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84 lines
2.8 KiB
C++
84 lines
2.8 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 mf { struct type { }; };
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struct mfc { template <typename ...> struct apply { struct type { }; }; };
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template <typename ...> struct tpl { };
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// make sure `integral(f)(...)` returns the right type
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction<mf>)()),
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mf<>::type
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction<mf>)(hana::type_c<x1>)),
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mf<x1>::type
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction<mf>)(hana::type_c<x1>, hana::type_c<x2>)),
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mf<x1, x2>::type
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::template_<tpl>)()),
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tpl<>
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::template_<tpl>)(hana::type_c<x1>)),
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tpl<x1>
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::template_<tpl>)(hana::type_c<x1>, hana::type_c<x2>)),
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tpl<x1, x2>
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction_class<mfc>)()),
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mfc::apply<>::type
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction_class<mfc>)(hana::type_c<x1>)),
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mfc::apply<x1>::type
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>{}, "");
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static_assert(std::is_same<
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decltype(hana::integral(hana::metafunction_class<mfc>)(hana::type_c<x1>, hana::type_c<x2>)),
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mfc::apply<x1, x2>::type
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>{}, "");
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// Make sure integral is SFINAE-friendly
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struct invalid_hana_metafunction {
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template <typename ...> struct apply { /* missing type alias */ };
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};
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auto invalid_integral = hana::integral(invalid_hana_metafunction{});
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BOOST_HANA_CONSTANT_CHECK(hana::not_(
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hana::is_valid(invalid_integral)(hana::type_c<void>, hana::type_c<void>)
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));
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int main() {
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// Make sure we can perform the call; we already made sure the return type was correct
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constexpr auto a = hana::integral(hana::metafunction<mf>)(); (void)a;
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constexpr auto b = hana::integral(hana::metafunction<mf>)(hana::type_c<x1>); (void)b;
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constexpr auto c = hana::integral(hana::metafunction<mf>)(hana::type_c<x1>, hana::type_c<x2>); (void)c;
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constexpr auto d = hana::integral(hana::metafunction<mf>)(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>); (void)d;
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// Make sure we don't read from a non-constexpr variable
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auto t = hana::type_c<x1>;
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constexpr auto r = hana::integral(hana::metafunction<mf>)(t);
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(void)r;
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}
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