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 // <iterator>
10 
11 // reverse_iterator
12 
13 // requires RandomAccessIterator<Iter>
14 // reverse_iterator& operator+=(difference_type n); // constexpr in C++17
15 
16 #include <iterator>
17 #include <cassert>
18 
19 #include "test_macros.h"
20 #include "test_iterators.h"
21 
22 template <class It>
23 TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
24     std::reverse_iterator<It> r(i);
25     std::reverse_iterator<It>& rr = r += n;
26     assert(r.base() == x);
27     assert(&rr == &r);
28 }
29 
30 TEST_CONSTEXPR_CXX17 bool tests() {
31     char const* s = "1234567890";
32     test(random_access_iterator<const char*>(s + 5), 5, random_access_iterator<const char*>(s));
33 #if TEST_STD_VER >= 20
34     test(cpp20_random_access_iterator<const char*>(s + 5), 5, cpp20_random_access_iterator<const char*>(s));
35 #endif
36     test(s+5, 5, s);
37     return true;
38 }
39 
40 int main(int, char**) {
41     tests();
42 #if TEST_STD_VER > 14
43     static_assert(tests(), "");
44 #endif
45     return 0;
46 }
47