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 // <numeric>
12 
13 // Became constexpr in C++20
14 // template<class InputIterator, class OutputIterator, class T>
15 //     OutputIterator exclusive_scan(InputIterator first, InputIterator last,
16 //                                   OutputIterator result, T init);
17 //
18 
19 #include <numeric>
20 #include <algorithm>
21 #include <array>
22 #include <cassert>
23 #include <functional>
24 #include <iterator>
25 
26 #include "test_macros.h"
27 #include "test_iterators.h"
28 
29 template <class Iter1, class T>
30 TEST_CONSTEXPR_CXX20 void
31 test(Iter1 first, Iter1 last, T init, const T *rFirst, const T *rLast)
32 {
33     assert((rLast - rFirst) <= 5);  // or else increase the size of "out"
34     T out[5];
35 
36     // Not in place
37     T *end = std::exclusive_scan(first, last, out, init);
38     assert(std::equal(out, end, rFirst, rLast));
39 
40     // In place
41     std::copy(first, last, out);
42     end = std::exclusive_scan(out, end, out, init);
43     assert(std::equal(out, end, rFirst, rLast));
44 }
45 
46 template <class Iter>
47 TEST_CONSTEXPR_CXX20 void
48 test()
49 {
50     int ia[]         = {1, 3, 5, 7,  9};
51     const int pRes[] = {0, 1, 4, 9, 16};
52     const unsigned sa = sizeof(ia) / sizeof(ia[0]);
53     static_assert(sa == sizeof(pRes) / sizeof(pRes[0]));       // just to be sure
54 
55     for (unsigned int i = 0; i < sa; ++i) {
56         test(Iter(ia), Iter(ia + i), 0, pRes, pRes + i);
57     }
58 }
59 
60 constexpr size_t triangle(size_t n) { return n*(n+1)/2; }
61 
62 //  Basic sanity
63 TEST_CONSTEXPR_CXX20 void
64 basic_tests()
65 {
66     {
67     std::array<size_t, 10> v;
68     std::fill(v.begin(), v.end(), 3);
69     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{50});
70     for (size_t i = 0; i < v.size(); ++i)
71         assert(v[i] == 50 + i * 3);
72     }
73 
74     {
75     std::array<size_t, 10> v;
76     std::iota(v.begin(), v.end(), 0);
77     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{30});
78     for (size_t i = 0; i < v.size(); ++i)
79         assert(v[i] == 30 + triangle(i-1));
80     }
81 
82     {
83     std::array<size_t, 10> v;
84     std::iota(v.begin(), v.end(), 1);
85     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{40});
86     for (size_t i = 0; i < v.size(); ++i)
87         assert(v[i] == 40 + triangle(i));
88     }
89 
90 }
91 
92 TEST_CONSTEXPR_CXX20 bool
93 test()
94 {
95     basic_tests();
96 
97 //  All the iterator categories
98     test<cpp17_input_iterator        <const int*> >();
99     test<forward_iterator      <const int*> >();
100     test<bidirectional_iterator<const int*> >();
101     test<random_access_iterator<const int*> >();
102     test<const int*>();
103     test<      int*>();
104 
105     return true;
106 }
107 
108 int main(int, char**)
109 {
110     test();
111 #if TEST_STD_VER > 17
112     static_assert(test());
113 #endif
114     return 0;
115 }
116