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, 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. This data member could
796 // also be defined as a variable template parameterized by the types of the
798 template<typename _Derived>
801 // Partially apply the arguments __args to the range adaptor _Derived,
802 // returning a range adaptor closure object.
803 template<typename... _Args>
804 requires __adaptor_partial_app_viable<_Derived, _Args...>
806 operator()(_Args&&... __args) const
808 return _Partial<_Derived, decay_t<_Args>...>{std::forward<_Args>(__args)...};
812 // True if the range adaptor closure _Adaptor has a simple operator(), i.e.
813 // one that's not overloaded according to constness or value category of the
815 template<typename _Adaptor>
816 concept __closure_has_simple_call_op = _Adaptor::_S_has_simple_call_op;
818 // True if the behavior of the range adaptor non-closure _Adaptor is
819 // independent of the value category of its extra arguments _Args.
820 template<typename _Adaptor, typename... _Args>
821 concept __adaptor_has_simple_extra_args = _Adaptor::_S_has_simple_extra_args
822 || _Adaptor::template _S_has_simple_extra_args<_Args...>;
824 // A range adaptor closure that represents partial application of
825 // the range adaptor _Adaptor with arguments _Args.
826 template<typename _Adaptor, typename... _Args>
827 struct _Partial : _RangeAdaptorClosure
829 tuple<_Args...> _M_args;
832 _Partial(_Args... __args)
833 : _M_args(std::move(__args)...)
836 // Invoke _Adaptor with arguments __r, _M_args... according to the
837 // value category of this _Partial object.
838 template<typename _Range>
839 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
841 operator()(_Range&& __r) const &
843 auto __forwarder = [&__r] (const auto&... __args) {
844 return _Adaptor{}(std::forward<_Range>(__r), __args...);
846 return std::apply(__forwarder, _M_args);
849 template<typename _Range>
850 requires __adaptor_invocable<_Adaptor, _Range, _Args...>
852 operator()(_Range&& __r) &&
854 auto __forwarder = [&__r] (auto&... __args) {
855 return _Adaptor{}(std::forward<_Range>(__r), std::move(__args)...);
857 return std::apply(__forwarder, _M_args);
860 template<typename _Range>
862 operator()(_Range&& __r) const && = delete;
865 // A lightweight specialization of the above primary template for
866 // the common case where _Adaptor accepts a single extra argument.
867 template<typename _Adaptor, typename _Arg>
868 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
874 : _M_arg(std::move(__arg))
877 template<typename _Range>
878 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
880 operator()(_Range&& __r) const &
881 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
883 template<typename _Range>
884 requires __adaptor_invocable<_Adaptor, _Range, _Arg>
886 operator()(_Range&& __r) &&
887 { return _Adaptor{}(std::forward<_Range>(__r), std::move(_M_arg)); }
889 template<typename _Range>
891 operator()(_Range&& __r) const && = delete;
894 // Partial specialization of the primary template for the case where the extra
895 // arguments of the adaptor can always be safely and efficiently forwarded by
896 // const reference. This lets us get away with a single operator() overload,
897 // which makes overload resolution failure diagnostics more concise.
898 template<typename _Adaptor, typename... _Args>
899 requires __adaptor_has_simple_extra_args<_Adaptor, _Args...>
900 && (is_trivially_copyable_v<_Args> && ...)
901 struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure
903 tuple<_Args...> _M_args;
906 _Partial(_Args... __args)
907 : _M_args(std::move(__args)...)
910 // Invoke _Adaptor with arguments __r, const _M_args&... regardless
911 // of the value category of this _Partial object.
912 template<typename _Range>
913 requires __adaptor_invocable<_Adaptor, _Range, const _Args&...>
915 operator()(_Range&& __r) const
917 auto __forwarder = [&__r] (const auto&... __args) {
918 return _Adaptor{}(std::forward<_Range>(__r), __args...);
920 return std::apply(__forwarder, _M_args);
923 static constexpr bool _S_has_simple_call_op = true;
926 // A lightweight specialization of the above template for the common case
927 // where _Adaptor accepts a single extra argument.
928 template<typename _Adaptor, typename _Arg>
929 requires __adaptor_has_simple_extra_args<_Adaptor, _Arg>
930 && is_trivially_copyable_v<_Arg>
931 struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure
937 : _M_arg(std::move(__arg))
940 template<typename _Range>
941 requires __adaptor_invocable<_Adaptor, _Range, const _Arg&>
943 operator()(_Range&& __r) const
944 { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); }
946 static constexpr bool _S_has_simple_call_op = true;
949 template<typename _Lhs, typename _Rhs, typename _Range>
950 concept __pipe_invocable
951 = requires { std::declval<_Rhs>()(std::declval<_Lhs>()(std::declval<_Range>())); };
953 // A range adaptor closure that represents composition of the range
954 // adaptor closures _Lhs and _Rhs.
955 template<typename _Lhs, typename _Rhs>
956 struct _Pipe : _RangeAdaptorClosure
958 [[no_unique_address]] _Lhs _M_lhs;
959 [[no_unique_address]] _Rhs _M_rhs;
962 _Pipe(_Lhs __lhs, _Rhs __rhs)
963 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
966 // Invoke _M_rhs(_M_lhs(__r)) according to the value category of this
967 // range adaptor closure object.
968 template<typename _Range>
969 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
971 operator()(_Range&& __r) const &
972 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
974 template<typename _Range>
975 requires __pipe_invocable<_Lhs, _Rhs, _Range>
977 operator()(_Range&& __r) &&
978 { return std::move(_M_rhs)(std::move(_M_lhs)(std::forward<_Range>(__r))); }
980 template<typename _Range>
982 operator()(_Range&& __r) const && = delete;
985 // A partial specialization of the above primary template for the case where
986 // both adaptor operands have a simple operator(). This in turn lets us
987 // implement composition using a single simple operator(), which makes
988 // overload resolution failure diagnostics more concise.
989 template<typename _Lhs, typename _Rhs>
990 requires __closure_has_simple_call_op<_Lhs>
991 && __closure_has_simple_call_op<_Rhs>
992 struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure
994 [[no_unique_address]] _Lhs _M_lhs;
995 [[no_unique_address]] _Rhs _M_rhs;
998 _Pipe(_Lhs __lhs, _Rhs __rhs)
999 : _M_lhs(std::move(__lhs)), _M_rhs(std::move(__rhs))
1002 template<typename _Range>
1003 requires __pipe_invocable<const _Lhs&, const _Rhs&, _Range>
1005 operator()(_Range&& __r) const
1006 { return _M_rhs(_M_lhs(std::forward<_Range>(__r))); }
1008 static constexpr bool _S_has_simple_call_op = true;
1010 } // namespace views::__adaptor
1012 template<range _Range> requires is_object_v<_Range>
1013 class ref_view : public view_interface<ref_view<_Range>>
1016 _Range* _M_r = nullptr;
1018 static void _S_fun(_Range&); // not defined
1019 static void _S_fun(_Range&&) = delete;
1023 ref_view() noexcept = default;
1025 template<__detail::__not_same_as<ref_view> _Tp>
1026 requires convertible_to<_Tp, _Range&>
1027 && requires { _S_fun(declval<_Tp>()); }
1030 : _M_r(std::__addressof(static_cast<_Range&>(std::forward<_Tp>(__t))))
1037 constexpr iterator_t<_Range>
1039 { return ranges::begin(*_M_r); }
1041 constexpr sentinel_t<_Range>
1043 { return ranges::end(*_M_r); }
1046 empty() const requires requires { ranges::empty(*_M_r); }
1047 { return ranges::empty(*_M_r); }
1050 size() const requires sized_range<_Range>
1051 { return ranges::size(*_M_r); }
1054 data() const requires contiguous_range<_Range>
1055 { return ranges::data(*_M_r); }
1058 template<typename _Range>
1059 ref_view(_Range&) -> ref_view<_Range>;
1061 template<typename _Tp>
1062 inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
1068 template<typename _Range>
1069 concept __can_ref_view = requires { ref_view{std::declval<_Range>()}; };
1071 template<typename _Range>
1072 concept __can_subrange = requires { subrange{std::declval<_Range>()}; };
1073 } // namespace __detail
1075 struct _All : __adaptor::_RangeAdaptorClosure
1077 template<viewable_range _Range>
1078 requires view<decay_t<_Range>>
1079 || __detail::__can_ref_view<_Range>
1080 || __detail::__can_subrange<_Range>
1082 operator()(_Range&& __r) const
1084 if constexpr (view<decay_t<_Range>>)
1085 return std::forward<_Range>(__r);
1086 else if constexpr (__detail::__can_ref_view<_Range>)
1087 return ref_view{std::forward<_Range>(__r)};
1089 return subrange{std::forward<_Range>(__r)};
1092 static constexpr bool _S_has_simple_call_op = true;
1095 inline constexpr _All all;
1097 template<viewable_range _Range>
1098 using all_t = decltype(all(std::declval<_Range>()));
1099 } // namespace views
1101 // The following simple algos are transcribed from ranges_algo.h to avoid
1102 // having to include that entire header.
1105 template<typename _Iter, typename _Sent, typename _Tp>
1107 find(_Iter __first, _Sent __last, const _Tp& __value)
1109 while (__first != __last
1110 && !(bool)(*__first == __value))
1115 template<typename _Iter, typename _Sent, typename _Pred>
1117 find_if(_Iter __first, _Sent __last, _Pred __pred)
1119 while (__first != __last
1120 && !(bool)std::__invoke(__pred, *__first))
1125 template<typename _Iter, typename _Sent, typename _Pred>
1127 find_if_not(_Iter __first, _Sent __last, _Pred __pred)
1129 while (__first != __last
1130 && (bool)std::__invoke(__pred, *__first))
1135 template<typename _Iter1, typename _Sent1, typename _Iter2, typename _Sent2>
1136 constexpr pair<_Iter1, _Iter2>
1137 mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2)
1139 while (__first1 != __last1 && __first2 != __last2
1140 && (bool)ranges::equal_to{}(*__first1, *__first2))
1145 return { std::move(__first1), std::move(__first2) };
1147 } // namespace __detail
1151 template<typename _Tp>
1152 struct __non_propagating_cache
1154 // When _Tp is not an object type (e.g. is a reference type), we make
1155 // __non_propagating_cache<_Tp> empty rather than ill-formed so that
1156 // users can easily conditionally declare data members with this type
1157 // (such as join_view::_M_inner).
1160 template<typename _Tp>
1161 requires is_object_v<_Tp>
1162 struct __non_propagating_cache<_Tp> : protected _Optional_base<_Tp>
1164 __non_propagating_cache() = default;
1167 __non_propagating_cache(const __non_propagating_cache&) noexcept
1171 __non_propagating_cache(__non_propagating_cache&& __other) noexcept
1172 { __other._M_reset(); }
1174 constexpr __non_propagating_cache&
1175 operator=(const __non_propagating_cache& __other) noexcept
1177 if (std::__addressof(__other) != this)
1182 constexpr __non_propagating_cache&
1183 operator=(__non_propagating_cache&& __other) noexcept
1191 operator*() noexcept
1192 { return this->_M_get(); }
1194 constexpr const _Tp&
1195 operator*() const noexcept
1196 { return this->_M_get(); }
1198 template<typename _Iter>
1200 _M_emplace_deref(const _Iter& __i)
1203 // Using _Optional_base::_M_construct to initialize from '*__i'
1204 // would incur an extra move due to the indirection, so we instead
1205 // use placement new directly.
1206 ::new ((void *) std::__addressof(this->_M_payload._M_payload)) _Tp(*__i);
1207 this->_M_payload._M_engaged = true;
1208 return this->_M_get();
1212 template<range _Range>
1213 struct _CachedPosition
1216 _M_has_value() const
1219 constexpr iterator_t<_Range>
1220 _M_get(const _Range&) const
1222 __glibcxx_assert(false);
1227 _M_set(const _Range&, const iterator_t<_Range>&) const
1231 template<forward_range _Range>
1232 struct _CachedPosition<_Range>
1233 : protected __non_propagating_cache<iterator_t<_Range>>
1236 _M_has_value() const
1237 { return this->_M_is_engaged(); }
1239 constexpr iterator_t<_Range>
1240 _M_get(const _Range&) const
1242 __glibcxx_assert(_M_has_value());
1247 _M_set(const _Range&, const iterator_t<_Range>& __it)
1249 __glibcxx_assert(!_M_has_value());
1250 std::construct_at(std::__addressof(this->_M_payload._M_payload),
1252 this->_M_payload._M_engaged = true;
1256 template<random_access_range _Range>
1257 requires (sizeof(range_difference_t<_Range>)
1258 <= sizeof(iterator_t<_Range>))
1259 struct _CachedPosition<_Range>
1262 range_difference_t<_Range> _M_offset = -1;
1265 _CachedPosition() = default;
1268 _CachedPosition(const _CachedPosition&) = default;
1271 _CachedPosition(_CachedPosition&& __other) noexcept
1272 { *this = std::move(__other); }
1274 constexpr _CachedPosition&
1275 operator=(const _CachedPosition&) = default;
1277 constexpr _CachedPosition&
1278 operator=(_CachedPosition&& __other) noexcept
1280 // Propagate the cached offset, but invalidate the source.
1281 _M_offset = __other._M_offset;
1282 __other._M_offset = -1;
1287 _M_has_value() const
1288 { return _M_offset >= 0; }
1290 constexpr iterator_t<_Range>
1291 _M_get(_Range& __r) const
1293 __glibcxx_assert(_M_has_value());
1294 return ranges::begin(__r) + _M_offset;
1298 _M_set(_Range& __r, const iterator_t<_Range>& __it)
1300 __glibcxx_assert(!_M_has_value());
1301 _M_offset = __it - ranges::begin(__r);
1304 } // namespace __detail
1308 template<typename _Base>
1309 struct __filter_view_iter_cat
1312 template<forward_range _Base>
1313 struct __filter_view_iter_cat<_Base>
1319 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1320 if constexpr (derived_from<_Cat, bidirectional_iterator_tag>)
1321 return bidirectional_iterator_tag{};
1322 else if constexpr (derived_from<_Cat, forward_iterator_tag>)
1323 return forward_iterator_tag{};
1328 using iterator_category = decltype(_S_iter_cat());
1330 } // namespace __detail
1332 template<input_range _Vp,
1333 indirect_unary_predicate<iterator_t<_Vp>> _Pred>
1334 requires view<_Vp> && is_object_v<_Pred>
1335 class filter_view : public view_interface<filter_view<_Vp, _Pred>>
1340 struct _Iterator : __detail::__filter_view_iter_cat<_Vp>
1343 static constexpr auto
1346 if constexpr (bidirectional_range<_Vp>)
1347 return bidirectional_iterator_tag{};
1348 else if constexpr (forward_range<_Vp>)
1349 return forward_iterator_tag{};
1351 return input_iterator_tag{};
1356 using _Vp_iter = iterator_t<_Vp>;
1358 _Vp_iter _M_current = _Vp_iter();
1359 filter_view* _M_parent = nullptr;
1362 using iterator_concept = decltype(_S_iter_concept());
1363 // iterator_category defined in __filter_view_iter_cat
1364 using value_type = range_value_t<_Vp>;
1365 using difference_type = range_difference_t<_Vp>;
1367 _Iterator() = default;
1370 _Iterator(filter_view* __parent, _Vp_iter __current)
1371 : _M_current(std::move(__current)),
1375 constexpr const _Vp_iter&
1376 base() const & noexcept
1377 { return _M_current; }
1381 { return std::move(_M_current); }
1383 constexpr range_reference_t<_Vp>
1385 { return *_M_current; }
1389 requires __detail::__has_arrow<_Vp_iter>
1390 && copyable<_Vp_iter>
1391 { return _M_current; }
1393 constexpr _Iterator&
1396 _M_current = __detail::find_if(std::move(++_M_current),
1397 ranges::end(_M_parent->_M_base),
1398 std::ref(*_M_parent->_M_pred));
1407 operator++(int) requires forward_range<_Vp>
1414 constexpr _Iterator&
1415 operator--() requires bidirectional_range<_Vp>
1419 while (!std::__invoke(*_M_parent->_M_pred, *_M_current));
1424 operator--(int) requires bidirectional_range<_Vp>
1431 friend constexpr bool
1432 operator==(const _Iterator& __x, const _Iterator& __y)
1433 requires equality_comparable<_Vp_iter>
1434 { return __x._M_current == __y._M_current; }
1436 friend constexpr range_rvalue_reference_t<_Vp>
1437 iter_move(const _Iterator& __i)
1438 noexcept(noexcept(ranges::iter_move(__i._M_current)))
1439 { return ranges::iter_move(__i._M_current); }
1441 friend constexpr void
1442 iter_swap(const _Iterator& __x, const _Iterator& __y)
1443 noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
1444 requires indirectly_swappable<_Vp_iter>
1445 { ranges::iter_swap(__x._M_current, __y._M_current); }
1451 sentinel_t<_Vp> _M_end = sentinel_t<_Vp>();
1454 __equal(const _Iterator& __i) const
1455 { return __i._M_current == _M_end; }
1458 _Sentinel() = default;
1461 _Sentinel(filter_view* __parent)
1462 : _M_end(ranges::end(__parent->_M_base))
1465 constexpr sentinel_t<_Vp>
1469 friend constexpr bool
1470 operator==(const _Iterator& __x, const _Sentinel& __y)
1471 { return __y.__equal(__x); }
1474 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
1475 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
1476 _Vp _M_base = _Vp();
1479 filter_view() = default;
1482 filter_view(_Vp __base, _Pred __pred)
1483 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
1487 base() const& requires copy_constructible<_Vp>
1492 { return std::move(_M_base); }
1494 constexpr const _Pred&
1496 { return *_M_pred; }
1501 if (_M_cached_begin._M_has_value())
1502 return {this, _M_cached_begin._M_get(_M_base)};
1504 __glibcxx_assert(_M_pred.has_value());
1505 auto __it = __detail::find_if(ranges::begin(_M_base),
1506 ranges::end(_M_base),
1507 std::ref(*_M_pred));
1508 _M_cached_begin._M_set(_M_base, __it);
1509 return {this, std::move(__it)};
1515 if constexpr (common_range<_Vp>)
1516 return _Iterator{this, ranges::end(_M_base)};
1518 return _Sentinel{this};
1522 template<typename _Range, typename _Pred>
1523 filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
1529 template<typename _Range, typename _Pred>
1530 concept __can_filter_view
1531 = requires { filter_view(std::declval<_Range>(), std::declval<_Pred>()); };
1532 } // namespace __detail
1534 struct _Filter : __adaptor::_RangeAdaptor<_Filter>
1536 template<viewable_range _Range, typename _Pred>
1537 requires __detail::__can_filter_view<_Range, _Pred>
1539 operator()(_Range&& __r, _Pred&& __p) const
1541 return filter_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
1544 using _RangeAdaptor<_Filter>::operator();
1545 static constexpr int _S_arity = 2;
1546 static constexpr bool _S_has_simple_extra_args = true;
1549 inline constexpr _Filter filter;
1550 } // namespace views
1552 template<input_range _Vp, copy_constructible _Fp>
1553 requires view<_Vp> && is_object_v<_Fp>
1554 && regular_invocable<_Fp&, range_reference_t<_Vp>>
1555 && std::__detail::__can_reference<invoke_result_t<_Fp&,
1556 range_reference_t<_Vp>>>
1557 class transform_view : public view_interface<transform_view<_Vp, _Fp>>
1560 template<bool _Const>
1561 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1563 template<bool _Const>
1567 template<bool _Const>
1568 requires forward_range<_Base<_Const>>
1569 struct __iter_cat<_Const>
1575 using _Base = transform_view::_Base<_Const>;
1576 using _Res = invoke_result_t<_Fp&, range_reference_t<_Base>>;
1577 if constexpr (is_lvalue_reference_v<_Res>)
1580 = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1581 if constexpr (derived_from<_Cat, contiguous_iterator_tag>)
1582 return random_access_iterator_tag{};
1587 return input_iterator_tag{};
1590 using iterator_category = decltype(_S_iter_cat());
1593 template<bool _Const>
1596 template<bool _Const>
1597 struct _Iterator : __iter_cat<_Const>
1600 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1601 using _Base = transform_view::_Base<_Const>;
1606 if constexpr (random_access_range<_Vp>)
1607 return random_access_iterator_tag{};
1608 else if constexpr (bidirectional_range<_Vp>)
1609 return bidirectional_iterator_tag{};
1610 else if constexpr (forward_range<_Vp>)
1611 return forward_iterator_tag{};
1613 return input_iterator_tag{};
1616 using _Base_iter = iterator_t<_Base>;
1618 _Base_iter _M_current = _Base_iter();
1619 _Parent* _M_parent = nullptr;
1622 using iterator_concept = decltype(_S_iter_concept());
1623 // iterator_category defined in __transform_view_iter_cat
1625 = remove_cvref_t<invoke_result_t<_Fp&, range_reference_t<_Base>>>;
1626 using difference_type = range_difference_t<_Base>;
1628 _Iterator() = default;
1631 _Iterator(_Parent* __parent, _Base_iter __current)
1632 : _M_current(std::move(__current)),
1637 _Iterator(_Iterator<!_Const> __i)
1639 && convertible_to<iterator_t<_Vp>, _Base_iter>
1640 : _M_current(std::move(__i._M_current)), _M_parent(__i._M_parent)
1643 constexpr const _Base_iter&
1644 base() const & noexcept
1645 { return _M_current; }
1647 constexpr _Base_iter
1649 { return std::move(_M_current); }
1651 constexpr decltype(auto)
1653 noexcept(noexcept(std::__invoke(*_M_parent->_M_fun, *_M_current)))
1654 { return std::__invoke(*_M_parent->_M_fun, *_M_current); }
1656 constexpr _Iterator&
1668 operator++(int) requires forward_range<_Base>
1675 constexpr _Iterator&
1676 operator--() requires bidirectional_range<_Base>
1683 operator--(int) requires bidirectional_range<_Base>
1690 constexpr _Iterator&
1691 operator+=(difference_type __n) requires random_access_range<_Base>
1697 constexpr _Iterator&
1698 operator-=(difference_type __n) requires random_access_range<_Base>
1704 constexpr decltype(auto)
1705 operator[](difference_type __n) const
1706 requires random_access_range<_Base>
1707 { return std::__invoke(*_M_parent->_M_fun, _M_current[__n]); }
1709 friend constexpr bool
1710 operator==(const _Iterator& __x, const _Iterator& __y)
1711 requires equality_comparable<_Base_iter>
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 __x._M_current < __y._M_current; }
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 !(__y < __x); }
1729 friend constexpr bool
1730 operator>=(const _Iterator& __x, const _Iterator& __y)
1731 requires random_access_range<_Base>
1732 { return !(__x < __y); }
1734 #ifdef __cpp_lib_three_way_comparison
1735 friend constexpr auto
1736 operator<=>(const _Iterator& __x, const _Iterator& __y)
1737 requires random_access_range<_Base>
1738 && three_way_comparable<_Base_iter>
1739 { return __x._M_current <=> __y._M_current; }
1742 friend constexpr _Iterator
1743 operator+(_Iterator __i, difference_type __n)
1744 requires random_access_range<_Base>
1745 { return {__i._M_parent, __i._M_current + __n}; }
1747 friend constexpr _Iterator
1748 operator+(difference_type __n, _Iterator __i)
1749 requires random_access_range<_Base>
1750 { return {__i._M_parent, __i._M_current + __n}; }
1752 friend constexpr _Iterator
1753 operator-(_Iterator __i, difference_type __n)
1754 requires random_access_range<_Base>
1755 { return {__i._M_parent, __i._M_current - __n}; }
1757 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1758 // 3483. transform_view::iterator's difference is overconstrained
1759 friend constexpr difference_type
1760 operator-(const _Iterator& __x, const _Iterator& __y)
1761 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
1762 { return __x._M_current - __y._M_current; }
1764 friend constexpr decltype(auto)
1765 iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
1767 if constexpr (is_lvalue_reference_v<decltype(*__i)>)
1768 return std::move(*__i);
1773 friend _Iterator<!_Const>;
1774 template<bool> friend struct _Sentinel;
1777 template<bool _Const>
1781 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1782 using _Base = transform_view::_Base<_Const>;
1784 template<bool _Const2>
1786 __distance_from(const _Iterator<_Const2>& __i) const
1787 { return _M_end - __i._M_current; }
1789 template<bool _Const2>
1791 __equal(const _Iterator<_Const2>& __i) const
1792 { return __i._M_current == _M_end; }
1794 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1797 _Sentinel() = default;
1800 _Sentinel(sentinel_t<_Base> __end)
1805 _Sentinel(_Sentinel<!_Const> __i)
1807 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1808 : _M_end(std::move(__i._M_end))
1811 constexpr sentinel_t<_Base>
1815 template<bool _Const2>
1816 requires sentinel_for<sentinel_t<_Base>,
1817 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
1818 friend constexpr bool
1819 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1820 { return __y.__equal(__x); }
1822 template<bool _Const2,
1823 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1824 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1825 friend constexpr range_difference_t<_Base2>
1826 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1827 { return -__y.__distance_from(__x); }
1829 template<bool _Const2,
1830 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1831 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1832 friend constexpr range_difference_t<_Base2>
1833 operator-(const _Sentinel& __y, const _Iterator<_Const2>& __x)
1834 { return __y.__distance_from(__x); }
1836 friend _Sentinel<!_Const>;
1839 [[no_unique_address]] __detail::__box<_Fp> _M_fun;
1840 _Vp _M_base = _Vp();
1843 transform_view() = default;
1846 transform_view(_Vp __base, _Fp __fun)
1847 : _M_fun(std::move(__fun)), _M_base(std::move(__base))
1851 base() const& requires copy_constructible<_Vp>
1852 { return _M_base ; }
1856 { return std::move(_M_base); }
1858 constexpr _Iterator<false>
1860 { return _Iterator<false>{this, ranges::begin(_M_base)}; }
1862 constexpr _Iterator<true>
1864 requires range<const _Vp>
1865 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1866 { return _Iterator<true>{this, ranges::begin(_M_base)}; }
1868 constexpr _Sentinel<false>
1870 { return _Sentinel<false>{ranges::end(_M_base)}; }
1872 constexpr _Iterator<false>
1873 end() requires common_range<_Vp>
1874 { return _Iterator<false>{this, ranges::end(_M_base)}; }
1876 constexpr _Sentinel<true>
1878 requires range<const _Vp>
1879 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1880 { return _Sentinel<true>{ranges::end(_M_base)}; }
1882 constexpr _Iterator<true>
1884 requires common_range<const _Vp>
1885 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1886 { return _Iterator<true>{this, ranges::end(_M_base)}; }
1889 size() requires sized_range<_Vp>
1890 { return ranges::size(_M_base); }
1893 size() const requires sized_range<const _Vp>
1894 { return ranges::size(_M_base); }
1897 template<typename _Range, typename _Fp>
1898 transform_view(_Range&&, _Fp) -> transform_view<views::all_t<_Range>, _Fp>;
1904 template<typename _Range, typename _Fp>
1905 concept __can_transform_view
1906 = requires { transform_view(std::declval<_Range>(), std::declval<_Fp>()); };
1907 } // namespace __detail
1909 struct _Transform : __adaptor::_RangeAdaptor<_Transform>
1911 template<viewable_range _Range, typename _Fp>
1912 requires __detail::__can_transform_view<_Range, _Fp>
1914 operator()(_Range&& __r, _Fp&& __f) const
1916 return transform_view(std::forward<_Range>(__r), std::forward<_Fp>(__f));
1919 using _RangeAdaptor<_Transform>::operator();
1920 static constexpr int _S_arity = 2;
1921 static constexpr bool _S_has_simple_extra_args = true;
1924 inline constexpr _Transform transform;
1925 } // namespace views
1928 class take_view : public view_interface<take_view<_Vp>>
1931 template<bool _Const>
1932 using _CI = counted_iterator<
1933 iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>;
1935 template<bool _Const>
1939 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1940 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1943 _Sentinel() = default;
1946 _Sentinel(sentinel_t<_Base> __end)
1951 _Sentinel(_Sentinel<!_Const> __s)
1952 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1953 : _M_end(std::move(__s._M_end))
1956 constexpr sentinel_t<_Base>
1960 friend constexpr bool
1961 operator==(const _CI<_Const>& __y, const _Sentinel& __x)
1962 { return __y.count() == 0 || __y.base() == __x._M_end; }
1964 template<bool _OtherConst = !_Const,
1965 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
1966 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1967 friend constexpr bool
1968 operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x)
1969 { return __y.count() == 0 || __y.base() == __x._M_end; }
1971 friend _Sentinel<!_Const>;
1974 range_difference_t<_Vp> _M_count = 0;
1975 _Vp _M_base = _Vp();
1978 take_view() = default;
1981 take_view(_Vp base, range_difference_t<_Vp> __count)
1982 : _M_count(std::move(__count)), _M_base(std::move(base))
1986 base() const& requires copy_constructible<_Vp>
1991 { return std::move(_M_base); }
1994 begin() requires (!__detail::__simple_view<_Vp>)
1996 if constexpr (sized_range<_Vp>)
1998 if constexpr (random_access_range<_Vp>)
1999 return ranges::begin(_M_base);
2003 return counted_iterator(ranges::begin(_M_base), __sz);
2007 return counted_iterator(ranges::begin(_M_base), _M_count);
2011 begin() const requires range<const _Vp>
2013 if constexpr (sized_range<const _Vp>)
2015 if constexpr (random_access_range<const _Vp>)
2016 return ranges::begin(_M_base);
2020 return counted_iterator(ranges::begin(_M_base), __sz);
2024 return counted_iterator(ranges::begin(_M_base), _M_count);
2028 end() requires (!__detail::__simple_view<_Vp>)
2030 if constexpr (sized_range<_Vp>)
2032 if constexpr (random_access_range<_Vp>)
2033 return ranges::begin(_M_base) + size();
2035 return default_sentinel;
2038 return _Sentinel<false>{ranges::end(_M_base)};
2042 end() const requires range<const _Vp>
2044 if constexpr (sized_range<const _Vp>)
2046 if constexpr (random_access_range<const _Vp>)
2047 return ranges::begin(_M_base) + size();
2049 return default_sentinel;
2052 return _Sentinel<true>{ranges::end(_M_base)};
2056 size() requires sized_range<_Vp>
2058 auto __n = ranges::size(_M_base);
2059 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2063 size() const requires sized_range<const _Vp>
2065 auto __n = ranges::size(_M_base);
2066 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2070 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2071 // 3447. Deduction guides for take_view and drop_view have different
2073 template<typename _Range>
2074 take_view(_Range&&, range_difference_t<_Range>)
2075 -> take_view<views::all_t<_Range>>;
2077 template<typename _Tp>
2078 inline constexpr bool enable_borrowed_range<take_view<_Tp>>
2079 = enable_borrowed_range<_Tp>;
2085 template<typename _Range, typename _Tp>
2086 concept __can_take_view
2087 = requires { take_view(std::declval<_Range>(), std::declval<_Tp>()); };
2088 } // namespace __detail
2090 struct _Take : __adaptor::_RangeAdaptor<_Take>
2092 template<viewable_range _Range, typename _Tp>
2093 requires __detail::__can_take_view<_Range, _Tp>
2095 operator()(_Range&& __r, _Tp&& __n) const
2097 return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2100 using _RangeAdaptor<_Take>::operator();
2101 static constexpr int _S_arity = 2;
2102 // The count argument of views::take is not always simple -- it can be
2103 // e.g. a move-only class that's implicitly convertible to the difference
2104 // type. But an integer-like count argument is surely simple.
2105 template<typename _Tp>
2106 static constexpr bool _S_has_simple_extra_args
2107 = ranges::__detail::__is_integer_like<_Tp>;
2110 inline constexpr _Take take;
2111 } // namespace views
2113 template<view _Vp, typename _Pred>
2114 requires input_range<_Vp> && is_object_v<_Pred>
2115 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2116 class take_while_view : public view_interface<take_while_view<_Vp, _Pred>>
2118 template<bool _Const>
2122 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2124 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2125 const _Pred* _M_pred = nullptr;
2128 _Sentinel() = default;
2131 _Sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
2132 : _M_end(__end), _M_pred(__pred)
2136 _Sentinel(_Sentinel<!_Const> __s)
2137 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2138 : _M_end(__s._M_end), _M_pred(__s._M_pred)
2141 constexpr sentinel_t<_Base>
2142 base() const { return _M_end; }
2144 friend constexpr bool
2145 operator==(const iterator_t<_Base>& __x, const _Sentinel& __y)
2146 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2148 template<bool _OtherConst = !_Const,
2149 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
2150 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
2151 friend constexpr bool
2152 operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y)
2153 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2155 friend _Sentinel<!_Const>;
2158 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2159 _Vp _M_base = _Vp();
2162 take_while_view() = default;
2165 take_while_view(_Vp base, _Pred __pred)
2166 : _M_pred(std::move(__pred)), _M_base(std::move(base))
2170 base() const& requires copy_constructible<_Vp>
2175 { return std::move(_M_base); }
2177 constexpr const _Pred&
2179 { return *_M_pred; }
2182 begin() requires (!__detail::__simple_view<_Vp>)
2183 { return ranges::begin(_M_base); }
2186 begin() const requires range<const _Vp>
2187 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2188 { return ranges::begin(_M_base); }
2191 end() requires (!__detail::__simple_view<_Vp>)
2192 { return _Sentinel<false>(ranges::end(_M_base),
2193 std::__addressof(*_M_pred)); }
2196 end() const requires range<const _Vp>
2197 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2198 { return _Sentinel<true>(ranges::end(_M_base),
2199 std::__addressof(*_M_pred)); }
2202 template<typename _Range, typename _Pred>
2203 take_while_view(_Range&&, _Pred)
2204 -> take_while_view<views::all_t<_Range>, _Pred>;
2210 template<typename _Range, typename _Pred>
2211 concept __can_take_while_view
2212 = requires { take_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2213 } // namespace __detail
2215 struct _TakeWhile : __adaptor::_RangeAdaptor<_TakeWhile>
2217 template<viewable_range _Range, typename _Pred>
2218 requires __detail::__can_take_while_view<_Range, _Pred>
2220 operator()(_Range&& __r, _Pred&& __p) const
2222 return take_while_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
2225 using _RangeAdaptor<_TakeWhile>::operator();
2226 static constexpr int _S_arity = 2;
2227 static constexpr bool _S_has_simple_extra_args = true;
2230 inline constexpr _TakeWhile take_while;
2231 } // namespace views
2234 class drop_view : public view_interface<drop_view<_Vp>>
2237 range_difference_t<_Vp> _M_count = 0;
2238 _Vp _M_base = _Vp();
2240 // ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
2241 // both random_access_range and sized_range. Otherwise, cache its result.
2242 static constexpr bool _S_needs_cached_begin
2243 = !(random_access_range<const _Vp> && sized_range<const _Vp>);
2244 [[no_unique_address]]
2245 __detail::__maybe_present_t<_S_needs_cached_begin,
2246 __detail::_CachedPosition<_Vp>>
2250 drop_view() = default;
2253 drop_view(_Vp __base, range_difference_t<_Vp> __count)
2254 : _M_count(__count), _M_base(std::move(__base))
2255 { __glibcxx_assert(__count >= 0); }
2258 base() const& requires copy_constructible<_Vp>
2263 { return std::move(_M_base); }
2265 // This overload is disabled for simple views with constant-time begin().
2268 requires (!(__detail::__simple_view<_Vp>
2269 && random_access_range<const _Vp>
2270 && sized_range<const _Vp>))
2272 if constexpr (_S_needs_cached_begin)
2273 if (_M_cached_begin._M_has_value())
2274 return _M_cached_begin._M_get(_M_base);
2276 auto __it = ranges::next(ranges::begin(_M_base),
2277 _M_count, ranges::end(_M_base));
2278 if constexpr (_S_needs_cached_begin)
2279 _M_cached_begin._M_set(_M_base, __it);
2283 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2284 // 3482. drop_view's const begin should additionally require sized_range
2287 requires random_access_range<const _Vp> && sized_range<const _Vp>
2289 return ranges::next(ranges::begin(_M_base), _M_count,
2290 ranges::end(_M_base));
2294 end() requires (!__detail::__simple_view<_Vp>)
2295 { return ranges::end(_M_base); }
2298 end() const requires range<const _Vp>
2299 { return ranges::end(_M_base); }
2302 size() requires sized_range<_Vp>
2304 const auto __s = ranges::size(_M_base);
2305 const auto __c = static_cast<decltype(__s)>(_M_count);
2306 return __s < __c ? 0 : __s - __c;
2310 size() const requires sized_range<const _Vp>
2312 const auto __s = ranges::size(_M_base);
2313 const auto __c = static_cast<decltype(__s)>(_M_count);
2314 return __s < __c ? 0 : __s - __c;
2318 template<typename _Range>
2319 drop_view(_Range&&, range_difference_t<_Range>)
2320 -> drop_view<views::all_t<_Range>>;
2322 template<typename _Tp>
2323 inline constexpr bool enable_borrowed_range<drop_view<_Tp>>
2324 = enable_borrowed_range<_Tp>;
2330 template<typename _Range, typename _Tp>
2331 concept __can_drop_view
2332 = requires { drop_view(std::declval<_Range>(), std::declval<_Tp>()); };
2333 } // namespace __detail
2335 struct _Drop : __adaptor::_RangeAdaptor<_Drop>
2337 template<viewable_range _Range, typename _Tp>
2338 requires __detail::__can_drop_view<_Range, _Tp>
2340 operator()(_Range&& __r, _Tp&& __n) const
2342 return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
2345 using _RangeAdaptor<_Drop>::operator();
2346 static constexpr int _S_arity = 2;
2347 template<typename _Tp>
2348 static constexpr bool _S_has_simple_extra_args
2349 = _Take::_S_has_simple_extra_args<_Tp>;
2352 inline constexpr _Drop drop;
2353 } // namespace views
2355 template<view _Vp, typename _Pred>
2356 requires input_range<_Vp> && is_object_v<_Pred>
2357 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2358 class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
2361 [[no_unique_address]] __detail::__box<_Pred> _M_pred;
2362 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
2363 _Vp _M_base = _Vp();
2366 drop_while_view() = default;
2369 drop_while_view(_Vp __base, _Pred __pred)
2370 : _M_pred(std::move(__pred)), _M_base(std::move(__base))
2374 base() const& requires copy_constructible<_Vp>
2379 { return std::move(_M_base); }
2381 constexpr const _Pred&
2383 { return *_M_pred; }
2388 if (_M_cached_begin._M_has_value())
2389 return _M_cached_begin._M_get(_M_base);
2391 auto __it = __detail::find_if_not(ranges::begin(_M_base),
2392 ranges::end(_M_base),
2393 std::cref(*_M_pred));
2394 _M_cached_begin._M_set(_M_base, __it);
2400 { return ranges::end(_M_base); }
2403 template<typename _Range, typename _Pred>
2404 drop_while_view(_Range&&, _Pred)
2405 -> drop_while_view<views::all_t<_Range>, _Pred>;
2407 template<typename _Tp, typename _Pred>
2408 inline constexpr bool enable_borrowed_range<drop_while_view<_Tp, _Pred>>
2409 = enable_borrowed_range<_Tp>;
2415 template<typename _Range, typename _Pred>
2416 concept __can_drop_while_view
2417 = requires { drop_while_view(std::declval<_Range>(), std::declval<_Pred>()); };
2418 } // namespace __detail
2420 struct _DropWhile : __adaptor::_RangeAdaptor<_DropWhile>
2422 template<viewable_range _Range, typename _Pred>
2423 requires __detail::__can_drop_while_view<_Range, _Pred>
2425 operator()(_Range&& __r, _Pred&& __p) const
2427 return drop_while_view(std::forward<_Range>(__r),
2428 std::forward<_Pred>(__p));
2431 using _RangeAdaptor<_DropWhile>::operator();
2432 static constexpr int _S_arity = 2;
2433 static constexpr bool _S_has_simple_extra_args = true;
2436 inline constexpr _DropWhile drop_while;
2437 } // namespace views
2439 template<input_range _Vp>
2440 requires view<_Vp> && input_range<range_reference_t<_Vp>>
2441 class join_view : public view_interface<join_view<_Vp>>
2444 using _InnerRange = range_reference_t<_Vp>;
2446 template<bool _Const>
2447 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2449 template<bool _Const>
2450 using _Outer_iter = iterator_t<_Base<_Const>>;
2452 template<bool _Const>
2453 using _Inner_iter = iterator_t<range_reference_t<_Base<_Const>>>;
2455 template<bool _Const>
2456 static constexpr bool _S_ref_is_glvalue
2457 = is_reference_v<range_reference_t<_Base<_Const>>>;
2459 template<bool _Const>
2463 template<bool _Const>
2464 requires _S_ref_is_glvalue<_Const>
2465 && forward_range<_Base<_Const>>
2466 && forward_range<range_reference_t<_Base<_Const>>>
2467 struct __iter_cat<_Const>
2470 static constexpr auto
2473 using _Outer_iter = join_view::_Outer_iter<_Const>;
2474 using _Inner_iter = join_view::_Inner_iter<_Const>;
2475 using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
2476 using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
2477 if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
2478 && derived_from<_InnerCat, bidirectional_iterator_tag>)
2479 return bidirectional_iterator_tag{};
2480 else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
2481 && derived_from<_InnerCat, forward_iterator_tag>)
2482 return forward_iterator_tag{};
2484 return input_iterator_tag{};
2487 using iterator_category = decltype(_S_iter_cat());
2490 template<bool _Const>
2493 template<bool _Const>
2494 struct _Iterator : __iter_cat<_Const>
2497 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2498 using _Base = join_view::_Base<_Const>;
2500 static constexpr bool _S_ref_is_glvalue
2501 = join_view::_S_ref_is_glvalue<_Const>;
2506 auto __update_inner = [this] (const iterator_t<_Base>& __x) -> auto&& {
2507 if constexpr (_S_ref_is_glvalue)
2510 return _M_parent->_M_inner._M_emplace_deref(__x);
2513 for (; _M_outer != ranges::end(_M_parent->_M_base); ++_M_outer)
2515 auto&& __inner = __update_inner(_M_outer);
2516 _M_inner = ranges::begin(__inner);
2517 if (_M_inner != ranges::end(__inner))
2521 if constexpr (_S_ref_is_glvalue)
2522 _M_inner = _Inner_iter();
2525 static constexpr auto
2528 if constexpr (_S_ref_is_glvalue
2529 && bidirectional_range<_Base>
2530 && bidirectional_range<range_reference_t<_Base>>)
2531 return bidirectional_iterator_tag{};
2532 else if constexpr (_S_ref_is_glvalue
2533 && forward_range<_Base>
2534 && forward_range<range_reference_t<_Base>>)
2535 return forward_iterator_tag{};
2537 return input_iterator_tag{};
2540 using _Outer_iter = join_view::_Outer_iter<_Const>;
2541 using _Inner_iter = join_view::_Inner_iter<_Const>;
2543 _Outer_iter _M_outer = _Outer_iter();
2544 _Inner_iter _M_inner = _Inner_iter();
2545 _Parent* _M_parent = nullptr;
2548 using iterator_concept = decltype(_S_iter_concept());
2549 // iterator_category defined in __join_view_iter_cat
2550 using value_type = range_value_t<range_reference_t<_Base>>;
2551 using difference_type
2552 = common_type_t<range_difference_t<_Base>,
2553 range_difference_t<range_reference_t<_Base>>>;
2555 _Iterator() = default;
2558 _Iterator(_Parent* __parent, _Outer_iter __outer)
2559 : _M_outer(std::move(__outer)),
2564 _Iterator(_Iterator<!_Const> __i)
2566 && convertible_to<iterator_t<_Vp>, _Outer_iter>
2567 && convertible_to<iterator_t<_InnerRange>, _Inner_iter>
2568 : _M_outer(std::move(__i._M_outer)), _M_inner(__i._M_inner),
2569 _M_parent(__i._M_parent)
2572 constexpr decltype(auto)
2574 { return *_M_inner; }
2576 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2577 // 3500. join_view::iterator::operator->() is bogus
2578 constexpr _Inner_iter
2580 requires __detail::__has_arrow<_Inner_iter>
2581 && copyable<_Inner_iter>
2582 { return _M_inner; }
2584 constexpr _Iterator&
2587 auto&& __inner_range = [this] () -> auto&& {
2588 if constexpr (_S_ref_is_glvalue)
2591 return *_M_parent->_M_inner;
2593 if (++_M_inner == ranges::end(__inner_range))
2607 requires _S_ref_is_glvalue && forward_range<_Base>
2608 && forward_range<range_reference_t<_Base>>
2615 constexpr _Iterator&
2617 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2618 && bidirectional_range<range_reference_t<_Base>>
2619 && common_range<range_reference_t<_Base>>
2621 if (_M_outer == ranges::end(_M_parent->_M_base))
2622 _M_inner = ranges::end(*--_M_outer);
2623 while (_M_inner == ranges::begin(*_M_outer))
2624 _M_inner = ranges::end(*--_M_outer);
2631 requires _S_ref_is_glvalue && bidirectional_range<_Base>
2632 && bidirectional_range<range_reference_t<_Base>>
2633 && common_range<range_reference_t<_Base>>
2640 friend constexpr bool
2641 operator==(const _Iterator& __x, const _Iterator& __y)
2642 requires _S_ref_is_glvalue
2643 && equality_comparable<_Outer_iter>
2644 && equality_comparable<_Inner_iter>
2646 return (__x._M_outer == __y._M_outer
2647 && __x._M_inner == __y._M_inner);
2650 friend constexpr decltype(auto)
2651 iter_move(const _Iterator& __i)
2652 noexcept(noexcept(ranges::iter_move(__i._M_inner)))
2653 { return ranges::iter_move(__i._M_inner); }
2655 friend constexpr void
2656 iter_swap(const _Iterator& __x, const _Iterator& __y)
2657 noexcept(noexcept(ranges::iter_swap(__x._M_inner, __y._M_inner)))
2658 requires indirectly_swappable<_Inner_iter>
2659 { return ranges::iter_swap(__x._M_inner, __y._M_inner); }
2661 friend _Iterator<!_Const>;
2662 template<bool> friend struct _Sentinel;
2665 template<bool _Const>
2669 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2670 using _Base = join_view::_Base<_Const>;
2672 template<bool _Const2>
2674 __equal(const _Iterator<_Const2>& __i) const
2675 { return __i._M_outer == _M_end; }
2677 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2680 _Sentinel() = default;
2683 _Sentinel(_Parent* __parent)
2684 : _M_end(ranges::end(__parent->_M_base))
2688 _Sentinel(_Sentinel<!_Const> __s)
2689 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2690 : _M_end(std::move(__s._M_end))
2693 template<bool _Const2>
2694 requires sentinel_for<sentinel_t<_Base>,
2695 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
2696 friend constexpr bool
2697 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
2698 { return __y.__equal(__x); }
2700 friend _Sentinel<!_Const>;
2703 [[no_unique_address]]
2704 __detail::__non_propagating_cache<remove_cv_t<_InnerRange>> _M_inner;
2705 _Vp _M_base = _Vp();
2708 join_view() = default;
2711 join_view(_Vp __base)
2712 : _M_base(std::move(__base))
2716 base() const& requires copy_constructible<_Vp>
2721 { return std::move(_M_base); }
2726 constexpr bool __use_const
2727 = (__detail::__simple_view<_Vp>
2728 && is_reference_v<range_reference_t<_Vp>>);
2729 return _Iterator<__use_const>{this, ranges::begin(_M_base)};
2734 requires input_range<const _Vp>
2735 && is_reference_v<range_reference_t<const _Vp>>
2737 return _Iterator<true>{this, ranges::begin(_M_base)};
2743 if constexpr (forward_range<_Vp> && is_reference_v<_InnerRange>
2744 && forward_range<_InnerRange>
2745 && common_range<_Vp> && common_range<_InnerRange>)
2746 return _Iterator<__detail::__simple_view<_Vp>>{this,
2747 ranges::end(_M_base)};
2749 return _Sentinel<__detail::__simple_view<_Vp>>{this};
2754 requires input_range<const _Vp>
2755 && is_reference_v<range_reference_t<const _Vp>>
2757 if constexpr (forward_range<const _Vp>
2758 && is_reference_v<range_reference_t<const _Vp>>
2759 && forward_range<range_reference_t<const _Vp>>
2760 && common_range<const _Vp>
2761 && common_range<range_reference_t<const _Vp>>)
2762 return _Iterator<true>{this, ranges::end(_M_base)};
2764 return _Sentinel<true>{this};
2768 template<typename _Range>
2769 explicit join_view(_Range&&) -> join_view<views::all_t<_Range>>;
2775 template<typename _Range>
2776 concept __can_join_view
2777 = requires { join_view<all_t<_Range>>{std::declval<_Range>()}; };
2778 } // namespace __detail
2780 struct _Join : __adaptor::_RangeAdaptorClosure
2782 template<viewable_range _Range>
2783 requires __detail::__can_join_view<_Range>
2785 operator()(_Range&& __r) const
2787 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2788 // 3474. Nesting join_views is broken because of CTAD
2789 return join_view<all_t<_Range>>{std::forward<_Range>(__r)};
2792 static constexpr bool _S_has_simple_call_op = true;
2795 inline constexpr _Join join;
2796 } // namespace views
2801 struct __require_constant;
2803 template<typename _Range>
2804 concept __tiny_range = sized_range<_Range>
2806 { typename __require_constant<remove_reference_t<_Range>::size()>; }
2807 && (remove_reference_t<_Range>::size() <= 1);
2809 template<typename _Base>
2810 struct __split_view_outer_iter_cat
2813 template<forward_range _Base>
2814 struct __split_view_outer_iter_cat<_Base>
2815 { using iterator_category = input_iterator_tag; };
2817 template<typename _Base>
2818 struct __split_view_inner_iter_cat
2821 template<forward_range _Base>
2822 struct __split_view_inner_iter_cat<_Base>
2825 static constexpr auto
2828 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
2829 if constexpr (derived_from<_Cat, forward_iterator_tag>)
2830 return forward_iterator_tag{};
2835 using iterator_category = decltype(_S_iter_cat());
2839 template<input_range _Vp, forward_range _Pattern>
2840 requires view<_Vp> && view<_Pattern>
2841 && indirectly_comparable<iterator_t<_Vp>, iterator_t<_Pattern>,
2843 && (forward_range<_Vp> || __detail::__tiny_range<_Pattern>)
2844 class split_view : public view_interface<split_view<_Vp, _Pattern>>
2847 template<bool _Const>
2848 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2850 template<bool _Const>
2853 template<bool _Const>
2855 : __detail::__split_view_outer_iter_cat<_Base<_Const>>
2858 using _Parent = __detail::__maybe_const_t<_Const, split_view>;
2859 using _Base = split_view::_Base<_Const>;
2863 { return __current() == ranges::end(_M_parent->_M_base); }
2865 // [range.split.outer] p1
2866 // Many of the following specifications refer to the notional member
2867 // current of outer-iterator. current is equivalent to current_ if
2868 // V models forward_range, and parent_->current_ otherwise.
2870 __current() noexcept
2872 if constexpr (forward_range<_Vp>)
2875 return _M_parent->_M_current;
2879 __current() const noexcept
2881 if constexpr (forward_range<_Vp>)
2884 return _M_parent->_M_current;
2887 _Parent* _M_parent = nullptr;
2889 // XXX: _M_current is present only if "V models forward_range"
2890 [[no_unique_address]]
2891 __detail::__maybe_present_t<forward_range<_Vp>,
2892 iterator_t<_Base>> _M_current;
2895 using iterator_concept = conditional_t<forward_range<_Base>,
2896 forward_iterator_tag,
2897 input_iterator_tag>;
2898 // iterator_category defined in __split_view_outer_iter_cat
2899 using difference_type = range_difference_t<_Base>;
2901 struct value_type : view_interface<value_type>
2904 _OuterIter _M_i = _OuterIter();
2907 value_type() = default;
2910 value_type(_OuterIter __i)
2911 : _M_i(std::move(__i))
2914 constexpr _InnerIter<_Const>
2916 requires copyable<_OuterIter>
2917 { return _InnerIter<_Const>{_M_i}; }
2919 constexpr _InnerIter<_Const>
2921 requires (!copyable<_OuterIter>)
2922 { return _InnerIter<_Const>{std::move(_M_i)}; }
2924 constexpr default_sentinel_t
2926 { return default_sentinel; }
2929 _OuterIter() = default;
2932 _OuterIter(_Parent* __parent) requires (!forward_range<_Base>)
2933 : _M_parent(__parent)
2937 _OuterIter(_Parent* __parent, iterator_t<_Base> __current)
2938 requires forward_range<_Base>
2939 : _M_parent(__parent),
2940 _M_current(std::move(__current))
2944 _OuterIter(_OuterIter<!_Const> __i)
2946 && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
2947 : _M_parent(__i._M_parent), _M_current(std::move(__i._M_current))
2950 constexpr value_type
2952 { return value_type{*this}; }
2954 constexpr _OuterIter&
2957 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2958 // 3505. split_view::outer-iterator::operator++ misspecified
2959 const auto __end = ranges::end(_M_parent->_M_base);
2960 if (__current() == __end)
2962 const auto [__pbegin, __pend] = subrange{_M_parent->_M_pattern};
2963 if (__pbegin == __pend)
2965 else if constexpr (__detail::__tiny_range<_Pattern>)
2967 __current() = __detail::find(std::move(__current()), __end,
2969 if (__current() != __end)
2976 = __detail::mismatch(__current(), __end, __pbegin, __pend);
2982 } while (++__current() != __end);
2986 constexpr decltype(auto)
2989 if constexpr (forward_range<_Base>)
2999 friend constexpr bool
3000 operator==(const _OuterIter& __x, const _OuterIter& __y)
3001 requires forward_range<_Base>
3002 { return __x._M_current == __y._M_current; }
3004 friend constexpr bool
3005 operator==(const _OuterIter& __x, default_sentinel_t)
3006 { return __x.__at_end(); };
3008 friend _OuterIter<!_Const>;
3009 friend _InnerIter<_Const>;
3012 template<bool _Const>
3014 : __detail::__split_view_inner_iter_cat<_Base<_Const>>
3017 using _Base = split_view::_Base<_Const>;
3022 auto [__pcur, __pend] = subrange{_M_i._M_parent->_M_pattern};
3023 auto __end = ranges::end(_M_i._M_parent->_M_base);
3024 if constexpr (__detail::__tiny_range<_Pattern>)
3026 const auto& __cur = _M_i_current();
3029 if (__pcur == __pend)
3030 return _M_incremented;
3031 return *__cur == *__pcur;
3035 auto __cur = _M_i_current();
3038 if (__pcur == __pend)
3039 return _M_incremented;
3042 if (*__cur != *__pcur)
3044 if (++__pcur == __pend)
3046 } while (++__cur != __end);
3052 _M_i_current() noexcept
3053 { return _M_i.__current(); }
3056 _M_i_current() const noexcept
3057 { return _M_i.__current(); }
3059 _OuterIter<_Const> _M_i = _OuterIter<_Const>();
3060 bool _M_incremented = false;
3063 using iterator_concept
3064 = typename _OuterIter<_Const>::iterator_concept;
3065 // iterator_category defined in __split_view_inner_iter_cat
3066 using value_type = range_value_t<_Base>;
3067 using difference_type = range_difference_t<_Base>;
3069 _InnerIter() = default;
3072 _InnerIter(_OuterIter<_Const> __i)
3073 : _M_i(std::move(__i))
3076 constexpr decltype(auto)
3078 { return *_M_i_current(); }
3080 constexpr _InnerIter&
3083 _M_incremented = true;
3084 if constexpr (!forward_range<_Base>)
3085 if constexpr (_Pattern::size() == 0)
3091 constexpr decltype(auto)
3094 if constexpr (forward_range<_Base>)
3104 friend constexpr bool
3105 operator==(const _InnerIter& __x, const _InnerIter& __y)
3106 requires forward_range<_Base>
3107 { return __x._M_i == __y._M_i; }
3109 friend constexpr bool
3110 operator==(const _InnerIter& __x, default_sentinel_t)
3111 { return __x.__at_end(); }
3113 friend constexpr decltype(auto)
3114 iter_move(const _InnerIter& __i)
3115 noexcept(noexcept(ranges::iter_move(__i._M_i_current())))
3116 { return ranges::iter_move(__i._M_i_current()); }
3118 friend constexpr void
3119 iter_swap(const _InnerIter& __x, const _InnerIter& __y)
3120 noexcept(noexcept(ranges::iter_swap(__x._M_i_current(),
3121 __y._M_i_current())))
3122 requires indirectly_swappable<iterator_t<_Base>>
3123 { ranges::iter_swap(__x._M_i_current(), __y._M_i_current()); }
3126 _Pattern _M_pattern = _Pattern();
3127 // XXX: _M_current is "present only if !forward_range<V>"
3128 [[no_unique_address]]
3129 __detail::__maybe_present_t<!forward_range<_Vp>,
3130 iterator_t<_Vp>> _M_current;
3131 _Vp _M_base = _Vp();
3135 split_view() = default;
3138 split_view(_Vp __base, _Pattern __pattern)
3139 : _M_pattern(std::move(__pattern)), _M_base(std::move(__base))
3142 template<input_range _Range>
3143 requires constructible_from<_Vp, views::all_t<_Range>>
3144 && constructible_from<_Pattern, single_view<range_value_t<_Range>>>
3146 split_view(_Range&& __r, range_value_t<_Range> __e)
3147 : _M_pattern(views::single(std::move(__e))),
3148 _M_base(views::all(std::forward<_Range>(__r)))
3152 base() const& requires copy_constructible<_Vp>
3157 { return std::move(_M_base); }
3162 if constexpr (forward_range<_Vp>)
3163 return _OuterIter<__detail::__simple_view<_Vp>>{
3164 this, ranges::begin(_M_base)};
3167 _M_current = ranges::begin(_M_base);
3168 return _OuterIter<false>{this};
3173 begin() const requires forward_range<_Vp> && forward_range<const _Vp>
3175 return _OuterIter<true>{this, ranges::begin(_M_base)};
3179 end() requires forward_range<_Vp> && common_range<_Vp>
3181 return _OuterIter<__detail::__simple_view<_Vp>>{
3182 this, ranges::end(_M_base)};
3188 if constexpr (forward_range<_Vp>
3189 && forward_range<const _Vp>
3190 && common_range<const _Vp>)
3191 return _OuterIter<true>{this, ranges::end(_M_base)};
3193 return default_sentinel;
3197 template<typename _Range, typename _Pattern>
3198 split_view(_Range&&, _Pattern&&)
3199 -> split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
3201 template<input_range _Range>
3202 split_view(_Range&&, range_value_t<_Range>)
3203 -> split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
3209 template<typename _Range, typename _Pattern>
3210 concept __can_split_view
3211 = requires { split_view(std::declval<_Range>(), std::declval<_Pattern>()); };
3212 } // namespace __detail
3214 struct _Split : __adaptor::_RangeAdaptor<_Split>
3216 template<viewable_range _Range, typename _Pattern>
3217 requires __detail::__can_split_view<_Range, _Pattern>
3219 operator()(_Range&& __r, _Pattern&& __f) const
3221 return split_view(std::forward<_Range>(__r), std::forward<_Pattern>(__f));
3224 using _RangeAdaptor<_Split>::operator();
3225 static constexpr int _S_arity = 2;
3226 // The pattern argument of views::split is not always simple -- it can be
3227 // a non-view range, the value category of which affects whether the call
3228 // is well-formed. But a scalar or a view pattern argument is surely
3230 template<typename _Pattern>
3231 static constexpr bool _S_has_simple_extra_args
3232 = is_scalar_v<_Pattern> || (view<_Pattern>
3233 && copy_constructible<_Pattern>);
3236 inline constexpr _Split split;
3237 } // namespace views
3243 template<input_or_output_iterator _Iter>
3245 operator()(_Iter __i, iter_difference_t<_Iter> __n) const
3247 if constexpr (random_access_iterator<_Iter>)
3248 return subrange(__i, __i + __n);
3250 return subrange(counted_iterator(std::move(__i), __n),
3255 inline constexpr _Counted counted{};
3256 } // namespace views
3259 requires (!common_range<_Vp>) && copyable<iterator_t<_Vp>>
3260 class common_view : public view_interface<common_view<_Vp>>
3263 _Vp _M_base = _Vp();
3266 common_view() = default;
3269 common_view(_Vp __r)
3270 : _M_base(std::move(__r))
3273 /* XXX: LWG 3280 didn't remove this constructor, but I think it should?
3274 template<viewable_range _Range>
3275 requires (!common_range<_Range>)
3276 && constructible_from<_Vp, views::all_t<_Range>>
3278 common_view(_Range&& __r)
3279 : _M_base(views::all(std::forward<_Range>(__r)))
3284 base() const& requires copy_constructible<_Vp>
3289 { return std::move(_M_base); }
3294 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3295 return ranges::begin(_M_base);
3297 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3298 (ranges::begin(_M_base));
3302 begin() const requires range<const _Vp>
3304 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3305 return ranges::begin(_M_base);
3307 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3308 (ranges::begin(_M_base));
3314 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3315 return ranges::begin(_M_base) + ranges::size(_M_base);
3317 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3318 (ranges::end(_M_base));
3322 end() const requires range<const _Vp>
3324 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3325 return ranges::begin(_M_base) + ranges::size(_M_base);
3327 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3328 (ranges::end(_M_base));
3332 size() requires sized_range<_Vp>
3333 { return ranges::size(_M_base); }
3336 size() const requires sized_range<const _Vp>
3337 { return ranges::size(_M_base); }
3340 template<typename _Range>
3341 common_view(_Range&&) -> common_view<views::all_t<_Range>>;
3343 template<typename _Tp>
3344 inline constexpr bool enable_borrowed_range<common_view<_Tp>>
3345 = enable_borrowed_range<_Tp>;
3351 template<typename _Range>
3352 concept __already_common = common_range<_Range>
3353 && requires { views::all(std::declval<_Range>()); };
3355 template<typename _Range>
3356 concept __can_common_view
3357 = requires { common_view{std::declval<_Range>()}; };
3358 } // namespace __detail
3360 struct _Common : __adaptor::_RangeAdaptorClosure
3362 template<viewable_range _Range>
3363 requires __detail::__already_common<_Range>
3364 || __detail::__can_common_view<_Range>
3366 operator()(_Range&& __r) const
3368 if constexpr (__detail::__already_common<_Range>)
3369 return views::all(std::forward<_Range>(__r));
3371 return common_view{std::forward<_Range>(__r)};
3374 static constexpr bool _S_has_simple_call_op = true;
3377 inline constexpr _Common common;
3378 } // namespace views
3381 requires bidirectional_range<_Vp>
3382 class reverse_view : public view_interface<reverse_view<_Vp>>
3385 static constexpr bool _S_needs_cached_begin
3386 = !common_range<_Vp> && !random_access_range<_Vp>;
3388 [[no_unique_address]]
3389 __detail::__maybe_present_t<_S_needs_cached_begin,
3390 __detail::_CachedPosition<_Vp>>
3392 _Vp _M_base = _Vp();
3395 reverse_view() = default;
3398 reverse_view(_Vp __r)
3399 : _M_base(std::move(__r))
3403 base() const& requires copy_constructible<_Vp>
3408 { return std::move(_M_base); }
3410 constexpr reverse_iterator<iterator_t<_Vp>>
3413 if constexpr (_S_needs_cached_begin)
3414 if (_M_cached_begin._M_has_value())
3415 return std::make_reverse_iterator(_M_cached_begin._M_get(_M_base));
3417 auto __it = ranges::next(ranges::begin(_M_base), ranges::end(_M_base));
3418 if constexpr (_S_needs_cached_begin)
3419 _M_cached_begin._M_set(_M_base, __it);
3420 return std::make_reverse_iterator(std::move(__it));
3424 begin() requires common_range<_Vp>
3425 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3428 begin() const requires common_range<const _Vp>
3429 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3431 constexpr reverse_iterator<iterator_t<_Vp>>
3433 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3436 end() const requires common_range<const _Vp>
3437 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3440 size() requires sized_range<_Vp>
3441 { return ranges::size(_M_base); }
3444 size() const requires sized_range<const _Vp>
3445 { return ranges::size(_M_base); }
3448 template<typename _Range>
3449 reverse_view(_Range&&) -> reverse_view<views::all_t<_Range>>;
3451 template<typename _Tp>
3452 inline constexpr bool enable_borrowed_range<reverse_view<_Tp>>
3453 = enable_borrowed_range<_Tp>;
3460 inline constexpr bool __is_reversible_subrange = false;
3462 template<typename _Iter, subrange_kind _Kind>
3463 inline constexpr bool
3464 __is_reversible_subrange<subrange<reverse_iterator<_Iter>,
3465 reverse_iterator<_Iter>,
3469 inline constexpr bool __is_reverse_view = false;
3471 template<typename _Vp>
3472 inline constexpr bool __is_reverse_view<reverse_view<_Vp>> = true;
3474 template<typename _Range>
3475 concept __can_reverse_view
3476 = requires { reverse_view{std::declval<_Range>()}; };
3477 } // namespace __detail
3479 struct _Reverse : __adaptor::_RangeAdaptorClosure
3481 template<viewable_range _Range>
3482 requires __detail::__is_reverse_view<remove_cvref_t<_Range>>
3483 || __detail::__is_reversible_subrange<remove_cvref_t<_Range>>
3484 || __detail::__can_reverse_view<_Range>
3486 operator()(_Range&& __r) const
3488 using _Tp = remove_cvref_t<_Range>;
3489 if constexpr (__detail::__is_reverse_view<_Tp>)
3490 return std::forward<_Range>(__r).base();
3491 else if constexpr (__detail::__is_reversible_subrange<_Tp>)
3493 using _Iter = decltype(ranges::begin(__r).base());
3494 if constexpr (sized_range<_Tp>)
3495 return subrange<_Iter, _Iter, subrange_kind::sized>
3496 {__r.end().base(), __r.begin().base(), __r.size()};
3498 return subrange<_Iter, _Iter, subrange_kind::unsized>
3499 {__r.end().base(), __r.begin().base()};
3502 return reverse_view{std::forward<_Range>(__r)};
3505 static constexpr bool _S_has_simple_call_op = true;
3508 inline constexpr _Reverse reverse;
3509 } // namespace views
3513 template<typename _Tp, size_t _Nm>
3514 concept __has_tuple_element = requires(_Tp __t)
3516 typename tuple_size<_Tp>::type;
3517 requires _Nm < tuple_size_v<_Tp>;
3518 typename tuple_element_t<_Nm, _Tp>;
3519 { std::get<_Nm>(__t) }
3520 -> convertible_to<const tuple_element_t<_Nm, _Tp>&>;
3523 template<typename _Tp, size_t _Nm>
3524 concept __returnable_element
3525 = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Nm, _Tp>>;
3528 template<input_range _Vp, size_t _Nm>
3530 && __detail::__has_tuple_element<range_value_t<_Vp>, _Nm>
3531 && __detail::__has_tuple_element<remove_reference_t<range_reference_t<_Vp>>,
3533 && __detail::__returnable_element<range_reference_t<_Vp>, _Nm>
3534 class elements_view : public view_interface<elements_view<_Vp, _Nm>>
3537 elements_view() = default;
3540 elements_view(_Vp base)
3541 : _M_base(std::move(base))
3544 constexpr const _Vp&
3545 base() const & noexcept
3550 { return std::move(_M_base); }
3553 begin() requires (!__detail::__simple_view<_Vp>)
3554 { return _Iterator<false>(ranges::begin(_M_base)); }
3557 begin() const requires range<const _Vp>
3558 { return _Iterator<true>(ranges::begin(_M_base)); }
3561 end() requires (!__detail::__simple_view<_Vp> && !common_range<_Vp>)
3562 { return _Sentinel<false>{ranges::end(_M_base)}; }
3565 end() requires (!__detail::__simple_view<_Vp> && common_range<_Vp>)
3566 { return _Iterator<false>{ranges::end(_M_base)}; }
3569 end() const requires range<const _Vp>
3570 { return _Sentinel<true>{ranges::end(_M_base)}; }
3573 end() const requires common_range<const _Vp>
3574 { return _Iterator<true>{ranges::end(_M_base)}; }
3577 size() requires sized_range<_Vp>
3578 { return ranges::size(_M_base); }
3581 size() const requires sized_range<const _Vp>
3582 { return ranges::size(_M_base); }
3585 template<bool _Const>
3586 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
3588 template<bool _Const>
3592 template<bool _Const>
3593 requires forward_range<_Base<_Const>>
3594 struct __iter_cat<_Const>
3597 static auto _S_iter_cat()
3599 using _Base = elements_view::_Base<_Const>;
3600 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
3601 using _Res = decltype((std::get<_Nm>(*std::declval<iterator_t<_Base>>())));
3602 if constexpr (!is_lvalue_reference_v<_Res>)
3603 return input_iterator_tag{};
3604 else if constexpr (derived_from<_Cat, random_access_iterator_tag>)
3605 return random_access_iterator_tag{};
3610 using iterator_category = decltype(_S_iter_cat());
3613 template<bool _Const>
3616 template<bool _Const>
3617 struct _Iterator : __iter_cat<_Const>
3620 using _Base = elements_view::_Base<_Const>;
3622 iterator_t<_Base> _M_current = iterator_t<_Base>();
3624 static constexpr decltype(auto)
3625 _S_get_element(const iterator_t<_Base>& __i)
3627 if constexpr (is_reference_v<range_reference_t<_Base>>)
3628 return std::get<_Nm>(*__i);
3631 using _Et = remove_cv_t<tuple_element_t<_Nm, range_reference_t<_Base>>>;
3632 return static_cast<_Et>(std::get<_Nm>(*__i));
3639 if constexpr (random_access_range<_Vp>)
3640 return random_access_iterator_tag{};
3641 else if constexpr (bidirectional_range<_Vp>)
3642 return bidirectional_iterator_tag{};
3643 else if constexpr (forward_range<_Vp>)
3644 return forward_iterator_tag{};
3646 return input_iterator_tag{};
3649 friend _Iterator<!_Const>;
3652 using iterator_concept = decltype(_S_iter_concept());
3653 // iterator_category defined in elements_view::__iter_cat
3655 = remove_cvref_t<tuple_element_t<_Nm, range_value_t<_Base>>>;
3656 using difference_type = range_difference_t<_Base>;
3658 _Iterator() = default;
3661 _Iterator(iterator_t<_Base> current)
3662 : _M_current(std::move(current))
3666 _Iterator(_Iterator<!_Const> i)
3667 requires _Const && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
3668 : _M_current(std::move(i._M_current))
3671 constexpr iterator_t<_Base>
3673 requires copyable<iterator_t<_Base>>
3674 { return _M_current; }
3676 constexpr iterator_t<_Base>
3678 { return std::move(_M_current); }
3680 constexpr decltype(auto)
3682 { return _S_get_element(_M_current); }
3684 constexpr _Iterator&
3696 operator++(int) requires forward_range<_Base>
3703 constexpr _Iterator&
3704 operator--() requires bidirectional_range<_Base>
3711 operator--(int) requires bidirectional_range<_Base>
3718 constexpr _Iterator&
3719 operator+=(difference_type __n)
3720 requires random_access_range<_Base>
3726 constexpr _Iterator&
3727 operator-=(difference_type __n)
3728 requires random_access_range<_Base>
3734 constexpr decltype(auto)
3735 operator[](difference_type __n) const
3736 requires random_access_range<_Base>
3737 { return _S_get_element(_M_current + __n); }
3739 friend constexpr bool
3740 operator==(const _Iterator& __x, const _Iterator& __y)
3741 requires equality_comparable<iterator_t<_Base>>
3742 { return __x._M_current == __y._M_current; }
3744 friend constexpr bool
3745 operator<(const _Iterator& __x, const _Iterator& __y)
3746 requires random_access_range<_Base>
3747 { return __x._M_current < __y._M_current; }
3749 friend constexpr bool
3750 operator>(const _Iterator& __x, const _Iterator& __y)
3751 requires random_access_range<_Base>
3752 { return __y._M_current < __x._M_current; }
3754 friend constexpr bool
3755 operator<=(const _Iterator& __x, const _Iterator& __y)
3756 requires random_access_range<_Base>
3757 { return !(__y._M_current > __x._M_current); }
3759 friend constexpr bool
3760 operator>=(const _Iterator& __x, const _Iterator& __y)
3761 requires random_access_range<_Base>
3762 { return !(__x._M_current > __y._M_current); }
3764 #ifdef __cpp_lib_three_way_comparison
3765 friend constexpr auto
3766 operator<=>(const _Iterator& __x, const _Iterator& __y)
3767 requires random_access_range<_Base>
3768 && three_way_comparable<iterator_t<_Base>>
3769 { return __x._M_current <=> __y._M_current; }
3772 friend constexpr _Iterator
3773 operator+(const _Iterator& __x, difference_type __y)
3774 requires random_access_range<_Base>
3775 { return _Iterator{__x} += __y; }
3777 friend constexpr _Iterator
3778 operator+(difference_type __x, const _Iterator& __y)
3779 requires random_access_range<_Base>
3780 { return __y + __x; }
3782 friend constexpr _Iterator
3783 operator-(const _Iterator& __x, difference_type __y)
3784 requires random_access_range<_Base>
3785 { return _Iterator{__x} -= __y; }
3787 // _GLIBCXX_RESOLVE_LIB_DEFECTS
3788 // 3483. transform_view::iterator's difference is overconstrained
3789 friend constexpr difference_type
3790 operator-(const _Iterator& __x, const _Iterator& __y)
3791 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
3792 { return __x._M_current - __y._M_current; }
3794 template <bool> friend struct _Sentinel;
3797 template<bool _Const>
3801 template<bool _Const2>
3803 _M_equal(const _Iterator<_Const2>& __x) const
3804 { return __x._M_current == _M_end; }
3806 template<bool _Const2>
3808 _M_distance_from(const _Iterator<_Const2>& __i) const
3809 { return _M_end - __i._M_current; }
3811 using _Base = elements_view::_Base<_Const>;
3812 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
3815 _Sentinel() = default;
3818 _Sentinel(sentinel_t<_Base> __end)
3819 : _M_end(std::move(__end))
3823 _Sentinel(_Sentinel<!_Const> __other)
3825 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
3826 : _M_end(std::move(__other._M_end))
3829 constexpr sentinel_t<_Base>
3833 template<bool _Const2>
3834 requires sentinel_for<sentinel_t<_Base>,
3835 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
3836 friend constexpr bool
3837 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3838 { return __y._M_equal(__x); }
3840 template<bool _Const2,
3841 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3842 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3843 friend constexpr range_difference_t<_Base2>
3844 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3845 { return -__y._M_distance_from(__x); }
3847 template<bool _Const2,
3848 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3849 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3850 friend constexpr range_difference_t<_Base2>
3851 operator-(const _Sentinel& __x, const _Iterator<_Const2>& __y)
3852 { return __x._M_distance_from(__y); }
3854 friend _Sentinel<!_Const>;
3857 _Vp _M_base = _Vp();
3860 template<typename _Tp, size_t _Nm>
3861 inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Nm>>
3862 = enable_borrowed_range<_Tp>;
3864 template<typename _Range>
3865 using keys_view = elements_view<views::all_t<_Range>, 0>;
3867 template<typename _Range>
3868 using values_view = elements_view<views::all_t<_Range>, 1>;
3874 template<size_t _Nm, typename _Range>
3875 concept __can_elements_view
3876 = requires { elements_view<all_t<_Range>, _Nm>{std::declval<_Range>()}; };
3877 } // namespace __detail
3879 template<size_t _Nm>
3880 struct _Elements : __adaptor::_RangeAdaptorClosure
3882 template<viewable_range _Range>
3883 requires __detail::__can_elements_view<_Nm, _Range>
3885 operator()(_Range&& __r) const
3887 return elements_view<all_t<_Range>, _Nm>{std::forward<_Range>(__r)};
3890 static constexpr bool _S_has_simple_call_op = true;
3893 template<size_t _Nm>
3894 inline constexpr _Elements<_Nm> elements;
3895 inline constexpr auto keys = elements<0>;
3896 inline constexpr auto values = elements<1>;
3897 } // namespace views
3899 } // namespace ranges
3901 namespace views = ranges::views;
3903 _GLIBCXX_END_NAMESPACE_VERSION
3905 #endif // library concepts
3907 #endif /* _GLIBCXX_RANGES */