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62 lines
2.0 KiB
C++
62 lines
2.0 KiB
C++
// Copyright Louis Dionne 2013-2022
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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#include <boost/hana/assert.hpp>
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#include <boost/hana/concept/metafunction.hpp>
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#include <boost/hana/equal.hpp>
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#include <boost/hana/not.hpp>
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#include <boost/hana/type.hpp>
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#include <type_traits>
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namespace hana = boost::hana;
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struct x1; struct x2; struct x3;
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struct y1 { }; struct y2 { }; struct y3 { };
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template <typename ...> struct f;
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BOOST_HANA_CONSTANT_CHECK(hana::equal(
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hana::template_<f>(),
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hana::type_c<f<>>
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));
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BOOST_HANA_CONSTANT_CHECK(hana::equal(
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hana::template_<f>(hana::type_c<x1>),
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hana::type_c<f<x1>>
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));
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BOOST_HANA_CONSTANT_CHECK(hana::equal(
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hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>),
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hana::type_c<f<x1, x2>>
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));
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BOOST_HANA_CONSTANT_CHECK(hana::equal(
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hana::template_<f>(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>),
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hana::type_c<f<x1, x2, x3>>
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));
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using F = decltype(hana::template_<f>);
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static_assert(std::is_same<F::apply<>::type, f<>>{}, "");
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static_assert(std::is_same<F::apply<x1>::type, f<x1>>{}, "");
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static_assert(std::is_same<F::apply<x1, x2>::type, f<x1, x2>>{}, "");
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static_assert(std::is_same<F::apply<x1, x2, x3>::type, f<x1, x2, x3>>{}, "");
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// Make sure we model the Metafunction concept
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static_assert(hana::Metafunction<decltype(hana::template_<f>)>::value, "");
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static_assert(hana::Metafunction<decltype(hana::template_<f>)&>::value, "");
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// Make sure we can use aliases
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template <typename T> using alias = T;
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static_assert(hana::template_<alias>(hana::type_c<x1>) == hana::type_c<x1>, "");
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// Make sure template_ is SFINAE-friendly
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template <typename T> struct unary;
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BOOST_HANA_CONSTANT_CHECK(hana::not_(
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hana::is_valid(hana::template_<unary>)(hana::type_c<void>, hana::type_c<void>)
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));
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// Make sure we don't read from a non-constexpr variable
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int main() {
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auto t = hana::type_c<x1>;
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constexpr auto r = hana::template_<f>(t);
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(void)r;
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}
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