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 <__iterator/concepts.h> 14 #include <__iterator/iter_swap.h> 15 #include <__iterator/iterator_traits.h> 16 #include <__ranges/access.h> 17 #include <__ranges/all.h> 18 #include <__ranges/concepts.h> 19 #include <__ranges/copyable_box.h> 20 #include <__ranges/empty.h> 21 #include <__ranges/size.h> 22 #include <__ranges/view_interface.h> 23 #include <concepts> 24 #include <type_traits> 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 #pragma GCC system_header 28 #endif 29 30 _LIBCPP_PUSH_MACROS 31 #include <__undef_macros> 32 33 _LIBCPP_BEGIN_NAMESPACE_STD 34 35 #if !defined(_LIBCPP_HAS_NO_RANGES) 36 37 namespace ranges { 38 39 template<class _View, class _Fn> 40 concept __transform_view_constraints = 41 view<_View> && is_object_v<_Fn> && 42 regular_invocable<_Fn&, range_reference_t<_View>> && 43 __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>; 44 45 template<input_range _View, copy_constructible _Fn> 46 requires __transform_view_constraints<_View, _Fn> 47 class transform_view : public view_interface<transform_view<_View, _Fn>> { 48 template<bool> class __iterator; 49 template<bool> class __sentinel; 50 51 [[no_unique_address]] __copyable_box<_Fn> __func_; 52 [[no_unique_address]] _View __base_ = _View(); 53 54 public: 55 _LIBCPP_HIDE_FROM_ABI 56 transform_view() 57 requires default_initializable<_View> && default_initializable<_Fn> = default; 58 59 _LIBCPP_HIDE_FROM_ABI 60 constexpr transform_view(_View __base, _Fn __func) 61 : __func_(_VSTD::in_place, _VSTD::move(__func)), __base_(_VSTD::move(__base)) {} 62 63 _LIBCPP_HIDE_FROM_ABI 64 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 65 _LIBCPP_HIDE_FROM_ABI 66 constexpr _View base() && { return _VSTD::move(__base_); } 67 68 _LIBCPP_HIDE_FROM_ABI 69 constexpr __iterator<false> begin() { 70 return __iterator<false>{*this, ranges::begin(__base_)}; 71 } 72 _LIBCPP_HIDE_FROM_ABI 73 constexpr __iterator<true> begin() const 74 requires range<const _View> && 75 regular_invocable<const _Fn&, range_reference_t<const _View>> 76 { 77 return __iterator<true>(*this, ranges::begin(__base_)); 78 } 79 80 _LIBCPP_HIDE_FROM_ABI 81 constexpr __sentinel<false> end() { 82 return __sentinel<false>(ranges::end(__base_)); 83 } 84 _LIBCPP_HIDE_FROM_ABI 85 constexpr __iterator<false> end() 86 requires common_range<_View> 87 { 88 return __iterator<false>(*this, ranges::end(__base_)); 89 } 90 _LIBCPP_HIDE_FROM_ABI 91 constexpr __sentinel<true> end() const 92 requires range<const _View> && 93 regular_invocable<const _Fn&, range_reference_t<const _View>> 94 { 95 return __sentinel<true>(ranges::end(__base_)); 96 } 97 _LIBCPP_HIDE_FROM_ABI 98 constexpr __iterator<true> end() const 99 requires common_range<const _View> && 100 regular_invocable<const _Fn&, range_reference_t<const _View>> 101 { 102 return __iterator<true>(*this, ranges::end(__base_)); 103 } 104 105 _LIBCPP_HIDE_FROM_ABI 106 constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); } 107 _LIBCPP_HIDE_FROM_ABI 108 constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); } 109 }; 110 111 template<class _Range, class _Fn> 112 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>; 113 114 template<class _View> 115 struct __transform_view_iterator_concept { using type = input_iterator_tag; }; 116 117 template<random_access_range _View> 118 struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; }; 119 120 template<bidirectional_range _View> 121 struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; }; 122 123 template<forward_range _View> 124 struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; }; 125 126 template<class, class> 127 struct __transform_view_iterator_category_base {}; 128 129 template<forward_range _View, class _Fn> 130 struct __transform_view_iterator_category_base<_View, _Fn> { 131 using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category; 132 133 using iterator_category = conditional_t< 134 is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>, 135 conditional_t< 136 derived_from<_Cat, contiguous_iterator_tag>, 137 random_access_iterator_tag, 138 _Cat 139 >, 140 input_iterator_tag 141 >; 142 }; 143 144 template<input_range _View, copy_constructible _Fn> 145 requires __transform_view_constraints<_View, _Fn> 146 template<bool _Const> 147 class transform_view<_View, _Fn>::__iterator 148 : public __transform_view_iterator_category_base<_View, _Fn> { 149 150 using _Parent = __maybe_const<_Const, transform_view>; 151 using _Base = __maybe_const<_Const, _View>; 152 153 _Parent *__parent_ = nullptr; 154 155 template<bool> 156 friend class transform_view<_View, _Fn>::__iterator; 157 158 template<bool> 159 friend class transform_view<_View, _Fn>::__sentinel; 160 161 public: 162 iterator_t<_Base> __current_ = iterator_t<_Base>(); 163 164 using iterator_concept = typename __transform_view_iterator_concept<_View>::type; 165 using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>; 166 using difference_type = range_difference_t<_Base>; 167 168 _LIBCPP_HIDE_FROM_ABI 169 __iterator() requires default_initializable<iterator_t<_Base>> = default; 170 171 _LIBCPP_HIDE_FROM_ABI 172 constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current) 173 : __parent_(_VSTD::addressof(__parent)), __current_(_VSTD::move(__current)) {} 174 175 // Note: `__i` should always be `__iterator<false>`, but directly using 176 // `__iterator<false>` is ill-formed when `_Const` is false 177 // (see http://wg21.link/class.copy.ctor#5). 178 _LIBCPP_HIDE_FROM_ABI 179 constexpr __iterator(__iterator<!_Const> __i) 180 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> 181 : __parent_(__i.__parent_), __current_(_VSTD::move(__i.__current_)) {} 182 183 _LIBCPP_HIDE_FROM_ABI 184 constexpr iterator_t<_Base> base() const& 185 requires copyable<iterator_t<_Base>> 186 { 187 return __current_; 188 } 189 190 _LIBCPP_HIDE_FROM_ABI 191 constexpr iterator_t<_Base> base() && { 192 return _VSTD::move(__current_); 193 } 194 195 _LIBCPP_HIDE_FROM_ABI 196 constexpr decltype(auto) operator*() const 197 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, *__current_))) 198 { 199 return _VSTD::invoke(*__parent_->__func_, *__current_); 200 } 201 202 _LIBCPP_HIDE_FROM_ABI 203 constexpr __iterator& operator++() { 204 ++__current_; 205 return *this; 206 } 207 208 _LIBCPP_HIDE_FROM_ABI 209 constexpr void operator++(int) { ++__current_; } 210 211 _LIBCPP_HIDE_FROM_ABI 212 constexpr __iterator operator++(int) 213 requires forward_range<_Base> 214 { 215 auto __tmp = *this; 216 ++*this; 217 return __tmp; 218 } 219 220 _LIBCPP_HIDE_FROM_ABI 221 constexpr __iterator& operator--() 222 requires bidirectional_range<_Base> 223 { 224 --__current_; 225 return *this; 226 } 227 228 _LIBCPP_HIDE_FROM_ABI 229 constexpr __iterator operator--(int) 230 requires bidirectional_range<_Base> 231 { 232 auto __tmp = *this; 233 --*this; 234 return __tmp; 235 } 236 237 _LIBCPP_HIDE_FROM_ABI 238 constexpr __iterator& operator+=(difference_type __n) 239 requires random_access_range<_Base> 240 { 241 __current_ += __n; 242 return *this; 243 } 244 245 _LIBCPP_HIDE_FROM_ABI 246 constexpr __iterator& operator-=(difference_type __n) 247 requires random_access_range<_Base> 248 { 249 __current_ -= __n; 250 return *this; 251 } 252 253 _LIBCPP_HIDE_FROM_ABI 254 constexpr decltype(auto) operator[](difference_type __n) const 255 noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, __current_[__n]))) 256 requires random_access_range<_Base> 257 { 258 return _VSTD::invoke(*__parent_->__func_, __current_[__n]); 259 } 260 261 _LIBCPP_HIDE_FROM_ABI 262 friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) 263 requires equality_comparable<iterator_t<_Base>> 264 { 265 return __x.__current_ == __y.__current_; 266 } 267 268 _LIBCPP_HIDE_FROM_ABI 269 friend constexpr bool operator<(const __iterator& __x, const __iterator& __y) 270 requires random_access_range<_Base> 271 { 272 return __x.__current_ < __y.__current_; 273 } 274 275 _LIBCPP_HIDE_FROM_ABI 276 friend constexpr bool operator>(const __iterator& __x, const __iterator& __y) 277 requires random_access_range<_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 // TODO: Fix this as soon as soon as three_way_comparable is implemented. 297 // _LIBCPP_HIDE_FROM_ABI 298 // 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 305 friend constexpr __iterator operator+(__iterator __i, difference_type __n) 306 requires random_access_range<_Base> 307 { 308 return __iterator{*__i.__parent_, __i.__current_ + __n}; 309 } 310 311 _LIBCPP_HIDE_FROM_ABI 312 friend constexpr __iterator operator+(difference_type __n, __iterator __i) 313 requires random_access_range<_Base> 314 { 315 return __iterator{*__i.__parent_, __i.__current_ + __n}; 316 } 317 318 _LIBCPP_HIDE_FROM_ABI 319 friend constexpr __iterator operator-(__iterator __i, difference_type __n) 320 requires random_access_range<_Base> 321 { 322 return __iterator{*__i.__parent_, __i.__current_ - __n}; 323 } 324 325 _LIBCPP_HIDE_FROM_ABI 326 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) 327 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> 328 { 329 return __x.__current_ - __y.__current_; 330 } 331 332 _LIBCPP_HIDE_FROM_ABI 333 friend constexpr decltype(auto) iter_move(const __iterator& __i) 334 noexcept(noexcept(*__i)) 335 { 336 if constexpr (is_lvalue_reference_v<decltype(*__i)>) 337 return _VSTD::move(*__i); 338 else 339 return *__i; 340 } 341 }; 342 343 template<input_range _View, copy_constructible _Fn> 344 requires __transform_view_constraints<_View, _Fn> 345 template<bool _Const> 346 class transform_view<_View, _Fn>::__sentinel { 347 using _Parent = __maybe_const<_Const, transform_view>; 348 using _Base = __maybe_const<_Const, _View>; 349 350 sentinel_t<_Base> __end_ = sentinel_t<_Base>(); 351 352 template<bool> 353 friend class transform_view<_View, _Fn>::__iterator; 354 355 template<bool> 356 friend class transform_view<_View, _Fn>::__sentinel; 357 358 public: 359 _LIBCPP_HIDE_FROM_ABI 360 __sentinel() = default; 361 362 _LIBCPP_HIDE_FROM_ABI 363 constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {} 364 365 // Note: `__i` should always be `__sentinel<false>`, but directly using 366 // `__sentinel<false>` is ill-formed when `_Const` is false 367 // (see http://wg21.link/class.copy.ctor#5). 368 _LIBCPP_HIDE_FROM_ABI 369 constexpr __sentinel(__sentinel<!_Const> __i) 370 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> 371 : __end_(_VSTD::move(__i.__end_)) {} 372 373 _LIBCPP_HIDE_FROM_ABI 374 constexpr sentinel_t<_Base> base() const { return __end_; } 375 376 template<bool _OtherConst> 377 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 378 _LIBCPP_HIDE_FROM_ABI 379 friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 380 return __x.__current_ == __y.__end_; 381 } 382 383 template<bool _OtherConst> 384 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 385 _LIBCPP_HIDE_FROM_ABI 386 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 387 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) { 388 return __x.__current_ - __y.__end_; 389 } 390 391 template<bool _OtherConst> 392 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> 393 _LIBCPP_HIDE_FROM_ABI 394 friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> 395 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) { 396 return __x.__end_ - __y.__current_; 397 } 398 }; 399 400 } // namespace ranges 401 402 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 403 404 _LIBCPP_END_NAMESPACE_STD 405 406 _LIBCPP_POP_MACROS 407 408 #endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H 409