libcxx/test/std/numerics/rand/rand.eng/rand.eng.lcong/values.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 // <random>
  10
  11 // template <class UIntType, UIntType a, UIntType c, UIntType m>
  12 // class linear_congruential_engine
  13 // {
  14 // public:
  15 //     engine characteristics
  16 //     static constexpr result_type multiplier = a;
  17 //     static constexpr result_type increment = c;
  18 //     static constexpr result_type modulus = m;
  19 //     static constexpr result_type min() { return c == 0u ? 1u: 0u;}
  20 //     static constexpr result_type max() { return m - 1u;}
  21 //     static constexpr result_type default_seed = 1u;
  22
  23 #include <random>
  24 #include <type_traits>
  25 #include <cassert>
  26
  27 #include "test_macros.h"
  28
  29 template <class T>
  30 void where(const T &) {}
  31
  32 template <class T, T a, T c, T m>
  33 void
  34 test1()
  35 {
  36     typedef std::linear_congruential_engine<T, a, c, m> LCE;
  37     typedef typename LCE::result_type result_type;
  38     static_assert((LCE::multiplier == a), "");
  39     static_assert((LCE::increment == c), "");
  40     static_assert((LCE::modulus == m), "");
  41 #if TEST_STD_VER >= 11
  42     static_assert((LCE::min() == (c == 0u ? 1u: 0u)), "");
  43 #else
  44     assert((LCE::min() == (c == 0u ? 1u: 0u)));
  45 #endif
  46
  47     TEST_DIAGNOSTIC_PUSH
  48     TEST_MSVC_DIAGNOSTIC_IGNORED(4310) // cast truncates constant value
  49
  50 #if TEST_STD_VER >= 11
  51     static_assert((LCE::max() == result_type(m - 1u)), "");
  52 #else
  53     assert((LCE::max() == result_type(m - 1u)));
  54 #endif
  55
  56     TEST_DIAGNOSTIC_POP
  57
  58     static_assert((LCE::default_seed == 1), "");
  59     where(LCE::multiplier);
  60     where(LCE::increment);
  61     where(LCE::modulus);
  62     where(LCE::default_seed);
  63 }
  64
  65 template <class T>
  66 void
  67 test()
  68 {
  69     test1<T, 0, 0, 0>();
  70     test1<T, 0, 1, 2>();
  71     test1<T, 1, 1, 2>();
  72     const T M(static_cast<T>(-1));
  73     test1<T, 0, 0, M>();
  74     test1<T, 0, M-2, M>();
  75     test1<T, 0, M-1, M>();
  76     test1<T, M-2, 0, M>();
  77     test1<T, M-2, M-2, M>();
  78     test1<T, M-2, M-1, M>();
  79     test1<T, M-1, 0, M>();
  80     test1<T, M-1, M-2, M>();
  81     test1<T, M-1, M-1, M>();
  82 }
  83
  84 int main(int, char**)
  85 {
  86     test<unsigned short>();
  87     test<unsigned int>();
  88     test<unsigned long>();
  89     test<unsigned long long>();
  90
  91   return 0;
  92 }