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 decltype(auto) 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
19template<class Iter>
20concept SubscriptEnabled = requires(Iter& iter) {
21 iter[1];
22};
23
24constexpr bool test() {
25 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
26
27 {
28 std::counted_iterator iter(random_access_iterator<int*>{buffer}, 8);
29 for (int i = 1; i < 9; ++i)
30 assert(iter[i - 1] == i);
31 }
32 {
33 std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 8);
34 for (int i = 1; i < 9; ++i)
35 assert(iter[i - 1] == i);
36 }
37
38 {
39 const std::counted_iterator iter(random_access_iterator<int*>{buffer}, 8);
40 assert(iter[0] == 1);
41 }
42 {
43 const std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 8);
44 assert(iter[7] == 8);
45 }
46
47 {
48 static_assert( SubscriptEnabled<std::counted_iterator<random_access_iterator<int*>>>);
49 static_assert(!SubscriptEnabled<std::counted_iterator<bidirectional_iterator<int*>>>);
50 }
51
52 return true;
53}
54
55int main(int, char**) {
56 test();
57 static_assert(test());
58
59 return 0;
60}
61

source code of libcxx/test/std/iterators/predef.iterators/counted.iterator/subscript.pass.cpp