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 <cstddef>
20 #include <type_traits>
21 
22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23 #  pragma GCC system_header
24 #endif
25 
26 _LIBCPP_BEGIN_NAMESPACE_STD
27 
28 #if _LIBCPP_STD_VER > 17
29 
30 namespace ranges {
31   template<class>
32   inline constexpr bool disable_sized_range = false;
33 } // namespace ranges
34 
35 // [range.prim.size]
36 
37 namespace ranges {
38 namespace __size {
39 void size(auto&) = delete;
40 void size(const auto&) = delete;
41 
42 template <class _Tp>
43 concept __size_enabled = !disable_sized_range<remove_cvref_t<_Tp>>;
44 
45 template <class _Tp>
46 concept __member_size =
47   __size_enabled<_Tp> &&
48   __workaround_52970<_Tp> &&
49   requires(_Tp&& __t) {
50     { _LIBCPP_AUTO_CAST(__t.size()) } -> __integer_like;
51   };
52 
53 template <class _Tp>
54 concept __unqualified_size =
55   __size_enabled<_Tp> &&
56   !__member_size<_Tp> &&
57   __class_or_enum<remove_cvref_t<_Tp>> &&
58   requires(_Tp&& __t) {
59     { _LIBCPP_AUTO_CAST(size(__t)) } -> __integer_like;
60   };
61 
62 template <class _Tp>
63 concept __difference =
64   !__member_size<_Tp> &&
65   !__unqualified_size<_Tp> &&
66   __class_or_enum<remove_cvref_t<_Tp>> &&
67   requires(_Tp&& __t) {
68     { ranges::begin(__t) } -> forward_iterator;
69     { ranges::end(__t) } -> sized_sentinel_for<decltype(ranges::begin(declval<_Tp>()))>;
70   };
71 
72 struct __fn {
73 
74   // `[range.prim.size]`: the array case (for rvalues).
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]`: the array case (for lvalues).
81   template <class _Tp, size_t _Sz>
82   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr size_t operator()(_Tp (&)[_Sz]) const noexcept {
83     return _Sz;
84   }
85 
86   // `[range.prim.size]`: `auto(t.size())` is a valid expression.
87   template <__member_size _Tp>
88   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
89       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.size()))) {
90     return _LIBCPP_AUTO_CAST(__t.size());
91   }
92 
93   // `[range.prim.size]`: `auto(size(t))` is a valid expression.
94   template <__unqualified_size _Tp>
95   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __integer_like auto operator()(_Tp&& __t) const
96       noexcept(noexcept(_LIBCPP_AUTO_CAST(size(__t)))) {
97     return _LIBCPP_AUTO_CAST(size(__t));
98   }
99 
100   // [range.prim.size]: the `to-unsigned-like` case.
101   template <__difference _Tp>
102   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
103     noexcept(noexcept(std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t))))
104     -> decltype(      std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t)))
105     { return          std::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t));
106   }
107 };
108 
109 } // namespace __size
110 
111 inline namespace __cpo {
112   inline constexpr auto size = __size::__fn{};
113 } // namespace __cpo
114 } // namespace ranges
115 
116 // [range.prim.ssize]
117 
118 namespace ranges {
119 namespace __ssize {
120 struct __fn {
121   template<class _Tp>
122     requires requires (_Tp&& __t) { ranges::size(__t); }
123   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr integral auto operator()(_Tp&& __t) const
124     noexcept(noexcept(ranges::size(__t))) {
125     using _Signed = make_signed_t<decltype(ranges::size(__t))>;
126     if constexpr (sizeof(ptrdiff_t) > sizeof(_Signed))
127       return static_cast<ptrdiff_t>(ranges::size(__t));
128     else
129       return static_cast<_Signed>(ranges::size(__t));
130   }
131 };
132 } // namespace __ssize
133 
134 inline namespace __cpo {
135   inline constexpr auto ssize = __ssize::__fn{};
136 } // namespace __cpo
137 } // namespace ranges
138 
139 #endif // _LIBCPP_STD_VER > 17
140 
141 _LIBCPP_END_NAMESPACE_STD
142 
143 #endif // _LIBCPP___RANGES_SIZE_H
144