ceph/src/boost/libs/hana/test/type/template.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/assert.hpp>
   6 #include <boost/hana/concept/metafunction.hpp>
   7 #include <boost/hana/equal.hpp>
   8 #include <boost/hana/type.hpp>
   9
  10 #include <type_traits>
  11 namespace hana = boost::hana;
  12
  13
  14 struct x1; struct x2; struct x3;
  15 struct y1 { }; struct y2 { }; struct y3 { };
  16 template <typename ...> struct f;
  17
  18 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  19     hana::template_<f>(),
  20     hana::type_c<f<>>
  21 ));
  22 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  23     hana::template_<f>(hana::type_c<x1>),
  24     hana::type_c<f<x1>>
  25 ));
  26 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  27     hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>),
  28     hana::type_c<f<x1, x2>>
  29 ));
  30 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  31     hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>),
  32     hana::type_c<f<x1, x2, x3>>
  33 ));
  34
  35 using F = decltype(hana::template_<f>);
  36 static_assert(std::is_same<F::apply<>::type, f<>>{}, "");
  37 static_assert(std::is_same<F::apply<x1>::type, f<x1>>{}, "");
  38 static_assert(std::is_same<F::apply<x1, x2>::type, f<x1, x2>>{}, "");
  39 static_assert(std::is_same<F::apply<x1, x2, x3>::type, f<x1, x2, x3>>{}, "");
  40
  41 // Make sure we model the Metafunction concept
  42 static_assert(hana::Metafunction<decltype(hana::template_<f>)>::value, "");
  43 static_assert(hana::Metafunction<decltype(hana::template_<f>)&>::value, "");
  44
  45 // Make sure we can use aliases
  46 template <typename T> using alias = T;
  47 static_assert(hana::template_<alias>(hana::type_c<x1>) == hana::type_c<x1>, "");
  48
  49
  50 // Make sure we don't read from a non-constexpr variable
  51 int main() {
  52     auto t = hana::type_c<x1>;
  53     constexpr auto r = hana::template_<f>(t);
  54     (void)r;
  55 }