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 #ifndef _LIBCPP___RANGES_SIZE_H
10 #define _LIBCPP___RANGES_SIZE_H
11 
12 #include <__concepts/class_or_enum.h>
13 #include <__config>
14 #include <__iterator/concepts.h>
15 #include <__iterator/iterator_traits.h>
16 #include <__ranges/access.h>
17 #include <__utility/auto_cast.h>
18 #include <concepts>
19 #include <type_traits>
20 
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 #  pragma GCC system_header
23 #endif
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 #if _LIBCPP_STD_VER > 17
28 
29 namespace ranges {
30   template<class>
31   inline constexpr bool disable_sized_range = false;
32 } // namespace ranges
33 
34 // [range.prim.size]
35 
36 namespace ranges {
37 namespace __size {
38 void size(auto&) = delete;
39 void size(const auto&) = delete;
40 
41 template <class _Tp>
42 concept __size_enabled = !disable_sized_range<remove_cvref_t<_Tp>>;
43 
44 template <class _Tp>
45 concept __member_size =
46   __size_enabled<_Tp> &&
47   __workaround_52970<_Tp> &&
48   requires(_Tp&& __t) {
49     { _LIBCPP_AUTO_CAST(__t.size()) } -> __integer_like;
50   };
51 
52 template <class _Tp>
53 concept __unqualified_size =
54   __size_enabled<_Tp> &&
55   !__member_size<_Tp> &&
56   __class_or_enum<remove_cvref_t<_Tp>> &&
57   requires(_Tp&& __t) {
58     { _LIBCPP_AUTO_CAST(size(__t)) } -> __integer_like;
59   };
60 
61 template <class _Tp>
62 concept __difference =
63   !__member_size<_Tp> &&
64   !__unqualified_size<_Tp> &&
65   __class_or_enum<remove_cvref_t<_Tp>> &&
66   requires(_Tp&& __t) {
67     { ranges::begin(__t) } -> forward_iterator;
68     { ranges::end(__t) } -> sized_sentinel_for<decltype(ranges::begin(declval<_Tp>()))>;
69   };
70 
71 struct __fn {
72 
73   // `[range.prim.size]`: the array case (for rvalues).
74   template <class _Tp, size_t _Sz>
75   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr size_t operator()(_Tp (&&)[_Sz]) const noexcept {
76     return _Sz;
77   }
78 
79   // `[range.prim.size]`: the array case (for lvalues).
80   template <class _Tp, size_t _Sz>
81   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr size_t operator()(_Tp (&)[_Sz]) const noexcept {
82     return _Sz;
83   }
84 
85   // `[range.prim.size]`: `auto(t.size())` is a valid expression.
86   template <__member_size _Tp>
87   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
88       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.size()))) {
89     return _LIBCPP_AUTO_CAST(__t.size());
90   }
91 
92   // `[range.prim.size]`: `auto(size(t))` is a valid expression.
93   template <__unqualified_size _Tp>
94   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
95       noexcept(noexcept(_LIBCPP_AUTO_CAST(size(__t)))) {
96     return _LIBCPP_AUTO_CAST(size(__t));
97   }
98 
99   // [range.prim.size]: the `to-unsigned-like` case.
100   template <__difference _Tp>
101   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
102     noexcept(noexcept(std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t))))
103     -> decltype(      std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t)))
104     { return          std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t));
105   }
106 };
107 
108 } // namespace __size
109 
110 inline namespace __cpo {
111   inline constexpr auto size = __size::__fn{};
112 } // namespace __cpo
113 } // namespace ranges
114 
115 // [range.prim.ssize]
116 
117 namespace ranges {
118 namespace __ssize {
119 struct __fn {
120   template<class _Tp>
121     requires requires (_Tp&& __t) { ranges::size(__t); }
122   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr integral auto operator()(_Tp&& __t) const
123     noexcept(noexcept(ranges::size(__t))) {
124     using _Signed = make_signed_t<decltype(ranges::size(__t))>;
125     if constexpr (sizeof(ptrdiff_t) > sizeof(_Signed))
126       return static_cast<ptrdiff_t>(ranges::size(__t));
127     else
128       return static_cast<_Signed>(ranges::size(__t));
129   }
130 };
131 } // namespace __ssize
132 
133 inline namespace __cpo {
134   inline constexpr auto ssize = __ssize::__fn{};
135 } // namespace __cpo
136 } // namespace ranges
137 
138 #endif // _LIBCPP_STD_VER > 17
139 
140 _LIBCPP_END_NAMESPACE_STD
141 
142 #endif // _LIBCPP___RANGES_SIZE_H
143