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, class BinaryOperation> 15 // T reduce(InputIterator first, InputIterator last, T init, BinaryOperation op); 16 17 #include <numeric> 18 #include <cassert> 19 20 #include "test_macros.h" 21 #include "test_iterators.h" 22 23 template <class Iter, class T, class Op> 24 TEST_CONSTEXPR_CXX20 void 25 test(Iter first, Iter last, T init, Op op, T x) 26 { 27 static_assert( std::is_same_v<T, decltype(std::reduce(first, last, init, op))>, "" ); 28 assert(std::reduce(first, last, init, op) == x); 29 } 30 31 template <class Iter> 32 TEST_CONSTEXPR_CXX20 void 33 test() 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, std::plus<>(), 0); 38 test(Iter(ia), Iter(ia), 1, std::multiplies<>(), 1); 39 test(Iter(ia), Iter(ia+1), 0, std::plus<>(), 1); 40 test(Iter(ia), Iter(ia+1), 2, std::multiplies<>(), 2); 41 test(Iter(ia), Iter(ia+2), 0, std::plus<>(), 3); 42 test(Iter(ia), Iter(ia+2), 3, std::multiplies<>(), 6); 43 test(Iter(ia), Iter(ia+sa), 0, std::plus<>(), 21); 44 test(Iter(ia), Iter(ia+sa), 4, std::multiplies<>(), 2880); 45 } 46 47 template <typename T, typename Init> 48 TEST_CONSTEXPR_CXX20 void 49 test_return_type() 50 { 51 T *p = nullptr; 52 static_assert( std::is_same_v<Init, decltype(std::reduce(p, p, Init{}, std::plus<>()))>, "" ); 53 } 54 55 TEST_CONSTEXPR_CXX20 bool 56 test() 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 // Make sure the math is done using the correct type 73 { 74 auto v = {1, 2, 3, 4, 5, 6, 7, 8}; 75 unsigned res = std::reduce(v.begin(), v.end(), 1U, std::multiplies<>()); 76 assert(res == 40320); // 8! will not fit into a char 77 } 78 79 return true; 80 } 81 82 int main(int, char**) 83 { 84 test(); 85 #if TEST_STD_VER > 17 86 static_assert(test()); 87 #endif 88 return 0; 89 } 90