ceph/src/boost/libs/hana/test/core/tag_of.cpp

   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
   5 #include <boost/hana/core/tag_of.hpp>
   6 #include <boost/hana/core/when.hpp>
   7
   8 #include <type_traits>
   9 namespace hana = boost::hana;
  10
  11
  12 template <typename T, typename ExpectedDatatype>
  13 struct test {
  14     static_assert(std::is_same<hana::tag_of_t<T>, ExpectedDatatype>::value, "");
  15     static_assert(std::is_same<hana::tag_of_t<T const>, ExpectedDatatype>::value, "");
  16     static_assert(std::is_same<hana::tag_of_t<T volatile>, ExpectedDatatype>::value, "");
  17     static_assert(std::is_same<hana::tag_of_t<T const volatile>, ExpectedDatatype>::value, "");
  18
  19     static_assert(std::is_same<hana::tag_of_t<T&>, ExpectedDatatype>::value, "");
  20     static_assert(std::is_same<hana::tag_of_t<T const&>, ExpectedDatatype>::value, "");
  21     static_assert(std::is_same<hana::tag_of_t<T volatile&>, ExpectedDatatype>::value, "");
  22     static_assert(std::is_same<hana::tag_of_t<T const volatile&>, ExpectedDatatype>::value, "");
  23
  24     static_assert(std::is_same<hana::tag_of_t<T&&>, ExpectedDatatype>::value, "");
  25     static_assert(std::is_same<hana::tag_of_t<T const&&>, ExpectedDatatype>::value, "");
  26     static_assert(std::is_same<hana::tag_of_t<T volatile&&>, ExpectedDatatype>::value, "");
  27     static_assert(std::is_same<hana::tag_of_t<T const volatile&&>, ExpectedDatatype>::value, "");
  28 };
  29
  30 struct NestedDatatype;
  31 struct Nested { struct hana_tag; };
  32 template struct test<Nested, Nested::hana_tag>;
  33
  34 struct NoNestedDatatype { };
  35 template struct test<NoNestedDatatype, NoNestedDatatype>;
  36
  37 struct NoNestedHana { };
  38 template struct test<NoNestedHana, NoNestedHana>;
  39
  40
  41 struct FullySpecializedDatatype;
  42 struct FullySpecialized;
  43 namespace boost { namespace hana {
  44     template <>
  45     struct tag_of<FullySpecialized> {
  46         using type = FullySpecializedDatatype;
  47     };
  48 }}
  49 template struct test<FullySpecialized, FullySpecializedDatatype>;
  50
  51
  52 struct PartiallySpecializedDatatype;
  53 template <typename> struct PartiallySpecialized;
  54 namespace boost { namespace hana {
  55     template <typename T>
  56     struct tag_of<PartiallySpecialized<T>> {
  57         using type = PartiallySpecializedDatatype;
  58     };
  59 }}
  60 template struct test<PartiallySpecialized<struct anything>, PartiallySpecializedDatatype>;
  61
  62
  63 struct PredicatedDatatype;
  64 struct Predicated { static constexpr bool predicate = true; };
  65 namespace boost { namespace hana {
  66     template <typename T>
  67     struct tag_of<T, hana::when<T::predicate>> {
  68         using type = PredicatedDatatype;
  69     };
  70 }}
  71 template struct test<Predicated, PredicatedDatatype>;
  72
  73
  74 int main() { }