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