blob: 64996f4a6f7b0c116ec0a386a11ae33d4ad3c63e (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___RANGES_EMPTY_H
#define _LIBCPP___RANGES_EMPTY_H
#include <__concepts/class_or_enum.h>
#include <__config>
#include <__iterator/concepts.h>
#include <__ranges/access.h>
#include <__ranges/size.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
// [range.prim.empty]
namespace ranges {
namespace __empty {
template <class _Tp>
concept __member_empty =
__workaround_52970<_Tp> &&
requires(_Tp&& __t) {
bool(__t.empty());
};
template<class _Tp>
concept __can_invoke_size =
!__member_empty<_Tp> &&
requires(_Tp&& __t) { ranges::size(__t); };
template <class _Tp>
concept __can_compare_begin_end =
!__member_empty<_Tp> &&
!__can_invoke_size<_Tp> &&
requires(_Tp&& __t) {
bool(ranges::begin(__t) == ranges::end(__t));
{ ranges::begin(__t) } -> forward_iterator;
};
struct __fn {
template <__member_empty _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const
noexcept(noexcept(bool(__t.empty()))) {
return bool(__t.empty());
}
template <__can_invoke_size _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const
noexcept(noexcept(ranges::size(__t))) {
return ranges::size(__t) == 0;
}
template<__can_compare_begin_end _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const
noexcept(noexcept(bool(ranges::begin(__t) == ranges::end(__t)))) {
return ranges::begin(__t) == ranges::end(__t);
}
};
} // namespace __empty
inline namespace __cpo {
inline constexpr auto empty = __empty::__fn{};
} // namespace __cpo
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_EMPTY_H
|
