libstdc++-v3/testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc

   1 // Copyright (C) 2018-2019 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do run { target c++11 } }
  19 // { dg-require-cstdint "" }
  20
  21 #include <random>
  22 #include <testsuite_hooks.h>
  23
  24 template<typename T>
  25 struct seed_seq
  26 {
  27   using result_type = unsigned;
  28
  29   seed_seq() { }
  30
  31   template<class U>
  32     seed_seq(std::initializer_list<U>) { }
  33
  34   template<class InputIterator>
  35     seed_seq(InputIterator, InputIterator) { }
  36
  37   template<class RandomAccessIterator>
  38     void generate(RandomAccessIterator first, RandomAccessIterator last)
  39     {
  40       called = true;
  41       if (first != last)
  42         *first = 42;
  43     }
  44
  45   size_t size() const { called = true; return 1; }
  46
  47   template<class OutputIterator>
  48     void param(OutputIterator dest) const { called = true; dest = 42; }
  49
  50   // Prevents this type being considered as a seed sequence when
  51   // T is convertible to the engine's result_type:
  52   operator T() const noexcept { return T(); }
  53
  54   bool called = false;
  55 };
  56
  57 using engine_type
  58   = std::discard_block_engine
  59     <
  60       std::subtract_with_carry_engine<unsigned long, 24, 10, 24>,
  61       389, 24
  62     >;
  63
  64 void
  65 test01()
  66 {
  67   seed_seq<unsigned> seed;
  68   engine_type x(seed);
  69   VERIFY( ! seed.called );
  70 }
  71
  72 void
  73 test02()
  74 {
  75   seed_seq<void*> seed;
  76   engine_type x(seed);
  77   VERIFY( seed.called );
  78
  79   static_assert(!std::is_constructible<engine_type, const seed_seq<void>&>(),
  80       "Cannot construct from a const seed_seq");
  81 }
  82
  83 int main()
  84 {
  85   test01();
  86   test02();
  87 }