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 #ifndef _LIBCPP___RANGES_TRANSFORM_VIEW_H 10 #define _LIBCPP___RANGES_TRANSFORM_VIEW_H 11 12 #include <__compare/three_way_comparable.h> 13 #include <__concepts/constructible.h> 14 #include <__concepts/convertible_to.h> 15 #include <__concepts/copyable.h> 16 #include <__concepts/derived_from.h> 17 #include <__concepts/equality_comparable.h> 18 #include <__concepts/invocable.h> 19 #include <__config> 20 #include <__functional/bind_back.h> 21 #include <__functional/invoke.h> 22 #include <__iterator/concepts.h> 23 #include <__iterator/iter_swap.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 <__utility/forward.h> 35 #include <__utility/in_place.h> 36 #include <__utility/move.h> 37 #include <type_traits> 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 !defined(_LIBCPP_HAS_NO_RANGES) 46 47 namespace ranges { 48 49 template<class _View, class _Fn> 50 concept __transform_view_constraints = 51 view<_View> && is_object_v<_Fn> && 52 regular_invocable<_Fn&, range_reference_t<_View>> && 53 __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>; 54 55 template<input_range _View, copy_constructible _Fn> 56 requires __transform_view_constraints<_View, _Fn> 57 class transform_view : public view_interface<transform_view<_View, _Fn>> { 58 template<bool> class __iterator; 59 template<bool> class __sentinel; 60 61 [[no_unique_address]] __copyable_box<_Fn> __func_; 62 [[no_unique_address]] _View __base_ = _View(); 63 64 public: 65 _LIBCPP_HIDE_FROM_ABI 66 transform_view() 67 requires default_initializable<_View> && default_initializable<_Fn> = default; 68 69 _LIBCPP_HIDE_FROM_ABI 70 constexpr transform_view(_View __base, _Fn __func) 71 : __func_(_VSTD::in_place, _VSTD::move(__func)), __base_(_VSTD::move(__base)) {} 72 73 _LIBCPP_HIDE_FROM_ABI 74 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 75 _LIBCPP_HIDE_FROM_ABI 76 constexpr _View base() && { return _VSTD::move(__base_); } 77 78 _LIBCPP_HIDE_FROM_ABI 79 constexpr __iterator<false> begin() { 80 return __iterator<false>{*this, ranges::begin(__base_)}; 81 } 82 _LIBCPP_HIDE_FROM_ABI 83 constexpr __iterator<true> begin() const 84 requires range<const _View> && 85 regular_invocable<const _Fn&, range_reference_t<const _View>> 86 { 87 return __iterator<true>(*this, ranges::begin(__base_)); 88 } 89 90 _LIBCPP_HIDE_FROM_ABI 91 constexpr __sentinel<false> end() { 92 return __sentinel<false>(ranges::end(__base_)); 93 } 94 _LIBCPP_HIDE_FROM_ABI 95 constexpr __iterator<false> end() 96 requires common_range<_View> 97 { 98 return __iterator<false>(*this, ranges::end(__base_)); 99 } 100 _LIBCPP_HIDE_FROM_ABI 101 constexpr __sentinel<true> end() const 102 requires range<const _View> && 103 regular_invocable<const _Fn&, range_reference_t<const _View>> 104 { 105 return __sentinel<true>(ranges::end(__base_)); 106 } 107 _LIBCPP_HIDE_FROM_ABI 108 constexpr __iterator<true> end() const 109 requires common_range<const _View> && 110 regular_invocable<const _Fn&, range_reference_t<const _View>> 111 { 112 return __iterator<true>(*this, ranges::end(__base_)); 113 } 114 115 _LIBCPP_HIDE_FROM_ABI 116 constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); } 117 _LIBCPP_HIDE_FROM_ABI 118 constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); } 119 }; 120 121 template<class _Range, class _Fn> 122 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 123 124 template<class _View> 125 struct __transform_view_iterator_concept { using type = input_iterator_tag; }; 126 127 template<random_access_range _View> 128 struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; }; 129 130 template<bidirectional_range _View> 131 struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; }; 132 133 template<forward_range _View> 134 struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; }; 135 136 template<class, class> 137 struct __transform_view_iterator_category_base {}; 138 139 template<forward_range _View, class _Fn> 140 struct __transform_view_iterator_category_base<_View, _Fn> { 141 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 142 143 using iterator_category = conditional_t< 144 is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 145 conditional_t< 146 derived_from<_Cat, contiguous_iterator_tag>, 147 random_access_iterator_tag, 148 _Cat 149 >, 150 input_iterator_tag 151 >; 152 }; 153 154 template<input_range _View, copy_constructible _Fn> 155 requires __transform_view_constraints<_View, _Fn> 156 template<bool _Const> 157 class transform_view<_View, _Fn>::__iterator 158 : public __transform_view_iterator_category_base<_View, _Fn> { 159 160 using _Parent = __maybe_const<_Const, transform_view>; 161 using _Base = __maybe_const<_Const, _View>; 162 163 _Parent *__parent_ = nullptr; 164 165 template<bool> 166 friend class transform_view<_View, _Fn>::__iterator; 167 168 template<bool> 169 friend class transform_view<_View, _Fn>::__sentinel; 170 171 public: 172 iterator_t<_Base> __current_ = iterator_t<_Base>(); 173 174 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 175 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 176 using difference_type = range_difference_t<_Base>; 177 178 _LIBCPP_HIDE_FROM_ABI 179 __iterator() requires default_initializable<iterator_t<_Base>> = default; 180 181 _LIBCPP_HIDE_FROM_ABI 182 constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 183 : __parent_(_VSTD::addressof(__parent)), __current_(_VSTD::move(__current)) {} 184 185 // Note: `__i` should always be `__iterator<false>`, but directly using 186 // `__iterator<false>` is ill-formed when `_Const` is false 187 // (see http://wg21.link/class.copy.ctor#5). 188 _LIBCPP_HIDE_FROM_ABI 189 constexpr __iterator(__iterator<!_Const> __i) 190 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 191 : __parent_(__i.__parent_), __current_(_VSTD::move(__i.__current_)) {} 192 193 _LIBCPP_HIDE_FROM_ABI 194 constexpr iterator_t<_Base> base() const& 195 requires copyable<iterator_t<_Base>> 196 { 197 return __current_; 198 } 199 200 _LIBCPP_HIDE_FROM_ABI 201 constexpr iterator_t<_Base> base() && { 202 return _VSTD::move(__current_); 203 } 204 205 _LIBCPP_HIDE_FROM_ABI 206 constexpr decltype(auto) operator*() const 207 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, *__current_))) 208 { 209 return _VSTD::invoke(*__parent_->__func_, *__current_); 210 } 211 212 _LIBCPP_HIDE_FROM_ABI 213 constexpr __iterator& operator++() { 214 ++__current_; 215 return *this; 216 } 217 218 _LIBCPP_HIDE_FROM_ABI 219 constexpr void operator++(int) { ++__current_; } 220 221 _LIBCPP_HIDE_FROM_ABI 222 constexpr __iterator operator++(int) 223 requires forward_range<_Base> 224 { 225 auto __tmp = *this; 226 ++*this; 227 return __tmp; 228 } 229 230 _LIBCPP_HIDE_FROM_ABI 231 constexpr __iterator& operator--() 232 requires bidirectional_range<_Base> 233 { 234 --__current_; 235 return *this; 236 } 237 238 _LIBCPP_HIDE_FROM_ABI 239 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 248 constexpr __iterator& operator+=(difference_type __n) 249 requires random_access_range<_Base> 250 { 251 __current_ += __n; 252 return *this; 253 } 254 255 _LIBCPP_HIDE_FROM_ABI 256 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 264 constexpr decltype(auto) operator[](difference_type __n) const 265 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, __current_[__n]))) 266 requires random_access_range<_Base> 267 { 268 return _VSTD::invoke(*__parent_->__func_, __current_[__n]); 269 } 270 271 _LIBCPP_HIDE_FROM_ABI 272 friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 273 requires equality_comparable<iterator_t<_Base>> 274 { 275 return __x.__current_ == __y.__current_; 276 } 277 278 _LIBCPP_HIDE_FROM_ABI 279 friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 280 requires random_access_range<_Base> 281 { 282 return __x.__current_ < __y.__current_; 283 } 284 285 _LIBCPP_HIDE_FROM_ABI 286 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 293 friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 294 requires random_access_range<_Base> 295 { 296 return __x.__current_ <= __y.__current_; 297 } 298 299 _LIBCPP_HIDE_FROM_ABI 300 friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 301 requires random_access_range<_Base> 302 { 303 return __x.__current_ >= __y.__current_; 304 } 305 306 #if !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) 307 _LIBCPP_HIDE_FROM_ABI 308 friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 309 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 310 { 311 return __x.__current_ <=> __y.__current_; 312 } 313 #endif // !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) 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 _VSTD::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_(_VSTD::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(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f)))) 418 -> decltype( transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f))) 419 { return transform_view(_VSTD::forward<_Range>(__range), _VSTD::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(_VSTD::__bind_back(*this, _VSTD::forward<_Fn>(__f))); } 427 }; 428 } 429 430 inline namespace __cpo { 431 inline constexpr auto transform = __transform::__fn{}; 432 } 433 } // namespace views 434 435 } // namespace ranges 436 437 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 438 439 _LIBCPP_END_NAMESPACE_STD 440 441 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 442