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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/at.hpp>
- #include <boost/hana/at_key.hpp>
- #include <boost/hana/back.hpp>
- #include <boost/hana/front.hpp>
- #include <boost/hana/integral_constant.hpp>
- #include <boost/hana/tuple.hpp>
- #include <utility>
- namespace hana = boost::hana;
- template <typename T>
- T const& cref(T& t) { return t; }
- // a non-movable, non-copyable type
- struct RefOnly {
- RefOnly() = default;
- RefOnly(RefOnly const&) = delete;
- RefOnly(RefOnly&&) = delete;
- };
- template <int i>
- struct RefOnly_i : hana::int_<i> {
- RefOnly_i() = default;
- RefOnly_i(RefOnly_i const&) = delete;
- RefOnly_i(RefOnly_i&&) = delete;
- };
- int main() {
- hana::tuple<RefOnly> t;
- // Make sure that we return the proper reference types from `at`.
- {
- RefOnly&& r1 = hana::at_c<0>(std::move(t));
- RefOnly& r2 = hana::at_c<0>(t);
- RefOnly const& r3 = hana::at_c<0>(cref(t));
- (void)r1; (void)r2; (void)r3;
- }
- // Make sure we return the proper reference types from `front`.
- {
- RefOnly&& r1 = hana::front(std::move(t));
- RefOnly& r2 = hana::front(t);
- RefOnly const& r3 = hana::front(cref(t));
- (void)r1; (void)r2; (void)r3;
- }
- // Make sure we return the proper reference types from `back`.
- {
- RefOnly&& r1 = hana::back(std::move(t));
- RefOnly& r2 = hana::back(t);
- RefOnly const& r3 = hana::back(cref(t));
- (void)r1; (void)r2; (void)r3;
- }
- // Make sure we return the proper reference types from `at_key`.
- {
- hana::tuple<RefOnly_i<3>> t{};
- RefOnly_i<3>& r1 = hana::at_key(t, RefOnly_i<3>{});
- RefOnly_i<3> const& r2 = hana::at_key(cref(t), RefOnly_i<3>{});
- RefOnly_i<3>&& r3 = hana::at_key(std::move(t), RefOnly_i<3>{});
- (void)r1; (void)r2; (void)r3;
- }
- }
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