libcxx/test/std/algorithms/alg.modifying.operations/alg.generate/generate_n.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 // <algorithm>
  10
  11 // template<class Iter, IntegralLike Size, Callable Generator>
  12 //   requires OutputIterator<Iter, Generator::result_type>
  13 //         && CopyConstructible<Generator>
  14 //   constexpr void      // constexpr after c++17
  15 //   generate_n(Iter first, Size n, Generator gen);
  16
  17 #include <algorithm>
  18 #include <cassert>
  19
  20 #include "test_iterators.h"
  21 #include "test_macros.h"
  22 #include "user_defined_integral.h"
  23
  24 TEST_MSVC_DIAGNOSTIC_IGNORED(4244) // conversion from 'const double' to 'int', possible loss of data
  25
  26 struct gen_test
  27 {
  28     TEST_CONSTEXPR int operator()() const {return 2;}
  29 };
  30
  31
  32 #if TEST_STD_VER > 17
  33 TEST_CONSTEXPR bool test_constexpr() {
  34     const std::size_t N = 5;
  35     int ib[] = {0, 0, 0, 0, 0, 0}; // one bigger than N
  36
  37     auto it = std::generate_n(std::begin(ib), N, gen_test());
  38
  39     return it == (std::begin(ib) + N)
  40         && std::all_of(std::begin(ib), it, [](int x) { return x == 2; })
  41         && *it == 0 // don't overwrite the last value in the output array
  42         ;
  43     }
  44 #endif
  45
  46
  47 template <class Iter, class Size>
  48 void
  49 test2()
  50 {
  51     const unsigned n = 4;
  52     int ia[n] = {0};
  53     assert(std::generate_n(Iter(ia), Size(n), gen_test()) == Iter(ia+n));
  54     assert(ia[0] == 2);
  55     assert(ia[1] == 2);
  56     assert(ia[2] == 2);
  57     assert(ia[3] == 2);
  58 }
  59
  60 template <class Iter>
  61 void
  62 test()
  63 {
  64     test2<Iter, int>();
  65     test2<Iter, unsigned int>();
  66     test2<Iter, long>();
  67     test2<Iter, unsigned long>();
  68     test2<Iter, UserDefinedIntegral<unsigned> >();
  69     test2<Iter, float>();
  70     test2<Iter, double>();  // this is PR#35498
  71     test2<Iter, long double>();
  72 }
  73
  74 int main(int, char**)
  75 {
  76     test<forward_iterator<int*> >();
  77     test<bidirectional_iterator<int*> >();
  78     test<random_access_iterator<int*> >();
  79     test<int*>();
  80
  81 #if TEST_STD_VER > 17
  82     static_assert(test_constexpr());
  83 #endif
  84
  85   return 0;
  86 }