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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
// <algorithm>
// template <class PopulationIterator, class SampleIterator, class Distance,
// class UniformRandomNumberGenerator>
// SampleIterator sample(PopulationIterator first, PopulationIterator last,
// SampleIterator out, Distance n,
// UniformRandomNumberGenerator &&g);
#include <algorithm>
#include <random>
#include <cassert>
#include "test_iterators.h"
// Stable if and only if PopulationIterator meets the requirements of a
// ForwardIterator type.
template <class PopulationIterator, class SampleIterator>
void test_stability(bool expect_stable) {
const unsigned kPopulationSize = 100;
int ia[kPopulationSize];
for (unsigned i = 0; i < kPopulationSize; ++i)
ia[i] = i;
PopulationIterator first(ia);
PopulationIterator last(ia + kPopulationSize);
const unsigned kSampleSize = 20;
int oa[kPopulationSize];
SampleIterator out(oa);
std::minstd_rand g;
const int kIterations = 1000;
bool unstable = false;
for (int i = 0; i < kIterations; ++i) {
std::sample(first, last, out, kSampleSize, g);
unstable |= !std::is_sorted(oa, oa + kSampleSize);
}
assert(expect_stable == !unstable);
}
int main() {
test_stability<forward_iterator<int *>, output_iterator<int *> >(true);
test_stability<input_iterator<int *>, random_access_iterator<int *> >(false);
}
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