()(_Iter __i, iter_difference_t<_Iter> __n) const
3231 if constexpr (random_access_iterator<_Iter>)
3232 return subrange(__i, __i + __n);
3234 return subrange(counted_iterator(std::move(__i), __n),
3239 inline constexpr _Counted counted{};
3240 } // namespace views
3243 requires (!common_range<_Vp>) && copyable<iterator_t<_Vp>>
3244 class common_view : public view_interface<common_view<_Vp>>
3247 _Vp _M_base = _Vp();
3250 common_view() = default;
3253 common_view(_Vp __r)
3254 : _M_base(std::move(__r))
3257 /* XXX: LWG 3280 didn't remove this constructor, but I think it should?
3258 template<viewable_range _Range>
3259 requires (!common_range<_Range>)
3260 && constructible_from<_Vp, views::all_t<_Range>>
3262 common_view(_Range&& __r)
3263 : _M_base(views::all(std::forward<_Range>(__r)))
3268 base() const& requires copy_constructible<_Vp>
3273 { return std::move(_M_base); }
3278 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3279 return ranges::begin(_M_base);
3281 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3282 (ranges::begin(_M_base));
3286 begin() const requires range<const _Vp>
3288 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3289 return ranges::begin(_M_base);
3291 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3292 (ranges::begin(_M_base));
3298 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3299 return ranges::begin(_M_base) + ranges::size(_M_base);
3301 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3302 (ranges::end(_M_base));
3306 end() const requires range<const _Vp>
3308 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3309 return ranges::begin(_M_base) + ranges::size(_M_base);
3311 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3312 (ranges::end(_M_base));
3316 size() requires sized_range<_Vp>
3317 { return ranges::size(_M_base); }
3320 size() const requires sized_range<const _Vp>
3321 { return ranges::size(_M_base); }
3324 template<typename _Range>
3325 common_view(_Range&&) -> common_view<views::all_t<_Range>>;
3327 template<typename _Tp>
3328 inline constexpr bool enable_borrowed_range<common_view<_Tp>>
3329 = enable_borrowed_range<_Tp>;
3335 template<typename _Range>
3336 concept __already_common = common_range<_Range>
3337 && requires { views::all(std::declval<_Range>()); };
3339 template<typename _Range>
3340 concept __can_common_view
3341 = requires { common_view{std::declval<_Range>()}; };
3342 } // namespace __detail
3344 struct _Common : __adaptor::_RangeAdaptorClosure
3346 template<viewable_range _Range>
3347 requires __detail::__already_common<_Range>
3348 || __detail::__can_common_view<_Range>
3350 operator()(_Range&& __r) const
3352 if constexpr (__detail::__already_common<_Range>)
3353 return views::all(std::forward<_Range>(__r));
3355 return common_view{std::forward<_Range>(__r)};
3358 static constexpr bool _S_has_simple_call_op = true;
3361 inline constexpr _Common common;
3362 } // namespace views
3365 requires bidirectional_range<_Vp>
3366 class reverse_view : public view_interface<reverse_view<_Vp>>
3369 static constexpr bool _S_needs_cached_begin
3370 = !common_range<_Vp> && !(random_access_range<_Vp>
3371 && sized_sentinel_for<sentinel_t<_Vp>,
3374 [[no_unique_address]]
3375 __detail::__maybe_present_t<_S_needs_cached_begin,
3376 __detail::_CachedPosition<_Vp>>
3378 _Vp _M_base = _Vp();
3381 reverse_view() = default;
3384 reverse_view(_Vp __r)
3385 : _M_base(std::move(__r))
3389 base() const& requires copy_constructible<_Vp>
3394 { return std::move(_M_base); }
3396 constexpr reverse_iterator<iterator_t<_Vp>>
3399 if constexpr (_S_needs_cached_begin)
3400 if (_M_cached_begin._M_has_value())
3401 return std::make_reverse_iterator(_M_cached_begin._M_get(_M_base));
3403 auto __it = ranges::next(ranges::begin(_M_base), ranges::end(_M_base));
3404 if constexpr (_S_needs_cached_begin)
3405 _M_cached_begin._M_set(_M_base, __it);
3406 return std::make_reverse_iterator(std::move(__it));
3410 begin() requires common_range<_Vp>
3411 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3414 begin() const requires common_range<const _Vp>
3415 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3417 constexpr reverse_iterator<iterator_t<_Vp>>
3419 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3422 end() const requires common_range<const _Vp>
3423 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3426 size() requires sized_range<_Vp>
3427 { return ranges::size(_M_base); }
3430 size() const requires sized_range<const _Vp>
3431 { return ranges::size(_M_base); }
3434 template<typename _Range>
3435 reverse_view(_Range&&) -> reverse_view<views::all_t<_Range>>;
3437 template<typename _Tp>
3438 inline constexpr bool enable_borrowed_range<reverse_view<_Tp>>
3439 = enable_borrowed_range<_Tp>;
3446 inline constexpr bool __is_reversible_subrange = false;
3448 template<typename _Iter, subrange_kind _Kind>
3449 inline constexpr bool
3450 __is_reversible_subrange<subrange<reverse_iterator<_Iter>,
3451 reverse_iterator<_Iter>,
3455 inline constexpr bool __is_reverse_view = false;
3457 template<typename _Vp>
3458 inline constexpr bool __is_reverse_view<reverse_view<_Vp>> = true;
3460 template<typename _Range>
3461 concept __can_reverse_view
3462 = requires { reverse_view{std::declval<_Range>()}; };
3463 } // namespace __detail
3465 struct _Reverse : __adaptor::_RangeAdaptorClosure
3467 template<viewable_range _Range>
3468 requires __detail::__is_reverse_view<remove_cvref_t<_Range>>
3469 || __detail::__is_reversible_subrange<remove_cvref_t<_Range>>
3470 || __detail::__can_reverse_view<_Range>
3472 operator()(_Range&& __r) const
3474 using _Tp = remove_cvref_t<_Range>;
3475 if constexpr (__detail::__is_reverse_view<_Tp>)
3476 return std::forward<_Range>(__r).base();
3477 else if constexpr (__detail::__is_reversible_subrange<_Tp>)
3479 using _Iter = decltype(ranges::begin(__r).base());
3480 if constexpr (sized_range<_Tp>)
3481 return subrange<_Iter, _Iter, subrange_kind::sized>
3482 {__r.end().base(), __r.begin().base(), __r.size()};
3484 return subrange<_Iter, _Iter, subrange_kind::unsized>
3485 {__r.end().base(), __r.begin().base()};
3488 return reverse_view{std::forward<_Range>(__r)};
3491 static constexpr bool _S_has_simple_call_op = true;
3494 inline constexpr _Reverse reverse;
3495 } // namespace views
3499 template<typename _Tp, size_t _Nm>
3500 concept __has_tuple_element = requires(_Tp __t)
3502 typename tuple_size<_Tp>::type;
3503 requires _Nm < tuple_size_v<_Tp>;
3504 typename tuple_element_t<_Nm, _Tp>;
3505 { std::get<_Nm>(__t) }
3506 -> convertible_to<const tuple_element_t<_Nm, _Tp>&>;
3509 template<typename _Tp, size_t _Nm>
3510 concept __returnable_element
3511 = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Nm, _Tp>>;
3514 template<input_range _Vp, size_t _Nm>
3516 && __detail::__has_tuple_element<range_value_t<_Vp>, _Nm>
3517 && __detail::__has_tuple_element<remove_reference_t<range_reference_t<_Vp>>,
3519 && __detail::__returnable_element<range_reference_t<_Vp>, _Nm>
3520 class elements_view : public view_interface<elements_view<_Vp, _Nm>>
3523 elements_view() = default;
3526 elements_view(_Vp base)
3527 : _M_base(std::move(base))
3530 constexpr const _Vp&
3531 base() const & noexcept
3536 { return std::move(_M_base); }
3539 begin() requires (!__detail::__simple_view<_Vp>)
3540 { return _Iterator<false>(ranges::begin(_M_base)); }
3543 begin() const requires range<const _Vp>
3544 { return _Iterator<true>(ranges::begin(_M_base)); }
3547 end() requires (!__detail::__simple_view<_Vp> && !common_range<_Vp>)
3548 { return _Sentinel<false>{ranges::end(_M_base)}; }
3551 end() requires (!__detail::__simple_view<_Vp> && common_range<_Vp>)
3552 { return _Iterator<false>{ranges::end(_M_base)}; }
3555 end() const requires range<const _Vp>
3556 { return _Sentinel<true>{ranges::end(_M_base)}; }
3559 end() const requires common_range<const _Vp>
3560 { return _Iterator<true>{ranges::end(_M_base)}; }
3563 size() requires sized_range<_Vp>
3564 { return ranges::size(_M_base); }
3567 size() const requires sized_range<const _Vp>
3568 { return ranges::size(_M_base); }
3571 template<bool _Const>
3572 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
3574 template<bool _Const>
3578 template<bool _Const>
3579 requires forward_range<_Base<_Const>>
3580 struct __iter_cat<_Const>
3583 static auto _S_iter_cat()
3585 using _Base = elements_view::_Base<_Const>;
3586 using _Cat = iterator_traits<iterator_t<_Base>>::iterator_category;
3587 using _Res = decltype((std::get<_Nm>(*std::declval<iterator_t<_Base>>())));
3588 if constexpr (!is_lvalue_reference_v<_Res>)
3589 return input_iterator_tag{};
3590 else if constexpr (derived_from<_Cat, random_access_iterator_tag>)
3591 return random_access_iterator_tag{};
3596 using iterator_category = decltype(_S_iter_cat());
3599 template<bool _Const>
3602 template<bool _Const>
3603 struct _Iterator : __iter_cat<_Const>
3606 using _Base = elements_view::_Base<_Const>;
3608 iterator_t<_Base> _M_current = iterator_t<_Base>();
3610 static constexpr decltype(auto)
3611 _S_get_element(const iterator_t<_Base>& __i)
3613 if constexpr (is_reference_v<range_reference_t<_Base>>)
3614 return std::get<_Nm>(*__i);
3617 using _Et = remove_cv_t<tuple_element_t<_Nm, range_reference_t<_Base>>>;
3618 return static_cast<_Et>(std::get<_Nm>(*__i));
3625 if constexpr (random_access_range<_Vp>)
3626 return random_access_iterator_tag{};
3627 else if constexpr (bidirectional_range<_Vp>)
3628 return bidirectional_iterator_tag{};
3629 else if constexpr (forward_range<_Vp>)
3630 return forward_iterator_tag{};
3632 return input_iterator_tag{};
3635 friend _Iterator<!_Const>;
3638 using iterator_concept = decltype(_S_iter_concept());
3639 // iterator_category defined in elements_view::__iter_cat
3641 = remove_cvref_t<tuple_element_t<_Nm, range_value_t<_Base>>>;
3642 using difference_type = range_difference_t<_Base>;
3644 _Iterator() = default;
3647 _Iterator(iterator_t<_Base> current)
3648 : _M_current(std::move(current))
3652 _Iterator(_Iterator<!_Const> i)
3653 requires _Const && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
3654 : _M_current(std::move(i._M_current))
3657 constexpr iterator_t<_Base>
3659 requires copyable<iterator_t<_Base>>
3660 { return _M_current; }
3662 constexpr iterator_t<_Base>
3664 { return std::move(_M_current); }
3666 constexpr decltype(auto)
3668 { return _S_get_element(_M_current); }
3670 constexpr _Iterator&
3682 operator++(int) requires forward_range<_Base>
3689 constexpr _Iterator&
3690 operator--() requires bidirectional_range<_Base>
3697 operator--(int) requires bidirectional_range<_Base>
3704 constexpr _Iterator&
3705 operator+=(difference_type __n)
3706 requires random_access_range<_Base>
3712 constexpr _Iterator&
3713 operator-=(difference_type __n)
3714 requires random_access_range<_Base>
3720 constexpr decltype(auto)
3721 operator[](difference_type __n) const
3722 requires random_access_range<_Base>
3723 { return _S_get_element(_M_current + __n); }
3725 friend constexpr bool
3726 operator==(const _Iterator& __x, const _Iterator& __y)
3727 requires equality_comparable<iterator_t<_Base>>
3728 { return __x._M_current == __y._M_current; }
3730 friend constexpr bool
3731 operator<(const _Iterator& __x, const _Iterator& __y)
3732 requires random_access_range<_Base>
3733 { return __x._M_current < __y._M_current; }
3735 friend constexpr bool
3736 operator>(const _Iterator& __x, const _Iterator& __y)
3737 requires random_access_range<_Base>
3738 { return __y._M_current < __x._M_current; }
3740 friend constexpr bool
3741 operator<=(const _Iterator& __x, const _Iterator& __y)
3742 requires random_access_range<_Base>
3743 { return !(__y._M_current > __x._M_current); }
3745 friend constexpr bool
3746 operator>=(const _Iterator& __x, const _Iterator& __y)
3747 requires random_access_range<_Base>
3748 { return !(__x._M_current > __y._M_current); }
3750 #ifdef __cpp_lib_three_way_comparison
3751 friend constexpr auto
3752 operator<=>(const _Iterator& __x, const _Iterator& __y)
3753 requires random_access_range<_Base>
3754 && three_way_comparable<iterator_t<_Base>>
3755 { return __x._M_current <=> __y._M_current; }
3758 friend constexpr _Iterator
3759 operator+(const _Iterator& __x, difference_type __y)
3760 requires random_access_range<_Base>
3761 { return _Iterator{__x} += __y; }
3763 friend constexpr _Iterator
3764 operator+(difference_type __x, const _Iterator& __y)
3765 requires random_access_range<_Base>
3766 { return __y + __x; }
3768 friend constexpr _Iterator
3769 operator-(const _Iterator& __x, difference_type __y)
3770 requires random_access_range<_Base>
3771 { return _Iterator{__x} -= __y; }
3773 // _GLIBCXX_RESOLVE_LIB_DEFECTS
3774 // 3483. transform_view::iterator's difference is overconstrained
3775 friend constexpr difference_type
3776 operator-(const _Iterator& __x, const _Iterator& __y)
3777 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
3778 { return __x._M_current - __y._M_current; }
3780 template <bool> friend struct _Sentinel;
3783 template<bool _Const>
3787 template<bool _Const2>
3789 _M_equal(const _Iterator<_Const2>& __x) const
3790 { return __x._M_current == _M_end; }
3792 template<bool _Const2>
3794 _M_distance_from(const _Iterator<_Const2>& __i) const
3795 { return _M_end - __i._M_current; }
3797 using _Base = elements_view::_Base<_Const>;
3798 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
3801 _Sentinel() = default;
3804 _Sentinel(sentinel_t<_Base> __end)
3805 : _M_end(std::move(__end))
3809 _Sentinel(_Sentinel<!_Const> __other)
3811 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
3812 : _M_end(std::move(__other._M_end))
3815 constexpr sentinel_t<_Base>
3819 template<bool _Const2>
3820 requires sentinel_for<sentinel_t<_Base>,
3821 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
3822 friend constexpr bool
3823 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3824 { return __y._M_equal(__x); }
3826 template<bool _Const2,
3827 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3828 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3829 friend constexpr range_difference_t<_Base2>
3830 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3831 { return -__y._M_distance_from(__x); }
3833 template<bool _Const2,
3834 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3835 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3836 friend constexpr range_difference_t<_Base2>
3837 operator-(const _Sentinel& __x, const _Iterator<_Const2>& __y)
3838 { return __x._M_distance_from(__y); }
3840 friend _Sentinel<!_Const>;
3843 _Vp _M_base = _Vp();
3846 template<typename _Tp, size_t _Nm>
3847 inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Nm>>
3848 = enable_borrowed_range<_Tp>;
3850 template<typename _Range>
3851 using keys_view = elements_view<views::all_t<_Range>, 0>;
3853 template<typename _Range>
3854 using values_view = elements_view<views::all_t<_Range>, 1>;
3860 template<size_t _Nm, typename _Range>
3861 concept __can_elements_view
3862 = requires { elements_view<all_t<_Range>, _Nm>{std::declval<_Range>()}; };
3863 } // namespace __detail
3865 template<size_t _Nm>
3866 struct _Elements : __adaptor::_RangeAdaptorClosure
3868 template<viewable_range _Range>
3869 requires __detail::__can_elements_view<_Nm, _Range>
3871 operator()(_Range&& __r) const
3873 return elements_view<all_t<_Range>, _Nm>{std::forward<_Range>(__r)};
3876 static constexpr bool _S_has_simple_call_op = true;
3879 template<size_t _Nm>
3880 inline constexpr _Elements<_Nm> elements;
3881 inline constexpr auto keys = elements<0>;
3882 inline constexpr auto values = elements<1>;
3883 } // namespace views
3885 } // namespace ranges
3887 namespace views = ranges::views;
3889 _GLIBCXX_END_NAMESPACE_VERSION
3891 #endif // library concepts
3893 #endif /* _GLIBCXX_RANGES */