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_ELEMENTS_VIEW_H 11 #define _LIBCPP___RANGES_ELEMENTS_VIEW_H 12 13 #include <__compare/three_way_comparable.h> 14 #include <__concepts/constructible.h> 15 #include <__concepts/convertible_to.h> 16 #include <__concepts/derived_from.h> 17 #include <__concepts/equality_comparable.h> 18 #include <__config> 19 #include <__fwd/get.h> 20 #include <__iterator/concepts.h> 21 #include <__iterator/iterator_traits.h> 22 #include <__ranges/access.h> 23 #include <__ranges/all.h> 24 #include <__ranges/concepts.h> 25 #include <__ranges/enable_borrowed_range.h> 26 #include <__ranges/range_adaptor.h> 27 #include <__ranges/size.h> 28 #include <__ranges/view_interface.h> 29 #include <__tuple/tuple_element.h> 30 #include <__tuple/tuple_like.h> 31 #include <__tuple/tuple_size.h> 32 #include <__type_traits/is_reference.h> 33 #include <__type_traits/maybe_const.h> 34 #include <__type_traits/remove_cv.h> 35 #include <__type_traits/remove_cvref.h> 36 #include <__type_traits/remove_reference.h> 37 #include <__utility/declval.h> 38 #include <__utility/forward.h> 39 #include <__utility/move.h> 40 #include <cstddef> 41 42 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 43 # pragma GCC system_header 44 #endif 45 46 _LIBCPP_PUSH_MACROS 47 #include <__undef_macros> 48 49 _LIBCPP_BEGIN_NAMESPACE_STD 50 51 #if _LIBCPP_STD_VER >= 20 52 53 namespace ranges { 54 55 template <class _Tp, size_t _Np> 56 concept __has_tuple_element = __tuple_like<_Tp> && _Np < tuple_size<_Tp>::value; 57 58 template <class _Tp, size_t _Np> 59 concept __returnable_element = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Np, _Tp>>; 60 61 template <input_range _View, size_t _Np> 62 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> && 63 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> && 64 __returnable_element<range_reference_t<_View>, _Np> 65 class elements_view : public view_interface<elements_view<_View, _Np>> { 66 private: 67 template <bool> 68 class __iterator; 69 70 template <bool> 71 class __sentinel; 72 73 public: 74 _LIBCPP_HIDE_FROM_ABI elements_view() 75 requires default_initializable<_View> 76 = default; 77 78 _LIBCPP_HIDE_FROM_ABI constexpr explicit elements_view(_View __base) : __base_(std::move(__base)) {} 79 80 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& 81 requires copy_constructible<_View> 82 { 83 return __base_; 84 } 85 86 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } 87 88 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() 89 requires(!__simple_view<_View>) 90 { 91 return __iterator</*_Const=*/false>(ranges::begin(__base_)); 92 } 93 94 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const 95 requires range<const _View> 96 { 97 return __iterator</*_Const=*/true>(ranges::begin(__base_)); 98 } 99 100 _LIBCPP_HIDE_FROM_ABI constexpr auto end() 101 requires(!__simple_view<_View> && !common_range<_View>) 102 { 103 return __sentinel</*_Const=*/false>{ranges::end(__base_)}; 104 } 105 106 _LIBCPP_HIDE_FROM_ABI constexpr auto end() 107 requires(!__simple_view<_View> && common_range<_View>) 108 { 109 return __iterator</*_Const=*/false>{ranges::end(__base_)}; 110 } 111 112 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const 113 requires range<const _View> 114 { 115 return __sentinel</*_Const=*/true>{ranges::end(__base_)}; 116 } 117 118 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const 119 requires common_range<const _View> 120 { 121 return __iterator</*_Const=*/true>{ranges::end(__base_)}; 122 } 123 124 _LIBCPP_HIDE_FROM_ABI constexpr auto size() 125 requires sized_range<_View> 126 { 127 return ranges::size(__base_); 128 } 129 130 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const 131 requires sized_range<const _View> 132 { 133 return ranges::size(__base_); 134 } 135 136 private: 137 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 138 }; 139 140 template <class, size_t> 141 struct __elements_view_iterator_category_base {}; 142 143 template <forward_range _Base, size_t _Np> 144 struct __elements_view_iterator_category_base<_Base, _Np> { 145 static consteval auto __get_iterator_category() { 146 using _Result = decltype(std::get<_Np>(*std::declval<iterator_t<_Base>>())); 147 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category; 148 149 if constexpr (!is_lvalue_reference_v<_Result>) { 150 return input_iterator_tag{}; 151 } else if constexpr (derived_from<_Cat, random_access_iterator_tag>) { 152 return random_access_iterator_tag{}; 153 } else { 154 return _Cat{}; 155 } 156 } 157 158 using iterator_category = decltype(__get_iterator_category()); 159 }; 160 161 template <input_range _View, size_t _Np> 162 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> && 163 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> && 164 __returnable_element<range_reference_t<_View>, _Np> 165 template <bool _Const> 166 class elements_view<_View, _Np>::__iterator 167 : public __elements_view_iterator_category_base<__maybe_const<_Const, _View>, _Np> { 168 template <bool> 169 friend class __iterator; 170 171 template <bool> 172 friend class __sentinel; 173 174 using _Base = __maybe_const<_Const, _View>; 175 176 iterator_t<_Base> __current_ = iterator_t<_Base>(); 177 178 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __get_element(const iterator_t<_Base>& __i) { 179 if constexpr (is_reference_v<range_reference_t<_Base>>) { 180 return std::get<_Np>(*__i); 181 } else { 182 using _Element = remove_cv_t<tuple_element_t<_Np, range_reference_t<_Base>>>; 183 return static_cast<_Element>(std::get<_Np>(*__i)); 184 } 185 } 186 187 static consteval auto __get_iterator_concept() { 188 if constexpr (random_access_range<_Base>) { 189 return random_access_iterator_tag{}; 190 } else if constexpr (bidirectional_range<_Base>) { 191 return bidirectional_iterator_tag{}; 192 } else if constexpr (forward_range<_Base>) { 193 return forward_iterator_tag{}; 194 } else { 195 return input_iterator_tag{}; 196 } 197 } 198 199 public: 200 using iterator_concept = decltype(__get_iterator_concept()); 201 using value_type = remove_cvref_t<tuple_element_t<_Np, range_value_t<_Base>>>; 202 using difference_type = range_difference_t<_Base>; 203 204 _LIBCPP_HIDE_FROM_ABI __iterator() 205 requires default_initializable<iterator_t<_Base>> 206 = default; 207 208 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(iterator_t<_Base> __current) : __current_(std::move(__current)) {} 209 210 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i) 211 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 212 : __current_(std::move(__i.__current_)) {} 213 214 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; } 215 216 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); } 217 218 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const { return __get_element(__current_); } 219 220 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() { 221 ++__current_; 222 return *this; 223 } 224 225 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; } 226 227 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) 228 requires forward_range<_Base> 229 { 230 auto __temp = *this; 231 ++__current_; 232 return __temp; 233 } 234 235 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--() 236 requires bidirectional_range<_Base> 237 { 238 --__current_; 239 return *this; 240 } 241 242 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int) 243 requires bidirectional_range<_Base> 244 { 245 auto __temp = *this; 246 --__current_; 247 return __temp; 248 } 249 250 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n) 251 requires random_access_range<_Base> 252 { 253 __current_ += __n; 254 return *this; 255 } 256 257 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n) 258 requires random_access_range<_Base> 259 { 260 __current_ -= __n; 261 return *this; 262 } 263 264 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const 265 requires random_access_range<_Base> 266 { 267 return __get_element(__current_ + __n); 268 } 269 270 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 271 requires equality_comparable<iterator_t<_Base>> 272 { 273 return __x.__current_ == __y.__current_; 274 } 275 276 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 277 requires random_access_range<_Base> 278 { 279 return __x.__current_ < __y.__current_; 280 } 281 282 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 283 requires random_access_range<_Base> 284 { 285 return __y < __x; 286 } 287 288 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 289 requires random_access_range<_Base> 290 { 291 return !(__y < __x); 292 } 293 294 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 295 requires random_access_range<_Base> 296 { 297 return !(__x < __y); 298 } 299 300 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 301 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 302 { 303 return __x.__current_ <=> __y.__current_; 304 } 305 306 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(const __iterator& __x, difference_type __y) 307 requires random_access_range<_Base> 308 { 309 return __iterator{__x} += __y; 310 } 311 312 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __x, const __iterator& __y) 313 requires random_access_range<_Base> 314 { 315 return __y + __x; 316 } 317 318 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(const __iterator& __x, difference_type __y) 319 requires random_access_range<_Base> 320 { 321 return __iterator{__x} -= __y; 322 } 323 324 _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 325 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 326 { 327 return __x.__current_ - __y.__current_; 328 } 329 }; 330 331 template <input_range _View, size_t _Np> 332 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> && 333 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> && 334 __returnable_element<range_reference_t<_View>, _Np> 335 template <bool _Const> 336 class elements_view<_View, _Np>::__sentinel { 337 private: 338 using _Base = __maybe_const<_Const, _View>; 339 _LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 340 341 template <bool> 342 friend class __sentinel; 343 344 template <bool _AnyConst> 345 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __get_current(const __iterator<_AnyConst>& __iter) { 346 return (__iter.__current_); 347 } 348 349 public: 350 _LIBCPP_HIDE_FROM_ABI __sentinel() = default; 351 352 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(std::move(__end)) {} 353 354 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __other) 355 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 356 : __end_(std::move(__other.__end_)) {} 357 358 _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; } 359 360 template <bool _OtherConst> 361 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 362 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 363 return __get_current(__x) == __y.__end_; 364 } 365 366 template <bool _OtherConst> 367 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 368 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 369 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 370 return __get_current(__x) - __y.__end_; 371 } 372 373 template <bool _OtherConst> 374 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 375 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 376 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 377 return __x.__end_ - __get_current(__y); 378 } 379 }; 380 381 template <class _Tp, size_t _Np> 382 inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Np>> = enable_borrowed_range<_Tp>; 383 384 template <class _Tp> 385 using keys_view = elements_view<_Tp, 0>; 386 template <class _Tp> 387 using values_view = elements_view<_Tp, 1>; 388 389 namespace views { 390 namespace __elements { 391 392 template <size_t _Np> 393 struct __fn : __range_adaptor_closure<__fn<_Np>> { 394 template <class _Range> 395 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const 396 /**/ noexcept(noexcept(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range)))) 397 /*------*/ -> decltype(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range))) { 398 /*-------------*/ return elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range)); 399 } 400 }; 401 } // namespace __elements 402 403 inline namespace __cpo { 404 template <size_t _Np> 405 inline constexpr auto elements = __elements::__fn<_Np>{}; 406 inline constexpr auto keys = elements<0>; 407 inline constexpr auto values = elements<1>; 408 } // namespace __cpo 409 } // namespace views 410 } // namespace ranges 411 412 #endif // _LIBCPP_STD_VER >= 20 413 414 _LIBCPP_END_NAMESPACE_STD 415 416 _LIBCPP_POP_MACROS 417 418 #endif // _LIBCPP___RANGES_ELEMENTS_VIEW_H 419