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Diffstat (limited to 'test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.stable.pass.cpp')
-rw-r--r-- | test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.stable.pass.cpp | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.stable.pass.cpp b/test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.stable.pass.cpp new file mode 100644 index 000000000000..db484238c95f --- /dev/null +++ b/test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.stable.pass.cpp @@ -0,0 +1,55 @@ +//===----------------------------------------------------------------------===// +// +// 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); +} |