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 // <algorithm>
11
12 // template<BidirectionalIterator Iter, StrictWeakOrder<auto, Iter::value_type> Compare>
13 // requires ShuffleIterator<Iter>
14 // && CopyConstructible<Compare>
15 // bool
16 // prev_permutation(Iter first, Iter last, Compare comp);
17
18 #include <algorithm>
19 #include <functional>
20 #include <cassert>
21
22 #include "test_iterators.h"
23
24 #include <cstdio>
25
factorial(int x)26 int factorial(int x)
27 {
28 int r = 1;
29 for (; x; --x)
30 r *= x;
31 return r;
32 }
33
34 template <class Iter>
35 void
test()36 test()
37 {
38 typedef std::greater<int> C;
39 int ia[] = {1, 2, 3, 4, 5, 6};
40 const int sa = sizeof(ia)/sizeof(ia[0]);
41 int prev[sa];
42 for (int e = 0; e <= sa; ++e)
43 {
44 int count = 0;
45 bool x;
46 do
47 {
48 std::copy(ia, ia+e, prev);
49 x = std::prev_permutation(Iter(ia), Iter(ia+e), C());
50 if (e > 1)
51 {
52 if (x)
53 assert(std::lexicographical_compare(ia, ia+e, prev, prev+e, C()));
54 else
55 assert(std::lexicographical_compare(prev, prev+e, ia, ia+e, C()));
56 }
57 ++count;
58 } while (x);
59 assert(count == factorial(e));
60 }
61 }
62
main()63 int main()
64 {
65 test<bidirectional_iterator<int*> >();
66 test<random_access_iterator<int*> >();
67 test<int*>();
68 }
69