libcxx/test/std/numerics/numeric.ops/inclusive.scan/inclusive_scan_op_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 OutputIterator, class T, class BinaryOperation>
  15 //     OutputIterator
  16 //     inclusive_scan(InputIterator first, InputIterator last,
  17 //                    OutputIterator result,
  18 //                    BinaryOperation binary_op, T init); // C++17
  19
  20 #include <algorithm>
  21 #include <array>
  22 #include <cassert>
  23 #include <cstddef>
  24 #include <functional>
  25 #include <numeric>
  26
  27 #include "test_macros.h"
  28 #include "test_iterators.h"
  29
  30 template <class Iter1, class T, class Op>
  31 TEST_CONSTEXPR_CXX20 void
  32 test(Iter1 first, Iter1 last, Op op, T init, const T *rFirst, const T *rLast)
  33 {
  34     assert((rLast - rFirst) <= 5);  // or else increase the size of "out"
  35     T out[5];
  36
  37     // Not in place
  38     T *end = std::inclusive_scan(first, last, out, op, init);
  39     assert(std::equal(out, end, rFirst, rLast));
  40
  41     // In place
  42     std::copy(first, last, out);
  43     end = std::inclusive_scan(out, end, out, op, init);
  44     assert(std::equal(out, end, rFirst, rLast));
  45 }
  46
  47
  48 template <class Iter>
  49 TEST_CONSTEXPR_CXX20 void
  50 test()
  51 {
  52     int ia[]         = {1, 3,  5,   7,   9};
  53     const int pRes[] = {1, 4,  9,  16,  25};
  54     const int mRes[] = {1, 3, 15, 105, 945};
  55     const unsigned sa = sizeof(ia) / sizeof(ia[0]);
  56     static_assert(sa == sizeof(pRes) / sizeof(pRes[0]));       // just to be sure
  57     static_assert(sa == sizeof(mRes) / sizeof(mRes[0]));       // just to be sure
  58
  59     for (unsigned int i = 0; i < sa; ++i ) {
  60         test(Iter(ia), Iter(ia + i), std::plus<>(),       0, pRes, pRes + i);
  61         test(Iter(ia), Iter(ia + i), std::multiplies<>(), 1, mRes, mRes + i);
  62     }
  63 }
  64
  65 constexpr std::size_t triangle(size_t n) { return n*(n+1)/2; }
  66
  67 //  Basic sanity
  68 TEST_CONSTEXPR_CXX20 void
  69 basic_tests()
  70 {
  71     {
  72     std::array<std::size_t, 10> v;
  73     std::fill(v.begin(), v.end(), 3);
  74     std::inclusive_scan(v.begin(), v.end(), v.begin(), std::plus<>(), std::size_t{50});
  75     for (std::size_t i = 0; i < v.size(); ++i)
  76         assert(v[i] == 50 + (i+1) * 3);
  77     }
  78
  79     {
  80     std::array<std::size_t, 10> v;
  81     std::iota(v.begin(), v.end(), 0);
  82     std::inclusive_scan(v.begin(), v.end(), v.begin(), std::plus<>(), std::size_t{40});
  83     for (std::size_t i = 0; i < v.size(); ++i)
  84         assert(v[i] == 40 + triangle(i));
  85     }
  86
  87     {
  88     std::array<std::size_t, 10> v;
  89     std::iota(v.begin(), v.end(), 1);
  90     std::inclusive_scan(v.begin(), v.end(), v.begin(), std::plus<>(), std::size_t{30});
  91     for (std::size_t i = 0; i < v.size(); ++i)
  92         assert(v[i] == 30 + triangle(i + 1));
  93     }
  94
  95     {
  96     std::array<std::size_t, 0> v, res;
  97     std::inclusive_scan(v.begin(), v.end(), res.begin(), std::plus<>(), std::size_t{40});
  98     assert(res.empty());
  99     }
 100
 101 //  Make sure that the calculations are done using the init typedef
 102     {
 103     std::array<unsigned char, 10> v;
 104     std::iota(v.begin(), v.end(), static_cast<unsigned char>(1));
 105     std::array<std::size_t, 10> res;
 106     std::inclusive_scan(v.begin(), v.end(), res.begin(), std::multiplies<>(), std::size_t{1});
 107
 108     assert(res.size() == 10);
 109     std::size_t j = 1;
 110     assert(res[0] == 1);
 111     for (std::size_t i = 1; i < v.size(); ++i)
 112     {
 113         j *= i + 1;
 114         assert(res[i] == j);
 115     }
 116     }
 117 }
 118
 119 TEST_CONSTEXPR_CXX20 bool
 120 test()
 121 {
 122     basic_tests();
 123
 124 //  All the iterator categories
 125     test<cpp17_input_iterator        <const int*> >();
 126     test<forward_iterator      <const int*> >();
 127     test<bidirectional_iterator<const int*> >();
 128     test<random_access_iterator<const int*> >();
 129     test<const int*>();
 130     test<      int*>();
 131
 132     return true;
 133 }
 134
 135 int main(int, char**)
 136 {
 137     test();
 138 #if TEST_STD_VER > 17
 139     static_assert(test());
 140 #endif
 141     return 0;
 142 }