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 // UNSUPPORTED: clang-8
11 // UNSUPPORTED: gcc-9
12 
13 // <numeric>
14 
15 // Became constexpr in C++20
16 // template<class InputIterator, class OutputIterator, class T>
17 //     OutputIterator exclusive_scan(InputIterator first, InputIterator last,
18 //                                   OutputIterator result, T init);
19 //
20 
21 #include <numeric>
22 #include <algorithm>
23 #include <array>
24 #include <cassert>
25 #include <functional>
26 #include <iterator>
27 
28 #include "test_macros.h"
29 #include "test_iterators.h"
30 
31 template <class Iter1, class T>
32 TEST_CONSTEXPR_CXX20 void
33 test(Iter1 first, Iter1 last, T init, const T *rFirst, const T *rLast)
34 {
35     assert((rLast - rFirst) <= 5);  // or else increase the size of "out"
36     T out[5];
37 
38     // Not in place
39     T *end = std::exclusive_scan(first, last, out, init);
40     assert(std::equal(out, end, rFirst, rLast));
41 
42     // In place
43     std::copy(first, last, out);
44     end = std::exclusive_scan(out, end, out, init);
45     assert(std::equal(out, end, rFirst, rLast));
46 }
47 
48 template <class Iter>
49 TEST_CONSTEXPR_CXX20 void
50 test()
51 {
52     int ia[]         = {1, 3, 5, 7,  9};
53     const int pRes[] = {0, 1, 4, 9, 16};
54     const unsigned sa = sizeof(ia) / sizeof(ia[0]);
55     static_assert(sa == sizeof(pRes) / sizeof(pRes[0]));       // just to be sure
56 
57     for (unsigned int i = 0; i < sa; ++i) {
58         test(Iter(ia), Iter(ia + i), 0, pRes, pRes + i);
59     }
60 }
61 
62 constexpr size_t triangle(size_t n) { return n*(n+1)/2; }
63 
64 //  Basic sanity
65 TEST_CONSTEXPR_CXX20 void
66 basic_tests()
67 {
68     {
69     std::array<size_t, 10> v;
70     std::fill(v.begin(), v.end(), 3);
71     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{50});
72     for (size_t i = 0; i < v.size(); ++i)
73         assert(v[i] == 50 + i * 3);
74     }
75 
76     {
77     std::array<size_t, 10> v;
78     std::iota(v.begin(), v.end(), 0);
79     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{30});
80     for (size_t i = 0; i < v.size(); ++i)
81         assert(v[i] == 30 + triangle(i-1));
82     }
83 
84     {
85     std::array<size_t, 10> v;
86     std::iota(v.begin(), v.end(), 1);
87     std::exclusive_scan(v.begin(), v.end(), v.begin(), size_t{40});
88     for (size_t i = 0; i < v.size(); ++i)
89         assert(v[i] == 40 + triangle(i));
90     }
91 
92 }
93 
94 TEST_CONSTEXPR_CXX20 bool
95 test()
96 {
97     basic_tests();
98 
99 //  All the iterator categories
100     test<input_iterator        <const int*> >();
101     test<forward_iterator      <const int*> >();
102     test<bidirectional_iterator<const int*> >();
103     test<random_access_iterator<const int*> >();
104     test<const int*>();
105     test<      int*>();
106 
107     return true;
108 }
109 
110 int main(int, char**)
111 {
112     test();
113 #if TEST_STD_VER > 17
114     static_assert(test());
115 #endif
116     return 0;
117 }
118