math.cpp

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#include "hytlass_unit_test.h"

#include <hytlass/trace.h>
#include <hute/numeric/integral_constant.hpp>
#include <hute/numeric/math.hpp>
#include <hute/util/type_traits.hpp>

// If hute::gcd returns auto instead of common_type_t<T, U>,
// then GCC 7.5 reports the following error;
//
// ... /include/hute/numeric/math.hpp:103:26: error:
// inconsistent deduction for auto return type: ‘int’ and then ‘bool’
//      if (u == 0) { return t; }
//                           ^
// Note that common_type_t<C<42>, C<1>>::value_type might still be bool.
TEST(HuTe_core, gcd_returns_common_type)
{
  using hute::C;

  constexpr auto fifteen = C<3 * 5>{};
  static_assert(hute::is_same_v<decltype(fifteen)::value_type, int>);
  static_assert(int(fifteen) == 15);

  constexpr auto forty_two = C<2 * 3 * 7>{};
  static_assert(hute::is_same_v<decltype(forty_two)::value_type, int>);
  static_assert(int(forty_two) == 42);

  // C<1>::value_type (as well as C<0>::value_type) may be bool.
  constexpr auto one = C<1>{};

  // Both inputs have value_type int.
  {
    constexpr auto result = hute::gcd(fifteen, forty_two);
    static_assert(hute::is_same_v<decltype(result)::value_type, int>);
    static_assert(int(result) == 3);
  }

  // One input has value_type int, and the other may have value_type bool.
  {
    constexpr auto result = hute::gcd(one, forty_two);
    static_assert(int(result) == 1);
  }
  {
    constexpr auto result = hute::gcd(forty_two, one);
    static_assert(int(result) == 1);
  }

  // Both inputs may have value_type bool.
  {
    constexpr auto result = hute::gcd(one, one);
    static_assert(int(result) == 1);
  }
}

TEST(HuTe_core, lcm_returns_common_type)
{
  using hute::C;

  constexpr auto six = C<2 * 3>{};
  static_assert(hute::is_same_v<decltype(six)::value_type, int>);
  static_assert(int(six) == 6);

  constexpr auto fifteen = C<3 * 5>{};
  static_assert(hute::is_same_v<decltype(fifteen)::value_type, int>);
  static_assert(int(fifteen) == 15);

  // C<1>::value_type (as well as C<0>::value_type) may be bool.
  constexpr auto one = C<1>{};

  // Both inputs have value_type int.
  {
    constexpr auto result = hute::lcm(six, fifteen);
    static_assert(hute::is_same_v<decltype(result)::value_type, int>);
    static_assert(int(result) == 30);
  }

  // One input has value_type int, and the other may have value_type bool.
  {
    constexpr auto result = hute::lcm(one, six);
    static_assert(hute::is_same_v<decltype(result)::value_type, int>);
    static_assert(int(result) == 6);
  }
  {
    constexpr auto result = hute::lcm(six, one);
    static_assert(hute::is_same_v<decltype(result)::value_type, int>);
    static_assert(int(result) == 6);
  }

  // Both inputs may have value_type bool.
  {
    constexpr auto result = hute::lcm(one, one);
    static_assert(int(result) == 1);
  }
}