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