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
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// UNSUPPORTED: libcpp-has-no-incomplete-ranges
// constexpr bool empty() requires requires { ranges::empty(r_); }
// constexpr bool empty() const requires requires { ranges::empty(r_); }
#include <ranges>
#include <array>
#include <cassert>
#include <concepts>
#include "test_iterators.h"
#include "test_macros.h"
template <class T>
concept HasEmpty = requires (T t) {
t.empty();
};
constexpr bool test()
{
{
struct ComparableIters {
forward_iterator<int*> begin();
forward_iterator<int*> end();
};
using OwningView = std::ranges::owning_view<ComparableIters>;
static_assert(HasEmpty<OwningView&>);
static_assert(HasEmpty<OwningView&&>);
static_assert(!HasEmpty<const OwningView&>);
static_assert(!HasEmpty<const OwningView&&>);
}
{
struct NoEmpty {
cpp20_input_iterator<int*> begin();
sentinel_wrapper<cpp20_input_iterator<int*>> end();
};
static_assert(std::ranges::range<NoEmpty&>);
static_assert(!std::invocable<decltype(std::ranges::empty), NoEmpty&>);
static_assert(!std::ranges::range<const NoEmpty&>); // no begin/end
static_assert(!std::invocable<decltype(std::ranges::empty), const NoEmpty&>);
using OwningView = std::ranges::owning_view<NoEmpty>;
static_assert(!HasEmpty<OwningView&>);
static_assert(!HasEmpty<OwningView&&>);
static_assert(!HasEmpty<const OwningView&>);
static_assert(!HasEmpty<const OwningView&&>);
}
{
struct EmptyMember {
cpp20_input_iterator<int*> begin();
sentinel_wrapper<cpp20_input_iterator<int*>> end();
bool empty() const;
};
static_assert(std::ranges::range<EmptyMember&>);
static_assert(std::invocable<decltype(std::ranges::empty), EmptyMember&>);
static_assert(!std::ranges::range<const EmptyMember&>); // no begin/end
static_assert(std::invocable<decltype(std::ranges::empty), const EmptyMember&>);
using OwningView = std::ranges::owning_view<EmptyMember>;
static_assert(std::ranges::range<OwningView&>);
static_assert(!std::ranges::range<const OwningView&>); // no begin/end
static_assert(HasEmpty<OwningView&>);
static_assert(HasEmpty<OwningView&&>);
static_assert(HasEmpty<const OwningView&>); // but it still has empty()
static_assert(HasEmpty<const OwningView&&>);
}
{
// Test an empty view.
int a[] = {1};
auto ov = std::ranges::owning_view(std::ranges::subrange(a, a));
assert(ov.empty());
assert(std::as_const(ov).empty());
}
{
// Test a non-empty view.
int a[] = {1};
auto ov = std::ranges::owning_view(std::ranges::subrange(a, a+1));
assert(!ov.empty());
assert(!std::as_const(ov).empty());
}
{
// Test a non-view.
std::array<int, 2> a = {1, 2};
auto ov = std::ranges::owning_view(std::move(a));
assert(!ov.empty());
assert(!std::as_const(ov).empty());
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
|
