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 // UNSUPPORTED: c++98, c++03, c++11, c++14
11
12 // <algorithm>
13
14 // template <class PopulationIterator, class SampleIterator, class Distance,
15 // class UniformRandomNumberGenerator>
16 // SampleIterator sample(PopulationIterator first, PopulationIterator last,
17 // SampleIterator out, Distance n,
18 // UniformRandomNumberGenerator &&g);
19
20 #include <algorithm>
21 #include <random>
22 #include <cassert>
23
24 #include "test_iterators.h"
25
26 // Stable if and only if PopulationIterator meets the requirements of a
27 // ForwardIterator type.
28 template <class PopulationIterator, class SampleIterator>
test_stability(bool expect_stable)29 void test_stability(bool expect_stable) {
30 const unsigned kPopulationSize = 100;
31 int ia[kPopulationSize];
32 for (unsigned i = 0; i < kPopulationSize; ++i)
33 ia[i] = i;
34 PopulationIterator first(ia);
35 PopulationIterator last(ia + kPopulationSize);
36
37 const unsigned kSampleSize = 20;
38 int oa[kPopulationSize];
39 SampleIterator out(oa);
40
41 std::minstd_rand g;
42
43 const int kIterations = 1000;
44 bool unstable = false;
45 for (int i = 0; i < kIterations; ++i) {
46 std::sample(first, last, out, kSampleSize, g);
47 unstable |= !std::is_sorted(oa, oa + kSampleSize);
48 }
49 assert(expect_stable == !unstable);
50 }
51
main()52 int main() {
53 test_stability<forward_iterator<int *>, output_iterator<int *> >(true);
54 test_stability<input_iterator<int *>, random_access_iterator<int *> >(false);
55 }
56