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 // <numeric> 10 // UNSUPPORTED: c++03, c++11, c++14 11 12 // Became constexpr in C++20 13 // template<class InputIterator, class T, class BinaryOperation> 14 // T reduce(InputIterator first, InputIterator last, T init, BinaryOperation op); 15 16 #include <numeric> 17 #include <cassert> 18 19 #include "test_macros.h" 20 #include "test_iterators.h" 21 22 template <class Iter, class T, class Op> 23 TEST_CONSTEXPR_CXX20 void 24 test(Iter first, Iter last, T init, Op op, T x) 25 { 26 static_assert( std::is_same_v<T, decltype(std::reduce(first, last, init, op))>, "" ); 27 assert(std::reduce(first, last, init, op) == x); 28 } 29 30 template <class Iter> 31 TEST_CONSTEXPR_CXX20 void 32 test() 33 { 34 int ia[] = {1, 2, 3, 4, 5, 6}; 35 unsigned sa = sizeof(ia) / sizeof(ia[0]); 36 test(Iter(ia), Iter(ia), 0, std::plus<>(), 0); 37 test(Iter(ia), Iter(ia), 1, std::multiplies<>(), 1); 38 test(Iter(ia), Iter(ia+1), 0, std::plus<>(), 1); 39 test(Iter(ia), Iter(ia+1), 2, std::multiplies<>(), 2); 40 test(Iter(ia), Iter(ia+2), 0, std::plus<>(), 3); 41 test(Iter(ia), Iter(ia+2), 3, std::multiplies<>(), 6); 42 test(Iter(ia), Iter(ia+sa), 0, std::plus<>(), 21); 43 test(Iter(ia), Iter(ia+sa), 4, std::multiplies<>(), 2880); 44 } 45 46 template <typename T, typename Init> 47 TEST_CONSTEXPR_CXX20 void 48 test_return_type() 49 { 50 T *p = nullptr; 51 static_assert( std::is_same_v<Init, decltype(std::reduce(p, p, Init{}, std::plus<>()))>, "" ); 52 } 53 54 TEST_CONSTEXPR_CXX20 bool 55 test() 56 { 57 test_return_type<char, int>(); 58 test_return_type<int, int>(); 59 test_return_type<int, unsigned long>(); 60 test_return_type<float, int>(); 61 test_return_type<short, float>(); 62 test_return_type<double, char>(); 63 test_return_type<char, double>(); 64 65 test<input_iterator<const int*> >(); 66 test<forward_iterator<const int*> >(); 67 test<bidirectional_iterator<const int*> >(); 68 test<random_access_iterator<const int*> >(); 69 test<const int*>(); 70 71 // Make sure the math is done using the correct type 72 { 73 auto v = {1, 2, 3, 4, 5, 6, 7, 8}; 74 unsigned res = std::reduce(v.begin(), v.end(), 1U, std::multiplies<>()); 75 assert(res == 40320); // 8! will not fit into a char 76 } 77 78 return true; 79 } 80 81 int main(int, char**) 82 { 83 test(); 84 #if TEST_STD_VER > 17 85 static_assert(test()); 86 #endif 87 return 0; 88 } 89