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