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- // Copyright Louis Dionne 2013-2017
- // Distributed under the Boost Software License, Version 1.0.
- // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- #include <boost/hana/assert.hpp>
- #include <boost/hana/concept/metafunction.hpp>
- #include <boost/hana/equal.hpp>
- #include <boost/hana/not.hpp>
- #include <boost/hana/type.hpp>
- #include <type_traits>
- namespace hana = boost::hana;
- struct x1; struct x2; struct x3;
- struct y1 { }; struct y2 { }; struct y3 { };
- struct f { template <typename ...> struct apply { struct type; }; };
- template <typename F, typename ...T>
- constexpr auto valid_call(F f, T ...t) -> decltype(((void)f(t...)), true)
- { return true; }
- constexpr auto valid_call(...)
- { return false; }
- BOOST_HANA_CONSTANT_CHECK(hana::equal(
- hana::metafunction_class<f>(),
- hana::type_c<f::apply<>::type>
- ));
- BOOST_HANA_CONSTANT_CHECK(hana::equal(
- hana::metafunction_class<f>(hana::type_c<x1>),
- hana::type_c<f::apply<x1>::type>
- ));
- BOOST_HANA_CONSTANT_CHECK(hana::equal(
- hana::metafunction_class<f>(hana::type_c<x1>, hana::type_c<x2>),
- hana::type_c<f::apply<x1, x2>::type>
- ));
- BOOST_HANA_CONSTANT_CHECK(hana::equal(
- hana::metafunction_class<f>(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>),
- hana::type_c<f::apply<x1, x2, x3>::type>
- ));
- using F = decltype(hana::metafunction_class<f>);
- static_assert(std::is_same<F::apply<>, f::apply<>>{}, "");
- static_assert(std::is_same<F::apply<x1>, f::apply<x1>>{}, "");
- static_assert(std::is_same<F::apply<x1, x2>, f::apply<x1, x2>>{}, "");
- static_assert(std::is_same<F::apply<x1, x2, x3>, f::apply<x1, x2, x3>>{}, "");
- // Make sure we're SFINAE-friendly
- struct no_type { template <typename ...> struct apply { }; };
- static_assert(!valid_call(hana::metafunction_class<no_type>), "");
- static_assert(!valid_call(hana::metafunction_class<no_type>, hana::type_c<x1>), "");
- // Make sure we model the Metafunction concept
- static_assert(hana::Metafunction<decltype(hana::metafunction_class<f>)>::value, "");
- static_assert(hana::Metafunction<decltype(hana::metafunction_class<f>)&>::value, "");
- // Make sure metafunction_class is SFINAE-friendly
- struct not_a_mfc1 { template <typename ...> struct apply { }; };
- struct not_a_mfc2 { };
- BOOST_HANA_CONSTANT_CHECK(hana::not_(
- hana::is_valid(hana::metafunction_class<not_a_mfc1>)(hana::type_c<void>)
- ));
- BOOST_HANA_CONSTANT_CHECK(hana::not_(
- hana::is_valid(hana::metafunction_class<not_a_mfc2>)(hana::type_c<void>)
- ));
- // Make sure we don't read from a non-constexpr variable
- int main() {
- auto t = hana::type_c<x1>;
- constexpr auto r = hana::metafunction_class<f>(t);
- (void)r;
- }
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