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 T>
15// T reduce(InputIterator first, InputIterator last, T init);
16
17#include <numeric>
18#include <cassert>
19
20#include "test_macros.h"
21#include "test_iterators.h"
22
23template <class Iter, class T>
24TEST_CONSTEXPR_CXX20 void
25test(Iter first, Iter last, T init, T x)
26{
27 static_assert( std::is_same_v<T, decltype(std::reduce(first, last, init))> );
28 assert(std::reduce(first, last, init) == x);
29}
30
31template <class Iter>
32TEST_CONSTEXPR_CXX20 void
33test()
34{
35 int ia[] = {1, 2, 3, 4, 5, 6};
36 unsigned sa = sizeof(ia) / sizeof(ia[0]);
37 test(Iter(ia), Iter(ia), 0, 0);
38 test(Iter(ia), Iter(ia), 1, 1);
39 test(Iter(ia), Iter(ia+1), 0, 1);
40 test(Iter(ia), Iter(ia+1), 2, 3);
41 test(Iter(ia), Iter(ia+2), 0, 3);
42 test(Iter(ia), Iter(ia+2), 3, 6);
43 test(Iter(ia), Iter(ia+sa), 0, 21);
44 test(Iter(ia), Iter(ia+sa), 4, 25);
45}
46
47template <typename T, typename Init>
48TEST_CONSTEXPR_CXX20 void
49test_return_type()
50{
51 T *p = nullptr;
52 static_assert( std::is_same_v<Init, decltype(std::reduce(p, p, Init{}))> );
53}
54
55TEST_CONSTEXPR_CXX20 bool
56test()
57{
58 test_return_type<char, int>();
59 test_return_type<int, int>();
60 test_return_type<int, unsigned long>();
61 test_return_type<float, int>();
62 test_return_type<short, float>();
63 test_return_type<double, char>();
64 test_return_type<char, double>();
65
66 test<cpp17_input_iterator<const int*> >();
67 test<forward_iterator<const int*> >();
68 test<bidirectional_iterator<const int*> >();
69 test<random_access_iterator<const int*> >();
70 test<const int*>();
71
72 return true;
73}
74
75int main(int, char**)
76{
77 test();
78#if TEST_STD_VER > 17
79 static_assert(test());
80#endif
81 return 0;
82}
83

source code of libcxx/test/std/numerics/numeric.ops/reduce/reduce_init.pass.cpp