1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10
11 // constexpr counted_iterator operator-(iter_difference_t<I> n) const
12 // requires random_access_iterator<I>;
13
14 #include <iterator>
15
16 #include "test_macros.h"
17 #include "test_iterators.h"
18
19 template<class Iter>
20 concept MinusEnabled = requires(Iter& iter) {
21 iter - 1;
22 };
23
test()24 constexpr bool test() {
25 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
26
27 {
28 using Counted = std::counted_iterator<random_access_iterator<int*>>;
29 Counted iter(random_access_iterator<int*>{buffer + 2}, 6);
30 assert(iter - 2 == Counted(random_access_iterator<int*>{buffer}, 8));
31 assert(iter - 0 == Counted(random_access_iterator<int*>{buffer + 2}, 6));
32 assert(iter.count() == 6);
33
34 ASSERT_SAME_TYPE(decltype(iter - 2), Counted);
35 }
36 {
37 using Counted = std::counted_iterator<random_access_iterator<int*>>;
38 const Counted iter(random_access_iterator<int*>{buffer + 2}, 6);
39 assert(iter - 2 == Counted(random_access_iterator<int*>{buffer}, 8));
40 assert(iter - 0 == Counted(random_access_iterator<int*>{buffer + 2}, 6));
41 assert(iter.count() == 6);
42
43 ASSERT_SAME_TYPE(decltype(iter - 2), Counted);
44 }
45 {
46 using Counted = std::counted_iterator<contiguous_iterator<int*>>;
47 Counted iter(contiguous_iterator<int*>{buffer + 2}, 6);
48 assert(iter - 2 == Counted(contiguous_iterator<int*>{buffer}, 8));
49 assert(iter - 0 == Counted(contiguous_iterator<int*>{buffer + 2}, 6));
50 assert(iter.count() == 6);
51
52 ASSERT_SAME_TYPE(decltype(iter - 2), Counted);
53 }
54 {
55 using Counted = std::counted_iterator<contiguous_iterator<int*>>;
56 const Counted iter(contiguous_iterator<int*>{buffer + 2}, 6);
57 assert(iter - 2 == Counted(contiguous_iterator<int*>{buffer}, 8));
58 assert(iter - 0 == Counted(contiguous_iterator<int*>{buffer + 2}, 6));
59 assert(iter.count() == 6);
60
61 ASSERT_SAME_TYPE(decltype(iter - 2), Counted);
62 }
63
64 {
65 static_assert( MinusEnabled<std::counted_iterator<random_access_iterator<int*>>>);
66 static_assert(!MinusEnabled<std::counted_iterator<bidirectional_iterator<int*>>>);
67 }
68
69 return true;
70 }
71
main(int,char **)72 int main(int, char**) {
73 test();
74 static_assert(test());
75
76 return 0;
77 }
78