1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 // UNSUPPORTED: c++03, c++11, c++14
10
11 // <algorithm>
12
13 // template <class PopulationIterator, class SampleIterator, class Distance,
14 // class UniformRandomNumberGenerator>
15 // SampleIterator sample(PopulationIterator first, PopulationIterator last,
16 // SampleIterator out, Distance n,
17 // UniformRandomNumberGenerator &&g);
18
19 #include <algorithm>
20 #include <random>
21 #include <type_traits>
22 #include <cassert>
23 #include <cstddef>
24
25 #include "test_iterators.h"
26 #include "test_macros.h"
27
28 struct ReservoirSampleExpectations {
29 enum { os = 4 };
30 static int oa1[os];
31 static int oa2[os];
32 };
33
34 int ReservoirSampleExpectations::oa1[] = {10, 5, 9, 4};
35 int ReservoirSampleExpectations::oa2[] = {5, 2, 10, 4};
36
37 struct SelectionSampleExpectations {
38 enum { os = 4 };
39 static int oa1[os];
40 static int oa2[os];
41 };
42
43 int SelectionSampleExpectations::oa1[] = {1, 4, 6, 7};
44 int SelectionSampleExpectations::oa2[] = {1, 2, 6, 8};
45
46 template <class IteratorCategory> struct TestExpectations
47 : public SelectionSampleExpectations {};
48
49 template <>
50 struct TestExpectations<std::input_iterator_tag>
51 : public ReservoirSampleExpectations {};
52
53 template <template<class...> class PopulationIteratorType, class PopulationItem,
54 template<class...> class SampleIteratorType, class SampleItem>
test()55 void test() {
56 typedef PopulationIteratorType<PopulationItem *> PopulationIterator;
57 typedef SampleIteratorType<SampleItem *> SampleIterator;
58 PopulationItem ia[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
59 const unsigned is = sizeof(ia) / sizeof(ia[0]);
60 typedef TestExpectations<typename std::iterator_traits<
61 PopulationIterator>::iterator_category> Expectations;
62 const unsigned os = Expectations::os;
63 SampleItem oa[os];
64 const int *oa1 = Expectations::oa1;
65 ((void)oa1); // Prevent unused warning
66 const int *oa2 = Expectations::oa2;
67 ((void)oa2); // Prevent unused warning
68 std::minstd_rand g;
69 SampleIterator end = std::sample(PopulationIterator(ia),
70 PopulationIterator(ia + is),
71 SampleIterator(oa), os, g);
72 assert(static_cast<std::size_t>(base(end) - oa) == std::min(os, is));
73 // sample() is deterministic but non-reproducible;
74 // its results can vary between implementations.
75 LIBCPP_ASSERT(std::equal(oa, oa + os, oa1));
76 end = std::sample(PopulationIterator(ia),
77 PopulationIterator(ia + is),
78 SampleIterator(oa), os, std::move(g));
79 assert(static_cast<std::size_t>(base(end) - oa) == std::min(os, is));
80 LIBCPP_ASSERT(std::equal(oa, oa + os, oa2));
81 }
82
83 template <template<class...> class PopulationIteratorType, class PopulationItem,
84 template<class...> class SampleIteratorType, class SampleItem>
test_empty_population()85 void test_empty_population() {
86 typedef PopulationIteratorType<PopulationItem *> PopulationIterator;
87 typedef SampleIteratorType<SampleItem *> SampleIterator;
88 PopulationItem ia[] = {42};
89 const unsigned os = 4;
90 SampleItem oa[os];
91 std::minstd_rand g;
92 SampleIterator end =
93 std::sample(PopulationIterator(ia), PopulationIterator(ia),
94 SampleIterator(oa), os, g);
95 assert(base(end) == oa);
96 }
97
98 template <template<class...> class PopulationIteratorType, class PopulationItem,
99 template<class...> class SampleIteratorType, class SampleItem>
test_empty_sample()100 void test_empty_sample() {
101 typedef PopulationIteratorType<PopulationItem *> PopulationIterator;
102 typedef SampleIteratorType<SampleItem *> SampleIterator;
103 PopulationItem ia[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
104 const unsigned is = sizeof(ia) / sizeof(ia[0]);
105 SampleItem oa[1];
106 std::minstd_rand g;
107 SampleIterator end =
108 std::sample(PopulationIterator(ia), PopulationIterator(ia + is),
109 SampleIterator(oa), 0, g);
110 assert(base(end) == oa);
111 }
112
113 template <template<class...> class PopulationIteratorType, class PopulationItem,
114 template<class...> class SampleIteratorType, class SampleItem>
test_small_population()115 void test_small_population() {
116 // The population size is less than the sample size.
117 typedef PopulationIteratorType<PopulationItem *> PopulationIterator;
118 typedef SampleIteratorType<SampleItem *> SampleIterator;
119 PopulationItem ia[] = {1, 2, 3, 4, 5};
120 const unsigned is = sizeof(ia) / sizeof(ia[0]);
121 const unsigned os = 8;
122 SampleItem oa[os];
123 const SampleItem oa1[] = {1, 2, 3, 4, 5};
124 std::minstd_rand g;
125 SampleIterator end = std::sample(PopulationIterator(ia),
126 PopulationIterator(ia + is),
127 SampleIterator(oa), os, g);
128 assert(static_cast<std::size_t>(base(end) - oa) == std::min(os, is));
129 typedef typename std::iterator_traits<PopulationIterator>::iterator_category PopulationCategory;
130 if (std::is_base_of<std::forward_iterator_tag, PopulationCategory>::value) {
131 assert(std::equal(oa, base(end), oa1));
132 } else {
133 assert(std::is_permutation(oa, base(end), oa1));
134 }
135 }
136
main(int,char **)137 int main(int, char**) {
138 test<cpp17_input_iterator, int, random_access_iterator, int>();
139 test<forward_iterator, int, cpp17_output_iterator, int>();
140 test<forward_iterator, int, random_access_iterator, int>();
141
142 test<cpp17_input_iterator, int, random_access_iterator, double>();
143 test<forward_iterator, int, cpp17_output_iterator, double>();
144 test<forward_iterator, int, random_access_iterator, double>();
145
146 test_empty_population<cpp17_input_iterator, int, random_access_iterator, int>();
147 test_empty_population<forward_iterator, int, cpp17_output_iterator, int>();
148 test_empty_population<forward_iterator, int, random_access_iterator, int>();
149
150 test_empty_sample<cpp17_input_iterator, int, random_access_iterator, int>();
151 test_empty_sample<forward_iterator, int, cpp17_output_iterator, int>();
152 test_empty_sample<forward_iterator, int, random_access_iterator, int>();
153
154 test_small_population<cpp17_input_iterator, int, random_access_iterator, int>();
155 test_small_population<forward_iterator, int, cpp17_output_iterator, int>();
156 test_small_population<forward_iterator, int, random_access_iterator, int>();
157
158 return 0;
159 }
160