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___RANGES_SUBRANGE_H
11#define _LIBCPP___RANGES_SUBRANGE_H
12
13#include <__assert>
14#include <__concepts/constructible.h>
15#include <__concepts/convertible_to.h>
16#include <__concepts/copyable.h>
17#include <__concepts/derived_from.h>
18#include <__concepts/different_from.h>
19#include <__config>
20#include <__fwd/get.h>
21#include <__fwd/subrange.h>
22#include <__iterator/advance.h>
23#include <__iterator/concepts.h>
24#include <__iterator/incrementable_traits.h>
25#include <__iterator/iterator_traits.h>
26#include <__ranges/access.h>
27#include <__ranges/concepts.h>
28#include <__ranges/dangling.h>
29#include <__ranges/enable_borrowed_range.h>
30#include <__ranges/size.h>
31#include <__ranges/view_interface.h>
32#include <__tuple/pair_like.h>
33#include <__tuple/tuple_element.h>
34#include <__tuple/tuple_size.h>
35#include <__type_traits/conditional.h>
36#include <__type_traits/decay.h>
37#include <__type_traits/is_pointer.h>
38#include <__type_traits/is_reference.h>
39#include <__type_traits/make_unsigned.h>
40#include <__type_traits/remove_const.h>
41#include <__type_traits/remove_pointer.h>
42#include <__utility/move.h>
43#include <cstddef>
44
45#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
46#  pragma GCC system_header
47#endif
48
49_LIBCPP_PUSH_MACROS
50#include <__undef_macros>
51
52_LIBCPP_BEGIN_NAMESPACE_STD
53
54#if _LIBCPP_STD_VER >= 20
55
56namespace ranges {
57template <class _From, class _To>
58concept __uses_nonqualification_pointer_conversion =
59    is_pointer_v<_From> && is_pointer_v<_To> &&
60    !convertible_to<remove_pointer_t<_From> (*)[], remove_pointer_t<_To> (*)[]>;
61
62template <class _From, class _To>
63concept __convertible_to_non_slicing =
64    convertible_to<_From, _To> && !__uses_nonqualification_pointer_conversion<decay_t<_From>, decay_t<_To>>;
65
66template <class _Pair, class _Iter, class _Sent>
67concept __pair_like_convertible_from =
68    !range<_Pair> && __pair_like<_Pair> && constructible_from<_Pair, _Iter, _Sent> &&
69    __convertible_to_non_slicing<_Iter, tuple_element_t<0, _Pair>> && convertible_to<_Sent, tuple_element_t<1, _Pair>>;
70
71template <input_or_output_iterator _Iter,
72          sentinel_for<_Iter> _Sent = _Iter,
73          subrange_kind _Kind       = sized_sentinel_for<_Sent, _Iter> ? subrange_kind::sized : subrange_kind::unsized>
74  requires(_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _Iter>)
75class _LIBCPP_TEMPLATE_VIS subrange : public view_interface<subrange<_Iter, _Sent, _Kind>> {
76public:
77  // Note: this is an internal implementation detail that is public only for internal usage.
78  static constexpr bool _StoreSize = (_Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _Iter>);
79
80private:
81  static constexpr bool _MustProvideSizeAtConstruction = !_StoreSize; // just to improve compiler diagnostics
82  struct _Empty {
83    _LIBCPP_HIDE_FROM_ABI constexpr _Empty(auto) noexcept {}
84  };
85  using _Size = conditional_t<_StoreSize, make_unsigned_t<iter_difference_t<_Iter>>, _Empty>;
86  _LIBCPP_NO_UNIQUE_ADDRESS _Iter __begin_ = _Iter();
87  _LIBCPP_NO_UNIQUE_ADDRESS _Sent __end_   = _Sent();
88  _LIBCPP_NO_UNIQUE_ADDRESS _Size __size_  = 0;
89
90public:
91  _LIBCPP_HIDE_FROM_ABI subrange()
92    requires default_initializable<_Iter>
93  = default;
94
95  _LIBCPP_HIDE_FROM_ABI constexpr subrange(__convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent)
96    requires _MustProvideSizeAtConstruction
97      : __begin_(std::move(__iter)), __end_(std::move(__sent)) {}
98
99  _LIBCPP_HIDE_FROM_ABI constexpr subrange(
100      __convertible_to_non_slicing<_Iter> auto __iter, _Sent __sent, make_unsigned_t<iter_difference_t<_Iter>> __n)
101    requires(_Kind == subrange_kind::sized)
102      : __begin_(std::move(__iter)), __end_(std::move(__sent)), __size_(__n) {
103    if constexpr (sized_sentinel_for<_Sent, _Iter>)
104      _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS((__end_ - __begin_) == static_cast<iter_difference_t<_Iter>>(__n),
105                                          "std::ranges::subrange was passed an invalid size hint");
106  }
107
108  template <__different_from<subrange> _Range>
109    requires borrowed_range<_Range> && __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
110             convertible_to<sentinel_t<_Range>, _Sent>
111             _LIBCPP_HIDE_FROM_ABI constexpr subrange(_Range&& __range)
112               requires(!_StoreSize)
113      : subrange(ranges::begin(__range), ranges::end(__range)) {}
114
115  template <__different_from<subrange> _Range>
116    requires borrowed_range<_Range> && __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
117             convertible_to<sentinel_t<_Range>, _Sent>
118             _LIBCPP_HIDE_FROM_ABI constexpr subrange(_Range&& __range)
119               requires _StoreSize && sized_range<_Range>
120      : subrange(__range, ranges::size(__range)) {}
121
122  template <borrowed_range _Range>
123    requires __convertible_to_non_slicing<iterator_t<_Range>, _Iter> &&
124             convertible_to<sentinel_t<_Range>, _Sent>
125             _LIBCPP_HIDE_FROM_ABI constexpr subrange(_Range&& __range, make_unsigned_t<iter_difference_t<_Iter>> __n)
126               requires(_Kind == subrange_kind::sized)
127      : subrange(ranges::begin(__range), ranges::end(__range), __n) {}
128
129  template <__different_from<subrange> _Pair>
130    requires __pair_like_convertible_from<_Pair, const _Iter&, const _Sent&>
131  _LIBCPP_HIDE_FROM_ABI constexpr operator _Pair() const {
132    return _Pair(__begin_, __end_);
133  }
134
135  _LIBCPP_HIDE_FROM_ABI constexpr _Iter begin() const
136    requires copyable<_Iter>
137  {
138    return __begin_;
139  }
140
141  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Iter begin()
142    requires(!copyable<_Iter>)
143  {
144    return std::move(__begin_);
145  }
146
147  _LIBCPP_HIDE_FROM_ABI constexpr _Sent end() const { return __end_; }
148
149  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const { return __begin_ == __end_; }
150
151  _LIBCPP_HIDE_FROM_ABI constexpr make_unsigned_t<iter_difference_t<_Iter>> size() const
152    requires(_Kind == subrange_kind::sized)
153  {
154    if constexpr (_StoreSize)
155      return __size_;
156    else
157      return std::__to_unsigned_like(__end_ - __begin_);
158  }
159
160  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange next(iter_difference_t<_Iter> __n = 1) const&
161    requires forward_iterator<_Iter>
162  {
163    auto __tmp = *this;
164    __tmp.advance(__n);
165    return __tmp;
166  }
167
168  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange next(iter_difference_t<_Iter> __n = 1) && {
169    advance(__n);
170    return std::move(*this);
171  }
172
173  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange prev(iter_difference_t<_Iter> __n = 1) const
174    requires bidirectional_iterator<_Iter>
175  {
176    auto __tmp = *this;
177    __tmp.advance(-__n);
178    return __tmp;
179  }
180
181  _LIBCPP_HIDE_FROM_ABI constexpr subrange& advance(iter_difference_t<_Iter> __n) {
182    if constexpr (bidirectional_iterator<_Iter>) {
183      if (__n < 0) {
184        ranges::advance(__begin_, __n);
185        if constexpr (_StoreSize)
186          __size_ += std::__to_unsigned_like(-__n);
187        return *this;
188      }
189    }
190
191    auto __d = __n - ranges::advance(__begin_, __n, __end_);
192    if constexpr (_StoreSize)
193      __size_ -= std::__to_unsigned_like(__d);
194    return *this;
195  }
196};
197
198template <input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent>
199subrange(_Iter, _Sent) -> subrange<_Iter, _Sent>;
200
201template <input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent>
202subrange(_Iter, _Sent, make_unsigned_t<iter_difference_t<_Iter>>) -> subrange<_Iter, _Sent, subrange_kind::sized>;
203
204template <borrowed_range _Range>
205subrange(_Range&&)
206    -> subrange<iterator_t<_Range>,
207                sentinel_t<_Range>,
208                (sized_range<_Range> || sized_sentinel_for<sentinel_t<_Range>, iterator_t<_Range>>)
209                    ? subrange_kind::sized
210                    : subrange_kind::unsized>;
211
212template <borrowed_range _Range>
213subrange(_Range&&, make_unsigned_t<range_difference_t<_Range>>)
214    -> subrange<iterator_t<_Range>, sentinel_t<_Range>, subrange_kind::sized>;
215
216template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
217  requires((_Index == 0 && copyable<_Iter>) || _Index == 1)
218_LIBCPP_HIDE_FROM_ABI constexpr auto get(const subrange<_Iter, _Sent, _Kind>& __subrange) {
219  if constexpr (_Index == 0)
220    return __subrange.begin();
221  else
222    return __subrange.end();
223}
224
225template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
226  requires(_Index < 2)
227_LIBCPP_HIDE_FROM_ABI constexpr auto get(subrange<_Iter, _Sent, _Kind>&& __subrange) {
228  if constexpr (_Index == 0)
229    return __subrange.begin();
230  else
231    return __subrange.end();
232}
233
234template <class _Ip, class _Sp, subrange_kind _Kp>
235inline constexpr bool enable_borrowed_range<subrange<_Ip, _Sp, _Kp>> = true;
236
237template <range _Rp>
238using borrowed_subrange_t = _If<borrowed_range<_Rp>, subrange<iterator_t<_Rp>>, dangling>;
239} // namespace ranges
240
241// [range.subrange.general]
242
243using ranges::get;
244
245// [ranges.syn]
246
247template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
248struct tuple_size<ranges::subrange<_Ip, _Sp, _Kp>> : integral_constant<size_t, 2> {};
249
250template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
251struct tuple_element<0, ranges::subrange<_Ip, _Sp, _Kp>> {
252  using type = _Ip;
253};
254
255template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
256struct tuple_element<1, ranges::subrange<_Ip, _Sp, _Kp>> {
257  using type = _Sp;
258};
259
260template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
261struct tuple_element<0, const ranges::subrange<_Ip, _Sp, _Kp>> {
262  using type = _Ip;
263};
264
265template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
266struct tuple_element<1, const ranges::subrange<_Ip, _Sp, _Kp>> {
267  using type = _Sp;
268};
269
270#endif // _LIBCPP_STD_VER >= 20
271
272_LIBCPP_END_NAMESPACE_STD
273
274_LIBCPP_POP_MACROS
275
276#endif // _LIBCPP___RANGES_SUBRANGE_H
277