comparable.cpp 2.6 KB

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  1. // Copyright Louis Dionne 2013-2017
  2. // Distributed under the Boost Software License, Version 1.0.
  3. // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  4. #include <boost/hana/assert.hpp>
  5. #include <boost/hana/concept/comparable.hpp>
  6. #include <boost/hana/equal.hpp>
  7. #include <boost/hana/not.hpp>
  8. #include <boost/hana/tuple.hpp>
  9. #include <laws/base.hpp>
  10. #include <laws/comparable.hpp>
  11. #include <type_traits>
  12. namespace hana = boost::hana;
  13. // Minimal EqualityComparable types
  14. struct eq1 { int value; };
  15. struct eq2 {
  16. int value;
  17. constexpr operator eq1() const { return {value}; }
  18. };
  19. template <typename T, typename U, typename = std::enable_if_t<
  20. (std::is_same<T, eq1>{} || std::is_same<T, eq2>{}) &&
  21. (std::is_same<U, eq1>{} || std::is_same<U, eq2>{})
  22. >>
  23. constexpr bool operator==(T a, U b)
  24. { return a.value == b.value; }
  25. template <typename T, typename U, typename = std::enable_if_t<
  26. (std::is_same<T, eq1>{} || std::is_same<T, eq2>{}) &&
  27. (std::is_same<U, eq1>{} || std::is_same<U, eq2>{})
  28. >>
  29. constexpr bool operator!=(T a, U b)
  30. { return !(a == b); }
  31. int main() {
  32. // equal
  33. {
  34. // Two objects of different data types are unequal by default,
  35. // and no model is provided for two objects of the same data type.
  36. struct Random1 { }; struct Random2 { };
  37. BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::equal(Random1{}, Random2{})));
  38. static_assert(!hana::Comparable<Random1>::value, "");
  39. static_assert(!hana::Comparable<Random2>::value, "");
  40. // Provided model for EqualityComparable types
  41. BOOST_HANA_CONSTEXPR_CHECK(hana::equal(eq1{0}, eq1{0}));
  42. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq1{0}, eq1{1})));
  43. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq1{1}, eq1{0})));
  44. BOOST_HANA_CONSTEXPR_CHECK(hana::equal(eq1{0}, eq2{0}));
  45. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq1{0}, eq2{1})));
  46. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq1{1}, eq2{0})));
  47. BOOST_HANA_CONSTEXPR_CHECK(hana::equal(eq2{0}, eq1{0}));
  48. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq2{0}, eq1{1})));
  49. BOOST_HANA_CONSTEXPR_CHECK(hana::not_(hana::equal(eq2{1}, eq1{0})));
  50. }
  51. // laws
  52. hana::test::TestComparable<int>{hana::make_tuple(0,1,2,3,4,5)};
  53. hana::test::TestComparable<unsigned int>{hana::make_tuple(0u,1u,2u,3u,4u,5u)};
  54. hana::test::TestComparable<long>{hana::make_tuple(0l,1l,2l,3l,4l,5l)};
  55. hana::test::TestComparable<unsigned long>{hana::make_tuple(0ul,1ul,2ul,3ul,4ul,5ul)};
  56. hana::test::TestComparable<eq1>{hana::make_tuple(eq1{0}, eq1{1}, eq1{2}, eq1{3}, eq1{4})};
  57. }