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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/bool.hpp>
- #include <boost/hana/fwd/hash.hpp>
- #include <boost/hana/map.hpp>
- #include <boost/hana/pair.hpp>
- #include <boost/hana/type.hpp>
- #include <type_traits>
- namespace hana = boost::hana;
- struct NoDefault {
- NoDefault() = delete;
- NoDefault(NoDefault const&) = default;
- constexpr explicit NoDefault(int) { }
- };
- auto operator==(NoDefault const&, NoDefault const&) { return hana::true_c; }
- auto operator!=(NoDefault const&, NoDefault const&) { return hana::false_c; }
- // Note: It is also useful to check with a non-empty class, because that
- // triggers different instantiations due to EBO.
- struct NoDefault_nonempty {
- NoDefault_nonempty() = delete;
- NoDefault_nonempty(NoDefault_nonempty const&) = default;
- constexpr explicit NoDefault_nonempty(int k) : i(k) { }
- int i;
- };
- auto operator==(NoDefault_nonempty const&, NoDefault_nonempty const&) { return hana::true_c; }
- auto operator!=(NoDefault_nonempty const&, NoDefault_nonempty const&) { return hana::false_c; }
- struct Default {
- Default() = default;
- Default(Default const&) = default;
- constexpr explicit Default(int) { }
- };
- auto operator==(Default const&, Default const&) { return hana::true_c; }
- auto operator!=(Default const&, Default const&) { return hana::false_c; }
- namespace boost { namespace hana {
- template <>
- struct hash_impl<NoDefault> {
- static constexpr auto apply(NoDefault const&)
- { return hana::type_c<NoDefault>; };
- };
- template <>
- struct hash_impl<NoDefault_nonempty> {
- static constexpr auto apply(NoDefault_nonempty const&)
- { return hana::type_c<NoDefault_nonempty>; };
- };
- template <>
- struct hash_impl<Default> {
- static constexpr auto apply(Default const&)
- { return hana::type_c<Default>; };
- };
- }}
- int main() {
- auto map1 = hana::make_map(hana::make_pair(Default(1), Default(1)));
- static_assert(std::is_default_constructible<decltype(map1)>::value, "");
- auto map2 = hana::make_map(hana::make_pair(NoDefault(1), NoDefault(1)));
- static_assert(!std::is_default_constructible<decltype(map2)>::value, "");
- auto map3 = hana::make_map(hana::make_pair(NoDefault_nonempty(1), NoDefault_nonempty(1)));
- static_assert(!std::is_default_constructible<decltype(map3)>::value, "");
- }
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