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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/first.hpp>
- #include <boost/hana/pair.hpp>
- #include <boost/hana/second.hpp>
- #include <type_traits>
- namespace hana = boost::hana;
- template <typename Target>
- struct implicit_to {
- constexpr operator Target() const { return Target{}; }
- };
- struct NoCopy {
- NoCopy() = default;
- NoCopy(NoCopy const&) = delete;
- };
- // Note: It is also useful to check with a non-empty class, because that
- // triggers different instantiations due to EBO.
- struct NoCopy_nonempty {
- NoCopy_nonempty() = default;
- NoCopy_nonempty(NoCopy_nonempty const&) = delete;
- int i;
- };
- int main() {
- {
- typedef std::pair<int, short> P1;
- hana::pair<int, short> p1(3, 4);
- hana::pair<int, short> p2 = p1;
- BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
- BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
- }
- static_assert(std::is_trivially_copy_constructible<hana::pair<int, int>>{}, "");
- // make sure it also works constexpr
- {
- constexpr hana::pair<int, short> p1(3, 4);
- constexpr hana::pair<int, short> p2 = p1;
- static_assert(hana::first(p2) == 3, "");
- static_assert(hana::second(p2) == 4, "");
- }
- // Make sure it works across pair types (pair<T, U> -> pair<U, V>)
- {
- hana::pair<int, short> p1(3, 4);
- hana::pair<double, long> p2 = p1;
- BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
- BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
- }
- {
- struct target1 { };
- struct target2 { };
- using Target = hana::pair<target1, target2>;
- auto p1_ = hana::make_pair(target1{}, target2{});
- Target p1(p1_); (void)p1;
- auto p2_ = hana::make_pair(implicit_to<target1>{}, target2{});
- Target p2(p2_); (void)p2;
- auto p3_ = hana::make_pair(target1{}, implicit_to<target2>{});
- Target p3(p3_); (void)p3;
- auto p4_ = hana::make_pair(implicit_to<target1>{}, implicit_to<target2>{});
- Target p4(p4_); (void)p4;
- }
- // And also constexpr across pair types
- {
- constexpr hana::pair<int, short> p1(3, 4);
- constexpr hana::pair<double, long> p2 = p1;
- static_assert(hana::first(p2) == 3, "");
- static_assert(hana::second(p2) == 4, "");
- }
- // Make sure we don't define the copy constructor when it shouldn't be defined.
- {
- using Pair1 = hana::pair<NoCopy, NoCopy>;
- Pair1 pair1; (void)pair1;
- static_assert(!std::is_copy_constructible<Pair1>::value, "");
- using Pair2 = hana::pair<NoCopy_nonempty, NoCopy_nonempty>;
- Pair2 pair2; (void)pair2;
- static_assert(!std::is_copy_constructible<Pair2>::value, "");
- }
- }
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