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 <class PopulationIterator, class SampleIterator, class Distance,
13 // class UniformRandomNumberGenerator>
14 // SampleIterator sample(PopulationIterator first, PopulationIterator last,
15 // SampleIterator out, Distance n,
16 // UniformRandomNumberGenerator &&g);
17
18 #include <experimental/algorithm>
19 #include <random>
20 #include <cassert>
21
22 #include "test_iterators.h"
23
24 // Stable if and only if PopulationIterator meets the requirements of a
25 // ForwardIterator type.
26 template <class PopulationIterator, class SampleIterator>
test_stability(bool expect_stable)27 void test_stability(bool expect_stable) {
28 const unsigned kPopulationSize = 100;
29 int ia[kPopulationSize];
30 for (unsigned i = 0; i < kPopulationSize; ++i)
31 ia[i] = i;
32 PopulationIterator first(ia);
33 PopulationIterator last(ia + kPopulationSize);
34
35 const unsigned kSampleSize = 20;
36 int oa[kPopulationSize];
37 SampleIterator out(oa);
38
39 std::minstd_rand g;
40
41 const int kIterations = 1000;
42 bool unstable = false;
43 for (int i = 0; i < kIterations; ++i) {
44 std::experimental::sample(first, last, out, kSampleSize, g);
45 unstable |= !std::is_sorted(oa, oa + kSampleSize);
46 }
47 assert(expect_stable == !unstable);
48 }
49
main()50 int main() {
51 test_stability<forward_iterator<int *>, output_iterator<int *> >(true);
52 test_stability<input_iterator<int *>, random_access_iterator<int *> >(false);
53 }
54