xref: /freebsd/contrib/llvm-project/libcxx/include/__ranges/zip_view.h (revision 2e3507c25e42292b45a5482e116d278f5515d04d) 
1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___RANGES_ZIP_VIEW_H
11 #define _LIBCPP___RANGES_ZIP_VIEW_H
12 
13 #include <__config>
14 
15 #include <__algorithm/ranges_min.h>
16 #include <__compare/three_way_comparable.h>
17 #include <__concepts/convertible_to.h>
18 #include <__concepts/equality_comparable.h>
19 #include <__functional/invoke.h>
20 #include <__functional/operations.h>
21 #include <__iterator/concepts.h>
22 #include <__iterator/incrementable_traits.h>
23 #include <__iterator/iter_move.h>
24 #include <__iterator/iter_swap.h>
25 #include <__iterator/iterator_traits.h>
26 #include <__ranges/access.h>
27 #include <__ranges/all.h>
28 #include <__ranges/concepts.h>
29 #include <__ranges/empty_view.h>
30 #include <__ranges/enable_borrowed_range.h>
31 #include <__ranges/size.h>
32 #include <__ranges/view_interface.h>
33 #include <__type_traits/is_nothrow_move_constructible.h>
34 #include <__type_traits/make_unsigned.h>
35 #include <__utility/declval.h>
36 #include <__utility/forward.h>
37 #include <__utility/integer_sequence.h>
38 #include <__utility/move.h>
39 #include <tuple>
40 
41 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
42 #  pragma GCC system_header
43 #endif
44 
45 _LIBCPP_PUSH_MACROS
46 #include <__undef_macros>
47 
48 _LIBCPP_BEGIN_NAMESPACE_STD
49 
50 #if _LIBCPP_STD_VER >= 23
51 
52 namespace ranges {
53 
54 template <class... _Ranges>
55 concept __zip_is_common = (sizeof...(_Ranges) == 1 && (common_range<_Ranges> && ...)) ||
56                           (!(bidirectional_range<_Ranges> && ...) && (common_range<_Ranges> && ...)) ||
57                           ((random_access_range<_Ranges> && ...) && (sized_range<_Ranges> && ...));
58 
59 template <typename _Tp, typename _Up>
60 auto __tuple_or_pair_test() -> pair<_Tp, _Up>;
61 
62 template <typename... _Types>
63   requires(sizeof...(_Types) != 2)
64 auto __tuple_or_pair_test() -> tuple<_Types...>;
65 
66 template <class... _Types>
67 using __tuple_or_pair = decltype(__tuple_or_pair_test<_Types...>());
68 
69 template <class _Fun, class _Tuple>
70 _LIBCPP_HIDE_FROM_ABI constexpr auto __tuple_transform(_Fun&& __f, _Tuple&& __tuple) {
71   return std::apply(
72       [&]<class... _Types>(_Types&&... __elements) {
73         return __tuple_or_pair<invoke_result_t<_Fun&, _Types>...>(
74             std::invoke(__f, std::forward<_Types>(__elements))...);
75       },
76       std::forward<_Tuple>(__tuple));
77 }
78 
79 template <class _Fun, class _Tuple>
80 _LIBCPP_HIDE_FROM_ABI constexpr void __tuple_for_each(_Fun&& __f, _Tuple&& __tuple) {
81   std::apply(
82       [&]<class... _Types>(_Types&&... __elements) {
83         (static_cast<void>(std::invoke(__f, std::forward<_Types>(__elements))), ...);
84       },
85       std::forward<_Tuple>(__tuple));
86 }
87 
88 template <class _Fun, class _Tuple1, class _Tuple2, size_t... _Indices>
89 _LIBCPP_HIDE_FROM_ABI constexpr __tuple_or_pair<
90     invoke_result_t<_Fun&, typename tuple_element<_Indices, remove_cvref_t<_Tuple1>>::type,
91                     typename tuple_element<_Indices, remove_cvref_t<_Tuple2>>::type>...>
92 __tuple_zip_transform(_Fun&& __f, _Tuple1&& __tuple1, _Tuple2&& __tuple2, index_sequence<_Indices...>) {
93   return {std::invoke(__f, std::get<_Indices>(std::forward<_Tuple1>(__tuple1)),
94                       std::get<_Indices>(std::forward<_Tuple2>(__tuple2)))...};
95 }
96 
97 template <class _Fun, class _Tuple1, class _Tuple2>
98 _LIBCPP_HIDE_FROM_ABI constexpr auto __tuple_zip_transform(_Fun&& __f, _Tuple1&& __tuple1, _Tuple2&& __tuple2) {
99   return ranges::__tuple_zip_transform(__f, std::forward<_Tuple1>(__tuple1), std::forward<_Tuple2>(__tuple2),
100                                        std::make_index_sequence<tuple_size<remove_cvref_t<_Tuple1>>::value>());
101 }
102 
103 template <class _Fun, class _Tuple1, class _Tuple2, size_t... _Indices>
104 _LIBCPP_HIDE_FROM_ABI constexpr void __tuple_zip_for_each(_Fun&& __f, _Tuple1&& __tuple1, _Tuple2&& __tuple2,
105                                                           index_sequence<_Indices...>) {
106   (std::invoke(__f, std::get<_Indices>(std::forward<_Tuple1>(__tuple1)),
107                std::get<_Indices>(std::forward<_Tuple2>(__tuple2))),
108    ...);
109 }
110 
111 template <class _Fun, class _Tuple1, class _Tuple2>
112 _LIBCPP_HIDE_FROM_ABI constexpr auto __tuple_zip_for_each(_Fun&& __f, _Tuple1&& __tuple1, _Tuple2&& __tuple2) {
113   return ranges::__tuple_zip_for_each(__f, std::forward<_Tuple1>(__tuple1), std::forward<_Tuple2>(__tuple2),
114                                       std::make_index_sequence<tuple_size<remove_cvref_t<_Tuple1>>::value>());
115 }
116 
117 template <class _Tuple1, class _Tuple2>
118 _LIBCPP_HIDE_FROM_ABI constexpr bool __tuple_any_equals(const _Tuple1& __tuple1, const _Tuple2& __tuple2) {
119   const auto __equals = ranges::__tuple_zip_transform(std::equal_to<>(), __tuple1, __tuple2);
120   return std::apply([](auto... __bools) { return (__bools || ...); }, __equals);
121 }
122 
123 // abs in cstdlib is not constexpr
124 // TODO : remove __abs once P0533R9 is implemented.
125 template <class _Tp>
126 _LIBCPP_HIDE_FROM_ABI constexpr _Tp __abs(_Tp __t) {
127   return __t < 0 ? -__t : __t;
128 }
129 
130 template <input_range... _Views>
131   requires(view<_Views> && ...) && (sizeof...(_Views) > 0)
132 class zip_view : public view_interface<zip_view<_Views...>> {
133 
134   _LIBCPP_NO_UNIQUE_ADDRESS tuple<_Views...> __views_;
135 
136   template <bool>
137   class __iterator;
138 
139   template <bool>
140   class __sentinel;
141 
142 public:
143   _LIBCPP_HIDE_FROM_ABI
144   zip_view() = default;
145 
146   _LIBCPP_HIDE_FROM_ABI
147   constexpr explicit zip_view(_Views... __views) : __views_(std::move(__views)...) {}
148 
149   _LIBCPP_HIDE_FROM_ABI
150   constexpr auto begin()
151     requires(!(__simple_view<_Views> && ...)) {
152     return __iterator<false>(ranges::__tuple_transform(ranges::begin, __views_));
153   }
154 
155   _LIBCPP_HIDE_FROM_ABI
156   constexpr auto begin() const
157     requires(range<const _Views> && ...) {
158     return __iterator<true>(ranges::__tuple_transform(ranges::begin, __views_));
159   }
160 
161   _LIBCPP_HIDE_FROM_ABI
162   constexpr auto end()
163     requires(!(__simple_view<_Views> && ...)) {
164     if constexpr (!__zip_is_common<_Views...>) {
165       return __sentinel<false>(ranges::__tuple_transform(ranges::end, __views_));
166     } else if constexpr ((random_access_range<_Views> && ...)) {
167       return begin() + iter_difference_t<__iterator<false>>(size());
168     } else {
169       return __iterator<false>(ranges::__tuple_transform(ranges::end, __views_));
170     }
171   }
172 
173   _LIBCPP_HIDE_FROM_ABI
174   constexpr auto end() const
175     requires(range<const _Views> && ...) {
176     if constexpr (!__zip_is_common<const _Views...>) {
177       return __sentinel<true>(ranges::__tuple_transform(ranges::end, __views_));
178     } else if constexpr ((random_access_range<const _Views> && ...)) {
179       return begin() + iter_difference_t<__iterator<true>>(size());
180     } else {
181       return __iterator<true>(ranges::__tuple_transform(ranges::end, __views_));
182     }
183   }
184 
185   _LIBCPP_HIDE_FROM_ABI
186   constexpr auto size()
187     requires(sized_range<_Views> && ...) {
188     return std::apply(
189         [](auto... __sizes) {
190           using _CT = make_unsigned_t<common_type_t<decltype(__sizes)...>>;
191           return ranges::min({_CT(__sizes)...});
192         },
193         ranges::__tuple_transform(ranges::size, __views_));
194   }
195 
196   _LIBCPP_HIDE_FROM_ABI
197   constexpr auto size() const
198     requires(sized_range<const _Views> && ...) {
199     return std::apply(
200         [](auto... __sizes) {
201           using _CT = make_unsigned_t<common_type_t<decltype(__sizes)...>>;
202           return ranges::min({_CT(__sizes)...});
203         },
204         ranges::__tuple_transform(ranges::size, __views_));
205   }
206 };
207 
208 template <class... _Ranges>
209 zip_view(_Ranges&&...) -> zip_view<views::all_t<_Ranges>...>;
210 
211 template <bool _Const, class... _Views>
212 concept __zip_all_random_access = (random_access_range<__maybe_const<_Const, _Views>> && ...);
213 
214 template <bool _Const, class... _Views>
215 concept __zip_all_bidirectional = (bidirectional_range<__maybe_const<_Const, _Views>> && ...);
216 
217 template <bool _Const, class... _Views>
218 concept __zip_all_forward = (forward_range<__maybe_const<_Const, _Views>> && ...);
219 
220 template <bool _Const, class... _Views>
221 consteval auto __get_zip_view_iterator_tag() {
222   if constexpr (__zip_all_random_access<_Const, _Views...>) {
223     return random_access_iterator_tag();
224   } else if constexpr (__zip_all_bidirectional<_Const, _Views...>) {
225     return bidirectional_iterator_tag();
226   } else if constexpr (__zip_all_forward<_Const, _Views...>) {
227     return forward_iterator_tag();
228   } else {
229     return input_iterator_tag();
230   }
231 }
232 
233 template <bool _Const, class... _Views>
234 struct __zip_view_iterator_category_base {};
235 
236 template <bool _Const, class... _Views>
237   requires __zip_all_forward<_Const, _Views...>
238 struct __zip_view_iterator_category_base<_Const, _Views...> {
239   using iterator_category = input_iterator_tag;
240 };
241 
242 template <input_range... _Views>
243   requires(view<_Views> && ...) && (sizeof...(_Views) > 0)
244 template <bool _Const>
245 class zip_view<_Views...>::__iterator : public __zip_view_iterator_category_base<_Const, _Views...> {
246 
247   __tuple_or_pair<iterator_t<__maybe_const<_Const, _Views>>...> __current_;
248 
249   _LIBCPP_HIDE_FROM_ABI
250   constexpr explicit __iterator(__tuple_or_pair<iterator_t<__maybe_const<_Const, _Views>>...> __current)
251       : __current_(std::move(__current)) {}
252 
253   template <bool>
254   friend class zip_view<_Views...>::__iterator;
255 
256   template <bool>
257   friend class zip_view<_Views...>::__sentinel;
258 
259   friend class zip_view<_Views...>;
260 
261 public:
262   using iterator_concept = decltype(__get_zip_view_iterator_tag<_Const, _Views...>());
263   using value_type = __tuple_or_pair<range_value_t<__maybe_const<_Const, _Views>>...>;
264   using difference_type = common_type_t<range_difference_t<__maybe_const<_Const, _Views>>...>;
265 
266   _LIBCPP_HIDE_FROM_ABI
267   __iterator() = default;
268 
269   _LIBCPP_HIDE_FROM_ABI
270   constexpr __iterator(__iterator<!_Const> __i)
271     requires _Const && (convertible_to<iterator_t<_Views>, iterator_t<__maybe_const<_Const, _Views>>> && ...)
272   : __current_(std::move(__i.__current_)) {}
273 
274   _LIBCPP_HIDE_FROM_ABI
275   constexpr auto operator*() const {
276     return ranges::__tuple_transform([](auto& __i) -> decltype(auto) { return *__i; }, __current_);
277   }
278 
279   _LIBCPP_HIDE_FROM_ABI
280   constexpr __iterator& operator++() {
281     ranges::__tuple_for_each([](auto& __i) { ++__i; }, __current_);
282     return *this;
283   }
284 
285   _LIBCPP_HIDE_FROM_ABI
286   constexpr void operator++(int) { ++*this; }
287 
288   _LIBCPP_HIDE_FROM_ABI
289   constexpr __iterator operator++(int)
290     requires __zip_all_forward<_Const, _Views...> {
291     auto __tmp = *this;
292     ++*this;
293     return __tmp;
294   }
295 
296   _LIBCPP_HIDE_FROM_ABI
297   constexpr __iterator& operator--()
298     requires __zip_all_bidirectional<_Const, _Views...> {
299     ranges::__tuple_for_each([](auto& __i) { --__i; }, __current_);
300     return *this;
301   }
302 
303   _LIBCPP_HIDE_FROM_ABI
304   constexpr __iterator operator--(int)
305     requires __zip_all_bidirectional<_Const, _Views...> {
306     auto __tmp = *this;
307     --*this;
308     return __tmp;
309   }
310 
311   _LIBCPP_HIDE_FROM_ABI
312   constexpr __iterator& operator+=(difference_type __x)
313     requires __zip_all_random_access<_Const, _Views...> {
314     ranges::__tuple_for_each([&]<class _Iter>(_Iter& __i) { __i += iter_difference_t<_Iter>(__x); }, __current_);
315     return *this;
316   }
317 
318   _LIBCPP_HIDE_FROM_ABI
319   constexpr __iterator& operator-=(difference_type __x)
320     requires __zip_all_random_access<_Const, _Views...> {
321     ranges::__tuple_for_each([&]<class _Iter>(_Iter& __i) { __i -= iter_difference_t<_Iter>(__x); }, __current_);
322     return *this;
323   }
324 
325   _LIBCPP_HIDE_FROM_ABI
326   constexpr auto operator[](difference_type __n) const
327     requires __zip_all_random_access<_Const, _Views...> {
328     return ranges::__tuple_transform(
329         [&]<class _Iter>(_Iter& __i) -> decltype(auto) { return __i[iter_difference_t<_Iter>(__n)]; }, __current_);
330   }
331 
332   _LIBCPP_HIDE_FROM_ABI
333   friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
334     requires(equality_comparable<iterator_t<__maybe_const<_Const, _Views>>> && ...) {
335     if constexpr (__zip_all_bidirectional<_Const, _Views...>) {
336       return __x.__current_ == __y.__current_;
337     } else {
338       return ranges::__tuple_any_equals(__x.__current_, __y.__current_);
339     }
340   }
341 
342   _LIBCPP_HIDE_FROM_ABI
343   friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
344     requires __zip_all_random_access<_Const, _Views...> {
345     return __x.__current_ < __y.__current_;
346   }
347 
348   _LIBCPP_HIDE_FROM_ABI
349   friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
350     requires __zip_all_random_access<_Const, _Views...> {
351     return __y < __x;
352   }
353 
354   _LIBCPP_HIDE_FROM_ABI
355   friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
356     requires __zip_all_random_access<_Const, _Views...> {
357     return !(__y < __x);
358   }
359 
360   _LIBCPP_HIDE_FROM_ABI
361   friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
362     requires __zip_all_random_access<_Const, _Views...> {
363     return !(__x < __y);
364   }
365 
366   _LIBCPP_HIDE_FROM_ABI
367   friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
368     requires __zip_all_random_access<_Const, _Views...> &&
369              (three_way_comparable<iterator_t<__maybe_const<_Const, _Views>>> && ...) {
370     return __x.__current_ <=> __y.__current_;
371   }
372 
373   _LIBCPP_HIDE_FROM_ABI
374   friend constexpr __iterator operator+(const __iterator& __i, difference_type __n)
375     requires __zip_all_random_access<_Const, _Views...> {
376     auto __r = __i;
377     __r += __n;
378     return __r;
379   }
380 
381   _LIBCPP_HIDE_FROM_ABI
382   friend constexpr __iterator operator+(difference_type __n, const __iterator& __i)
383     requires __zip_all_random_access<_Const, _Views...> {
384     return __i + __n;
385   }
386 
387   _LIBCPP_HIDE_FROM_ABI
388   friend constexpr __iterator operator-(const __iterator& __i, difference_type __n)
389     requires __zip_all_random_access<_Const, _Views...> {
390     auto __r = __i;
391     __r -= __n;
392     return __r;
393   }
394 
395   _LIBCPP_HIDE_FROM_ABI
396   friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
397     requires(sized_sentinel_for<iterator_t<__maybe_const<_Const, _Views>>, iterator_t<__maybe_const<_Const, _Views>>> &&
398              ...) {
399     const auto __diffs = ranges::__tuple_zip_transform(minus<>(), __x.__current_, __y.__current_);
400     return std::apply(
401         [](auto... __ds) {
402           return ranges::min({difference_type(__ds)...},
403                              [](auto __a, auto __b) { return ranges::__abs(__a) < ranges::__abs(__b); });
404         },
405         __diffs);
406   }
407 
408   _LIBCPP_HIDE_FROM_ABI
409   friend constexpr auto iter_move(const __iterator& __i) noexcept(
410       (noexcept(ranges::iter_move(std::declval<const iterator_t<__maybe_const<_Const, _Views>>&>())) && ...) &&
411       (is_nothrow_move_constructible_v<range_rvalue_reference_t<__maybe_const<_Const, _Views>>> && ...)) {
412     return ranges::__tuple_transform(ranges::iter_move, __i.__current_);
413   }
414 
415   _LIBCPP_HIDE_FROM_ABI
416   friend constexpr void iter_swap(const __iterator& __l, const __iterator& __r) noexcept(
417       (noexcept(ranges::iter_swap(std::declval<const iterator_t<__maybe_const<_Const, _Views>>&>(),
418                                   std::declval<const iterator_t<__maybe_const<_Const, _Views>>&>())) &&
419        ...))
420     requires(indirectly_swappable<iterator_t<__maybe_const<_Const, _Views>>> && ...) {
421     ranges::__tuple_zip_for_each(ranges::iter_swap, __l.__current_, __r.__current_);
422   }
423 };
424 
425 template <input_range... _Views>
426   requires(view<_Views> && ...) && (sizeof...(_Views) > 0)
427 template <bool _Const>
428 class zip_view<_Views...>::__sentinel {
429 
430   __tuple_or_pair<sentinel_t<__maybe_const<_Const, _Views>>...> __end_;
431 
432   _LIBCPP_HIDE_FROM_ABI
433   constexpr explicit __sentinel(__tuple_or_pair<sentinel_t<__maybe_const<_Const, _Views>>...> __end) : __end_(__end) {}
434 
435   friend class zip_view<_Views...>;
436 
437   // hidden friend cannot access private member of iterator because they are friends of friends
438   template <bool _OtherConst>
439   _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto)
440   __iter_current(zip_view<_Views...>::__iterator<_OtherConst> const& __it) {
441     return (__it.__current_);
442   }
443 
444 public:
445   _LIBCPP_HIDE_FROM_ABI
446   __sentinel() = default;
447 
448   _LIBCPP_HIDE_FROM_ABI
449   constexpr __sentinel(__sentinel<!_Const> __i)
450     requires _Const && (convertible_to<sentinel_t<_Views>, sentinel_t<__maybe_const<_Const, _Views>>> && ...)
451   : __end_(std::move(__i.__end_)) {}
452 
453   template <bool _OtherConst>
454     requires(sentinel_for<sentinel_t<__maybe_const<_Const, _Views>>, iterator_t<__maybe_const<_OtherConst, _Views>>> &&
455              ...)
456   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
457     return ranges::__tuple_any_equals(__iter_current(__x), __y.__end_);
458   }
459 
460   template <bool _OtherConst>
461     requires(
462         sized_sentinel_for<sentinel_t<__maybe_const<_Const, _Views>>, iterator_t<__maybe_const<_OtherConst, _Views>>> &&
463         ...)
464   _LIBCPP_HIDE_FROM_ABI friend constexpr common_type_t<range_difference_t<__maybe_const<_OtherConst, _Views>>...>
465   operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
466     const auto __diffs = ranges::__tuple_zip_transform(minus<>(), __iter_current(__x), __y.__end_);
467     return std::apply(
468         [](auto... __ds) {
469           using _Diff = common_type_t<range_difference_t<__maybe_const<_OtherConst, _Views>>...>;
470           return ranges::min({_Diff(__ds)...},
471                              [](auto __a, auto __b) { return ranges::__abs(__a) < ranges::__abs(__b); });
472         },
473         __diffs);
474   }
475 
476   template <bool _OtherConst>
477     requires(
478         sized_sentinel_for<sentinel_t<__maybe_const<_Const, _Views>>, iterator_t<__maybe_const<_OtherConst, _Views>>> &&
479         ...)
480   _LIBCPP_HIDE_FROM_ABI friend constexpr common_type_t<range_difference_t<__maybe_const<_OtherConst, _Views>>...>
481   operator-(const __sentinel& __y, const __iterator<_OtherConst>& __x) {
482     return -(__x - __y);
483   }
484 };
485 
486 template <class... _Views>
487 inline constexpr bool enable_borrowed_range<zip_view<_Views...>> = (enable_borrowed_range<_Views> && ...);
488 
489 namespace views {
490 namespace __zip {
491 
492 struct __fn {
493   _LIBCPP_HIDE_FROM_ABI constexpr auto operator()() const noexcept { return empty_view<tuple<>>{}; }
494 
495   template <class... _Ranges>
496   _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ranges&&... __rs) const
497       noexcept(noexcept(zip_view<all_t<_Ranges&&>...>(std::forward<_Ranges>(__rs)...)))
498           -> decltype(zip_view<all_t<_Ranges&&>...>(std::forward<_Ranges>(__rs)...)) {
499     return zip_view<all_t<_Ranges>...>(std::forward<_Ranges>(__rs)...);
500   }
501 };
502 
503 } // namespace __zip
504 inline namespace __cpo {
505   inline constexpr auto zip = __zip::__fn{};
506 } // namespace __cpo
507 } // namespace views
508 } // namespace ranges
509 
510 #endif // _LIBCPP_STD_VER >= 23
511 
512 _LIBCPP_END_NAMESPACE_STD
513 
514 _LIBCPP_POP_MACROS
515 
516 #endif // _LIBCPP___RANGES_ZIP_VIEW_H
517