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_SIZE_H
11#define _LIBCPP___RANGES_SIZE_H
12
13#include <__concepts/arithmetic.h>
14#include <__concepts/class_or_enum.h>
15#include <__config>
16#include <__cstddef/ptrdiff_t.h>
17#include <__cstddef/size_t.h>
18#include <__iterator/concepts.h>
19#include <__iterator/iterator_traits.h>
20#include <__ranges/access.h>
21#include <__type_traits/decay.h>
22#include <__type_traits/make_signed.h>
23#include <__type_traits/make_unsigned.h>
24#include <__type_traits/remove_cvref.h>
25#include <__utility/auto_cast.h>
26#include <__utility/declval.h>
27
28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
29# pragma GCC system_header
30#endif
31
32_LIBCPP_BEGIN_NAMESPACE_STD
33
34#if _LIBCPP_STD_VER >= 20
35
36namespace ranges {
37template <class>
38inline constexpr bool disable_sized_range = false;
39} // namespace ranges
40
41// [range.prim.size]
42
43namespace ranges {
44namespace __size {
45void size() = delete;
46
47template <class _Tp>
48concept __size_enabled = !disable_sized_range<remove_cvref_t<_Tp>>;
49
50template <class _Tp>
51concept __member_size = __size_enabled<_Tp> && requires(_Tp&& __t) {
52 { _LIBCPP_AUTO_CAST(__t.size()) } -> __integer_like;
53};
54
55template <class _Tp>
56concept __unqualified_size =
57 __size_enabled<_Tp> && !__member_size<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {
58 { _LIBCPP_AUTO_CAST(size(__t)) } -> __integer_like;
59 };
60
61template <class _Tp>
62concept __difference =
63 !__member_size<_Tp> && !__unqualified_size<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {
64 { ranges::begin(__t) } -> forward_iterator;
65 { ranges::end(__t) } -> sized_sentinel_for<decltype(ranges::begin(std::declval<_Tp>()))>;
66 };
67
68struct __fn {
69 // `[range.prim.size]`: the array case (for rvalues).
70 template <class _Tp, size_t _Sz>
71 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr size_t operator()(_Tp (&&)[_Sz]) const noexcept {
72 return _Sz;
73 }
74
75 // `[range.prim.size]`: the array case (for lvalues).
76 template <class _Tp, size_t _Sz>
77 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr size_t operator()(_Tp (&)[_Sz]) const noexcept {
78 return _Sz;
79 }
80
81 // `[range.prim.size]`: `auto(t.size())` is a valid expression.
82 template <__member_size _Tp>
83 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
84 noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.size()))) {
85 return _LIBCPP_AUTO_CAST(__t.size());
86 }
87
88 // `[range.prim.size]`: `auto(size(t))` is a valid expression.
89 template <__unqualified_size _Tp>
90 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
91 noexcept(noexcept(_LIBCPP_AUTO_CAST(size(__t)))) {
92 return _LIBCPP_AUTO_CAST(size(__t));
93 }
94
95 // [range.prim.size]: the `to-unsigned-like` case.
96 template <__difference _Tp>
97 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
98 noexcept(noexcept(std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t))))
99 -> decltype(std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t))) {
100 return std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t));
101 }
102};
103
104} // namespace __size
105
106inline namespace __cpo {
107inline constexpr auto size = __size::__fn{};
108} // namespace __cpo
109} // namespace ranges
110
111// [range.prim.ssize]
112
113namespace ranges {
114namespace __ssize {
115struct __fn {
116 template <class _Tp>
117 requires requires(_Tp&& __t) { ranges::size(__t); }
118 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr integral auto operator()(_Tp&& __t) const
119 noexcept(noexcept(ranges::size(__t))) {
120 using _Signed = make_signed_t<decltype(ranges::size(__t))>;
121 if constexpr (sizeof(ptrdiff_t) > sizeof(_Signed))
122 return static_cast<ptrdiff_t>(ranges::size(__t));
123 else
124 return static_cast<_Signed>(ranges::size(__t));
125 }
126};
127} // namespace __ssize
128
129inline namespace __cpo {
130inline constexpr auto ssize = __ssize::__fn{};
131} // namespace __cpo
132} // namespace ranges
133
134#endif // _LIBCPP_STD_VER >= 20
135
136_LIBCPP_END_NAMESPACE_STD
137
138#endif // _LIBCPP___RANGES_SIZE_H
139