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 _Fn, class _View> 50 concept __regular_invocable_with_range_ref = 51 regular_invocable<_Fn, range_reference_t<_View>>; 52 53 template<class _View, class _Fn> 54 concept __transform_view_constraints = 55 view<_View> && is_object_v<_Fn> && 56 regular_invocable<_Fn&, range_reference_t<_View>> && 57 __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>; 58 59 template<input_range _View, copy_constructible _Fn> 60 requires __transform_view_constraints<_View, _Fn> 61 class transform_view : public view_interface<transform_view<_View, _Fn>> { 62 template<bool> class __iterator; 63 template<bool> class __sentinel; 64 65 [[no_unique_address]] __copyable_box<_Fn> __func_; 66 [[no_unique_address]] _View __base_ = _View(); 67 68 public: 69 _LIBCPP_HIDE_FROM_ABI 70 transform_view() 71 requires default_initializable<_View> && default_initializable<_Fn> = default; 72 73 _LIBCPP_HIDE_FROM_ABI 74 constexpr transform_view(_View __base, _Fn __func) 75 : __func_(_VSTD::in_place, _VSTD::move(__func)), __base_(_VSTD::move(__base)) {} 76 77 _LIBCPP_HIDE_FROM_ABI 78 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 79 _LIBCPP_HIDE_FROM_ABI 80 constexpr _View base() && { return _VSTD::move(__base_); } 81 82 _LIBCPP_HIDE_FROM_ABI 83 constexpr __iterator<false> begin() { 84 return __iterator<false>{*this, ranges::begin(__base_)}; 85 } 86 _LIBCPP_HIDE_FROM_ABI 87 constexpr __iterator<true> begin() const 88 requires range<const _View> && 89 __regular_invocable_with_range_ref<const _Fn&, const _View> 90 { 91 return __iterator<true>(*this, ranges::begin(__base_)); 92 } 93 94 _LIBCPP_HIDE_FROM_ABI 95 constexpr __sentinel<false> end() { 96 return __sentinel<false>(ranges::end(__base_)); 97 } 98 _LIBCPP_HIDE_FROM_ABI 99 constexpr __iterator<false> end() 100 requires common_range<_View> 101 { 102 return __iterator<false>(*this, ranges::end(__base_)); 103 } 104 _LIBCPP_HIDE_FROM_ABI 105 constexpr __sentinel<true> end() const 106 requires range<const _View> && 107 __regular_invocable_with_range_ref<const _Fn&, const _View> 108 { 109 return __sentinel<true>(ranges::end(__base_)); 110 } 111 _LIBCPP_HIDE_FROM_ABI 112 constexpr __iterator<true> end() const 113 requires common_range<const _View> && 114 __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 120 constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); } 121 _LIBCPP_HIDE_FROM_ABI 122 constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); } 123 }; 124 125 template<class _Range, class _Fn> 126 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 127 128 template<class _View> 129 struct __transform_view_iterator_concept { using type = input_iterator_tag; }; 130 131 template<random_access_range _View> 132 struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; }; 133 134 template<bidirectional_range _View> 135 struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; }; 136 137 template<forward_range _View> 138 struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; }; 139 140 template<class, class> 141 struct __transform_view_iterator_category_base {}; 142 143 template<forward_range _View, class _Fn> 144 struct __transform_view_iterator_category_base<_View, _Fn> { 145 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 146 147 using iterator_category = conditional_t< 148 is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 149 conditional_t< 150 derived_from<_Cat, contiguous_iterator_tag>, 151 random_access_iterator_tag, 152 _Cat 153 >, 154 input_iterator_tag 155 >; 156 }; 157 158 template<input_range _View, copy_constructible _Fn> 159 requires __transform_view_constraints<_View, _Fn> 160 template<bool _Const> 161 class transform_view<_View, _Fn>::__iterator 162 : public __transform_view_iterator_category_base<_View, _Fn> { 163 164 using _Parent = __maybe_const<_Const, transform_view>; 165 using _Base = __maybe_const<_Const, _View>; 166 167 _Parent *__parent_ = nullptr; 168 169 template<bool> 170 friend class transform_view<_View, _Fn>::__iterator; 171 172 template<bool> 173 friend class transform_view<_View, _Fn>::__sentinel; 174 175 public: 176 iterator_t<_Base> __current_ = iterator_t<_Base>(); 177 178 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 179 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 180 using difference_type = range_difference_t<_Base>; 181 182 _LIBCPP_HIDE_FROM_ABI 183 __iterator() requires default_initializable<iterator_t<_Base>> = default; 184 185 _LIBCPP_HIDE_FROM_ABI 186 constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 187 : __parent_(_VSTD::addressof(__parent)), __current_(_VSTD::move(__current)) {} 188 189 // Note: `__i` should always be `__iterator<false>`, but directly using 190 // `__iterator<false>` is ill-formed when `_Const` is false 191 // (see http://wg21.link/class.copy.ctor#5). 192 _LIBCPP_HIDE_FROM_ABI 193 constexpr __iterator(__iterator<!_Const> __i) 194 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 195 : __parent_(__i.__parent_), __current_(_VSTD::move(__i.__current_)) {} 196 197 _LIBCPP_HIDE_FROM_ABI 198 constexpr iterator_t<_Base> base() const& 199 requires copyable<iterator_t<_Base>> 200 { 201 return __current_; 202 } 203 204 _LIBCPP_HIDE_FROM_ABI 205 constexpr iterator_t<_Base> base() && { 206 return _VSTD::move(__current_); 207 } 208 209 _LIBCPP_HIDE_FROM_ABI 210 constexpr decltype(auto) operator*() const 211 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, *__current_))) 212 { 213 return _VSTD::invoke(*__parent_->__func_, *__current_); 214 } 215 216 _LIBCPP_HIDE_FROM_ABI 217 constexpr __iterator& operator++() { 218 ++__current_; 219 return *this; 220 } 221 222 _LIBCPP_HIDE_FROM_ABI 223 constexpr void operator++(int) { ++__current_; } 224 225 _LIBCPP_HIDE_FROM_ABI 226 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 235 constexpr __iterator& operator--() 236 requires bidirectional_range<_Base> 237 { 238 --__current_; 239 return *this; 240 } 241 242 _LIBCPP_HIDE_FROM_ABI 243 constexpr __iterator operator--(int) 244 requires bidirectional_range<_Base> 245 { 246 auto __tmp = *this; 247 --*this; 248 return __tmp; 249 } 250 251 _LIBCPP_HIDE_FROM_ABI 252 constexpr __iterator& operator+=(difference_type __n) 253 requires random_access_range<_Base> 254 { 255 __current_ += __n; 256 return *this; 257 } 258 259 _LIBCPP_HIDE_FROM_ABI 260 constexpr __iterator& operator-=(difference_type __n) 261 requires random_access_range<_Base> 262 { 263 __current_ -= __n; 264 return *this; 265 } 266 267 _LIBCPP_HIDE_FROM_ABI 268 constexpr decltype(auto) operator[](difference_type __n) const 269 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, __current_[__n]))) 270 requires random_access_range<_Base> 271 { 272 return _VSTD::invoke(*__parent_->__func_, __current_[__n]); 273 } 274 275 _LIBCPP_HIDE_FROM_ABI 276 friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 277 requires equality_comparable<iterator_t<_Base>> 278 { 279 return __x.__current_ == __y.__current_; 280 } 281 282 _LIBCPP_HIDE_FROM_ABI 283 friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 284 requires random_access_range<_Base> 285 { 286 return __x.__current_ < __y.__current_; 287 } 288 289 _LIBCPP_HIDE_FROM_ABI 290 friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 291 requires random_access_range<_Base> 292 { 293 return __x.__current_ > __y.__current_; 294 } 295 296 _LIBCPP_HIDE_FROM_ABI 297 friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y) 298 requires random_access_range<_Base> 299 { 300 return __x.__current_ <= __y.__current_; 301 } 302 303 _LIBCPP_HIDE_FROM_ABI 304 friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y) 305 requires random_access_range<_Base> 306 { 307 return __x.__current_ >= __y.__current_; 308 } 309 310 _LIBCPP_HIDE_FROM_ABI 311 friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) 312 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> 313 { 314 return __x.__current_ <=> __y.__current_; 315 } 316 317 _LIBCPP_HIDE_FROM_ABI 318 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 325 friend constexpr __iterator operator+(difference_type __n, __iterator __i) 326 requires random_access_range<_Base> 327 { 328 return __iterator{*__i.__parent_, __i.__current_ + __n}; 329 } 330 331 _LIBCPP_HIDE_FROM_ABI 332 friend constexpr __iterator operator-(__iterator __i, difference_type __n) 333 requires random_access_range<_Base> 334 { 335 return __iterator{*__i.__parent_, __i.__current_ - __n}; 336 } 337 338 _LIBCPP_HIDE_FROM_ABI 339 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 340 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 341 { 342 return __x.__current_ - __y.__current_; 343 } 344 345 _LIBCPP_HIDE_FROM_ABI 346 friend constexpr decltype(auto) iter_move(const __iterator& __i) 347 noexcept(noexcept(*__i)) 348 { 349 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 350 return _VSTD::move(*__i); 351 else 352 return *__i; 353 } 354 }; 355 356 template<input_range _View, copy_constructible _Fn> 357 requires __transform_view_constraints<_View, _Fn> 358 template<bool _Const> 359 class transform_view<_View, _Fn>::__sentinel { 360 using _Parent = __maybe_const<_Const, transform_view>; 361 using _Base = __maybe_const<_Const, _View>; 362 363 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 364 365 template<bool> 366 friend class transform_view<_View, _Fn>::__iterator; 367 368 template<bool> 369 friend class transform_view<_View, _Fn>::__sentinel; 370 371 public: 372 _LIBCPP_HIDE_FROM_ABI 373 __sentinel() = default; 374 375 _LIBCPP_HIDE_FROM_ABI 376 constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 377 378 // Note: `__i` should always be `__sentinel<false>`, but directly using 379 // `__sentinel<false>` is ill-formed when `_Const` is false 380 // (see http://wg21.link/class.copy.ctor#5). 381 _LIBCPP_HIDE_FROM_ABI 382 constexpr __sentinel(__sentinel<!_Const> __i) 383 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 384 : __end_(_VSTD::move(__i.__end_)) {} 385 386 _LIBCPP_HIDE_FROM_ABI 387 constexpr sentinel_t<_Base> base() const { return __end_; } 388 389 template<bool _OtherConst> 390 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 391 _LIBCPP_HIDE_FROM_ABI 392 friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 393 return __x.__current_ == __y.__end_; 394 } 395 396 template<bool _OtherConst> 397 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 398 _LIBCPP_HIDE_FROM_ABI 399 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 400 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 401 return __x.__current_ - __y.__end_; 402 } 403 404 template<bool _OtherConst> 405 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 406 _LIBCPP_HIDE_FROM_ABI 407 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 408 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 409 return __x.__end_ - __y.__current_; 410 } 411 }; 412 413 namespace views { 414 namespace __transform { 415 struct __fn { 416 template<class _Range, class _Fn> 417 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 418 constexpr auto operator()(_Range&& __range, _Fn&& __f) const 419 noexcept(noexcept(transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f)))) 420 -> decltype( transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f))) 421 { return transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f)); } 422 423 template<class _Fn> 424 requires constructible_from<decay_t<_Fn>, _Fn> 425 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 426 constexpr auto operator()(_Fn&& __f) const 427 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) 428 { return __range_adaptor_closure_t(_VSTD::__bind_back(*this, _VSTD::forward<_Fn>(__f))); } 429 }; 430 } 431 432 inline namespace __cpo { 433 inline constexpr auto transform = __transform::__fn{}; 434 } 435 } // namespace views 436 437 } // namespace ranges 438 439 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 440 441 _LIBCPP_END_NAMESPACE_STD 442 443 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 444