ceph/src/boost/libs/hana/example/type/metafunction.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/equal.hpp>
   7 #include <boost/hana/type.hpp>
   8
   9 #include <type_traits>
  10 namespace hana = boost::hana;
  11
  12
  13 template <typename ...> struct f { struct type; };
  14 struct x;
  15 struct y;
  16
  17 BOOST_HANA_CONSTANT_CHECK(hana::metafunction<f>() == hana::type_c<f<>::type>);
  18 BOOST_HANA_CONSTANT_CHECK(hana::metafunction<f>(hana::type_c<x>) == hana::type_c<f<x>::type>);
  19 BOOST_HANA_CONSTANT_CHECK(hana::metafunction<f>(hana::type_c<x>, hana::type_c<y>) == hana::type_c<f<x, y>::type>);
  20
  21 static_assert(std::is_same<
  22     decltype(hana::metafunction<f>)::apply<x, y>::type,
  23     f<x, y>::type
  24 >::value, "");
  25
  26 int main() { }