56a8c6438a
Following specification in "C++ Extensions for Library Fundamentals": http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4480.html#alg.random.sample git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@237264 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <algorithm>
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// template <class PopulationIterator, class SampleIterator, class Distance,
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// class UniformRandomNumberGenerator>
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// SampleIterator sample(PopulationIterator first, PopulationIterator last,
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// SampleIterator out, Distance n,
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// UniformRandomNumberGenerator &&g);
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#include <experimental/algorithm>
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#include <random>
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#include <cassert>
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#include "test_iterators.h"
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// Stable if and only if PopulationIterator meets the requirements of a
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// ForwardIterator type.
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template <class PopulationIterator, class SampleIterator>
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void test_stability(bool expect_stable) {
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const unsigned kPopulationSize = 100;
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int ia[kPopulationSize];
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for (unsigned i = 0; i < kPopulationSize; ++i)
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ia[i] = i;
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PopulationIterator first(ia);
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PopulationIterator last(ia + kPopulationSize);
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const unsigned kSampleSize = 20;
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int oa[kPopulationSize];
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SampleIterator out(oa);
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std::minstd_rand g;
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const int kIterations = 1000;
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bool unstable = false;
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for (int i = 0; i < kIterations; ++i) {
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std::experimental::sample(first, last, out, kSampleSize, g);
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unstable |= !std::is_sorted(oa, oa + kSampleSize);
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}
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assert(expect_stable == !unstable);
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}
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int main() {
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test_stability<forward_iterator<int *>, output_iterator<int *> >(true);
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test_stability<input_iterator<int *>, random_access_iterator<int *> >(false);
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}
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