libcxx/test/std/numerics/numeric.ops/reduce/reduce_init_op.pass.cpp

   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 #include <functional>
  20
  21 #include "test_macros.h"
  22 #include "test_iterators.h"
  23
  24 template <class Iter, class T, class Op>
  25 TEST_CONSTEXPR_CXX20 void
  26 test(Iter first, Iter last, T init, Op op, T x)
  27 {
  28     static_assert( std::is_same_v<T, decltype(std::reduce(first, last, init, op))>, "" );
  29     assert(std::reduce(first, last, init, op) == x);
  30 }
  31
  32 template <class Iter>
  33 TEST_CONSTEXPR_CXX20 void
  34 test()
  35 {
  36     int ia[] = {1, 2, 3, 4, 5, 6};
  37     unsigned sa = sizeof(ia) / sizeof(ia[0]);
  38     test(Iter(ia), Iter(ia), 0, std::plus<>(), 0);
  39     test(Iter(ia), Iter(ia), 1, std::multiplies<>(), 1);
  40     test(Iter(ia), Iter(ia+1), 0, std::plus<>(), 1);
  41     test(Iter(ia), Iter(ia+1), 2, std::multiplies<>(), 2);
  42     test(Iter(ia), Iter(ia+2), 0, std::plus<>(), 3);
  43     test(Iter(ia), Iter(ia+2), 3, std::multiplies<>(), 6);
  44     test(Iter(ia), Iter(ia+sa), 0, std::plus<>(), 21);
  45     test(Iter(ia), Iter(ia+sa), 4, std::multiplies<>(), 2880);
  46 }
  47
  48 template <typename T, typename Init>
  49 TEST_CONSTEXPR_CXX20 void
  50 test_return_type()
  51 {
  52     T *p = nullptr;
  53     static_assert( std::is_same_v<Init, decltype(std::reduce(p, p, Init{}, std::plus<>()))>, "" );
  54 }
  55
  56 TEST_CONSTEXPR_CXX20 bool
  57 test()
  58 {
  59     test_return_type<char, int>();
  60     test_return_type<int, int>();
  61     test_return_type<int, unsigned long>();
  62     test_return_type<float, int>();
  63     test_return_type<short, float>();
  64     test_return_type<double, char>();
  65     test_return_type<char, double>();
  66
  67     test<cpp17_input_iterator<const int*> >();
  68     test<forward_iterator<const int*> >();
  69     test<bidirectional_iterator<const int*> >();
  70     test<random_access_iterator<const int*> >();
  71     test<const int*>();
  72
  73 //  Make sure the math is done using the correct type
  74     {
  75     auto v = {1, 2, 3, 4, 5, 6, 7, 8};
  76     unsigned res = std::reduce(v.begin(), v.end(), 1U, std::multiplies<>());
  77     assert(res == 40320);       // 8! will not fit into a char
  78     }
  79
  80     return true;
  81 }
  82
  83 int main(int, char**)
  84 {
  85     test();
  86 #if TEST_STD_VER > 17
  87     static_assert(test());
  88 #endif
  89     return 0;
  90 }