1 // <ranges> -*- C++ -*-
3 // Copyright (C) 2019-2020 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
41 #include <bits/refwrap.h>
43 #include <initializer_list>
49 * @defgroup ranges Ranges
51 * Components for dealing with ranges of elements.
54 namespace std _GLIBCXX_VISIBILITY(default)
56 _GLIBCXX_BEGIN_NAMESPACE_VERSION
59 // [range.range] The range concept.
60 // [range.sized] The sized_range concept.
61 // Defined in <bits/range_access.h>
63 // [range.refinements]
64 // Defined in <bits/range_access.h>
68 template<typename _Tp>
69 inline constexpr bool enable_view = derived_from<_Tp, view_base>;
71 template<typename _Tp>
73 = range<_Tp> && movable<_Tp> && default_initializable<_Tp>
76 /// A range which can be safely converted to a view.
77 template<typename _Tp>
78 concept viewable_range = range<_Tp>
79 && (borrowed_range<_Tp> || view<remove_cvref_t<_Tp>>);
83 template<typename _Range>
84 concept __simple_view = view<_Range> && range<const _Range>
85 && same_as<iterator_t<_Range>, iterator_t<const _Range>>
86 && same_as<sentinel_t<_Range>, sentinel_t<const _Range>>;
88 template<typename _It>
89 concept __has_arrow = input_iterator<_It>
90 && (is_pointer_v<_It> || requires(_It __it) { __it.operator->(); });
92 template<typename _Tp, typename _Up>
94 = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
95 } // namespace __detail
97 template<typename _Derived>
98 requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>>
99 class view_interface : public view_base
102 constexpr _Derived& _M_derived() noexcept
104 static_assert(derived_from<_Derived, view_interface<_Derived>>);
105 static_assert(view<_Derived>);
106 return static_cast<_Derived&>(*this);
109 constexpr const _Derived& _M_derived() const noexcept
111 static_assert(derived_from<_Derived, view_interface<_Derived>>);
112 static_assert(view<_Derived>);
113 return static_cast<const _Derived&>(*this);
118 empty() requires forward_range<_Derived>
119 { return ranges::begin(_M_derived()) == ranges::end(_M_derived()); }
122 empty() const requires forward_range<const _Derived>
123 { return ranges::begin(_M_derived()) == ranges::end(_M_derived()); }
126 operator bool() requires requires { ranges::empty(_M_derived()); }
127 { return !ranges::empty(_M_derived()); }
130 operator bool() const requires requires { ranges::empty(_M_derived()); }
131 { return !ranges::empty(_M_derived()); }
134 data() requires contiguous_iterator<iterator_t<_Derived>>
135 { return to_address(ranges::begin(_M_derived())); }
139 requires range<const _Derived>
140 && contiguous_iterator<iterator_t<const _Derived>>
141 { return to_address(ranges::begin(_M_derived())); }
145 requires forward_range<_Derived>
146 && sized_sentinel_for<sentinel_t<_Derived>, iterator_t<_Derived>>
147 { return ranges::end(_M_derived()) - ranges::begin(_M_derived()); }
151 requires forward_range<const _Derived>
152 && sized_sentinel_for<sentinel_t<const _Derived>,
153 iterator_t<const _Derived>>
154 { return ranges::end(_M_derived()) - ranges::begin(_M_derived()); }
156 constexpr decltype(auto)
157 front() requires forward_range<_Derived>
159 __glibcxx_assert(!empty());
160 return *ranges::begin(_M_derived());
163 constexpr decltype(auto)
164 front() const requires forward_range<const _Derived>
166 __glibcxx_assert(!empty());
167 return *ranges::begin(_M_derived());
170 constexpr decltype(auto)
172 requires bidirectional_range<_Derived> && common_range<_Derived>
174 __glibcxx_assert(!empty());
175 return *ranges::prev(ranges::end(_M_derived()));
178 constexpr decltype(auto)
180 requires bidirectional_range<const _Derived>
181 && common_range<const _Derived>
183 __glibcxx_assert(!empty());
184 return *ranges::prev(ranges::end(_M_derived()));
187 template<random_access_range _Range = _Derived>
188 constexpr decltype(auto)
189 operator[](range_difference_t<_Range> __n)
190 { return ranges::begin(_M_derived())[__n]; }
192 template<random_access_range _Range = const _Derived>
193 constexpr decltype(auto)
194 operator[](range_difference_t<_Range> __n) const
195 { return ranges::begin(_M_derived())[__n]; }
200 template<class _From, class _To>
201 concept __convertible_to_non_slicing = convertible_to<_From, _To>
202 && !(is_pointer_v<decay_t<_From>> && is_pointer_v<decay_t<_To>>
203 && __not_same_as<remove_pointer_t<decay_t<_From>>,
204 remove_pointer_t<decay_t<_To>>>);
206 template<typename _Tp>
208 = !is_reference_v<_Tp> && requires(_Tp __t)
210 typename tuple_size<_Tp>::type;
211 requires derived_from<tuple_size<_Tp>, integral_constant<size_t, 2>>;
212 typename tuple_element_t<0, remove_const_t<_Tp>>;
213 typename tuple_element_t<1, remove_const_t<_Tp>>;
214 { get<0>(__t) } -> convertible_to<const tuple_element_t<0, _Tp>&>;
215 { get<1>(__t) } -> convertible_to<const tuple_element_t<1, _Tp>&>;
218 template<typename _Tp, typename _Up, typename _Vp>
219 concept __pair_like_convertible_from
220 = !range<_Tp> && __pair_like<_Tp>
221 && constructible_from<_Tp, _Up, _Vp>
222 && __convertible_to_non_slicing<_Up, tuple_element_t<0, _Tp>>
223 && convertible_to<_Vp, tuple_element_t<1, _Tp>>;
225 } // namespace __detail
227 enum class subrange_kind : bool { unsized, sized };
229 template<input_or_output_iterator _It, sentinel_for<_It> _Sent = _It,
230 subrange_kind _Kind = sized_sentinel_for<_Sent, _It>
231 ? subrange_kind::sized : subrange_kind::unsized>
232 requires (_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _It>)
233 class subrange : public view_interface<subrange<_It, _Sent, _Kind>>
236 // XXX: gcc complains when using constexpr here
237 static const bool _S_store_size
238 = _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>;
240 _It _M_begin = _It();
241 _Sent _M_end = _Sent();
243 template<typename, bool = _S_store_size>
247 template<typename _Tp>
248 struct _Size<_Tp, true>
249 { __detail::__make_unsigned_like_t<_Tp> _M_size; };
251 [[no_unique_address]] _Size<iter_difference_t<_It>> _M_size = {};
254 subrange() = default;
257 subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s)
258 requires (!_S_store_size)
259 : _M_begin(std::move(__i)), _M_end(__s)
263 subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s,
264 __detail::__make_unsigned_like_t<iter_difference_t<_It>> __n)
265 requires (_Kind == subrange_kind::sized)
266 : _M_begin(std::move(__i)), _M_end(__s)
268 using __detail::__to_unsigned_like;
269 __glibcxx_assert(__n == __to_unsigned_like(ranges::distance(__i, __s)));
270 if constexpr (_S_store_size)
271 _M_size._M_size = __n;
274 template<__detail::__not_same_as<subrange> _Rng>
275 requires borrowed_range<_Rng>
276 && __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
277 && convertible_to<sentinel_t<_Rng>, _Sent>
279 subrange(_Rng&& __r) requires _S_store_size && sized_range<_Rng>
280 : subrange(__r, ranges::size(__r))
283 template<__detail::__not_same_as<subrange> _Rng>
284 requires borrowed_range<_Rng>
285 && __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
286 && convertible_to<sentinel_t<_Rng>, _Sent>
288 subrange(_Rng&& __r) requires (!_S_store_size)
289 : subrange{ranges::begin(__r), ranges::end(__r)}
292 template<borrowed_range _Rng>
293 requires __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
294 && convertible_to<sentinel_t<_Rng>, _Sent>
297 __detail::__make_unsigned_like_t<iter_difference_t<_It>> __n)
298 requires (_Kind == subrange_kind::sized)
299 : subrange{ranges::begin(__r), ranges::end(__r), __n}
302 template<__detail::__not_same_as<subrange> _PairLike>
303 requires __detail::__pair_like_convertible_from<_PairLike, const _It&,
306 operator _PairLike() const
307 { return _PairLike(_M_begin, _M_end); }
310 begin() const requires copyable<_It>
313 [[nodiscard]] constexpr _It
314 begin() requires (!copyable<_It>)
315 { return std::move(_M_begin); }
317 constexpr _Sent end() const { return _M_end; }
319 constexpr bool empty() const { return _M_begin == _M_end; }
321 constexpr __detail::__make_unsigned_like_t<iter_difference_t<_It>>
322 size() const requires (_Kind == subrange_kind::sized)
324 if constexpr (_S_store_size)
325 return _M_size._M_size;
327 return __detail::__to_unsigned_like(_M_end - _M_begin);
330 [[nodiscard]] constexpr subrange
331 next(iter_difference_t<_It> __n = 1) const &
332 requires forward_iterator<_It>
339 [[nodiscard]] constexpr subrange
340 next(iter_difference_t<_It> __n = 1) &&
343 return std::move(*this);
346 [[nodiscard]] constexpr subrange
347 prev(iter_difference_t<_It> __n = 1) const
348 requires bidirectional_iterator<_It>
356 advance(iter_difference_t<_It> __n)
358 // _GLIBCXX_RESOLVE_LIB_DEFECTS
359 // 3433. subrange::advance(n) has UB when n < 0
360 if constexpr (bidirectional_iterator<_It>)
363 ranges::advance(_M_begin, __n);
364 if constexpr (_S_store_size)
365 _M_size._M_size += __detail::__to_unsigned_like(-__n);
369 __glibcxx_assert(__n >= 0);
370 auto __d = __n - ranges::advance(_M_begin, __n, _M_end);
371 if constexpr (_S_store_size)
372 _M_size._M_size -= __detail::__to_unsigned_like(__d);
377 template<input_or_output_iterator _It, sentinel_for<_It> _Sent>
378 subrange(_It, _Sent) -> subrange<_It, _Sent>;
380 template<input_or_output_iterator _It, sentinel_for<_It> _Sent>
382 __detail::__make_unsigned_like_t<iter_difference_t<_It>>)
383 -> subrange<_It, _Sent, subrange_kind::sized>;
385 template<borrowed_range _Rng>
387 -> subrange<iterator_t<_Rng>, sentinel_t<_Rng>,
389 || sized_sentinel_for<sentinel_t<_Rng>, iterator_t<_Rng>>)
390 ? subrange_kind::sized : subrange_kind::unsized>;
392 template<borrowed_range _Rng>
394 __detail::__make_unsigned_like_t<range_difference_t<_Rng>>)
395 -> subrange<iterator_t<_Rng>, sentinel_t<_Rng>, subrange_kind::sized>;
397 template<size_t _Num, class _It, class _Sent, subrange_kind _Kind>
400 get(const subrange<_It, _Sent, _Kind>& __r)
402 if constexpr (_Num == 0)
408 template<size_t _Num, class _It, class _Sent, subrange_kind _Kind>
411 get(subrange<_It, _Sent, _Kind>&& __r)
413 if constexpr (_Num == 0)
419 template<input_or_output_iterator _It, sentinel_for<_It> _Sent,
421 inline constexpr bool
422 enable_borrowed_range<subrange<_It, _Sent, _Kind>> = true;
424 } // namespace ranges
430 /// Type returned by algorithms instead of a dangling iterator or subrange.
433 constexpr dangling() noexcept = default;
434 template<typename... _Args>
435 constexpr dangling(_Args&&...) noexcept { }
438 template<range _Range>
439 using borrowed_iterator_t = conditional_t<borrowed_range<_Range>,
443 template<range _Range>
444 using borrowed_subrange_t = conditional_t<borrowed_range<_Range>,
445 subrange<iterator_t<_Range>>,
448 template<typename _Tp> requires is_object_v<_Tp>
450 : public view_interface<empty_view<_Tp>>
453 static constexpr _Tp* begin() noexcept { return nullptr; }
454 static constexpr _Tp* end() noexcept { return nullptr; }
455 static constexpr _Tp* data() noexcept { return nullptr; }
456 static constexpr size_t size() noexcept { return 0; }
457 static constexpr bool empty() noexcept { return true; }
460 template<typename _Tp>
461 inline constexpr bool enable_borrowed_range<empty_view<_Tp>> = true;
465 template<copy_constructible _Tp> requires is_object_v<_Tp>
466 struct __box : std::optional<_Tp>
468 using std::optional<_Tp>::optional;
472 noexcept(is_nothrow_default_constructible_v<_Tp>)
473 requires default_initializable<_Tp>
474 : std::optional<_Tp>{std::in_place}
477 __box(const __box&) = default;
478 __box(__box&&) = default;
480 using std::optional<_Tp>::operator=;
482 // _GLIBCXX_RESOLVE_LIB_DEFECTS
483 // 3477. Simplify constraints for semiregular-box
485 operator=(const __box& __that)
486 noexcept(is_nothrow_copy_constructible_v<_Tp>)
487 requires (!copyable<_Tp>)
490 this->emplace(*__that);
497 operator=(__box&& __that)
498 noexcept(is_nothrow_move_constructible_v<_Tp>)
499 requires (!movable<_Tp>)
502 this->emplace(std::move(*__that));
509 } // namespace __detail
511 /// A view that contains exactly one element.
512 template<copy_constructible _Tp> requires is_object_v<_Tp>
513 class single_view : public view_interface<single_view<_Tp>>
516 single_view() = default;
519 single_view(const _Tp& __t)
524 single_view(_Tp&& __t)
525 : _M_value(std::move(__t))
528 // _GLIBCXX_RESOLVE_LIB_DEFECTS
529 // 3428. single_view's in place constructor should be explicit
530 template<typename... _Args>
531 requires constructible_from<_Tp, _Args...>
533 single_view(in_place_t, _Args&&... __args)
534 : _M_value{in_place, std::forward<_Args>(__args)...}
542 begin() const noexcept
547 { return data() + 1; }
551 { return data() + 1; }
553 static constexpr size_t
559 { return _M_value.operator->(); }
562 data() const noexcept
563 { return _M_value.operator->(); }
566 __detail::__box<_Tp> _M_value;
571 template<typename _Wp>
572 constexpr auto __to_signed_like(_Wp __w) noexcept
574 if constexpr (!integral<_Wp>)
575 return iter_difference_t<_Wp>();
576 else if constexpr (sizeof(iter_difference_t<_Wp>) > sizeof(_Wp))
577 return iter_difference_t<_Wp>(__w);
578 else if constexpr (sizeof(ptrdiff_t) > sizeof(_Wp))
579 return ptrdiff_t(__w);
580 else if constexpr (sizeof(long long) > sizeof(_Wp))
581 return (long long)(__w);
582 #ifdef __SIZEOF_INT128__
583 else if constexpr (__SIZEOF_INT128__ > sizeof(_Wp))
584 return __int128(__w);
587 return __max_diff_type(__w);
590 template<typename _Wp>
591 using __iota_diff_t = decltype(__to_signed_like(std::declval<_Wp>()));
593 template<typename _It>
594 concept __decrementable = incrementable<_It>
597 { --__i } -> same_as<_It&>;
598 { __i-- } -> same_as<_It>;
601 template<typename _It>
602 concept __advanceable = __decrementable<_It> && totally_ordered<_It>
603 && requires( _It __i, const _It __j, const __iota_diff_t<_It> __n)
605 { __i += __n } -> same_as<_It&>;
606 { __i -= __n } -> same_as<_It&>;
610 { __j - __j } -> convertible_to<__iota_diff_t<_It>>;
613 template<typename _Winc>
614 struct __iota_view_iter_cat
617 template<incrementable _Winc>
618 struct __iota_view_iter_cat<_Winc>
619 { using iterator_category = input_iterator_tag; };
620 } // namespace __detail
622 template<weakly_incrementable _Winc,
623 semiregular _Bound = unreachable_sentinel_t>
624 requires std::__detail::__weakly_eq_cmp_with<_Winc, _Bound>
625 && semiregular<_Winc>
626 class iota_view : public view_interface<iota_view<_Winc, _Bound>>
631 struct _Iterator : __detail::__iota_view_iter_cat<_Winc>
637 using namespace __detail;
638 if constexpr (__advanceable<_Winc>)
639 return random_access_iterator_tag{};
640 else if constexpr (__decrementable<_Winc>)
641 return bidirectional_iterator_tag{};
642 else if constexpr (incrementable<_Winc>)
643 return forward_iterator_tag{};
645 return input_iterator_tag{};
649 using iterator_concept = decltype(_S_iter_concept());
650 // iterator_category defined in __iota_view_iter_cat
651 using value_type = _Winc;
652 using difference_type = __detail::__iota_diff_t<_Winc>;
654 _Iterator() = default;
657 _Iterator(_Winc __value)
658 : _M_value(__value) { }
661 operator*() const noexcept(is_nothrow_copy_constructible_v<_Winc>)
676 operator++(int) requires incrementable<_Winc>
684 operator--() requires __detail::__decrementable<_Winc>
691 operator--(int) requires __detail::__decrementable<_Winc>
699 operator+=(difference_type __n) requires __detail::__advanceable<_Winc>
701 using __detail::__is_integer_like;
702 using __detail::__is_signed_integer_like;
703 if constexpr (__is_integer_like<_Winc>
704 && !__is_signed_integer_like<_Winc>)
706 if (__n >= difference_type(0))
707 _M_value += static_cast<_Winc>(__n);
709 _M_value -= static_cast<_Winc>(-__n);
717 operator-=(difference_type __n) requires __detail::__advanceable<_Winc>
719 using __detail::__is_integer_like;
720 using __detail::__is_signed_integer_like;
721 if constexpr (__is_integer_like<_Winc>
722 && !__is_signed_integer_like<_Winc>)
724 if (__n >= difference_type(0))
725 _M_value -= static_cast<_Winc>(__n);
727 _M_value += static_cast<_Winc>(-__n);
735 operator[](difference_type __n) const
736 requires __detail::__advanceable<_Winc>
737 { return _Winc(_M_value + __n); }
739 friend constexpr bool
740 operator==(const _Iterator& __x, const _Iterator& __y)
741 requires equality_comparable<_Winc>
742 { return __x._M_value == __y._M_value; }
744 friend constexpr bool
745 operator<(const _Iterator& __x, const _Iterator& __y)
746 requires totally_ordered<_Winc>
747 { return __x._M_value < __y._M_value; }
749 friend constexpr bool
750 operator>(const _Iterator& __x, const _Iterator& __y)
751 requires totally_ordered<_Winc>
752 { return __y < __x; }
754 friend constexpr bool
755 operator<=(const _Iterator& __x, const _Iterator& __y)
756 requires totally_ordered<_Winc>
757 { return !(__y < __x); }
759 friend constexpr bool
760 operator>=(const _Iterator& __x, const _Iterator& __y)
761 requires totally_ordered<_Winc>
762 { return !(__x < __y); }
764 #ifdef __cpp_lib_three_way_comparison
765 friend constexpr auto
766 operator<=>(const _Iterator& __x, const _Iterator& __y)
767 requires totally_ordered<_Winc> && three_way_comparable<_Winc>
768 { return __x._M_value <=> __y._M_value; }
771 friend constexpr _Iterator
772 operator+(_Iterator __i, difference_type __n)
773 requires __detail::__advanceable<_Winc>
774 { return __i += __n; }
776 friend constexpr _Iterator
777 operator+(difference_type __n, _Iterator __i)
778 requires __detail::__advanceable<_Winc>
779 { return __i += __n; }
781 friend constexpr _Iterator
782 operator-(_Iterator __i, difference_type __n)
783 requires __detail::__advanceable<_Winc>
784 { return __i -= __n; }
786 friend constexpr difference_type
787 operator-(const _Iterator& __x, const _Iterator& __y)
788 requires __detail::__advanceable<_Winc>
790 using __detail::__is_integer_like;
791 using __detail::__is_signed_integer_like;
792 using _Dt = difference_type;
793 if constexpr (__is_integer_like<_Winc>)
795 if constexpr (__is_signed_integer_like<_Winc>)
796 return _Dt(_Dt(__x._M_value) - _Dt(__y._M_value));
798 return (__y._M_value > __x._M_value)
799 ? _Dt(-_Dt(__y._M_value - __x._M_value))
800 : _Dt(__x._M_value - __y._M_value);
803 return __x._M_value - __y._M_value;
807 _Winc _M_value = _Winc();
816 _M_equal(const _Iterator& __x) const
817 { return __x._M_value == _M_bound; }
820 _M_distance_from(const _Iterator& __x) const
821 { return _M_bound - __x._M_value; }
823 _Bound _M_bound = _Bound();
826 _Sentinel() = default;
829 _Sentinel(_Bound __bound)
830 : _M_bound(__bound) { }
832 friend constexpr bool
833 operator==(const _Iterator& __x, const _Sentinel& __y)
834 { return __y._M_equal(__x); }
836 friend constexpr iter_difference_t<_Winc>
837 operator-(const _Iterator& __x, const _Sentinel& __y)
838 requires sized_sentinel_for<_Bound, _Winc>
839 { return -__y._M_distance_from(__x); }
841 friend constexpr iter_difference_t<_Winc>
842 operator-(const _Sentinel& __x, const _Iterator& __y)
843 requires sized_sentinel_for<_Bound, _Winc>
844 { return __x._M_distance_from(__y); }
847 _Winc _M_value = _Winc();
848 _Bound _M_bound = _Bound();
851 iota_view() = default;
854 iota_view(_Winc __value)
859 iota_view(type_identity_t<_Winc> __value,
860 type_identity_t<_Bound> __bound)
861 : _M_value(__value), _M_bound(__bound)
863 if constexpr (totally_ordered_with<_Winc, _Bound>)
865 __glibcxx_assert( bool(__value <= __bound) );
870 begin() const { return _Iterator{_M_value}; }
875 if constexpr (same_as<_Bound, unreachable_sentinel_t>)
876 return unreachable_sentinel;
878 return _Sentinel{_M_bound};
882 end() const requires same_as<_Winc, _Bound>
883 { return _Iterator{_M_bound}; }
887 requires (same_as<_Winc, _Bound> && __detail::__advanceable<_Winc>)
888 || (integral<_Winc> && integral<_Bound>)
889 || sized_sentinel_for<_Bound, _Winc>
891 using __detail::__is_integer_like;
892 using __detail::__to_unsigned_like;
893 if constexpr (integral<_Winc> && integral<_Bound>)
895 using _Up = make_unsigned_t<decltype(_M_bound - _M_value)>;
896 return _Up(_M_bound) - _Up(_M_value);
898 else if constexpr (__is_integer_like<_Winc>)
899 return __to_unsigned_like(_M_bound) - __to_unsigned_like(_M_value);
901 return __to_unsigned_like(_M_bound - _M_value);
905 template<typename _Winc, typename _Bound>
906 requires (!__detail::__is_integer_like<_Winc>
907 || !__detail::__is_integer_like<_Bound>
908 || (__detail::__is_signed_integer_like<_Winc>
909 == __detail::__is_signed_integer_like<_Bound>))
910 iota_view(_Winc, _Bound) -> iota_view<_Winc, _Bound>;
912 template<weakly_incrementable _Winc, semiregular _Bound>
913 inline constexpr bool
914 enable_borrowed_range<iota_view<_Winc, _Bound>> = true;
918 template<typename _Tp>
919 inline constexpr empty_view<_Tp> empty{};
923 template<typename _Tp>
925 operator()(_Tp&& __e) const
926 { return single_view{std::forward<_Tp>(__e)}; }
929 inline constexpr _Single single{};
933 template<typename _Tp>
935 operator()(_Tp&& __e) const
936 { return iota_view{std::forward<_Tp>(__e)}; }
938 template<typename _Tp, typename _Up>
940 operator()(_Tp&& __e, _Up&& __f) const
941 { return iota_view{std::forward<_Tp>(__e), std::forward<_Up>(__f)}; }
944 inline constexpr _Iota iota{};
949 template<typename _Val, typename _CharT, typename _Traits>
950 concept __stream_extractable
951 = requires(basic_istream<_CharT, _Traits>& is, _Val& t) { is >> t; };
952 } // namespace __detail
954 template<movable _Val, typename _CharT,
955 typename _Traits = char_traits<_CharT>>
956 requires default_initializable<_Val>
957 && __detail::__stream_extractable<_Val, _CharT, _Traits>
958 class basic_istream_view
959 : public view_interface<basic_istream_view<_Val, _CharT, _Traits>>
962 basic_istream_view() = default;
965 basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
966 : _M_stream(std::__addressof(__stream))
972 if (_M_stream != nullptr)
973 *_M_stream >> _M_object;
974 return _Iterator{this};
977 constexpr default_sentinel_t
979 { return default_sentinel; }
982 basic_istream<_CharT, _Traits>* _M_stream = nullptr;
983 _Val _M_object = _Val();
988 using iterator_concept = input_iterator_tag;
989 using difference_type = ptrdiff_t;
990 using value_type = _Val;
992 _Iterator() = default;
995 _Iterator(basic_istream_view* __parent) noexcept
996 : _M_parent(__parent)
999 _Iterator(const _Iterator&) = delete;
1000 _Iterator(_Iterator&&) = default;
1001 _Iterator& operator=(const _Iterator&) = delete;
1002 _Iterator& operator=(_Iterator&&) = default;
1007 __glibcxx_assert(_M_parent->_M_stream != nullptr);
1008 *_M_parent->_M_stream >> _M_parent->_M_object;
1019 __glibcxx_assert(_M_parent->_M_stream != nullptr);
1020 return _M_parent->_M_object;
1024 operator==(const _Iterator& __x, default_sentinel_t)
1025 { return __x._M_at_end(); }
1028 basic_istream_view* _M_parent = nullptr;
1032 { return _M_parent == nullptr || !*_M_parent->_M_stream; }
1038 template<typename _Val, typename _CharT, typename _Traits>
1039 basic_istream_view<_Val, _CharT, _Traits>
1040 istream_view(basic_istream<_CharT, _Traits>& __s)
1041 { return basic_istream_view<_Val, _CharT, _Traits>{__s}; }
1047 // Alias for a type that is conditionally present
1048 // (and is an empty type otherwise).
1049 // Data members using this alias should use [[no_unique_address]] so that
1050 // they take no space when not needed.
1051 template<bool _Present, typename _Tp>
1052 using __maybe_present_t = conditional_t<_Present, _Tp, _Empty>;
1054 // Alias for a type that is conditionally const.
1055 template<bool _Const, typename _Tp>
1056 using __maybe_const_t = conditional_t<_Const, const _Tp, _Tp>;
1058 } // namespace __detail
1064 template<typename _Tp>
1065 inline constexpr auto
1066 __maybe_refwrap(_Tp& __arg)
1067 { return reference_wrapper<_Tp>{__arg}; }
1069 template<typename _Tp>
1070 inline constexpr auto
1071 __maybe_refwrap(const _Tp& __arg)
1072 { return reference_wrapper<const _Tp>{__arg}; }
1074 template<typename _Tp>
1075 inline constexpr decltype(auto)
1076 __maybe_refwrap(_Tp&& __arg)
1077 { return std::forward<_Tp>(__arg); }
1079 template<typename _Callable>
1080 struct _RangeAdaptorClosure;
1082 template<typename _Callable>
1083 struct _RangeAdaptor
1086 [[no_unique_address]]
1087 __detail::__maybe_present_t<!is_default_constructible_v<_Callable>,
1088 _Callable> _M_callable;
1092 _RangeAdaptor(const _Callable& = {})
1093 requires is_default_constructible_v<_Callable>
1097 _RangeAdaptor(_Callable __callable)
1098 requires (!is_default_constructible_v<_Callable>)
1099 : _M_callable(std::move(__callable))
1102 template<typename... _Args>
1103 requires (sizeof...(_Args) >= 1)
1105 operator()(_Args&&... __args) const
1107 // [range.adaptor.object]: If a range adaptor object accepts more
1108 // than one argument, then the following expressions are equivalent:
1110 // (1) adaptor(range, args...)
1111 // (2) adaptor(args...)(range)
1112 // (3) range | adaptor(args...)
1114 // In this case, adaptor(args...) is a range adaptor closure object.
1116 // We handle (1) and (2) here, and (3) is just a special case of a
1117 // more general case already handled by _RangeAdaptorClosure.
1118 if constexpr (is_invocable_v<_Callable, _Args...>)
1120 static_assert(sizeof...(_Args) != 1,
1121 "a _RangeAdaptor that accepts only one argument "
1122 "should be defined as a _RangeAdaptorClosure");
1123 // Here we handle adaptor(range, args...) -- just forward all
1124 // arguments to the underlying adaptor routine.
1125 return _Callable{}(std::forward<_Args>(__args)...);
1129 // Here we handle adaptor(args...)(range).
1130 // Given args..., we return a _RangeAdaptorClosure that takes a
1131 // range argument, such that (2) is equivalent to (1).
1133 // We need to be careful about how we capture args... in this
1134 // closure. By using __maybe_refwrap, we capture lvalue
1135 // references by reference (through a reference_wrapper) and
1136 // otherwise capture by value.
1138 = [...__args(__maybe_refwrap(std::forward<_Args>(__args)))]
1139 <typename _Range> (_Range&& __r) {
1140 // This static_cast has two purposes: it forwards a
1141 // reference_wrapper<T> capture as a T&, and otherwise
1142 // forwards the captured argument as an rvalue.
1143 return _Callable{}(std::forward<_Range>(__r),
1144 (static_cast<unwrap_reference_t
1145 <remove_const_t<decltype(__args)>>>
1148 using _ClosureType = decltype(__closure);
1149 return _RangeAdaptorClosure<_ClosureType>(std::move(__closure));
1154 template<typename _Callable>
1155 _RangeAdaptor(_Callable) -> _RangeAdaptor<_Callable>;
1157 template<typename _Callable>
1158 struct _RangeAdaptorClosure : public _RangeAdaptor<_Callable>
1160 using _RangeAdaptor<_Callable>::_RangeAdaptor;
1162 template<viewable_range _Range>
1163 requires requires { declval<_Callable>()(declval<_Range>()); }
1165 operator()(_Range&& __r) const
1167 if constexpr (is_default_constructible_v<_Callable>)
1168 return _Callable{}(std::forward<_Range>(__r));
1170 return this->_M_callable(std::forward<_Range>(__r));
1173 template<viewable_range _Range>
1174 requires requires { declval<_Callable>()(declval<_Range>()); }
1175 friend constexpr auto
1176 operator|(_Range&& __r, const _RangeAdaptorClosure& __o)
1177 { return __o(std::forward<_Range>(__r)); }
1179 template<typename _Tp>
1180 friend constexpr auto
1181 operator|(const _RangeAdaptorClosure<_Tp>& __x,
1182 const _RangeAdaptorClosure& __y)
1184 if constexpr (is_default_constructible_v<_Tp>
1185 && is_default_constructible_v<_Callable>)
1187 auto __closure = [] <typename _Up> (_Up&& __e) {
1188 return std::forward<_Up>(__e) | decltype(__x){} | decltype(__y){};
1190 return _RangeAdaptorClosure<decltype(__closure)>(__closure);
1192 else if constexpr (is_default_constructible_v<_Tp>
1193 && !is_default_constructible_v<_Callable>)
1195 auto __closure = [__y] <typename _Up> (_Up&& __e) {
1196 return std::forward<_Up>(__e) | decltype(__x){} | __y;
1198 return _RangeAdaptorClosure<decltype(__closure)>(__closure);
1200 else if constexpr (!is_default_constructible_v<_Tp>
1201 && is_default_constructible_v<_Callable>)
1203 auto __closure = [__x] <typename _Up> (_Up&& __e) {
1204 return std::forward<_Up>(__e) | __x | decltype(__y){};
1206 return _RangeAdaptorClosure<decltype(__closure)>(__closure);
1210 auto __closure = [__x, __y] <typename _Up> (_Up&& __e) {
1211 return std::forward<_Up>(__e) | __x | __y;
1213 return _RangeAdaptorClosure<decltype(__closure)>(__closure);
1218 template<typename _Callable>
1219 _RangeAdaptorClosure(_Callable) -> _RangeAdaptorClosure<_Callable>;
1220 } // namespace __adaptor
1221 } // namespace views
1223 template<range _Range> requires is_object_v<_Range>
1224 class ref_view : public view_interface<ref_view<_Range>>
1227 _Range* _M_r = nullptr;
1229 static void _S_fun(_Range&); // not defined
1230 static void _S_fun(_Range&&) = delete;
1234 ref_view() noexcept = default;
1236 template<__detail::__not_same_as<ref_view> _Tp>
1237 requires convertible_to<_Tp, _Range&>
1238 && requires { _S_fun(declval<_Tp>()); }
1241 : _M_r(std::__addressof(static_cast<_Range&>(std::forward<_Tp>(__t))))
1248 constexpr iterator_t<_Range>
1250 { return ranges::begin(*_M_r); }
1252 constexpr sentinel_t<_Range>
1254 { return ranges::end(*_M_r); }
1257 empty() const requires requires { ranges::empty(*_M_r); }
1258 { return ranges::empty(*_M_r); }
1261 size() const requires sized_range<_Range>
1262 { return ranges::size(*_M_r); }
1265 data() const requires contiguous_range<_Range>
1266 { return ranges::data(*_M_r); }
1269 template<typename _Range>
1270 ref_view(_Range&) -> ref_view<_Range>;
1272 template<typename _Tp>
1273 inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
1277 inline constexpr __adaptor::_RangeAdaptorClosure all
1278 = [] <viewable_range _Range> (_Range&& __r)
1280 if constexpr (view<decay_t<_Range>>)
1281 return std::forward<_Range>(__r);
1282 else if constexpr (requires { ref_view{std::forward<_Range>(__r)}; })
1283 return ref_view{std::forward<_Range>(__r)};
1285 return subrange{std::forward<_Range>(__r)};
1288 template<viewable_range _Range>
1289 using all_t = decltype(all(std::declval<_Range>()));
1291 } // namespace views
1293 // The following simple algos are transcribed from ranges_algo.h to avoid
1294 // having to include that entire header.
1297 template<typename _Iter, typename _Sent, typename _Tp>
1299 find(_Iter __first, _Sent __last, const _Tp& __value)
1301 while (__first != __last
1302 && !(bool)(*__first == __value))
1307 template<typename _Iter, typename _Sent, typename _Pred>
1309 find_if(_Iter __first, _Sent __last, _Pred __pred)
1311 while (__first != __last
1312 && !(bool)std::__invoke(__pred, *__first))
1317 template<typename _Iter, typename _Sent, typename _Pred>
1319 find_if_not(_Iter __first, _Sent __last, _Pred __pred)
1321 while (__first != __last
1322 && (bool)std::__invoke(__pred, *__first))
1327 template<typename _Iter1, typename _Sent1, typename _Iter2, typename _Sent2>
1328 constexpr pair<_Iter1, _Iter2>
1329 mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2)
1331 while (__first1 != __last1 && __first2 != __last2
1332 && (bool)ranges::equal_to{}(*__first1, *__first2))
1337 return { std::move(__first1), std::move(__first2) };
1339 } // namespace __detail
1343 template<range _Range>
1344 struct _CachedPosition
1347 _M_has_value() const
1350 constexpr iterator_t<_Range>
1351 _M_get(const _Range&) const
1353 __glibcxx_assert(false);
1358 _M_set(const _Range&, const iterator_t<_Range>&) const
1362 template<forward_range _Range>
1363 struct _CachedPosition<_Range>
1366 iterator_t<_Range> _M_iter{};
1370 _M_has_value() const
1371 { return _M_iter != iterator_t<_Range>{}; }
1373 constexpr iterator_t<_Range>
1374 _M_get(const _Range&) const
1376 __glibcxx_assert(_M_has_value());
1381 _M_set(const _Range&, const iterator_t<_Range>& __it)
1383 __glibcxx_assert(!_M_has_value());
1388 template<random_access_range _Range>
1389 requires (sizeof(range_difference_t<_Range>)
1390 <= sizeof(iterator_t<_Range>))
1391 struct _CachedPosition<_Range>
1394 range_difference_t<_Range> _M_offset = -1;
1398 _M_has_value() const
1399 { return _M_offset >= 0; }
1401 constexpr iterator_t<_Range>
1402 _M_get(_Range& __r) const
1404 __glibcxx_assert(_M_has_value());
1405 return ranges::begin(__r) + _M_offset;
1409 _M_set(_Range& __r, const iterator_t<_Range>& __it)
1411 __glibcxx_assert(!_M_has_value());
1412 _M_offset = __it - ranges::begin(__r);
1415 } // namespace __detail
1419 template<typename _Base>
1420 struct __filter_view_iter_cat
1423 template<forward_range _Base>
1424 struct __filter_view_iter_cat<_Base>
1430 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1431 if constexpr (derived_from<_Cat, bidirectional_iterator_tag>)
1432 return bidirectional_iterator_tag{};
1433 else if constexpr (derived_from<_Cat, forward_iterator_tag>)
1434 return forward_iterator_tag{};
1439 using iterator_category = decltype(_S_iter_cat());
1441 } // namespace __detail
1443 template<input_range _Vp,
1444 indirect_unary_predicate<iterator_t<_Vp>> _Pred>
1445 requires view<_Vp> && is_object_v<_Pred>
1446 class filter_view : public view_interface<filter_view<_Vp, _Pred>>
1451 struct _Iterator : __detail::__filter_view_iter_cat<_Vp>
1454 static constexpr auto
1457 if constexpr (bidirectional_range<_Vp>)
1458 return bidirectional_iterator_tag{};
1459 else if constexpr (forward_range<_Vp>)
1460 return forward_iterator_tag{};
1462 return input_iterator_tag{};
1467 using _Vp_iter = iterator_t<_Vp>;
1469 _Vp_iter _M_current = _Vp_iter();
1470 filter_view* _M_parent = nullptr;
1473 using iterator_concept = decltype(_S_iter_concept());
1474 // iterator_category defined in __filter_view_iter_cat
1475 using value_type = range_value_t<_Vp>;
1476 using difference_type = range_difference_t<_Vp>;
1478 _Iterator() = default;
1481 _Iterator(filter_view* __parent, _Vp_iter __current)
1482 : _M_current(std::move(__current)),
1486 constexpr const _Vp_iter&
1487 base() const & noexcept
1488 { return _M_current; }
1492 { return std::move(_M_current); }
1494 constexpr range_reference_t<_Vp>
1496 { return *_M_current; }
1500 requires __detail::__has_arrow<_Vp_iter>
1501 && copyable<_Vp_iter>
1502 { return _M_current; }
1504 constexpr _Iterator&
1507 _M_current = __detail::find_if(std::move(++_M_current),
1508 ranges::end(_M_parent->_M_base),
1509 std::ref(*_M_parent->_M_pred));
1518 operator++(int) requires forward_range<_Vp>
1525 constexpr _Iterator&
1526 operator--() requires bidirectional_range<_Vp>
1530 while (!std::__invoke(*_M_parent->_M_pred, *_M_current));
1535 operator--(int) requires bidirectional_range<_Vp>
1542 friend constexpr bool
1543 operator==(const _Iterator& __x, const _Iterator& __y)
1544 requires equality_comparable<_Vp_iter>
1545 { return __x._M_current == __y._M_current; }
1547 friend constexpr range_rvalue_reference_t<_Vp>
1548 iter_move(const _Iterator& __i)
1549 noexcept(noexcept(ranges::iter_move(__i._M_current)))
1550 { return ranges::iter_move(__i._M_current); }
1552 friend constexpr void
1553 iter_swap(const _Iterator& __x, const _Iterator& __y)
1554 noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
1555 requires indirectly_swappable<_Vp_iter>
1556 { ranges::iter_swap(__x._M_current, __y._M_current); }
1562 sentinel_t<_Vp> _M_end = sentinel_t<_Vp>();
1565 __equal(const _Iterator& __i) const
1566 { return __i._M_current == _M_end; }
1569 _Sentinel() = default;
1572 _Sentinel(filter_view* __parent)
1573 : _M_end(ranges::end(__parent->_M_base))
1576 constexpr sentinel_t<_Vp>
1580 friend constexpr bool
1581 operator==(const _Iterator& __x, const _Sentinel& __y)
1582 { return __y.__equal(__x); }
1585 _Vp _M_base = _Vp();
1586 __detail::__box<_Pred> _M_pred;
1587 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
1590 filter_view() = default;
1593 filter_view(_Vp __base, _Pred __pred)
1594 : _M_base(std::move(__base)), _M_pred(std::move(__pred))
1598 base() const& requires copy_constructible<_Vp>
1603 { return std::move(_M_base); }
1605 constexpr const _Pred&
1607 { return *_M_pred; }
1612 if (_M_cached_begin._M_has_value())
1613 return {this, _M_cached_begin._M_get(_M_base)};
1615 __glibcxx_assert(_M_pred.has_value());
1616 auto __it = __detail::find_if(ranges::begin(_M_base),
1617 ranges::end(_M_base),
1618 std::ref(*_M_pred));
1619 _M_cached_begin._M_set(_M_base, __it);
1620 return {this, std::move(__it)};
1626 if constexpr (common_range<_Vp>)
1627 return _Iterator{this, ranges::end(_M_base)};
1629 return _Sentinel{this};
1633 template<typename _Range, typename _Pred>
1634 filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
1638 inline constexpr __adaptor::_RangeAdaptor filter
1639 = [] <viewable_range _Range, typename _Pred> (_Range&& __r, _Pred&& __p)
1641 return filter_view{std::forward<_Range>(__r), std::forward<_Pred>(__p)};
1643 } // namespace views
1645 template<input_range _Vp, copy_constructible _Fp>
1646 requires view<_Vp> && is_object_v<_Fp>
1647 && regular_invocable<_Fp&, range_reference_t<_Vp>>
1648 && std::__detail::__can_reference<invoke_result_t<_Fp&,
1649 range_reference_t<_Vp>>>
1650 class transform_view : public view_interface<transform_view<_Vp, _Fp>>
1653 template<bool _Const>
1654 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
1656 template<bool _Const>
1660 template<bool _Const>
1661 requires forward_range<_Base<_Const>>
1662 struct __iter_cat<_Const>
1668 using _Base = transform_view::_Base<_Const>;
1669 using _Res = invoke_result_t<_Fp&, range_reference_t<_Base>>;
1670 if constexpr (is_lvalue_reference_v<_Res>)
1673 = typename iterator_traits<iterator_t<_Base>>::iterator_category;
1674 if constexpr (derived_from<_Cat, contiguous_iterator_tag>)
1675 return random_access_iterator_tag{};
1680 return input_iterator_tag{};
1683 using iterator_category = decltype(_S_iter_cat());
1686 template<bool _Const>
1689 template<bool _Const>
1690 struct _Iterator : __iter_cat<_Const>
1693 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1694 using _Base = transform_view::_Base<_Const>;
1699 if constexpr (random_access_range<_Vp>)
1700 return random_access_iterator_tag{};
1701 else if constexpr (bidirectional_range<_Vp>)
1702 return bidirectional_iterator_tag{};
1703 else if constexpr (forward_range<_Vp>)
1704 return forward_iterator_tag{};
1706 return input_iterator_tag{};
1709 using _Base_iter = iterator_t<_Base>;
1711 _Base_iter _M_current = _Base_iter();
1712 _Parent* _M_parent = nullptr;
1715 using iterator_concept = decltype(_S_iter_concept());
1716 // iterator_category defined in __transform_view_iter_cat
1718 = remove_cvref_t<invoke_result_t<_Fp&, range_reference_t<_Base>>>;
1719 using difference_type = range_difference_t<_Base>;
1721 _Iterator() = default;
1724 _Iterator(_Parent* __parent, _Base_iter __current)
1725 : _M_current(std::move(__current)),
1730 _Iterator(_Iterator<!_Const> __i)
1732 && convertible_to<iterator_t<_Vp>, _Base_iter>
1733 : _M_current(std::move(__i._M_current)), _M_parent(__i._M_parent)
1736 constexpr const _Base_iter&
1737 base() const & noexcept
1738 { return _M_current; }
1740 constexpr _Base_iter
1742 { return std::move(_M_current); }
1744 constexpr decltype(auto)
1746 noexcept(noexcept(std::__invoke(*_M_parent->_M_fun, *_M_current)))
1747 { return std::__invoke(*_M_parent->_M_fun, *_M_current); }
1749 constexpr _Iterator&
1761 operator++(int) requires forward_range<_Base>
1768 constexpr _Iterator&
1769 operator--() requires bidirectional_range<_Base>
1776 operator--(int) requires bidirectional_range<_Base>
1783 constexpr _Iterator&
1784 operator+=(difference_type __n) requires random_access_range<_Base>
1790 constexpr _Iterator&
1791 operator-=(difference_type __n) requires random_access_range<_Base>
1797 constexpr decltype(auto)
1798 operator[](difference_type __n) const
1799 requires random_access_range<_Base>
1800 { return std::__invoke(*_M_parent->_M_fun, _M_current[__n]); }
1802 friend constexpr bool
1803 operator==(const _Iterator& __x, const _Iterator& __y)
1804 requires equality_comparable<_Base_iter>
1805 { return __x._M_current == __y._M_current; }
1807 friend constexpr bool
1808 operator<(const _Iterator& __x, const _Iterator& __y)
1809 requires random_access_range<_Base>
1810 { return __x._M_current < __y._M_current; }
1812 friend constexpr bool
1813 operator>(const _Iterator& __x, const _Iterator& __y)
1814 requires random_access_range<_Base>
1815 { return __y < __x; }
1817 friend constexpr bool
1818 operator<=(const _Iterator& __x, const _Iterator& __y)
1819 requires random_access_range<_Base>
1820 { return !(__y < __x); }
1822 friend constexpr bool
1823 operator>=(const _Iterator& __x, const _Iterator& __y)
1824 requires random_access_range<_Base>
1825 { return !(__x < __y); }
1827 #ifdef __cpp_lib_three_way_comparison
1828 friend constexpr auto
1829 operator<=>(const _Iterator& __x, const _Iterator& __y)
1830 requires random_access_range<_Base>
1831 && three_way_comparable<_Base_iter>
1832 { return __x._M_current <=> __y._M_current; }
1835 friend constexpr _Iterator
1836 operator+(_Iterator __i, difference_type __n)
1837 requires random_access_range<_Base>
1838 { return {__i._M_parent, __i._M_current + __n}; }
1840 friend constexpr _Iterator
1841 operator+(difference_type __n, _Iterator __i)
1842 requires random_access_range<_Base>
1843 { return {__i._M_parent, __i._M_current + __n}; }
1845 friend constexpr _Iterator
1846 operator-(_Iterator __i, difference_type __n)
1847 requires random_access_range<_Base>
1848 { return {__i._M_parent, __i._M_current - __n}; }
1850 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1851 // 3483. transform_view::iterator's difference is overconstrained
1852 friend constexpr difference_type
1853 operator-(const _Iterator& __x, const _Iterator& __y)
1854 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
1855 { return __x._M_current - __y._M_current; }
1857 friend constexpr decltype(auto)
1858 iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
1860 if constexpr (is_lvalue_reference_v<decltype(*__i)>)
1861 return std::move(*__i);
1866 friend _Iterator<!_Const>;
1867 template<bool> friend struct _Sentinel;
1870 template<bool _Const>
1874 using _Parent = __detail::__maybe_const_t<_Const, transform_view>;
1875 using _Base = transform_view::_Base<_Const>;
1877 template<bool _Const2>
1879 __distance_from(const _Iterator<_Const2>& __i) const
1880 { return _M_end - __i._M_current; }
1882 template<bool _Const2>
1884 __equal(const _Iterator<_Const2>& __i) const
1885 { return __i._M_current == _M_end; }
1887 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
1890 _Sentinel() = default;
1893 _Sentinel(sentinel_t<_Base> __end)
1898 _Sentinel(_Sentinel<!_Const> __i)
1900 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
1901 : _M_end(std::move(__i._M_end))
1904 constexpr sentinel_t<_Base>
1908 template<bool _Const2>
1909 requires sentinel_for<sentinel_t<_Base>,
1910 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
1911 friend constexpr bool
1912 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1913 { return __y.__equal(__x); }
1915 template<bool _Const2,
1916 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1917 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1918 friend constexpr range_difference_t<_Base2>
1919 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
1920 { return -__y.__distance_from(__x); }
1922 template<bool _Const2,
1923 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
1924 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
1925 friend constexpr range_difference_t<_Base2>
1926 operator-(const _Sentinel& __y, const _Iterator<_Const2>& __x)
1927 { return __y.__distance_from(__x); }
1929 friend _Sentinel<!_Const>;
1932 _Vp _M_base = _Vp();
1933 __detail::__box<_Fp> _M_fun;
1936 transform_view() = default;
1939 transform_view(_Vp __base, _Fp __fun)
1940 : _M_base(std::move(__base)), _M_fun(std::move(__fun))
1944 base() const& requires copy_constructible<_Vp>
1945 { return _M_base ; }
1949 { return std::move(_M_base); }
1951 constexpr _Iterator<false>
1953 { return _Iterator<false>{this, ranges::begin(_M_base)}; }
1955 constexpr _Iterator<true>
1957 requires range<const _Vp>
1958 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1959 { return _Iterator<true>{this, ranges::begin(_M_base)}; }
1961 constexpr _Sentinel<false>
1963 { return _Sentinel<false>{ranges::end(_M_base)}; }
1965 constexpr _Iterator<false>
1966 end() requires common_range<_Vp>
1967 { return _Iterator<false>{this, ranges::end(_M_base)}; }
1969 constexpr _Sentinel<true>
1971 requires range<const _Vp>
1972 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1973 { return _Sentinel<true>{ranges::end(_M_base)}; }
1975 constexpr _Iterator<true>
1977 requires common_range<const _Vp>
1978 && regular_invocable<const _Fp&, range_reference_t<const _Vp>>
1979 { return _Iterator<true>{this, ranges::end(_M_base)}; }
1982 size() requires sized_range<_Vp>
1983 { return ranges::size(_M_base); }
1986 size() const requires sized_range<const _Vp>
1987 { return ranges::size(_M_base); }
1990 template<typename _Range, typename _Fp>
1991 transform_view(_Range&&, _Fp) -> transform_view<views::all_t<_Range>, _Fp>;
1995 inline constexpr __adaptor::_RangeAdaptor transform
1996 = [] <viewable_range _Range, typename _Fp> (_Range&& __r, _Fp&& __f)
1998 return transform_view{std::forward<_Range>(__r), std::forward<_Fp>(__f)};
2000 } // namespace views
2003 class take_view : public view_interface<take_view<_Vp>>
2006 template<bool _Const>
2007 using _CI = counted_iterator<
2008 iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>;
2010 template<bool _Const>
2014 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2015 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2018 _Sentinel() = default;
2021 _Sentinel(sentinel_t<_Base> __end)
2026 _Sentinel(_Sentinel<!_Const> __s)
2027 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2028 : _M_end(std::move(__s._M_end))
2031 constexpr sentinel_t<_Base>
2035 friend constexpr bool
2036 operator==(const _CI<_Const>& __y, const _Sentinel& __x)
2037 { return __y.count() == 0 || __y.base() == __x._M_end; }
2039 template<bool _OtherConst = !_Const,
2040 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
2041 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
2042 friend constexpr bool
2043 operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x)
2044 { return __y.count() == 0 || __y.base() == __x._M_end; }
2046 friend _Sentinel<!_Const>;
2049 _Vp _M_base = _Vp();
2050 range_difference_t<_Vp> _M_count = 0;
2053 take_view() = default;
2056 take_view(_Vp base, range_difference_t<_Vp> __count)
2057 : _M_base(std::move(base)), _M_count(std::move(__count))
2061 base() const& requires copy_constructible<_Vp>
2066 { return std::move(_M_base); }
2069 begin() requires (!__detail::__simple_view<_Vp>)
2071 if constexpr (sized_range<_Vp>)
2073 if constexpr (random_access_range<_Vp>)
2074 return ranges::begin(_M_base);
2078 return counted_iterator{ranges::begin(_M_base), __sz};
2082 return counted_iterator{ranges::begin(_M_base), _M_count};
2086 begin() const requires range<const _Vp>
2088 if constexpr (sized_range<const _Vp>)
2090 if constexpr (random_access_range<const _Vp>)
2091 return ranges::begin(_M_base);
2095 return counted_iterator{ranges::begin(_M_base), __sz};
2099 return counted_iterator{ranges::begin(_M_base), _M_count};
2103 end() requires (!__detail::__simple_view<_Vp>)
2105 if constexpr (sized_range<_Vp>)
2107 if constexpr (random_access_range<_Vp>)
2108 return ranges::begin(_M_base) + size();
2110 return default_sentinel;
2113 return _Sentinel<false>{ranges::end(_M_base)};
2117 end() const requires range<const _Vp>
2119 if constexpr (sized_range<const _Vp>)
2121 if constexpr (random_access_range<const _Vp>)
2122 return ranges::begin(_M_base) + size();
2124 return default_sentinel;
2127 return _Sentinel<true>{ranges::end(_M_base)};
2131 size() requires sized_range<_Vp>
2133 auto __n = ranges::size(_M_base);
2134 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2138 size() const requires sized_range<const _Vp>
2140 auto __n = ranges::size(_M_base);
2141 return std::min(__n, static_cast<decltype(__n)>(_M_count));
2145 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2146 // 3447. Deduction guides for take_view and drop_view have different
2148 template<typename _Range>
2149 take_view(_Range&&, range_difference_t<_Range>)
2150 -> take_view<views::all_t<_Range>>;
2152 template<typename _Tp>
2153 inline constexpr bool enable_borrowed_range<take_view<_Tp>>
2154 = enable_borrowed_range<_Tp>;
2158 inline constexpr __adaptor::_RangeAdaptor take
2159 = [] <viewable_range _Range, typename _Tp> (_Range&& __r, _Tp&& __n)
2161 return take_view{std::forward<_Range>(__r), std::forward<_Tp>(__n)};
2163 } // namespace views
2165 template<view _Vp, typename _Pred>
2166 requires input_range<_Vp> && is_object_v<_Pred>
2167 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2168 class take_while_view : public view_interface<take_while_view<_Vp, _Pred>>
2170 template<bool _Const>
2174 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2176 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
2177 const _Pred* _M_pred = nullptr;
2180 _Sentinel() = default;
2183 _Sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
2184 : _M_end(__end), _M_pred(__pred)
2188 _Sentinel(_Sentinel<!_Const> __s)
2189 requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
2190 : _M_end(__s._M_end), _M_pred(__s._M_pred)
2193 constexpr sentinel_t<_Base>
2194 base() const { return _M_end; }
2196 friend constexpr bool
2197 operator==(const iterator_t<_Base>& __x, const _Sentinel& __y)
2198 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2200 template<bool _OtherConst = !_Const,
2201 typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>>
2202 requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
2203 friend constexpr bool
2204 operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y)
2205 { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); }
2207 friend _Sentinel<!_Const>;
2210 _Vp _M_base = _Vp();
2211 __detail::__box<_Pred> _M_pred;
2214 take_while_view() = default;
2217 take_while_view(_Vp base, _Pred __pred)
2218 : _M_base(std::move(base)), _M_pred(std::move(__pred))
2223 base() const& requires copy_constructible<_Vp>
2228 { return std::move(_M_base); }
2230 constexpr const _Pred&
2232 { return *_M_pred; }
2235 begin() requires (!__detail::__simple_view<_Vp>)
2236 { return ranges::begin(_M_base); }
2239 begin() const requires range<const _Vp>
2240 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2241 { return ranges::begin(_M_base); }
2244 end() requires (!__detail::__simple_view<_Vp>)
2245 { return _Sentinel<false>(ranges::end(_M_base),
2246 std::__addressof(*_M_pred)); }
2249 end() const requires range<const _Vp>
2250 && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>
2251 { return _Sentinel<true>(ranges::end(_M_base),
2252 std::__addressof(*_M_pred)); }
2255 template<typename _Range, typename _Pred>
2256 take_while_view(_Range&&, _Pred)
2257 -> take_while_view<views::all_t<_Range>, _Pred>;
2261 inline constexpr __adaptor::_RangeAdaptor take_while
2262 = [] <viewable_range _Range, typename _Pred> (_Range&& __r, _Pred&& __p)
2264 return take_while_view{std::forward<_Range>(__r), std::forward<_Pred>(__p)};
2266 } // namespace views
2269 class drop_view : public view_interface<drop_view<_Vp>>
2272 _Vp _M_base = _Vp();
2273 range_difference_t<_Vp> _M_count = 0;
2275 // ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
2276 // both random_access_range and sized_range. Otherwise, cache its result.
2277 static constexpr bool _S_needs_cached_begin
2278 = !(random_access_range<const _Vp> && sized_range<const _Vp>);
2279 [[no_unique_address]]
2280 __detail::__maybe_present_t<_S_needs_cached_begin,
2281 __detail::_CachedPosition<_Vp>>
2285 drop_view() = default;
2288 drop_view(_Vp __base, range_difference_t<_Vp> __count)
2289 : _M_base(std::move(__base)), _M_count(__count)
2290 { __glibcxx_assert(__count >= 0); }
2293 base() const& requires copy_constructible<_Vp>
2298 { return std::move(_M_base); }
2300 // This overload is disabled for simple views with constant-time begin().
2303 requires (!(__detail::__simple_view<_Vp>
2304 && random_access_range<const _Vp>
2305 && sized_range<const _Vp>))
2307 if constexpr (_S_needs_cached_begin)
2308 if (_M_cached_begin._M_has_value())
2309 return _M_cached_begin._M_get(_M_base);
2311 auto __it = ranges::next(ranges::begin(_M_base),
2312 _M_count, ranges::end(_M_base));
2313 if constexpr (_S_needs_cached_begin)
2314 _M_cached_begin._M_set(_M_base, __it);
2318 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2319 // 3482. drop_view's const begin should additionally require sized_range
2322 requires random_access_range<const _Vp> && sized_range<const _Vp>
2324 return ranges::next(ranges::begin(_M_base), _M_count,
2325 ranges::end(_M_base));
2329 end() requires (!__detail::__simple_view<_Vp>)
2330 { return ranges::end(_M_base); }
2333 end() const requires range<const _Vp>
2334 { return ranges::end(_M_base); }
2337 size() requires sized_range<_Vp>
2339 const auto __s = ranges::size(_M_base);
2340 const auto __c = static_cast<decltype(__s)>(_M_count);
2341 return __s < __c ? 0 : __s - __c;
2345 size() const requires sized_range<const _Vp>
2347 const auto __s = ranges::size(_M_base);
2348 const auto __c = static_cast<decltype(__s)>(_M_count);
2349 return __s < __c ? 0 : __s - __c;
2353 template<typename _Range>
2354 drop_view(_Range&&, range_difference_t<_Range>)
2355 -> drop_view<views::all_t<_Range>>;
2357 template<typename _Tp>
2358 inline constexpr bool enable_borrowed_range<drop_view<_Tp>>
2359 = enable_borrowed_range<_Tp>;
2363 inline constexpr __adaptor::_RangeAdaptor drop
2364 = [] <viewable_range _Range, typename _Tp> (_Range&& __r, _Tp&& __n)
2366 return drop_view{std::forward<_Range>(__r), std::forward<_Tp>(__n)};
2368 } // namespace views
2370 template<view _Vp, typename _Pred>
2371 requires input_range<_Vp> && is_object_v<_Pred>
2372 && indirect_unary_predicate<const _Pred, iterator_t<_Vp>>
2373 class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
2376 _Vp _M_base = _Vp();
2377 __detail::__box<_Pred> _M_pred;
2378 [[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
2381 drop_while_view() = default;
2384 drop_while_view(_Vp __base, _Pred __pred)
2385 : _M_base(std::move(__base)), _M_pred(std::move(__pred))
2389 base() const& requires copy_constructible<_Vp>
2394 { return std::move(_M_base); }
2396 constexpr const _Pred&
2398 { return *_M_pred; }
2403 if (_M_cached_begin._M_has_value())
2404 return _M_cached_begin._M_get(_M_base);
2406 auto __it = __detail::find_if_not(ranges::begin(_M_base),
2407 ranges::end(_M_base),
2408 std::cref(*_M_pred));
2409 _M_cached_begin._M_set(_M_base, __it);
2415 { return ranges::end(_M_base); }
2418 template<typename _Range, typename _Pred>
2419 drop_while_view(_Range&&, _Pred)
2420 -> drop_while_view<views::all_t<_Range>, _Pred>;
2422 template<typename _Tp, typename _Pred>
2423 inline constexpr bool enable_borrowed_range<drop_while_view<_Tp, _Pred>>
2424 = enable_borrowed_range<_Tp>;
2428 inline constexpr __adaptor::_RangeAdaptor drop_while
2429 = [] <viewable_range _Range, typename _Pred> (_Range&& __r, _Pred&& __p)
2431 return drop_while_view{std::forward<_Range>(__r),
2432 std::forward<_Pred>(__p)};
2434 } // namespace views
2436 template<input_range _Vp>
2437 requires view<_Vp> && input_range<range_reference_t<_Vp>>
2438 && (is_reference_v<range_reference_t<_Vp>>
2439 || view<range_value_t<_Vp>>)
2440 class join_view : public view_interface<join_view<_Vp>>
2443 using _InnerRange = range_reference_t<_Vp>;
2445 template<bool _Const>
2446 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2448 template<bool _Const>
2449 using _Outer_iter = iterator_t<_Base<_Const>>;
2451 template<bool _Const>
2452 using _Inner_iter = iterator_t<range_reference_t<_Base<_Const>>>;
2454 template<bool _Const>
2455 static constexpr bool _S_ref_is_glvalue
2456 = is_reference_v<range_reference_t<_Base<_Const>>>;
2458 template<bool _Const>
2462 template<bool _Const>
2463 requires _S_ref_is_glvalue<_Const>
2464 && forward_range<_Base<_Const>>
2465 && forward_range<range_reference_t<_Base<_Const>>>
2466 struct __iter_cat<_Const>
2469 static constexpr auto
2472 using _Outer_iter = join_view::_Outer_iter<_Const>;
2473 using _Inner_iter = join_view::_Inner_iter<_Const>;
2474 using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
2475 using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
2476 if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
2477 && derived_from<_InnerCat, bidirectional_iterator_tag>)
2478 return bidirectional_iterator_tag{};
2479 else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
2480 && derived_from<_InnerCat, forward_iterator_tag>)
2481 return forward_iterator_tag{};
2483 return input_iterator_tag{};
2486 using iterator_category = decltype(_S_iter_cat());
2489 template<bool _Const>
2492 template<bool _Const>
2493 struct _Iterator : __iter_cat<_Const>
2496 using _Parent = __detail::__maybe_const_t<_Const, join_view>;
2497 using _Base = join_view::_Base<_Const>;
2499 static constexpr bool _S_ref_is_glvalue
2500 = join_view::_S_ref_is_glvalue<_Const>;
2505 auto __update_inner = [this] (range_reference_t<_Base> __x) -> auto&
2507 if constexpr (_S_ref_is_glvalue)
2510 return (_M_parent->_M_inner = views::all(std::move(__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 _Vp _M_base = _Vp();
2705 // XXX: _M_inner is "present only when !is_reference_v<_InnerRange>"
2706 [[no_unique_address]]
2707 __detail::__maybe_present_t<!is_reference_v<_InnerRange>,
2708 views::all_t<_InnerRange>> _M_inner;
2711 join_view() = default;
2714 join_view(_Vp __base)
2715 : _M_base(std::move(__base))
2719 base() const& requires copy_constructible<_Vp>
2724 { return std::move(_M_base); }
2729 constexpr bool __use_const
2730 = (__detail::__simple_view<_Vp>
2731 && is_reference_v<range_reference_t<_Vp>>);
2732 return _Iterator<__use_const>{this, ranges::begin(_M_base)};
2737 requires input_range<const _Vp>
2738 && is_reference_v<range_reference_t<const _Vp>>
2740 return _Iterator<true>{this, ranges::begin(_M_base)};
2746 if constexpr (forward_range<_Vp> && is_reference_v<_InnerRange>
2747 && forward_range<_InnerRange>
2748 && common_range<_Vp> && common_range<_InnerRange>)
2749 return _Iterator<__detail::__simple_view<_Vp>>{this,
2750 ranges::end(_M_base)};
2752 return _Sentinel<__detail::__simple_view<_Vp>>{this};
2757 requires input_range<const _Vp>
2758 && is_reference_v<range_reference_t<const _Vp>>
2760 if constexpr (forward_range<const _Vp>
2761 && is_reference_v<range_reference_t<const _Vp>>
2762 && forward_range<range_reference_t<const _Vp>>
2763 && common_range<const _Vp>
2764 && common_range<range_reference_t<const _Vp>>)
2765 return _Iterator<true>{this, ranges::end(_M_base)};
2767 return _Sentinel<true>{this};
2771 template<typename _Range>
2772 explicit join_view(_Range&&) -> join_view<views::all_t<_Range>>;
2776 inline constexpr __adaptor::_RangeAdaptorClosure join
2777 = [] <viewable_range _Range> (_Range&& __r)
2779 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2780 // 3474. Nesting join_views is broken because of CTAD
2781 return join_view<views::all_t<_Range>>{std::forward<_Range>(__r)};
2783 } // namespace views
2788 struct __require_constant;
2790 template<typename _Range>
2791 concept __tiny_range = sized_range<_Range>
2793 { typename __require_constant<remove_reference_t<_Range>::size()>; }
2794 && (remove_reference_t<_Range>::size() <= 1);
2796 template<typename _Base>
2797 struct __split_view_outer_iter_cat
2800 template<forward_range _Base>
2801 struct __split_view_outer_iter_cat<_Base>
2802 { using iterator_category = input_iterator_tag; };
2804 template<typename _Base>
2805 struct __split_view_inner_iter_cat
2808 template<forward_range _Base>
2809 struct __split_view_inner_iter_cat<_Base>
2812 static constexpr auto
2815 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
2816 if constexpr (derived_from<_Cat, forward_iterator_tag>)
2817 return forward_iterator_tag{};
2822 using iterator_category = decltype(_S_iter_cat());
2826 template<input_range _Vp, forward_range _Pattern>
2827 requires view<_Vp> && view<_Pattern>
2828 && indirectly_comparable<iterator_t<_Vp>, iterator_t<_Pattern>,
2830 && (forward_range<_Vp> || __detail::__tiny_range<_Pattern>)
2831 class split_view : public view_interface<split_view<_Vp, _Pattern>>
2834 template<bool _Const>
2835 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
2837 template<bool _Const>
2840 template<bool _Const>
2842 : __detail::__split_view_outer_iter_cat<_Base<_Const>>
2845 using _Parent = __detail::__maybe_const_t<_Const, split_view>;
2846 using _Base = split_view::_Base<_Const>;
2850 { return __current() == ranges::end(_M_parent->_M_base); }
2852 // [range.split.outer] p1
2853 // Many of the following specifications refer to the notional member
2854 // current of outer-iterator. current is equivalent to current_ if
2855 // V models forward_range, and parent_->current_ otherwise.
2857 __current() noexcept
2859 if constexpr (forward_range<_Vp>)
2862 return _M_parent->_M_current;
2866 __current() const noexcept
2868 if constexpr (forward_range<_Vp>)
2871 return _M_parent->_M_current;
2874 _Parent* _M_parent = nullptr;
2876 // XXX: _M_current is present only if "V models forward_range"
2877 [[no_unique_address]]
2878 __detail::__maybe_present_t<forward_range<_Vp>,
2879 iterator_t<_Base>> _M_current;
2882 using iterator_concept = conditional_t<forward_range<_Base>,
2883 forward_iterator_tag,
2884 input_iterator_tag>;
2885 // iterator_category defined in __split_view_outer_iter_cat
2886 using difference_type = range_difference_t<_Base>;
2888 struct value_type : view_interface<value_type>
2891 _OuterIter _M_i = _OuterIter();
2894 value_type() = default;
2897 value_type(_OuterIter __i)
2898 : _M_i(std::move(__i))
2901 constexpr _InnerIter<_Const>
2903 requires copyable<_OuterIter>
2904 { return _InnerIter<_Const>{_M_i}; }
2906 constexpr _InnerIter<_Const>
2908 requires (!copyable<_OuterIter>)
2909 { return _InnerIter<_Const>{std::move(_M_i)}; }
2911 constexpr default_sentinel_t
2913 { return default_sentinel; }
2916 _OuterIter() = default;
2919 _OuterIter(_Parent* __parent) requires (!forward_range<_Base>)
2920 : _M_parent(__parent)
2924 _OuterIter(_Parent* __parent, iterator_t<_Base> __current)
2925 requires forward_range<_Base>
2926 : _M_parent(__parent),
2927 _M_current(std::move(__current))
2931 _OuterIter(_OuterIter<!_Const> __i)
2933 && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
2934 : _M_parent(__i._M_parent), _M_current(std::move(__i._M_current))
2937 constexpr value_type
2939 { return value_type{*this}; }
2941 constexpr _OuterIter&
2944 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2945 // 3505. split_view::outer-iterator::operator++ misspecified
2946 const auto __end = ranges::end(_M_parent->_M_base);
2947 if (__current() == __end)
2949 const auto [__pbegin, __pend] = subrange{_M_parent->_M_pattern};
2950 if (__pbegin == __pend)
2952 else if constexpr (__detail::__tiny_range<_Pattern>)
2954 __current() = __detail::find(std::move(__current()), __end,
2956 if (__current() != __end)
2963 = __detail::mismatch(__current(), __end, __pbegin, __pend);
2969 } while (++__current() != __end);
2973 constexpr decltype(auto)
2976 if constexpr (forward_range<_Base>)
2986 friend constexpr bool
2987 operator==(const _OuterIter& __x, const _OuterIter& __y)
2988 requires forward_range<_Base>
2989 { return __x._M_current == __y._M_current; }
2991 friend constexpr bool
2992 operator==(const _OuterIter& __x, default_sentinel_t)
2993 { return __x.__at_end(); };
2995 friend _OuterIter<!_Const>;
2996 friend _InnerIter<_Const>;
2999 template<bool _Const>
3001 : __detail::__split_view_inner_iter_cat<_Base<_Const>>
3004 using _Base = split_view::_Base<_Const>;
3009 auto [__pcur, __pend] = subrange{_M_i._M_parent->_M_pattern};
3010 auto __end = ranges::end(_M_i._M_parent->_M_base);
3011 if constexpr (__detail::__tiny_range<_Pattern>)
3013 const auto& __cur = _M_i_current();
3016 if (__pcur == __pend)
3017 return _M_incremented;
3018 return *__cur == *__pcur;
3022 auto __cur = _M_i_current();
3025 if (__pcur == __pend)
3026 return _M_incremented;
3029 if (*__cur != *__pcur)
3031 if (++__pcur == __pend)
3033 } while (++__cur != __end);
3039 _M_i_current() noexcept
3040 { return _M_i.__current(); }
3043 _M_i_current() const noexcept
3044 { return _M_i.__current(); }
3046 _OuterIter<_Const> _M_i = _OuterIter<_Const>();
3047 bool _M_incremented = false;
3050 using iterator_concept
3051 = typename _OuterIter<_Const>::iterator_concept;
3052 // iterator_category defined in __split_view_inner_iter_cat
3053 using value_type = range_value_t<_Base>;
3054 using difference_type = range_difference_t<_Base>;
3056 _InnerIter() = default;
3059 _InnerIter(_OuterIter<_Const> __i)
3060 : _M_i(std::move(__i))
3063 constexpr decltype(auto)
3065 { return *_M_i_current(); }
3067 constexpr _InnerIter&
3070 _M_incremented = true;
3071 if constexpr (!forward_range<_Base>)
3072 if constexpr (_Pattern::size() == 0)
3078 constexpr decltype(auto)
3081 if constexpr (forward_range<_Base>)
3091 friend constexpr bool
3092 operator==(const _InnerIter& __x, const _InnerIter& __y)
3093 requires forward_range<_Base>
3094 { return __x._M_i == __y._M_i; }
3096 friend constexpr bool
3097 operator==(const _InnerIter& __x, default_sentinel_t)
3098 { return __x.__at_end(); }
3100 friend constexpr decltype(auto)
3101 iter_move(const _InnerIter& __i)
3102 noexcept(noexcept(ranges::iter_move(__i._M_i_current())))
3103 { return ranges::iter_move(__i._M_i_current()); }
3105 friend constexpr void
3106 iter_swap(const _InnerIter& __x, const _InnerIter& __y)
3107 noexcept(noexcept(ranges::iter_swap(__x._M_i_current(),
3108 __y._M_i_current())))
3109 requires indirectly_swappable<iterator_t<_Base>>
3110 { ranges::iter_swap(__x._M_i_current(), __y._M_i_current()); }
3113 _Vp _M_base = _Vp();
3114 _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>, iterator_t<_Vp>>
3123 split_view() = default;
3126 split_view(_Vp __base, _Pattern __pattern)
3127 : _M_base(std::move(__base)), _M_pattern(std::move(__pattern))
3130 template<input_range _Range>
3131 requires constructible_from<_Vp, views::all_t<_Range>>
3132 && constructible_from<_Pattern, single_view<range_value_t<_Range>>>
3134 split_view(_Range&& __r, range_value_t<_Range> __e)
3135 : _M_base(views::all(std::forward<_Range>(__r))),
3136 _M_pattern(std::move(__e))
3140 base() const& requires copy_constructible<_Vp>
3145 { return std::move(_M_base); }
3150 if constexpr (forward_range<_Vp>)
3151 return _OuterIter<__detail::__simple_view<_Vp>>{
3152 this, ranges::begin(_M_base)};
3155 _M_current = ranges::begin(_M_base);
3156 return _OuterIter<false>{this};
3161 begin() const requires forward_range<_Vp> && forward_range<const _Vp>
3163 return _OuterIter<true>{this, ranges::begin(_M_base)};
3167 end() requires forward_range<_Vp> && common_range<_Vp>
3169 return _OuterIter<__detail::__simple_view<_Vp>>{
3170 this, ranges::end(_M_base)};
3176 if constexpr (forward_range<_Vp>
3177 && forward_range<const _Vp>
3178 && common_range<const _Vp>)
3179 return _OuterIter<true>{this, ranges::end(_M_base)};
3181 return default_sentinel;
3185 template<typename _Range, typename _Pred>
3186 split_view(_Range&&, _Pred&&)
3187 -> split_view<views::all_t<_Range>, views::all_t<_Pred>>;
3189 template<input_range _Range>
3190 split_view(_Range&&, range_value_t<_Range>)
3191 -> split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
3195 inline constexpr __adaptor::_RangeAdaptor split
3196 = [] <viewable_range _Range, typename _Fp> (_Range&& __r, _Fp&& __f)
3198 return split_view{std::forward<_Range>(__r), std::forward<_Fp>(__f)};
3200 } // namespace views
3206 template<input_or_output_iterator _Iter>
3208 operator()(_Iter __i, iter_difference_t<_Iter> __n) const
3210 if constexpr (random_access_iterator<_Iter>)
3211 return subrange{__i, __i + __n};
3213 return subrange{counted_iterator{std::move(__i), __n},
3218 inline constexpr _Counted counted{};
3219 } // namespace views
3222 requires (!common_range<_Vp>) && copyable<iterator_t<_Vp>>
3223 class common_view : public view_interface<common_view<_Vp>>
3226 _Vp _M_base = _Vp();
3229 common_view() = default;
3232 common_view(_Vp __r)
3233 : _M_base(std::move(__r))
3236 /* XXX: LWG 3280 didn't remove this constructor, but I think it should?
3237 template<viewable_range _Range>
3238 requires (!common_range<_Range>)
3239 && constructible_from<_Vp, views::all_t<_Range>>
3241 common_view(_Range&& __r)
3242 : _M_base(views::all(std::forward<_Range>(__r)))
3247 base() const& requires copy_constructible<_Vp>
3252 { return std::move(_M_base); }
3257 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3258 return ranges::begin(_M_base);
3260 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3261 (ranges::begin(_M_base));
3265 begin() const requires range<const _Vp>
3267 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3268 return ranges::begin(_M_base);
3270 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3271 (ranges::begin(_M_base));
3277 if constexpr (random_access_range<_Vp> && sized_range<_Vp>)
3278 return ranges::begin(_M_base) + ranges::size(_M_base);
3280 return common_iterator<iterator_t<_Vp>, sentinel_t<_Vp>>
3281 (ranges::end(_M_base));
3285 end() const requires range<const _Vp>
3287 if constexpr (random_access_range<const _Vp> && sized_range<const _Vp>)
3288 return ranges::begin(_M_base) + ranges::size(_M_base);
3290 return common_iterator<iterator_t<const _Vp>, sentinel_t<const _Vp>>
3291 (ranges::end(_M_base));
3295 size() requires sized_range<_Vp>
3296 { return ranges::size(_M_base); }
3299 size() const requires sized_range<const _Vp>
3300 { return ranges::size(_M_base); }
3303 template<typename _Range>
3304 common_view(_Range&&) -> common_view<views::all_t<_Range>>;
3306 template<typename _Tp>
3307 inline constexpr bool enable_borrowed_range<common_view<_Tp>>
3308 = enable_borrowed_range<_Tp>;
3312 inline constexpr __adaptor::_RangeAdaptorClosure common
3313 = [] <viewable_range _Range> (_Range&& __r)
3315 if constexpr (common_range<_Range>
3316 && requires { views::all(std::forward<_Range>(__r)); })
3317 return views::all(std::forward<_Range>(__r));
3319 return common_view{std::forward<_Range>(__r)};
3322 } // namespace views
3325 requires bidirectional_range<_Vp>
3326 class reverse_view : public view_interface<reverse_view<_Vp>>
3329 _Vp _M_base = _Vp();
3331 static constexpr bool _S_needs_cached_begin
3332 = !common_range<_Vp> && !random_access_range<_Vp>;
3333 [[no_unique_address]]
3334 __detail::__maybe_present_t<_S_needs_cached_begin,
3335 __detail::_CachedPosition<_Vp>>
3339 reverse_view() = default;
3342 reverse_view(_Vp __r)
3343 : _M_base(std::move(__r))
3347 base() const& requires copy_constructible<_Vp>
3352 { return std::move(_M_base); }
3354 constexpr reverse_iterator<iterator_t<_Vp>>
3357 if constexpr (_S_needs_cached_begin)
3358 if (_M_cached_begin._M_has_value())
3359 return std::make_reverse_iterator(_M_cached_begin._M_get(_M_base));
3361 auto __it = ranges::next(ranges::begin(_M_base), ranges::end(_M_base));
3362 if constexpr (_S_needs_cached_begin)
3363 _M_cached_begin._M_set(_M_base, __it);
3364 return std::make_reverse_iterator(std::move(__it));
3368 begin() requires common_range<_Vp>
3369 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3372 begin() const requires common_range<const _Vp>
3373 { return std::make_reverse_iterator(ranges::end(_M_base)); }
3375 constexpr reverse_iterator<iterator_t<_Vp>>
3377 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3380 end() const requires common_range<const _Vp>
3381 { return std::make_reverse_iterator(ranges::begin(_M_base)); }
3384 size() requires sized_range<_Vp>
3385 { return ranges::size(_M_base); }
3388 size() const requires sized_range<const _Vp>
3389 { return ranges::size(_M_base); }
3392 template<typename _Range>
3393 reverse_view(_Range&&) -> reverse_view<views::all_t<_Range>>;
3395 template<typename _Tp>
3396 inline constexpr bool enable_borrowed_range<reverse_view<_Tp>>
3397 = enable_borrowed_range<_Tp>;
3404 inline constexpr bool __is_reversible_subrange = false;
3406 template<typename _Iter, subrange_kind _Kind>
3407 inline constexpr bool
3408 __is_reversible_subrange<subrange<reverse_iterator<_Iter>,
3409 reverse_iterator<_Iter>,
3413 inline constexpr bool __is_reverse_view = false;
3415 template<typename _Vp>
3416 inline constexpr bool __is_reverse_view<reverse_view<_Vp>> = true;
3419 inline constexpr __adaptor::_RangeAdaptorClosure reverse
3420 = [] <viewable_range _Range> (_Range&& __r)
3422 using _Tp = remove_cvref_t<_Range>;
3423 if constexpr (__detail::__is_reverse_view<_Tp>)
3424 return std::forward<_Range>(__r).base();
3425 else if constexpr (__detail::__is_reversible_subrange<_Tp>)
3427 using _Iter = decltype(ranges::begin(__r).base());
3428 if constexpr (sized_range<_Tp>)
3429 return subrange<_Iter, _Iter, subrange_kind::sized>
3430 (__r.end().base(), __r.begin().base(), __r.size());
3432 return subrange<_Iter, _Iter, subrange_kind::unsized>
3433 (__r.end().base(), __r.begin().base());
3436 return reverse_view{std::forward<_Range>(__r)};
3438 } // namespace views
3442 template<typename _Tp, size_t _Nm>
3443 concept __has_tuple_element = requires(_Tp __t)
3445 typename tuple_size<_Tp>::type;
3446 requires _Nm < tuple_size_v<_Tp>;
3447 typename tuple_element_t<_Nm, _Tp>;
3448 { std::get<_Nm>(__t) }
3449 -> convertible_to<const tuple_element_t<_Nm, _Tp>&>;
3452 template<typename _Tp, size_t _Nm>
3453 concept __returnable_element
3454 = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Nm, _Tp>>;
3457 template<input_range _Vp, size_t _Nm>
3459 && __detail::__has_tuple_element<range_value_t<_Vp>, _Nm>
3460 && __detail::__has_tuple_element<remove_reference_t<range_reference_t<_Vp>>,
3462 && __detail::__returnable_element<range_reference_t<_Vp>, _Nm>
3463 class elements_view : public view_interface<elements_view<_Vp, _Nm>>
3466 elements_view() = default;
3469 elements_view(_Vp base)
3470 : _M_base(std::move(base))
3473 constexpr const _Vp&
3474 base() const & noexcept
3479 { return std::move(_M_base); }
3482 begin() requires (!__detail::__simple_view<_Vp>)
3483 { return _Iterator<false>(ranges::begin(_M_base)); }
3486 begin() const requires range<const _Vp>
3487 { return _Iterator<true>(ranges::begin(_M_base)); }
3490 end() requires (!__detail::__simple_view<_Vp> && !common_range<_Vp>)
3491 { return _Sentinel<false>{ranges::end(_M_base)}; }
3494 end() requires (!__detail::__simple_view<_Vp> && common_range<_Vp>)
3495 { return _Iterator<false>{ranges::end(_M_base)}; }
3498 end() const requires range<const _Vp>
3499 { return _Sentinel<true>{ranges::end(_M_base)}; }
3502 end() const requires common_range<const _Vp>
3503 { return _Iterator<true>{ranges::end(_M_base)}; }
3506 size() requires sized_range<_Vp>
3507 { return ranges::size(_M_base); }
3510 size() const requires sized_range<const _Vp>
3511 { return ranges::size(_M_base); }
3514 template<bool _Const>
3515 using _Base = __detail::__maybe_const_t<_Const, _Vp>;
3517 template<bool _Const>
3521 template<bool _Const>
3522 requires forward_range<_Base<_Const>>
3523 struct __iter_cat<_Const>
3526 static auto _S_iter_cat()
3528 using _Base = elements_view::_Base<_Const>;
3529 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
3530 using _Res = decltype((std::get<_Nm>(*std::declval<iterator_t<_Base>>())));
3531 if constexpr (!is_lvalue_reference_v<_Res>)
3532 return input_iterator_tag{};
3533 else if constexpr (derived_from<_Cat, random_access_iterator_tag>)
3534 return random_access_iterator_tag{};
3539 using iterator_category = decltype(_S_iter_cat());
3542 template<bool _Const>
3545 template<bool _Const>
3546 struct _Iterator : __iter_cat<_Const>
3549 using _Base = elements_view::_Base<_Const>;
3551 iterator_t<_Base> _M_current = iterator_t<_Base>();
3553 static constexpr decltype(auto)
3554 _S_get_element(const iterator_t<_Base>& __i)
3556 if constexpr (is_reference_v<range_reference_t<_Base>>)
3557 return std::get<_Nm>(*__i);
3560 using _Et = remove_cv_t<tuple_element_t<_Nm, range_reference_t<_Base>>>;
3561 return static_cast<_Et>(std::get<_Nm>(*__i));
3568 if constexpr (random_access_range<_Vp>)
3569 return random_access_iterator_tag{};
3570 else if constexpr (bidirectional_range<_Vp>)
3571 return bidirectional_iterator_tag{};
3572 else if constexpr (forward_range<_Vp>)
3573 return forward_iterator_tag{};
3575 return input_iterator_tag{};
3578 friend _Iterator<!_Const>;
3581 using iterator_concept = decltype(_S_iter_concept());
3582 // iterator_category defined in elements_view::__iter_cat
3584 = remove_cvref_t<tuple_element_t<_Nm, range_value_t<_Base>>>;
3585 using difference_type = range_difference_t<_Base>;
3587 _Iterator() = default;
3590 _Iterator(iterator_t<_Base> current)
3591 : _M_current(std::move(current))
3595 _Iterator(_Iterator<!_Const> i)
3596 requires _Const && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
3597 : _M_current(std::move(i._M_current))
3600 constexpr iterator_t<_Base>
3602 requires copyable<iterator_t<_Base>>
3603 { return _M_current; }
3605 constexpr iterator_t<_Base>
3607 { return std::move(_M_current); }
3609 constexpr decltype(auto)
3611 { return _S_get_element(_M_current); }
3613 constexpr _Iterator&
3625 operator++(int) requires forward_range<_Base>
3632 constexpr _Iterator&
3633 operator--() requires bidirectional_range<_Base>
3640 operator--(int) requires bidirectional_range<_Base>
3647 constexpr _Iterator&
3648 operator+=(difference_type __n)
3649 requires random_access_range<_Base>
3655 constexpr _Iterator&
3656 operator-=(difference_type __n)
3657 requires random_access_range<_Base>
3663 constexpr decltype(auto)
3664 operator[](difference_type __n) const
3665 requires random_access_range<_Base>
3666 { return _S_get_element(_M_current + __n); }
3668 friend constexpr bool
3669 operator==(const _Iterator& __x, const _Iterator& __y)
3670 requires equality_comparable<iterator_t<_Base>>
3671 { return __x._M_current == __y._M_current; }
3673 friend constexpr bool
3674 operator<(const _Iterator& __x, const _Iterator& __y)
3675 requires random_access_range<_Base>
3676 { return __x._M_current < __y._M_current; }
3678 friend constexpr bool
3679 operator>(const _Iterator& __x, const _Iterator& __y)
3680 requires random_access_range<_Base>
3681 { return __y._M_current < __x._M_current; }
3683 friend constexpr bool
3684 operator<=(const _Iterator& __x, const _Iterator& __y)
3685 requires random_access_range<_Base>
3686 { return !(__y._M_current > __x._M_current); }
3688 friend constexpr bool
3689 operator>=(const _Iterator& __x, const _Iterator& __y)
3690 requires random_access_range<_Base>
3691 { return !(__x._M_current > __y._M_current); }
3693 #ifdef __cpp_lib_three_way_comparison
3694 friend constexpr auto
3695 operator<=>(const _Iterator& __x, const _Iterator& __y)
3696 requires random_access_range<_Base>
3697 && three_way_comparable<iterator_t<_Base>>
3698 { return __x._M_current <=> __y._M_current; }
3701 friend constexpr _Iterator
3702 operator+(const _Iterator& __x, difference_type __y)
3703 requires random_access_range<_Base>
3704 { return _Iterator{__x} += __y; }
3706 friend constexpr _Iterator
3707 operator+(difference_type __x, const _Iterator& __y)
3708 requires random_access_range<_Base>
3709 { return __y + __x; }
3711 friend constexpr _Iterator
3712 operator-(const _Iterator& __x, difference_type __y)
3713 requires random_access_range<_Base>
3714 { return _Iterator{__x} -= __y; }
3716 // _GLIBCXX_RESOLVE_LIB_DEFECTS
3717 // 3483. transform_view::iterator's difference is overconstrained
3718 friend constexpr difference_type
3719 operator-(const _Iterator& __x, const _Iterator& __y)
3720 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
3721 { return __x._M_current - __y._M_current; }
3723 template <bool> friend struct _Sentinel;
3726 template<bool _Const>
3730 template<bool _Const2>
3732 _M_equal(const _Iterator<_Const2>& __x) const
3733 { return __x._M_current == _M_end; }
3735 template<bool _Const2>
3737 _M_distance_from(const _Iterator<_Const2>& __i) const
3738 { return _M_end - __i._M_current; }
3740 using _Base = elements_view::_Base<_Const>;
3741 sentinel_t<_Base> _M_end = sentinel_t<_Base>();
3744 _Sentinel() = default;
3747 _Sentinel(sentinel_t<_Base> __end)
3748 : _M_end(std::move(__end))
3752 _Sentinel(_Sentinel<!_Const> __other)
3754 && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
3755 : _M_end(std::move(__other._M_end))
3758 constexpr sentinel_t<_Base>
3762 template<bool _Const2>
3763 requires sentinel_for<sentinel_t<_Base>,
3764 iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>>
3765 friend constexpr bool
3766 operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3767 { return __y._M_equal(__x); }
3769 template<bool _Const2,
3770 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3771 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3772 friend constexpr range_difference_t<_Base2>
3773 operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
3774 { return -__y._M_distance_from(__x); }
3776 template<bool _Const2,
3777 typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>
3778 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
3779 friend constexpr range_difference_t<_Base2>
3780 operator-(const _Sentinel& __x, const _Iterator<_Const2>& __y)
3781 { return __x._M_distance_from(__y); }
3783 friend _Sentinel<!_Const>;
3786 _Vp _M_base = _Vp();
3789 template<typename _Tp, size_t _Nm>
3790 inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Nm>>
3791 = enable_borrowed_range<_Tp>;
3793 template<typename _Range>
3794 using keys_view = elements_view<views::all_t<_Range>, 0>;
3796 template<typename _Range>
3797 using values_view = elements_view<views::all_t<_Range>, 1>;
3801 template<size_t _Nm>
3802 inline constexpr __adaptor::_RangeAdaptorClosure elements
3803 = [] <viewable_range _Range> (_Range&& __r)
3805 using _El = elements_view<views::all_t<_Range>, _Nm>;
3806 return _El{std::forward<_Range>(__r)};
3809 inline constexpr __adaptor::_RangeAdaptorClosure keys = elements<0>;
3810 inline constexpr __adaptor::_RangeAdaptorClosure values = elements<1>;
3811 } // namespace views
3813 } // namespace ranges
3815 namespace views = ranges::views;
3817 template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind>
3818 struct tuple_size<ranges::subrange<_Iter, _Sent, _Kind>>
3819 : integral_constant<size_t, 2>
3822 template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind>
3823 struct tuple_element<0, ranges::subrange<_Iter, _Sent, _Kind>>
3824 { using type = _Iter; };
3826 template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind>
3827 struct tuple_element<1, ranges::subrange<_Iter, _Sent, _Kind>>
3828 { using type = _Sent; };
3830 template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind>
3831 struct tuple_element<0, const ranges::subrange<_Iter, _Sent, _Kind>>
3832 { using type = _Iter; };
3834 template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind>
3835 struct tuple_element<1, const ranges::subrange<_Iter, _Sent, _Kind>>
3836 { using type = _Sent; };
3838 _GLIBCXX_END_NAMESPACE_VERSION
3840 #endif // library concepts
3842 #endif /* _GLIBCXX_RANGES */