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 <__functional/perfect_forward.h> 24 #include <__iterator/concepts.h> 25 #include <__iterator/iterator_traits.h> 26 #include <__memory/addressof.h> 27 #include <__ranges/access.h> 28 #include <__ranges/all.h> 29 #include <__ranges/concepts.h> 30 #include <__ranges/empty.h> 31 #include <__ranges/movable_box.h> 32 #include <__ranges/range_adaptor.h> 33 #include <__ranges/size.h> 34 #include <__ranges/view_interface.h> 35 #include <__type_traits/conditional.h> 36 #include <__type_traits/decay.h> 37 #include <__type_traits/is_nothrow_constructible.h> 38 #include <__type_traits/is_object.h> 39 #include <__type_traits/is_reference.h> 40 #include <__type_traits/maybe_const.h> 41 #include <__type_traits/remove_cvref.h> 42 #include <__utility/forward.h> 43 #include <__utility/in_place.h> 44 #include <__utility/move.h> 45 46 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 47 # pragma GCC system_header 48 #endif 49 50 _LIBCPP_PUSH_MACROS 51 #include <__undef_macros> 52 53 _LIBCPP_BEGIN_NAMESPACE_STD 54 55 #if _LIBCPP_STD_VER >= 20 56 57 namespace ranges { 58 59 template <class _Fn, class _View> 60 concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_reference_t<_View>>; 61 62 template <class _View, class _Fn> 63 concept __transform_view_constraints = 64 view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> && 65 __can_reference<invoke_result_t<_Fn&, range_reference_t<_View>>>; 66 67 # if _LIBCPP_STD_VER >= 23 68 template <input_range _View, move_constructible _Fn> 69 # else 70 template <input_range _View, copy_constructible _Fn> 71 # endif 72 requires __transform_view_constraints<_View, _Fn> 73 class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS transform_view : public view_interface<transform_view<_View, _Fn>> { 74 template <bool> 75 class __iterator; 76 template <bool> 77 class __sentinel; 78 79 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Fn> __func_; 80 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 81 82 public: 83 _LIBCPP_HIDE_FROM_ABI transform_view() 84 requires default_initializable<_View> && default_initializable<_Fn> 85 = default; 86 transform_view(_View __base,_Fn __func)87 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 transform_view(_View __base, _Fn __func) 88 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {} 89 base()90 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& 91 requires copy_constructible<_View> 92 { 93 return __base_; 94 } base()95 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } 96 begin()97 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> begin() { return __iterator<false>{*this, ranges::begin(__base_)}; } begin()98 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> begin() const 99 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View> 100 { 101 return __iterator<true>(*this, ranges::begin(__base_)); 102 } 103 end()104 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<false> end() { return __sentinel<false>(ranges::end(__base_)); } end()105 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> end() 106 requires common_range<_View> 107 { 108 return __iterator<false>(*this, ranges::end(__base_)); 109 } end()110 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<true> end() const 111 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View> 112 { 113 return __sentinel<true>(ranges::end(__base_)); 114 } end()115 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> end() const 116 requires common_range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View> 117 { 118 return __iterator<true>(*this, ranges::end(__base_)); 119 } 120 size()121 _LIBCPP_HIDE_FROM_ABI constexpr auto size() 122 requires sized_range<_View> 123 { 124 return ranges::size(__base_); 125 } size()126 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const 127 requires sized_range<const _View> 128 { 129 return ranges::size(__base_); 130 } 131 }; 132 133 template <class _Range, class _Fn> 134 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 135 136 template <class _View> 137 struct __transform_view_iterator_concept { 138 using type = input_iterator_tag; 139 }; 140 141 template <random_access_range _View> 142 struct __transform_view_iterator_concept<_View> { 143 using type = random_access_iterator_tag; 144 }; 145 146 template <bidirectional_range _View> 147 struct __transform_view_iterator_concept<_View> { 148 using type = bidirectional_iterator_tag; 149 }; 150 151 template <forward_range _View> 152 struct __transform_view_iterator_concept<_View> { 153 using type = forward_iterator_tag; 154 }; 155 156 template <class, class> 157 struct __transform_view_iterator_category_base {}; 158 159 template <forward_range _View, class _Fn> 160 struct __transform_view_iterator_category_base<_View, _Fn> { 161 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 162 163 using iterator_category = 164 conditional_t< is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 165 conditional_t< derived_from<_Cat, contiguous_iterator_tag>, random_access_iterator_tag, _Cat >, 166 input_iterator_tag >; 167 }; 168 169 # if _LIBCPP_STD_VER >= 23 170 template <input_range _View, move_constructible _Fn> 171 # else 172 template <input_range _View, copy_constructible _Fn> 173 # endif 174 requires __transform_view_constraints<_View, _Fn> 175 template <bool _Const> 176 class transform_view<_View, _Fn>::__iterator : public __transform_view_iterator_category_base<_View, _Fn> { 177 178 using _Parent = __maybe_const<_Const, transform_view>; 179 using _Base = __maybe_const<_Const, _View>; 180 181 _Parent* __parent_ = nullptr; 182 183 template <bool> 184 friend class transform_view<_View, _Fn>::__iterator; 185 186 template <bool> 187 friend class transform_view<_View, _Fn>::__sentinel; 188 189 public: 190 iterator_t<_Base> __current_ = iterator_t<_Base>(); 191 192 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 193 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 194 using difference_type = range_difference_t<_Base>; 195 196 _LIBCPP_HIDE_FROM_ABI __iterator() 197 requires default_initializable<iterator_t<_Base>> 198 = default; 199 200 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 201 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {} 202 203 // Note: `__i` should always be `__iterator<false>`, but directly using 204 // `__iterator<false>` is ill-formed when `_Const` is false 205 // (see http://wg21.link/class.copy.ctor#5). 206 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i) 207 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 208 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {} 209 210 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; } 211 212 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); } 213 214 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const 215 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) { 216 return std::invoke(*__parent_->__func_, *__current_); 217 } 218 219 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() { 220 ++__current_; 221 return *this; 222 } 223 224 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; } 225 226 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) 227 requires forward_range<_Base> 228 { 229 auto __tmp = *this; 230 ++*this; 231 return __tmp; 232 } 233 234 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--() 235 requires bidirectional_range<_Base> 236 { 237 --__current_; 238 return *this; 239 } 240 241 _LIBCPP_HIDE_FROM_ABI 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 constexpr __iterator& operator+=(difference_type __n) 250 requires random_access_range<_Base> 251 { 252 __current_ += __n; 253 return *this; 254 } 255 256 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n) 257 requires random_access_range<_Base> 258 { 259 __current_ -= __n; 260 return *this; 261 } 262 263 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const 264 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n]))) 265 requires random_access_range<_Base> 266 { 267 return std::invoke(*__parent_->__func_, __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 __x.__current_ > __y.__current_; 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 __x.__current_ <= __y.__current_; 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.__current_ >= __y.__current_; 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+(__iterator __i, difference_type __n) 307 requires random_access_range<_Base> 308 { 309 return __iterator{*__i.__parent_, __i.__current_ + __n}; 310 } 311 312 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i) 313 requires random_access_range<_Base> 314 { 315 return __iterator{*__i.__parent_, __i.__current_ + __n}; 316 } 317 318 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(__iterator __i, difference_type __n) 319 requires random_access_range<_Base> 320 { 321 return __iterator{*__i.__parent_, __i.__current_ - __n}; 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 _LIBCPP_HIDE_FROM_ABI friend constexpr decltype(auto) iter_move(const __iterator& __i) noexcept(noexcept(*__i)) { 331 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 332 return std::move(*__i); 333 else 334 return *__i; 335 } 336 }; 337 338 # if _LIBCPP_STD_VER >= 23 339 template <input_range _View, move_constructible _Fn> 340 # else 341 template <input_range _View, copy_constructible _Fn> 342 # endif 343 requires __transform_view_constraints<_View, _Fn> 344 template <bool _Const> 345 class transform_view<_View, _Fn>::__sentinel { 346 using _Parent = __maybe_const<_Const, transform_view>; 347 using _Base = __maybe_const<_Const, _View>; 348 349 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 350 351 template <bool> 352 friend class transform_view<_View, _Fn>::__iterator; 353 354 template <bool> 355 friend class transform_view<_View, _Fn>::__sentinel; 356 357 public: 358 _LIBCPP_HIDE_FROM_ABI __sentinel() = default; 359 360 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 361 362 // Note: `__i` should always be `__sentinel<false>`, but directly using 363 // `__sentinel<false>` is ill-formed when `_Const` is false 364 // (see http://wg21.link/class.copy.ctor#5). 365 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i) 366 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 367 : __end_(std::move(__i.__end_)) {} 368 369 _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; } 370 371 template <bool _OtherConst> 372 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 373 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 374 return __x.__current_ == __y.__end_; 375 } 376 377 template <bool _OtherConst> 378 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 379 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 380 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 381 return __x.__current_ - __y.__end_; 382 } 383 384 template <bool _OtherConst> 385 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 386 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 387 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 388 return __x.__end_ - __y.__current_; 389 } 390 }; 391 392 namespace views { 393 namespace __transform { 394 struct __fn { 395 template <class _Range, class _Fn> 396 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Fn&& __f) const 397 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)))) 398 -> decltype(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) { 399 return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)); 400 } 401 402 template <class _Fn> 403 requires constructible_from<decay_t<_Fn>, _Fn> 404 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f) const 405 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) { 406 return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Fn>(__f))); 407 } 408 }; 409 } // namespace __transform 410 411 inline namespace __cpo { 412 inline constexpr auto transform = __transform::__fn{}; 413 } // namespace __cpo 414 } // namespace views 415 416 } // namespace ranges 417 418 #endif // _LIBCPP_STD_VER >= 20 419 420 _LIBCPP_END_NAMESPACE_STD 421 422 _LIBCPP_POP_MACROS 423 424 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 425