libcxx/test/std/numerics/numeric.ops/reduce/reduce_init.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>
  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
  23 template <class Iter, class T>
  24 TEST_CONSTEXPR_CXX20 void
  25 test(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
  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, 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
  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{}))> );
  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     return true;
  73 }
  74
  75 int main(int, char**)
  76 {
  77     test();
  78 #if TEST_STD_VER > 17
  79     static_assert(test());
  80 #endif
  81     return 0;
  82 }