libcxx/include/__cxx03/__ranges/transform_view.h

   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___CXX03___RANGES_TRANSFORM_VIEW_H
  11 #define _LIBCPP___CXX03___RANGES_TRANSFORM_VIEW_H
  12
  13 #include <__cxx03/__compare/three_way_comparable.h>
  14 #include <__cxx03/__concepts/constructible.h>
  15 #include <__cxx03/__concepts/convertible_to.h>
  16 #include <__cxx03/__concepts/copyable.h>
  17 #include <__cxx03/__concepts/derived_from.h>
  18 #include <__cxx03/__concepts/equality_comparable.h>
  19 #include <__cxx03/__concepts/invocable.h>
  20 #include <__cxx03/__config>
  21 #include <__cxx03/__functional/bind_back.h>
  22 #include <__cxx03/__functional/invoke.h>
  23 #include <__cxx03/__functional/perfect_forward.h>
  24 #include <__cxx03/__iterator/concepts.h>
  25 #include <__cxx03/__iterator/iterator_traits.h>
  26 #include <__cxx03/__memory/addressof.h>
  27 #include <__cxx03/__ranges/access.h>
  28 #include <__cxx03/__ranges/all.h>
  29 #include <__cxx03/__ranges/concepts.h>
  30 #include <__cxx03/__ranges/empty.h>
  31 #include <__cxx03/__ranges/movable_box.h>
  32 #include <__cxx03/__ranges/range_adaptor.h>
  33 #include <__cxx03/__ranges/size.h>
  34 #include <__cxx03/__ranges/view_interface.h>
  35 #include <__cxx03/__type_traits/conditional.h>
  36 #include <__cxx03/__type_traits/decay.h>
  37 #include <__cxx03/__type_traits/is_nothrow_constructible.h>
  38 #include <__cxx03/__type_traits/is_object.h>
  39 #include <__cxx03/__type_traits/is_reference.h>
  40 #include <__cxx03/__type_traits/maybe_const.h>
  41 #include <__cxx03/__type_traits/remove_cvref.h>
  42 #include <__cxx03/__utility/forward.h>
  43 #include <__cxx03/__utility/in_place.h>
  44 #include <__cxx03/__utility/move.h>
  45
  46 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  47 #  pragma GCC system_header
  48 #endif
  49
  50 _LIBCPP_PUSH_MACROS
  51 #include <__cxx03/__undef_macros>
  52
  53 _LIBCPP_BEGIN_NAMESPACE_STD
  54
  55 #if _LIBCPP_STD_VER >= 20
  56
  57 namespace ranges {
  58
  59 template <class _Fn, class _View>
  60 concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_reference_t<_View>>;
  61
  62 template <class _View, class _Fn>
  63 concept __transform_view_constraints =
  64     view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> &&
  65     __can_reference<invoke_result_t<_Fn&, range_reference_t<_View>>>;
  66
  67 #  if _LIBCPP_STD_VER >= 23
  68 template <input_range _View, move_constructible _Fn>
  69 #  else
  70 template <input_range _View, copy_constructible _Fn>
  71 #  endif
  72   requires __transform_view_constraints<_View, _Fn>
  73 class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS transform_view : public view_interface<transform_view<_View, _Fn>> {
  74   template <bool>
  75   class __iterator;
  76   template <bool>
  77   class __sentinel;
  78
  79   _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Fn> __func_;
  80   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
  81
  82 public:
  83   _LIBCPP_HIDE_FROM_ABI transform_view()
  84     requires default_initializable<_View> && default_initializable<_Fn>
  85   = default;
  86
  87   _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 transform_view(_View __base, _Fn __func)
  88       : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {}
  89
  90   _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
  91     requires copy_constructible<_View>
  92   {
  93     return __base_;
  94   }
  95   _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
  96
  97   _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> begin() { return __iterator<false>{*this, ranges::begin(__base_)}; }
  98   _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> begin() const
  99     requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
 100   {
 101     return __iterator<true>(*this, ranges::begin(__base_));
 102   }
 103
 104   _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<false> end() { return __sentinel<false>(ranges::end(__base_)); }
 105   _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> end()
 106     requires common_range<_View>
 107   {
 108     return __iterator<false>(*this, ranges::end(__base_));
 109   }
 110   _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<true> end() const
 111     requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
 112   {
 113     return __sentinel<true>(ranges::end(__base_));
 114   }
 115   _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> end() const
 116     requires common_range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
 117   {
 118     return __iterator<true>(*this, ranges::end(__base_));
 119   }
 120
 121   _LIBCPP_HIDE_FROM_ABI constexpr auto size()
 122     requires sized_range<_View>
 123   {
 124     return ranges::size(__base_);
 125   }
 126   _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
 127     requires sized_range<const _View>
 128   {
 129     return ranges::size(__base_);
 130   }
 131 };
 132
 133 template <class _Range, class _Fn>
 134 transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>;
 135
 136 template <class _View>
 137 struct __transform_view_iterator_concept {
 138   using type = input_iterator_tag;
 139 };
 140
 141 template <random_access_range _View>
 142 struct __transform_view_iterator_concept<_View> {
 143   using type = random_access_iterator_tag;
 144 };
 145
 146 template <bidirectional_range _View>
 147 struct __transform_view_iterator_concept<_View> {
 148   using type = bidirectional_iterator_tag;
 149 };
 150
 151 template <forward_range _View>
 152 struct __transform_view_iterator_concept<_View> {
 153   using type = forward_iterator_tag;
 154 };
 155
 156 template <class, class>
 157 struct __transform_view_iterator_category_base {};
 158
 159 template <forward_range _View, class _Fn>
 160 struct __transform_view_iterator_category_base<_View, _Fn> {
 161   using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category;
 162
 163   using iterator_category =
 164       conditional_t< is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>,
 165                      conditional_t< derived_from<_Cat, contiguous_iterator_tag>, random_access_iterator_tag, _Cat >,
 166                      input_iterator_tag >;
 167 };
 168
 169 #  if _LIBCPP_STD_VER >= 23
 170 template <input_range _View, move_constructible _Fn>
 171 #  else
 172 template <input_range _View, copy_constructible _Fn>
 173 #  endif
 174   requires __transform_view_constraints<_View, _Fn>
 175 template <bool _Const>
 176 class transform_view<_View, _Fn>::__iterator : public __transform_view_iterator_category_base<_View, _Fn> {
 177
 178   using _Parent = __maybe_const<_Const, transform_view>;
 179   using _Base   = __maybe_const<_Const, _View>;
 180
 181   _Parent* __parent_ = nullptr;
 182
 183   template <bool>
 184   friend class transform_view<_View, _Fn>::__iterator;
 185
 186   template <bool>
 187   friend class transform_view<_View, _Fn>::__sentinel;
 188
 189 public:
 190   iterator_t<_Base> __current_ = iterator_t<_Base>();
 191
 192   using iterator_concept = typename __transform_view_iterator_concept<_View>::type;
 193   using value_type       = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>;
 194   using difference_type  = range_difference_t<_Base>;
 195
 196   _LIBCPP_HIDE_FROM_ABI __iterator()
 197     requires default_initializable<iterator_t<_Base>>
 198   = default;
 199
 200   _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current)
 201       : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {}
 202
 203   // Note: `__i` should always be `__iterator<false>`, but directly using
 204   // `__iterator<false>` is ill-formed when `_Const` is false
 205   // (see http://wg21.link/class.copy.ctor#5).
 206   _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
 207     requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
 208       : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {}
 209
 210   _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; }
 211
 212   _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); }
 213
 214   _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const
 215       noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) {
 216     return std::invoke(*__parent_->__func_, *__current_);
 217   }
 218
 219   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
 220     ++__current_;
 221     return *this;
 222   }
 223
 224   _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; }
 225
 226   _LIBCPP_HIDE_FROM_ABI 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 constexpr __iterator& operator--()
 235     requires bidirectional_range<_Base>
 236   {
 237     --__current_;
 238     return *this;
 239   }
 240
 241   _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
 242     requires bidirectional_range<_Base>
 243   {
 244     auto __tmp = *this;
 245     --*this;
 246     return __tmp;
 247   }
 248
 249   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n)
 250     requires random_access_range<_Base>
 251   {
 252     __current_ += __n;
 253     return *this;
 254   }
 255
 256   _LIBCPP_HIDE_FROM_ABI 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 constexpr decltype(auto) operator[](difference_type __n) const
 264       noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n])))
 265     requires random_access_range<_Base>
 266   {
 267     return std::invoke(*__parent_->__func_, __current_[__n]);
 268   }
 269
 270   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
 271     requires equality_comparable<iterator_t<_Base>>
 272   {
 273     return __x.__current_ == __y.__current_;
 274   }
 275
 276   _LIBCPP_HIDE_FROM_ABI 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 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 friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
 289     requires random_access_range<_Base>
 290   {
 291     return __x.__current_ <= __y.__current_;
 292   }
 293
 294   _LIBCPP_HIDE_FROM_ABI 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   _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
 301     requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
 302   {
 303     return __x.__current_ <=> __y.__current_;
 304   }
 305
 306   _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n)
 307     requires random_access_range<_Base>
 308   {
 309     return __iterator{*__i.__parent_, __i.__current_ + __n};
 310   }
 311
 312   _LIBCPP_HIDE_FROM_ABI 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 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 friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
 325     requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
 326   {
 327     return __x.__current_ - __y.__current_;
 328   }
 329 };
 330
 331 #  if _LIBCPP_STD_VER >= 23
 332 template <input_range _View, move_constructible _Fn>
 333 #  else
 334 template <input_range _View, copy_constructible _Fn>
 335 #  endif
 336   requires __transform_view_constraints<_View, _Fn>
 337 template <bool _Const>
 338 class transform_view<_View, _Fn>::__sentinel {
 339   using _Parent = __maybe_const<_Const, transform_view>;
 340   using _Base   = __maybe_const<_Const, _View>;
 341
 342   sentinel_t<_Base> __end_ = sentinel_t<_Base>();
 343
 344   template <bool>
 345   friend class transform_view<_View, _Fn>::__iterator;
 346
 347   template <bool>
 348   friend class transform_view<_View, _Fn>::__sentinel;
 349
 350 public:
 351   _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
 352
 353   _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {}
 354
 355   // Note: `__i` should always be `__sentinel<false>`, but directly using
 356   // `__sentinel<false>` is ill-formed when `_Const` is false
 357   // (see http://wg21.link/class.copy.ctor#5).
 358   _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i)
 359     requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
 360       : __end_(std::move(__i.__end_)) {}
 361
 362   _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
 363
 364   template <bool _OtherConst>
 365     requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
 366   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
 367     return __x.__current_ == __y.__end_;
 368   }
 369
 370   template <bool _OtherConst>
 371     requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
 372   _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
 373   operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
 374     return __x.__current_ - __y.__end_;
 375   }
 376
 377   template <bool _OtherConst>
 378     requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
 379   _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
 380   operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) {
 381     return __x.__end_ - __y.__current_;
 382   }
 383 };
 384
 385 namespace views {
 386 namespace __transform {
 387 struct __fn {
 388   template <class _Range, class _Fn>
 389   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Fn&& __f) const
 390       noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))))
 391           -> decltype(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) {
 392     return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f));
 393   }
 394
 395   template <class _Fn>
 396     requires constructible_from<decay_t<_Fn>, _Fn>
 397   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f) const
 398       noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) {
 399     return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Fn>(__f)));
 400   }
 401 };
 402 } // namespace __transform
 403
 404 inline namespace __cpo {
 405 inline constexpr auto transform = __transform::__fn{};
 406 } // namespace __cpo
 407 } // namespace views
 408
 409 } // namespace ranges
 410
 411 #endif // _LIBCPP_STD_VER >= 20
 412
 413 _LIBCPP_END_NAMESPACE_STD
 414
 415 _LIBCPP_POP_MACROS
 416
 417 #endif // _LIBCPP___CXX03___RANGES_TRANSFORM_VIEW_H