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/not.hpp>
   9 #include <boost/hana/type.hpp>
  10
  11 #include <type_traits>
  12 namespace hana = boost::hana;
  13
  14
  15 struct x1; struct x2; struct x3;
  16 struct y1 { }; struct y2 { }; struct y3 { };
  17 template <typename ...> struct f;
  18
  19 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  20     hana::template_<f>(),
  21     hana::type_c<f<>>
  22 ));
  23 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  24     hana::template_<f>(hana::type_c<x1>),
  25     hana::type_c<f<x1>>
  26 ));
  27 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  28     hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>),
  29     hana::type_c<f<x1, x2>>
  30 ));
  31 BOOST_HANA_CONSTANT_CHECK(hana::equal(
  32     hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>),
  33     hana::type_c<f<x1, x2, x3>>
  34 ));
  35
  36 using F = decltype(hana::template_<f>);
  37 static_assert(std::is_same<F::apply<>::type, f<>>{}, "");
  38 static_assert(std::is_same<F::apply<x1>::type, f<x1>>{}, "");
  39 static_assert(std::is_same<F::apply<x1, x2>::type, f<x1, x2>>{}, "");
  40 static_assert(std::is_same<F::apply<x1, x2, x3>::type, f<x1, x2, x3>>{}, "");
  41
  42 // Make sure we model the Metafunction concept
  43 static_assert(hana::Metafunction<decltype(hana::template_<f>)>::value, "");
  44 static_assert(hana::Metafunction<decltype(hana::template_<f>)&>::value, "");
  45
  46 // Make sure we can use aliases
  47 template <typename T> using alias = T;
  48 static_assert(hana::template_<alias>(hana::type_c<x1>) == hana::type_c<x1>, "");
  49
  50 // Make sure template_ is SFINAE-friendly
  51 template <typename T> struct unary;
  52 BOOST_HANA_CONSTANT_CHECK(hana::not_(
  53     hana::is_valid(hana::template_<unary>)(hana::type_c<void>, hana::type_c<void>)
  54 ));
  55
  56 // Make sure we don't read from a non-constexpr variable
  57 int main() {
  58     auto t = hana::type_c<x1>;
  59     constexpr auto r = hana::template_<f>(t);
  60     (void)r;
  61 }