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