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> 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 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
