v1/__ranges/repeat_view.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___RANGES_REPEAT_VIEW_H
0011 #define _LIBCPP___RANGES_REPEAT_VIEW_H
0012
0013 #include <__assert>
0014 #include <__concepts/constructible.h>
0015 #include <__concepts/same_as.h>
0016 #include <__concepts/semiregular.h>
0017 #include <__config>
0018 #include <__cstddef/ptrdiff_t.h>
0019 #include <__iterator/concepts.h>
0020 #include <__iterator/iterator_traits.h>
0021 #include <__iterator/unreachable_sentinel.h>
0022 #include <__memory/addressof.h>
0023 #include <__ranges/iota_view.h>
0024 #include <__ranges/movable_box.h>
0025 #include <__ranges/view_interface.h>
0026 #include <__type_traits/decay.h>
0027 #include <__type_traits/is_object.h>
0028 #include <__type_traits/make_unsigned.h>
0029 #include <__type_traits/remove_cv.h>
0030 #include <__utility/forward.h>
0031 #include <__utility/in_place.h>
0032 #include <__utility/move.h>
0033 #include <__utility/piecewise_construct.h>
0034 #include <tuple>
0035
0036 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0037 #  pragma GCC system_header
0038 #endif
0039
0040 _LIBCPP_PUSH_MACROS
0041 #include <__undef_macros>
0042
0043 _LIBCPP_BEGIN_NAMESPACE_STD
0044
0045 #if _LIBCPP_STD_VER >= 23
0046
0047 namespace ranges {
0048
0049 template <class _Tp>
0050 concept __integer_like_with_usable_difference_type =
0051     __signed_integer_like<_Tp> || (__integer_like<_Tp> && weakly_incrementable<_Tp>);
0052
0053 template <class _Tp>
0054 struct __repeat_view_iterator_difference {
0055   using type = _IotaDiffT<_Tp>;
0056 };
0057
0058 template <__signed_integer_like _Tp>
0059 struct __repeat_view_iterator_difference<_Tp> {
0060   using type = _Tp;
0061 };
0062
0063 template <class _Tp>
0064 using __repeat_view_iterator_difference_t _LIBCPP_NODEBUG = typename __repeat_view_iterator_difference<_Tp>::type;
0065
0066 namespace views::__drop {
0067 struct __fn;
0068 } // namespace views::__drop
0069
0070 namespace views::__take {
0071 struct __fn;
0072 } // namespace views::__take
0073
0074 template <move_constructible _Tp, semiregular _Bound = unreachable_sentinel_t>
0075   requires(is_object_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> &&
0076            (__integer_like_with_usable_difference_type<_Bound> || same_as<_Bound, unreachable_sentinel_t>))
0077 class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS repeat_view : public view_interface<repeat_view<_Tp, _Bound>> {
0078   friend struct views::__take::__fn;
0079   friend struct views::__drop::__fn;
0080   class __iterator;
0081
0082 public:
0083   _LIBCPP_HIDE_FROM_ABI repeat_view()
0084     requires default_initializable<_Tp>
0085   = default;
0086
0087   _LIBCPP_HIDE_FROM_ABI constexpr explicit repeat_view(const _Tp& __value, _Bound __bound_sentinel = _Bound())
0088     requires copy_constructible<_Tp>
0089       : __value_(in_place, __value), __bound_(__bound_sentinel) {
0090     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0091       _LIBCPP_ASSERT_UNCATEGORIZED(__bound_ >= 0, "The value of bound must be greater than or equal to 0");
0092   }
0093
0094   _LIBCPP_HIDE_FROM_ABI constexpr explicit repeat_view(_Tp&& __value, _Bound __bound_sentinel = _Bound())
0095       : __value_(in_place, std::move(__value)), __bound_(__bound_sentinel) {
0096     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0097       _LIBCPP_ASSERT_UNCATEGORIZED(__bound_ >= 0, "The value of bound must be greater than or equal to 0");
0098   }
0099
0100   template <class... _TpArgs, class... _BoundArgs>
0101     requires(constructible_from<_Tp, _TpArgs...> && constructible_from<_Bound, _BoundArgs...>)
0102   _LIBCPP_HIDE_FROM_ABI constexpr explicit repeat_view(
0103       piecewise_construct_t, tuple<_TpArgs...> __value_args, tuple<_BoundArgs...> __bound_args = tuple<>{})
0104       : __value_(in_place, std::make_from_tuple<_Tp>(std::move(__value_args))),
0105         __bound_(std::make_from_tuple<_Bound>(std::move(__bound_args))) {
0106     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0107       _LIBCPP_ASSERT_UNCATEGORIZED(
0108           __bound_ >= 0, "The behavior is undefined if Bound is not unreachable_sentinel_t and bound is negative");
0109   }
0110
0111   _LIBCPP_HIDE_FROM_ABI constexpr __iterator begin() const { return __iterator(std::addressof(*__value_)); }
0112
0113   _LIBCPP_HIDE_FROM_ABI constexpr __iterator end() const
0114     requires(!same_as<_Bound, unreachable_sentinel_t>)
0115   {
0116     return __iterator(std::addressof(*__value_), __bound_);
0117   }
0118
0119   _LIBCPP_HIDE_FROM_ABI constexpr unreachable_sentinel_t end() const noexcept { return unreachable_sentinel; }
0120
0121   _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
0122     requires(!same_as<_Bound, unreachable_sentinel_t>)
0123   {
0124     return std::__to_unsigned_like(__bound_);
0125   }
0126
0127 private:
0128   _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Tp> __value_;
0129   _LIBCPP_NO_UNIQUE_ADDRESS _Bound __bound_ = _Bound();
0130 };
0131
0132 template <class _Tp, class _Bound = unreachable_sentinel_t>
0133 repeat_view(_Tp, _Bound = _Bound()) -> repeat_view<_Tp, _Bound>;
0134
0135 // [range.repeat.iterator]
0136 template <move_constructible _Tp, semiregular _Bound>
0137   requires(is_object_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> &&
0138            (__integer_like_with_usable_difference_type<_Bound> || same_as<_Bound, unreachable_sentinel_t>))
0139 class repeat_view<_Tp, _Bound>::__iterator {
0140   friend class repeat_view;
0141
0142   using _IndexT _LIBCPP_NODEBUG = conditional_t<same_as<_Bound, unreachable_sentinel_t>, ptrdiff_t, _Bound>;
0143
0144   _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(const _Tp* __value, _IndexT __bound_sentinel = _IndexT())
0145       : __value_(__value), __current_(__bound_sentinel) {}
0146
0147 public:
0148   using iterator_concept  = random_access_iterator_tag;
0149   using iterator_category = random_access_iterator_tag;
0150   using value_type        = _Tp;
0151   using difference_type   = __repeat_view_iterator_difference_t<_IndexT>;
0152
0153   _LIBCPP_HIDE_FROM_ABI __iterator() = default;
0154
0155   _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator*() const noexcept { return *__value_; }
0156
0157   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
0158     ++__current_;
0159     return *this;
0160   }
0161
0162   _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) {
0163     auto __tmp = *this;
0164     ++*this;
0165     return __tmp;
0166   }
0167
0168   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--() {
0169     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0170       _LIBCPP_ASSERT_UNCATEGORIZED(__current_ > 0, "The value of bound must be greater than or equal to 0");
0171     --__current_;
0172     return *this;
0173   }
0174
0175   _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int) {
0176     auto __tmp = *this;
0177     --*this;
0178     return __tmp;
0179   }
0180
0181   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n) {
0182     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0183       _LIBCPP_ASSERT_UNCATEGORIZED(__current_ + __n >= 0, "The value of bound must be greater than or equal to 0");
0184     __current_ += __n;
0185     return *this;
0186   }
0187
0188   _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n) {
0189     if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
0190       _LIBCPP_ASSERT_UNCATEGORIZED(__current_ - __n >= 0, "The value of bound must be greater than or equal to 0");
0191     __current_ -= __n;
0192     return *this;
0193   }
0194
0195   _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator[](difference_type __n) const noexcept { return *(*this + __n); }
0196
0197   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) {
0198     return __x.__current_ == __y.__current_;
0199   }
0200
0201   _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y) {
0202     return __x.__current_ <=> __y.__current_;
0203   }
0204
0205   _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n) {
0206     __i += __n;
0207     return __i;
0208   }
0209
0210   _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i) {
0211     __i += __n;
0212     return __i;
0213   }
0214
0215   _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(__iterator __i, difference_type __n) {
0216     __i -= __n;
0217     return __i;
0218   }
0219
0220   _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y) {
0221     return static_cast<difference_type>(__x.__current_) - static_cast<difference_type>(__y.__current_);
0222   }
0223
0224 private:
0225   const _Tp* __value_ = nullptr;
0226   _IndexT __current_  = _IndexT();
0227 };
0228
0229 // clang-format off
0230 namespace views {
0231 namespace __repeat {
0232 struct __fn {
0233   template <class _Tp>
0234   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Tp&& __value)
0235     noexcept(noexcept(ranges::repeat_view<decay_t<_Tp>>(std::forward<_Tp>(__value))))
0236     -> decltype(      ranges::repeat_view<decay_t<_Tp>>(std::forward<_Tp>(__value)))
0237     { return          ranges::repeat_view<decay_t<_Tp>>(std::forward<_Tp>(__value)); }
0238
0239   template <class _Tp, class _Bound>
0240   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Tp&& __value, _Bound&& __bound_sentinel)
0241     noexcept(noexcept(ranges::repeat_view(std::forward<_Tp>(__value), std::forward<_Bound>(__bound_sentinel))))
0242     -> decltype(      ranges::repeat_view(std::forward<_Tp>(__value), std::forward<_Bound>(__bound_sentinel)))
0243     { return          ranges::repeat_view(std::forward<_Tp>(__value), std::forward<_Bound>(__bound_sentinel)); }
0244 };
0245 } // namespace __repeat
0246 // clang-format on
0247
0248 inline namespace __cpo {
0249 inline constexpr auto repeat = __repeat::__fn{};
0250 } // namespace __cpo
0251 } // namespace views
0252
0253 template <class _Tp>
0254 inline constexpr bool __is_repeat_specialization = false;
0255
0256 template <class _Tp, class _Bound>
0257 inline constexpr bool __is_repeat_specialization<repeat_view<_Tp, _Bound>> = true;
0258
0259 } // namespace ranges
0260
0261 #endif // _LIBCPP_STD_VER >= 23
0262
0263 _LIBCPP_END_NAMESPACE_STD
0264
0265 _LIBCPP_POP_MACROS
0266
0267 #endif // _LIBCPP___RANGES_REPEAT_VIEW_H