1// -*- C++ -*-
2//===-- nth_element.pass.cpp ----------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10// UNSUPPORTED: c++03, c++11, c++14
11
12#include "support/pstl_test_config.h"
13
14#include <iostream>
15#include <execution>
16#include <algorithm>
17
18#include "support/utils.h"
19
20using namespace TestUtils;
21
22// User defined type with minimal requirements
23template <typename T>
24struct DataType
25{
26 explicit DataType(int32_t k) : my_val(k) {}
27 DataType(DataType&& input)
28 {
29 my_val = std::move(input.my_val);
30 input.my_val = T(0);
31 }
32 DataType&
33 operator=(DataType&& input)
34 {
35 my_val = std::move(input.my_val);
36 input.my_val = T(0);
37 return *this;
38 }
39 T
40 get_val() const
41 {
42 return my_val;
43 }
44
45 friend std::ostream&
46 operator<<(std::ostream& stream, const DataType<T>& input)
47 {
48 return stream << input.my_val;
49 }
50
51 private:
52 T my_val;
53};
54
55template <typename T>
56bool
57is_equal(const DataType<T>& x, const DataType<T>& y)
58{
59 return x.get_val() == y.get_val();
60}
61
62template <typename T>
63bool
64is_equal(const T& x, const T& y)
65{
66 return x == y;
67}
68
69struct test_one_policy
70{
71#if defined(_PSTL_ICC_17_VC141_TEST_SIMD_LAMBDA_DEBUG_32_BROKEN) || \
72 defined(_PSTL_ICC_16_VC14_TEST_SIMD_LAMBDA_DEBUG_32_BROKEN) // dummy specialization by policy type, in case of broken configuration
73 template <typename Iterator1, typename Size, typename Generator1, typename Generator2, typename Compare>
74 typename std::enable_if<is_same_iterator_category<Iterator1, std::random_access_iterator_tag>::value, void>::type
75 operator()(pstl::execution::unsequenced_policy, Iterator1 first1, Iterator1 last1, Iterator1 first2,
76 Iterator1 last2, Size n, Size m, Generator1 generator1, Generator2 generator2, Compare comp)
77 {
78 }
79 template <typename Iterator1, typename Size, typename Generator1, typename Generator2, typename Compare>
80 typename std::enable_if<is_same_iterator_category<Iterator1, std::random_access_iterator_tag>::value, void>::type
81 operator()(pstl::execution::parallel_unsequenced_policy, Iterator1 first1, Iterator1 last1, Iterator1 first2,
82 Iterator1 last2, Size n, Size m, Generator1 generator1, Generator2 generator2, Compare comp)
83 {
84 }
85#endif
86
87 // nth_element works only with random access iterators
88 template <typename Policy, typename Iterator1, typename Size, typename Generator1, typename Generator2,
89 typename Compare>
90 typename std::enable_if<is_same_iterator_category<Iterator1, std::random_access_iterator_tag>::value, void>::type
91 operator()(Policy&& exec, Iterator1 first1, Iterator1 last1, Iterator1 first2, Iterator1 last2, Size n, Size m,
92 Generator1 generator1, Generator2 generator2, Compare comp)
93 {
94
95 using T = typename std::iterator_traits<Iterator1>::value_type;
96 const Iterator1 mid1 = std::next(first1, m);
97 const Iterator1 mid2 = std::next(first2, m);
98
99 fill_data(first1, mid1, generator1);
100 fill_data(mid1, last1, generator2);
101 fill_data(first2, mid2, generator1);
102 fill_data(mid2, last2, generator2);
103 std::nth_element(first1, mid1, last1, comp);
104 std::nth_element(exec, first2, mid2, last2, comp);
105 if (m > 0 && m < n)
106 {
107 EXPECT_TRUE(is_equal(*mid1, *mid2), "wrong result from nth_element with predicate");
108 }
109 EXPECT_TRUE(std::find_first_of(first2, mid2, mid2, last2, [comp](T& x, T& y) { return comp(y, x); }) == mid2,
110 "wrong effect from nth_element with predicate");
111 }
112
113 template <typename Policy, typename Iterator1, typename Size, typename Generator1, typename Generator2,
114 typename Compare>
115 typename std::enable_if<!is_same_iterator_category<Iterator1, std::random_access_iterator_tag>::value, void>::type
116 operator()(Policy&&, Iterator1, Iterator1, Iterator1, Iterator1, Size, Size, Generator1, Generator2, Compare)
117 {
118 }
119};
120
121template <typename T, typename Generator1, typename Generator2, typename Compare>
122void
123test_by_type(Generator1 generator1, Generator2 generator2, Compare comp)
124{
125 using namespace std;
126 size_t max_size = 10000;
127 Sequence<T> in1(max_size, [](size_t v) { return T(v); });
128 Sequence<T> exp(max_size, [](size_t v) { return T(v); });
129 size_t m;
130
131 for (size_t n = 0; n <= max_size; n = n <= 16 ? n + 1 : size_t(3.1415 * n))
132 {
133 m = 0;
134 invoke_on_all_policies(test_one_policy(), exp.begin(), exp.begin() + n, in1.begin(), in1.begin() + n, n, m,
135 generator1, generator2, comp);
136 m = n / 7;
137 invoke_on_all_policies(test_one_policy(), exp.begin(), exp.begin() + n, in1.begin(), in1.begin() + n, n, m,
138 generator1, generator2, comp);
139 m = 3 * n / 5;
140 invoke_on_all_policies(test_one_policy(), exp.begin(), exp.begin() + n, in1.begin(), in1.begin() + n, n, m,
141 generator1, generator2, comp);
142 }
143 invoke_on_all_policies(test_one_policy(), exp.begin(), exp.begin() + max_size, in1.begin(), in1.begin() + max_size,
144 max_size, max_size, generator1, generator2, comp);
145}
146
147template <typename T>
148struct test_non_const
149{
150 template <typename Policy, typename Iterator>
151 void
152 operator()(Policy&& exec, Iterator iter)
153 {
154 invoke_if(exec, [&]() { nth_element(exec, iter, iter, iter, non_const(std::less<T>())); });
155 }
156};
157
158int
159main()
160{
161 test_by_type<int32_t>(generator1: [](int32_t i) { return 10 * i; }, generator2: [](int32_t i) { return i + 1; }, comp: std::less<int32_t>());
162 test_by_type<int32_t>(generator1: [](int32_t) { return 0; }, generator2: [](int32_t) { return 0; }, comp: std::less<int32_t>());
163
164 test_by_type<float64_t>(generator1: [](int32_t i) { return -2 * i; }, generator2: [](int32_t i) { return -(2 * i + 1); },
165 comp: [](const float64_t x, const float64_t y) { return x > y; });
166
167 test_by_type<DataType<float32_t>>(
168 generator1: [](int32_t i) { return DataType<float32_t>(2 * i + 1); }, generator2: [](int32_t i) { return DataType<float32_t>(2 * i); },
169 comp: [](const DataType<float32_t>& x, const DataType<float32_t>& y) { return x.get_val() < y.get_val(); });
170
171 test_algo_basic_single<int32_t>(f: run_for_rnd<test_non_const<int32_t>>());
172
173 std::cout << done() << std::endl;
174 return 0;
175}
176

source code of pstl/test/std/algorithms/alg.nonmodifying/nth_element.pass.cpp