1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // <iterator>
11
12 // reverse_iterator
13
14 // requires RandomAccessIterator<Iter>
15 // constexpr reverse_iterator operator-(difference_type n) const;
16 //
17 // constexpr in C++17
18
19 #include <iterator>
20 #include <cassert>
21
22 #include "test_macros.h"
23 #include "test_iterators.h"
24
25 template <class It>
26 void
test(It i,typename std::iterator_traits<It>::difference_type n,It x)27 test(It i, typename std::iterator_traits<It>::difference_type n, It x)
28 {
29 const std::reverse_iterator<It> r(i);
30 std::reverse_iterator<It> rr = r - n;
31 assert(rr.base() == x);
32 }
33
main()34 int main()
35 {
36 const char* s = "1234567890";
37 test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
38 test(s+5, 5, s+10);
39
40 #if TEST_STD_VER > 14
41 {
42 constexpr const char *p = "123456789";
43 typedef std::reverse_iterator<const char *> RI;
44 constexpr RI it1 = std::make_reverse_iterator(p);
45 constexpr RI it2 = std::make_reverse_iterator(p + 5);
46 constexpr RI it3 = it1 - 5;
47 static_assert(it1 != it2, "");
48 static_assert(it1 != it3, "");
49 static_assert(it2 == it3, "");
50 }
51 #endif
52 }
53