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 #include <type_traits> 39 40 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 41 # pragma GCC system_header 42 #endif 43 44 _LIBCPP_BEGIN_NAMESPACE_STD 45 46 #if _LIBCPP_STD_VER > 17 47 48 namespace ranges { 49 50 template<class _Fn, class _View> 51 concept __regular_invocable_with_range_ref = 52 regular_invocable<_Fn, range_reference_t<_View>>; 53 54 template<class _View, class _Fn> 55 concept __transform_view_constraints = 56 view<_View> && is_object_v<_Fn> && 57 regular_invocable<_Fn&, range_reference_t<_View>> && 58 __can_reference<invoke_result_t<_Fn&, range_reference_t<_View>>>; 59 60 template<input_range _View, copy_constructible _Fn> 61 requires __transform_view_constraints<_View, _Fn> 62 class transform_view : public view_interface<transform_view<_View, _Fn>> { 63 template<bool> class __iterator; 64 template<bool> class __sentinel; 65 66 _LIBCPP_NO_UNIQUE_ADDRESS __copyable_box<_Fn> __func_; 67 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 68 69 public: 70 _LIBCPP_HIDE_FROM_ABI 71 transform_view() 72 requires default_initializable<_View> && default_initializable<_Fn> = default; 73 74 _LIBCPP_HIDE_FROM_ABI 75 constexpr transform_view(_View __base, _Fn __func) 76 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {} 77 78 _LIBCPP_HIDE_FROM_ABI 79 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 80 _LIBCPP_HIDE_FROM_ABI 81 constexpr _View base() && { return std::move(__base_); } 82 83 _LIBCPP_HIDE_FROM_ABI 84 constexpr __iterator<false> begin() { 85 return __iterator<false>{*this, ranges::begin(__base_)}; 86 } 87 _LIBCPP_HIDE_FROM_ABI 88 constexpr __iterator<true> begin() const 89 requires range<const _View> && 90 __regular_invocable_with_range_ref<const _Fn&, const _View> 91 { 92 return __iterator<true>(*this, ranges::begin(__base_)); 93 } 94 95 _LIBCPP_HIDE_FROM_ABI 96 constexpr __sentinel<false> end() { 97 return __sentinel<false>(ranges::end(__base_)); 98 } 99 _LIBCPP_HIDE_FROM_ABI 100 constexpr __iterator<false> end() 101 requires common_range<_View> 102 { 103 return __iterator<false>(*this, ranges::end(__base_)); 104 } 105 _LIBCPP_HIDE_FROM_ABI 106 constexpr __sentinel<true> end() const 107 requires range<const _View> && 108 __regular_invocable_with_range_ref<const _Fn&, const _View> 109 { 110 return __sentinel<true>(ranges::end(__base_)); 111 } 112 _LIBCPP_HIDE_FROM_ABI 113 constexpr __iterator<true> end() const 114 requires common_range<const _View> && 115 __regular_invocable_with_range_ref<const _Fn&, const _View> 116 { 117 return __iterator<true>(*this, ranges::end(__base_)); 118 } 119 120 _LIBCPP_HIDE_FROM_ABI 121 constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); } 122 _LIBCPP_HIDE_FROM_ABI 123 constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); } 124 }; 125 126 template<class _Range, class _Fn> 127 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 128 129 template<class _View> 130 struct __transform_view_iterator_concept { using type = input_iterator_tag; }; 131 132 template<random_access_range _View> 133 struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; }; 134 135 template<bidirectional_range _View> 136 struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; }; 137 138 template<forward_range _View> 139 struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; }; 140 141 template<class, class> 142 struct __transform_view_iterator_category_base {}; 143 144 template<forward_range _View, class _Fn> 145 struct __transform_view_iterator_category_base<_View, _Fn> { 146 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 147 148 using iterator_category = conditional_t< 149 is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 150 conditional_t< 151 derived_from<_Cat, contiguous_iterator_tag>, 152 random_access_iterator_tag, 153 _Cat 154 >, 155 input_iterator_tag 156 >; 157 }; 158 159 template<input_range _View, copy_constructible _Fn> 160 requires __transform_view_constraints<_View, _Fn> 161 template<bool _Const> 162 class transform_view<_View, _Fn>::__iterator 163 : public __transform_view_iterator_category_base<_View, _Fn> { 164 165 using _Parent = __maybe_const<_Const, transform_view>; 166 using _Base = __maybe_const<_Const, _View>; 167 168 _Parent *__parent_ = nullptr; 169 170 template<bool> 171 friend class transform_view<_View, _Fn>::__iterator; 172 173 template<bool> 174 friend class transform_view<_View, _Fn>::__sentinel; 175 176 public: 177 iterator_t<_Base> __current_ = iterator_t<_Base>(); 178 179 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 180 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 181 using difference_type = range_difference_t<_Base>; 182 183 _LIBCPP_HIDE_FROM_ABI 184 __iterator() requires default_initializable<iterator_t<_Base>> = default; 185 186 _LIBCPP_HIDE_FROM_ABI 187 constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 188 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {} 189 190 // Note: `__i` should always be `__iterator<false>`, but directly using 191 // `__iterator<false>` is ill-formed when `_Const` is false 192 // (see http://wg21.link/class.copy.ctor#5). 193 _LIBCPP_HIDE_FROM_ABI 194 constexpr __iterator(__iterator<!_Const> __i) 195 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 196 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {} 197 198 _LIBCPP_HIDE_FROM_ABI 199 constexpr const iterator_t<_Base>& base() const& noexcept { 200 return __current_; 201 } 202 203 _LIBCPP_HIDE_FROM_ABI 204 constexpr iterator_t<_Base> base() && { 205 return std::move(__current_); 206 } 207 208 _LIBCPP_HIDE_FROM_ABI 209 constexpr decltype(auto) operator*() const 210 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) 211 { 212 return std::invoke(*__parent_->__func_, *__current_); 213 } 214 215 _LIBCPP_HIDE_FROM_ABI 216 constexpr __iterator& operator++() { 217 ++__current_; 218 return *this; 219 } 220 221 _LIBCPP_HIDE_FROM_ABI 222 constexpr void operator++(int) { ++__current_; } 223 224 _LIBCPP_HIDE_FROM_ABI 225 constexpr __iterator operator++(int) 226 requires forward_range<_Base> 227 { 228 auto __tmp = *this; 229 ++*this; 230 return __tmp; 231 } 232 233 _LIBCPP_HIDE_FROM_ABI 234 constexpr __iterator& operator--() 235 requires bidirectional_range<_Base> 236 { 237 --__current_; 238 return *this; 239 } 240 241 _LIBCPP_HIDE_FROM_ABI 242 constexpr __iterator operator--(int) 243 requires bidirectional_range<_Base> 244 { 245 auto __tmp = *this; 246 --*this; 247 return __tmp; 248 } 249 250 _LIBCPP_HIDE_FROM_ABI 251 constexpr __iterator& operator+=(difference_type __n) 252 requires random_access_range<_Base> 253 { 254 __current_ += __n; 255 return *this; 256 } 257 258 _LIBCPP_HIDE_FROM_ABI 259 constexpr __iterator& operator-=(difference_type __n) 260 requires random_access_range<_Base> 261 { 262 __current_ -= __n; 263 return *this; 264 } 265 266 _LIBCPP_HIDE_FROM_ABI 267 constexpr decltype(auto) operator[](difference_type __n) const 268 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n]))) 269 requires random_access_range<_Base> 270 { 271 return std::invoke(*__parent_->__func_, __current_[__n]); 272 } 273 274 _LIBCPP_HIDE_FROM_ABI 275 friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 276 requires equality_comparable<iterator_t<_Base>> 277 { 278 return __x.__current_ == __y.__current_; 279 } 280 281 _LIBCPP_HIDE_FROM_ABI 282 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 289 friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 290 requires random_access_range<_Base> 291 { 292 return __x.__current_ > __y.__current_; 293 } 294 295 _LIBCPP_HIDE_FROM_ABI 296 friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 297 requires random_access_range<_Base> 298 { 299 return __x.__current_ <= __y.__current_; 300 } 301 302 _LIBCPP_HIDE_FROM_ABI 303 friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 304 requires random_access_range<_Base> 305 { 306 return __x.__current_ >= __y.__current_; 307 } 308 309 _LIBCPP_HIDE_FROM_ABI 310 friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 311 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 312 { 313 return __x.__current_ <=> __y.__current_; 314 } 315 316 _LIBCPP_HIDE_FROM_ABI 317 friend constexpr __iterator operator+(__iterator __i, difference_type __n) 318 requires random_access_range<_Base> 319 { 320 return __iterator{*__i.__parent_, __i.__current_ + __n}; 321 } 322 323 _LIBCPP_HIDE_FROM_ABI 324 friend constexpr __iterator operator+(difference_type __n, __iterator __i) 325 requires random_access_range<_Base> 326 { 327 return __iterator{*__i.__parent_, __i.__current_ + __n}; 328 } 329 330 _LIBCPP_HIDE_FROM_ABI 331 friend constexpr __iterator operator-(__iterator __i, difference_type __n) 332 requires random_access_range<_Base> 333 { 334 return __iterator{*__i.__parent_, __i.__current_ - __n}; 335 } 336 337 _LIBCPP_HIDE_FROM_ABI 338 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 339 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 340 { 341 return __x.__current_ - __y.__current_; 342 } 343 344 _LIBCPP_HIDE_FROM_ABI 345 friend constexpr decltype(auto) iter_move(const __iterator& __i) 346 noexcept(noexcept(*__i)) 347 { 348 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 349 return std::move(*__i); 350 else 351 return *__i; 352 } 353 }; 354 355 template<input_range _View, copy_constructible _Fn> 356 requires __transform_view_constraints<_View, _Fn> 357 template<bool _Const> 358 class transform_view<_View, _Fn>::__sentinel { 359 using _Parent = __maybe_const<_Const, transform_view>; 360 using _Base = __maybe_const<_Const, _View>; 361 362 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 363 364 template<bool> 365 friend class transform_view<_View, _Fn>::__iterator; 366 367 template<bool> 368 friend class transform_view<_View, _Fn>::__sentinel; 369 370 public: 371 _LIBCPP_HIDE_FROM_ABI 372 __sentinel() = default; 373 374 _LIBCPP_HIDE_FROM_ABI 375 constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 376 377 // Note: `__i` should always be `__sentinel<false>`, but directly using 378 // `__sentinel<false>` is ill-formed when `_Const` is false 379 // (see http://wg21.link/class.copy.ctor#5). 380 _LIBCPP_HIDE_FROM_ABI 381 constexpr __sentinel(__sentinel<!_Const> __i) 382 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 383 : __end_(std::move(__i.__end_)) {} 384 385 _LIBCPP_HIDE_FROM_ABI 386 constexpr sentinel_t<_Base> base() const { return __end_; } 387 388 template<bool _OtherConst> 389 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 390 _LIBCPP_HIDE_FROM_ABI 391 friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 392 return __x.__current_ == __y.__end_; 393 } 394 395 template<bool _OtherConst> 396 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 397 _LIBCPP_HIDE_FROM_ABI 398 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 399 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 400 return __x.__current_ - __y.__end_; 401 } 402 403 template<bool _OtherConst> 404 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 405 _LIBCPP_HIDE_FROM_ABI 406 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 407 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 408 return __x.__end_ - __y.__current_; 409 } 410 }; 411 412 namespace views { 413 namespace __transform { 414 struct __fn { 415 template<class _Range, class _Fn> 416 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 417 constexpr auto operator()(_Range&& __range, _Fn&& __f) const 418 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)))) 419 -> decltype( transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) 420 { return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f)); } 421 422 template<class _Fn> 423 requires constructible_from<decay_t<_Fn>, _Fn> 424 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 425 constexpr auto operator()(_Fn&& __f) const 426 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) 427 { return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Fn>(__f))); } 428 }; 429 } // namespace __transform 430 431 inline namespace __cpo { 432 inline constexpr auto transform = __transform::__fn{}; 433 } // namespace __cpo 434 } // namespace views 435 436 } // namespace ranges 437 438 #endif // _LIBCPP_STD_VER > 17 439 440 _LIBCPP_END_NAMESPACE_STD 441 442 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 443