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_BEGIN_NAMESPACE_STD 51 52 #if _LIBCPP_STD_VER >= 20 53 54 namespace ranges { 55 56 template <class _Fn, class _View> 57 concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_reference_t<_View>>; 58 59 template <class _View, class _Fn> 60 concept __transform_view_constraints = 61 view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> && 62 __can_reference<invoke_result_t<_Fn&, range_reference_t<_View>>>; 63 64 # if _LIBCPP_STD_VER >= 23 65 template <input_range _View, move_constructible _Fn> 66 # else 67 template <input_range _View, copy_constructible _Fn> 68 # endif 69 requires __transform_view_constraints<_View, _Fn> 70 class _LIBCPP_ABI_2023_OVERLAPPING_SUBOBJECT_FIX_TAG transform_view 71 : public view_interface<transform_view<_View, _Fn>> { 72 template <bool> 73 class __iterator; 74 template <bool> 75 class __sentinel; 76 77 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Fn> __func_; 78 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 79 80 public: 81 _LIBCPP_HIDE_FROM_ABI transform_view() 82 requires default_initializable<_View> && default_initializable<_Fn> 83 = default; 84 85 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 transform_view(_View __base, _Fn __func) 86 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {} 87 88 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& 89 requires copy_constructible<_View> 90 { 91 return __base_; 92 } 93 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } 94 95 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> begin() { return __iterator<false>{*this, ranges::begin(__base_)}; } 96 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> begin() const 97 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View> 98 { 99 return __iterator<true>(*this, ranges::begin(__base_)); 100 } 101 102 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<false> end() { return __sentinel<false>(ranges::end(__base_)); } 103 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> end() 104 requires common_range<_View> 105 { 106 return __iterator<false>(*this, ranges::end(__base_)); 107 } 108 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<true> end() const 109 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View> 110 { 111 return __sentinel<true>(ranges::end(__base_)); 112 } 113 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> end() const 114 requires common_range<const _View> && __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 constexpr auto size() 120 requires sized_range<_View> 121 { 122 return ranges::size(__base_); 123 } 124 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const 125 requires sized_range<const _View> 126 { 127 return ranges::size(__base_); 128 } 129 }; 130 131 template <class _Range, class _Fn> 132 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 133 134 template <class _View> 135 struct __transform_view_iterator_concept { 136 using type = input_iterator_tag; 137 }; 138 139 template <random_access_range _View> 140 struct __transform_view_iterator_concept<_View> { 141 using type = random_access_iterator_tag; 142 }; 143 144 template <bidirectional_range _View> 145 struct __transform_view_iterator_concept<_View> { 146 using type = bidirectional_iterator_tag; 147 }; 148 149 template <forward_range _View> 150 struct __transform_view_iterator_concept<_View> { 151 using type = forward_iterator_tag; 152 }; 153 154 template <class, class> 155 struct __transform_view_iterator_category_base {}; 156 157 template <forward_range _View, class _Fn> 158 struct __transform_view_iterator_category_base<_View, _Fn> { 159 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 160 161 using iterator_category = 162 conditional_t< is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 163 conditional_t< derived_from<_Cat, contiguous_iterator_tag>, random_access_iterator_tag, _Cat >, 164 input_iterator_tag >; 165 }; 166 167 # if _LIBCPP_STD_VER >= 23 168 template <input_range _View, move_constructible _Fn> 169 # else 170 template <input_range _View, copy_constructible _Fn> 171 # endif 172 requires __transform_view_constraints<_View, _Fn> 173 template <bool _Const> 174 class transform_view<_View, _Fn>::__iterator : public __transform_view_iterator_category_base<_View, _Fn> { 175 176 using _Parent = __maybe_const<_Const, transform_view>; 177 using _Base = __maybe_const<_Const, _View>; 178 179 _Parent* __parent_ = nullptr; 180 181 template <bool> 182 friend class transform_view<_View, _Fn>::__iterator; 183 184 template <bool> 185 friend class transform_view<_View, _Fn>::__sentinel; 186 187 public: 188 iterator_t<_Base> __current_ = iterator_t<_Base>(); 189 190 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 191 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 192 using difference_type = range_difference_t<_Base>; 193 194 _LIBCPP_HIDE_FROM_ABI __iterator() 195 requires default_initializable<iterator_t<_Base>> 196 = default; 197 198 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 199 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {} 200 201 // Note: `__i` should always be `__iterator<false>`, but directly using 202 // `__iterator<false>` is ill-formed when `_Const` is false 203 // (see http://wg21.link/class.copy.ctor#5). 204 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i) 205 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 206 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {} 207 208 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; } 209 210 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); } 211 212 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const 213 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) { 214 return std::invoke(*__parent_->__func_, *__current_); 215 } 216 217 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() { 218 ++__current_; 219 return *this; 220 } 221 222 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; } 223 224 _LIBCPP_HIDE_FROM_ABI 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 constexpr __iterator& operator--() 233 requires bidirectional_range<_Base> 234 { 235 --__current_; 236 return *this; 237 } 238 239 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int) 240 requires bidirectional_range<_Base> 241 { 242 auto __tmp = *this; 243 --*this; 244 return __tmp; 245 } 246 247 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n) 248 requires random_access_range<_Base> 249 { 250 __current_ += __n; 251 return *this; 252 } 253 254 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n) 255 requires random_access_range<_Base> 256 { 257 __current_ -= __n; 258 return *this; 259 } 260 261 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const 262 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n]))) 263 requires random_access_range<_Base> 264 { 265 return std::invoke(*__parent_->__func_, __current_[__n]); 266 } 267 268 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 269 requires equality_comparable<iterator_t<_Base>> 270 { 271 return __x.__current_ == __y.__current_; 272 } 273 274 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 275 requires random_access_range<_Base> 276 { 277 return __x.__current_ < __y.__current_; 278 } 279 280 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 281 requires random_access_range<_Base> 282 { 283 return __x.__current_ > __y.__current_; 284 } 285 286 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 287 requires random_access_range<_Base> 288 { 289 return __x.__current_ <= __y.__current_; 290 } 291 292 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 293 requires random_access_range<_Base> 294 { 295 return __x.__current_ >= __y.__current_; 296 } 297 298 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 299 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 300 { 301 return __x.__current_ <=> __y.__current_; 302 } 303 304 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n) 305 requires random_access_range<_Base> 306 { 307 return __iterator{*__i.__parent_, __i.__current_ + __n}; 308 } 309 310 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i) 311 requires random_access_range<_Base> 312 { 313 return __iterator{*__i.__parent_, __i.__current_ + __n}; 314 } 315 316 _LIBCPP_HIDE_FROM_ABI 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 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 323 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 324 { 325 return __x.__current_ - __y.__current_; 326 } 327 328 _LIBCPP_HIDE_FROM_ABI friend constexpr decltype(auto) iter_move(const __iterator& __i) noexcept(noexcept(*__i)) { 329 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 330 return std::move(*__i); 331 else 332 return *__i; 333 } 334 }; 335 336 # if _LIBCPP_STD_VER >= 23 337 template <input_range _View, move_constructible _Fn> 338 # else 339 template <input_range _View, copy_constructible _Fn> 340 # endif 341 requires __transform_view_constraints<_View, _Fn> 342 template <bool _Const> 343 class transform_view<_View, _Fn>::__sentinel { 344 using _Parent = __maybe_const<_Const, transform_view>; 345 using _Base = __maybe_const<_Const, _View>; 346 347 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 348 349 template <bool> 350 friend class transform_view<_View, _Fn>::__iterator; 351 352 template <bool> 353 friend class transform_view<_View, _Fn>::__sentinel; 354 355 public: 356 _LIBCPP_HIDE_FROM_ABI __sentinel() = default; 357 358 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 359 360 // Note: `__i` should always be `__sentinel<false>`, but directly using 361 // `__sentinel<false>` is ill-formed when `_Const` is false 362 // (see http://wg21.link/class.copy.ctor#5). 363 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i) 364 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 365 : __end_(std::move(__i.__end_)) {} 366 367 _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; } 368 369 template <bool _OtherConst> 370 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 371 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 372 return __x.__current_ == __y.__end_; 373 } 374 375 template <bool _OtherConst> 376 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 377 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 378 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 379 return __x.__current_ - __y.__end_; 380 } 381 382 template <bool _OtherConst> 383 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 384 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 385 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 386 return __x.__end_ - __y.__current_; 387 } 388 }; 389 390 namespace views { 391 namespace __transform { 392 struct __fn { 393 template <class _Range, class _Fn> 394 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Fn&& __f) const 395 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)))) 396 -> decltype(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) { 397 return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)); 398 } 399 400 template <class _Fn> 401 requires constructible_from<decay_t<_Fn>, _Fn> 402 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f) const 403 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) { 404 return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Fn>(__f))); 405 } 406 }; 407 } // namespace __transform 408 409 inline namespace __cpo { 410 inline constexpr auto transform = __transform::__fn{}; 411 } // namespace __cpo 412 } // namespace views 413 414 } // namespace ranges 415 416 #endif // _LIBCPP_STD_VER >= 20 417 418 _LIBCPP_END_NAMESPACE_STD 419 420 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 421