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