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_TRANSFORM_VIEW_H 11 #define _LIBCPP___RANGES_TRANSFORM_VIEW_H 12 13 #include <__compare/three_way_comparable.h> 14 #include <__concepts/constructible.h> 15 #include <__concepts/convertible_to.h> 16 #include <__concepts/copyable.h> 17 #include <__concepts/derived_from.h> 18 #include <__concepts/equality_comparable.h> 19 #include <__concepts/invocable.h> 20 #include <__config> 21 #include <__functional/bind_back.h> 22 #include <__functional/invoke.h> 23 #include <__iterator/concepts.h> 24 #include <__iterator/iterator_traits.h> 25 #include <__memory/addressof.h> 26 #include <__ranges/access.h> 27 #include <__ranges/all.h> 28 #include <__ranges/concepts.h> 29 #include <__ranges/copyable_box.h> 30 #include <__ranges/empty.h> 31 #include <__ranges/range_adaptor.h> 32 #include <__ranges/size.h> 33 #include <__ranges/view_interface.h> 34 #include <__type_traits/maybe_const.h> 35 #include <__utility/forward.h> 36 #include <__utility/in_place.h> 37 #include <__utility/move.h> 38 39 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 40 # pragma GCC system_header 41 #endif 42 43 _LIBCPP_BEGIN_NAMESPACE_STD 44 45 #if _LIBCPP_STD_VER >= 20 46 47 namespace ranges { 48 49 template<class _Fn, class _View> 50 concept __regular_invocable_with_range_ref = 51 regular_invocable<_Fn, range_reference_t<_View>>; 52 53 template<class _View, class _Fn> 54 concept __transform_view_constraints = 55 view<_View> && is_object_v<_Fn> && 56 regular_invocable<_Fn&, range_reference_t<_View>> && 57 __can_reference<invoke_result_t<_Fn&, range_reference_t<_View>>>; 58 59 template<input_range _View, copy_constructible _Fn> 60 requires __transform_view_constraints<_View, _Fn> 61 class transform_view : public view_interface<transform_view<_View, _Fn>> { 62 template<bool> class __iterator; 63 template<bool> class __sentinel; 64 65 _LIBCPP_NO_UNIQUE_ADDRESS __copyable_box<_Fn> __func_; 66 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 67 68 public: 69 _LIBCPP_HIDE_FROM_ABI 70 transform_view() 71 requires default_initializable<_View> && default_initializable<_Fn> = default; 72 73 _LIBCPP_HIDE_FROM_ABI transform_view(_View __base,_Fn __func)74 constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 transform_view(_View __base, _Fn __func) 75 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {} 76 77 _LIBCPP_HIDE_FROM_ABI base()78 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 79 _LIBCPP_HIDE_FROM_ABI base()80 constexpr _View base() && { return std::move(__base_); } 81 82 _LIBCPP_HIDE_FROM_ABI begin()83 constexpr __iterator<false> begin() { 84 return __iterator<false>{*this, ranges::begin(__base_)}; 85 } 86 _LIBCPP_HIDE_FROM_ABI begin()87 constexpr __iterator<true> begin() const 88 requires range<const _View> && 89 __regular_invocable_with_range_ref<const _Fn&, const _View> 90 { 91 return __iterator<true>(*this, ranges::begin(__base_)); 92 } 93 94 _LIBCPP_HIDE_FROM_ABI end()95 constexpr __sentinel<false> end() { 96 return __sentinel<false>(ranges::end(__base_)); 97 } 98 _LIBCPP_HIDE_FROM_ABI end()99 constexpr __iterator<false> end() 100 requires common_range<_View> 101 { 102 return __iterator<false>(*this, ranges::end(__base_)); 103 } 104 _LIBCPP_HIDE_FROM_ABI end()105 constexpr __sentinel<true> end() const 106 requires range<const _View> && 107 __regular_invocable_with_range_ref<const _Fn&, const _View> 108 { 109 return __sentinel<true>(ranges::end(__base_)); 110 } 111 _LIBCPP_HIDE_FROM_ABI end()112 constexpr __iterator<true> end() const 113 requires common_range<const _View> && 114 __regular_invocable_with_range_ref<const _Fn&, const _View> 115 { 116 return __iterator<true>(*this, ranges::end(__base_)); 117 } 118 119 _LIBCPP_HIDE_FROM_ABI size()120 constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); } 121 _LIBCPP_HIDE_FROM_ABI size()122 constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); } 123 }; 124 125 template<class _Range, class _Fn> 126 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 127 128 template<class _View> 129 struct __transform_view_iterator_concept { using type = input_iterator_tag; }; 130 131 template<random_access_range _View> 132 struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; }; 133 134 template<bidirectional_range _View> 135 struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; }; 136 137 template<forward_range _View> 138 struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; }; 139 140 template<class, class> 141 struct __transform_view_iterator_category_base {}; 142 143 template<forward_range _View, class _Fn> 144 struct __transform_view_iterator_category_base<_View, _Fn> { 145 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 146 147 using iterator_category = conditional_t< 148 is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 149 conditional_t< 150 derived_from<_Cat, contiguous_iterator_tag>, 151 random_access_iterator_tag, 152 _Cat 153 >, 154 input_iterator_tag 155 >; 156 }; 157 158 template<input_range _View, copy_constructible _Fn> 159 requires __transform_view_constraints<_View, _Fn> 160 template<bool _Const> 161 class transform_view<_View, _Fn>::__iterator 162 : public __transform_view_iterator_category_base<_View, _Fn> { 163 164 using _Parent = __maybe_const<_Const, transform_view>; 165 using _Base = __maybe_const<_Const, _View>; 166 167 _Parent *__parent_ = nullptr; 168 169 template<bool> 170 friend class transform_view<_View, _Fn>::__iterator; 171 172 template<bool> 173 friend class transform_view<_View, _Fn>::__sentinel; 174 175 public: 176 iterator_t<_Base> __current_ = iterator_t<_Base>(); 177 178 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 179 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 180 using difference_type = range_difference_t<_Base>; 181 182 _LIBCPP_HIDE_FROM_ABI 183 __iterator() requires default_initializable<iterator_t<_Base>> = default; 184 185 _LIBCPP_HIDE_FROM_ABI 186 constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 187 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {} 188 189 // Note: `__i` should always be `__iterator<false>`, but directly using 190 // `__iterator<false>` is ill-formed when `_Const` is false 191 // (see http://wg21.link/class.copy.ctor#5). 192 _LIBCPP_HIDE_FROM_ABI 193 constexpr __iterator(__iterator<!_Const> __i) 194 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 195 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {} 196 197 _LIBCPP_HIDE_FROM_ABI 198 constexpr const iterator_t<_Base>& base() const& noexcept { 199 return __current_; 200 } 201 202 _LIBCPP_HIDE_FROM_ABI 203 constexpr iterator_t<_Base> base() && { 204 return std::move(__current_); 205 } 206 207 _LIBCPP_HIDE_FROM_ABI 208 constexpr decltype(auto) operator*() const 209 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) 210 { 211 return std::invoke(*__parent_->__func_, *__current_); 212 } 213 214 _LIBCPP_HIDE_FROM_ABI 215 constexpr __iterator& operator++() { 216 ++__current_; 217 return *this; 218 } 219 220 _LIBCPP_HIDE_FROM_ABI 221 constexpr void operator++(int) { ++__current_; } 222 223 _LIBCPP_HIDE_FROM_ABI 224 constexpr __iterator operator++(int) 225 requires forward_range<_Base> 226 { 227 auto __tmp = *this; 228 ++*this; 229 return __tmp; 230 } 231 232 _LIBCPP_HIDE_FROM_ABI 233 constexpr __iterator& operator--() 234 requires bidirectional_range<_Base> 235 { 236 --__current_; 237 return *this; 238 } 239 240 _LIBCPP_HIDE_FROM_ABI 241 constexpr __iterator operator--(int) 242 requires bidirectional_range<_Base> 243 { 244 auto __tmp = *this; 245 --*this; 246 return __tmp; 247 } 248 249 _LIBCPP_HIDE_FROM_ABI 250 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 258 constexpr __iterator& operator-=(difference_type __n) 259 requires random_access_range<_Base> 260 { 261 __current_ -= __n; 262 return *this; 263 } 264 265 _LIBCPP_HIDE_FROM_ABI 266 constexpr decltype(auto) operator[](difference_type __n) const 267 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n]))) 268 requires random_access_range<_Base> 269 { 270 return std::invoke(*__parent_->__func_, __current_[__n]); 271 } 272 273 _LIBCPP_HIDE_FROM_ABI 274 friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 275 requires equality_comparable<iterator_t<_Base>> 276 { 277 return __x.__current_ == __y.__current_; 278 } 279 280 _LIBCPP_HIDE_FROM_ABI 281 friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 282 requires random_access_range<_Base> 283 { 284 return __x.__current_ < __y.__current_; 285 } 286 287 _LIBCPP_HIDE_FROM_ABI 288 friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 289 requires random_access_range<_Base> 290 { 291 return __x.__current_ > __y.__current_; 292 } 293 294 _LIBCPP_HIDE_FROM_ABI 295 friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 296 requires random_access_range<_Base> 297 { 298 return __x.__current_ <= __y.__current_; 299 } 300 301 _LIBCPP_HIDE_FROM_ABI 302 friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 303 requires random_access_range<_Base> 304 { 305 return __x.__current_ >= __y.__current_; 306 } 307 308 _LIBCPP_HIDE_FROM_ABI 309 friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 310 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 311 { 312 return __x.__current_ <=> __y.__current_; 313 } 314 315 _LIBCPP_HIDE_FROM_ABI 316 friend constexpr __iterator operator+(__iterator __i, difference_type __n) 317 requires random_access_range<_Base> 318 { 319 return __iterator{*__i.__parent_, __i.__current_ + __n}; 320 } 321 322 _LIBCPP_HIDE_FROM_ABI 323 friend constexpr __iterator operator+(difference_type __n, __iterator __i) 324 requires random_access_range<_Base> 325 { 326 return __iterator{*__i.__parent_, __i.__current_ + __n}; 327 } 328 329 _LIBCPP_HIDE_FROM_ABI 330 friend constexpr __iterator operator-(__iterator __i, difference_type __n) 331 requires random_access_range<_Base> 332 { 333 return __iterator{*__i.__parent_, __i.__current_ - __n}; 334 } 335 336 _LIBCPP_HIDE_FROM_ABI 337 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 338 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 339 { 340 return __x.__current_ - __y.__current_; 341 } 342 343 _LIBCPP_HIDE_FROM_ABI 344 friend constexpr decltype(auto) iter_move(const __iterator& __i) 345 noexcept(noexcept(*__i)) 346 { 347 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 348 return std::move(*__i); 349 else 350 return *__i; 351 } 352 }; 353 354 template<input_range _View, copy_constructible _Fn> 355 requires __transform_view_constraints<_View, _Fn> 356 template<bool _Const> 357 class transform_view<_View, _Fn>::__sentinel { 358 using _Parent = __maybe_const<_Const, transform_view>; 359 using _Base = __maybe_const<_Const, _View>; 360 361 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 362 363 template<bool> 364 friend class transform_view<_View, _Fn>::__iterator; 365 366 template<bool> 367 friend class transform_view<_View, _Fn>::__sentinel; 368 369 public: 370 _LIBCPP_HIDE_FROM_ABI 371 __sentinel() = default; 372 373 _LIBCPP_HIDE_FROM_ABI 374 constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 375 376 // Note: `__i` should always be `__sentinel<false>`, but directly using 377 // `__sentinel<false>` is ill-formed when `_Const` is false 378 // (see http://wg21.link/class.copy.ctor#5). 379 _LIBCPP_HIDE_FROM_ABI 380 constexpr __sentinel(__sentinel<!_Const> __i) 381 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 382 : __end_(std::move(__i.__end_)) {} 383 384 _LIBCPP_HIDE_FROM_ABI 385 constexpr sentinel_t<_Base> base() const { return __end_; } 386 387 template<bool _OtherConst> 388 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 389 _LIBCPP_HIDE_FROM_ABI 390 friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 391 return __x.__current_ == __y.__end_; 392 } 393 394 template<bool _OtherConst> 395 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 396 _LIBCPP_HIDE_FROM_ABI 397 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 398 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 399 return __x.__current_ - __y.__end_; 400 } 401 402 template<bool _OtherConst> 403 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 404 _LIBCPP_HIDE_FROM_ABI 405 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 406 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 407 return __x.__end_ - __y.__current_; 408 } 409 }; 410 411 namespace views { 412 namespace __transform { 413 struct __fn { 414 template<class _Range, class _Fn> 415 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 416 constexpr auto operator()(_Range&& __range, _Fn&& __f) const 417 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)))) 418 -> decltype( transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) 419 { return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)); } 420 421 template<class _Fn> 422 requires constructible_from<decay_t<_Fn>, _Fn> 423 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 424 constexpr auto operator()(_Fn&& __f) const 425 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) 426 { return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Fn>(__f))); } 427 }; 428 } // namespace __transform 429 430 inline namespace __cpo { 431 inline constexpr auto transform = __transform::__fn{}; 432 } // namespace __cpo 433 } // namespace views 434 435 } // namespace ranges 436 437 #endif // _LIBCPP_STD_VER >= 20 438 439 _LIBCPP_END_NAMESPACE_STD 440 441 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 442