95 lines
2.9 KiB
C++
95 lines
2.9 KiB
C++
// Copyright Louis Dionne 2013-2017
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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/first.hpp>
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#include <boost/hana/pair.hpp>
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#include <boost/hana/second.hpp>
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#include <type_traits>
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namespace hana = boost::hana;
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template <typename Target>
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struct implicit_to {
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constexpr operator Target() const { return Target{}; }
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};
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struct NoCopy {
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NoCopy() = default;
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NoCopy(NoCopy const&) = delete;
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};
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// Note: It is also useful to check with a non-empty class, because that
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// triggers different instantiations due to EBO.
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struct NoCopy_nonempty {
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NoCopy_nonempty() = default;
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NoCopy_nonempty(NoCopy_nonempty const&) = delete;
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int i;
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};
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int main() {
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{
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typedef std::pair<int, short> P1;
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hana::pair<int, short> p1(3, 4);
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hana::pair<int, short> p2 = p1;
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BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
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BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
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}
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static_assert(std::is_trivially_copy_constructible<hana::pair<int, int>>{}, "");
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// make sure it also works constexpr
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{
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constexpr hana::pair<int, short> p1(3, 4);
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constexpr hana::pair<int, short> p2 = p1;
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static_assert(hana::first(p2) == 3, "");
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static_assert(hana::second(p2) == 4, "");
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}
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// Make sure it works across pair types (pair<T, U> -> pair<U, V>)
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{
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hana::pair<int, short> p1(3, 4);
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hana::pair<double, long> p2 = p1;
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BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
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BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
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}
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{
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struct target1 { };
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struct target2 { };
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using Target = hana::pair<target1, target2>;
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auto p1_ = hana::make_pair(target1{}, target2{});
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Target p1(p1_); (void)p1;
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auto p2_ = hana::make_pair(implicit_to<target1>{}, target2{});
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Target p2(p2_); (void)p2;
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auto p3_ = hana::make_pair(target1{}, implicit_to<target2>{});
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Target p3(p3_); (void)p3;
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auto p4_ = hana::make_pair(implicit_to<target1>{}, implicit_to<target2>{});
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Target p4(p4_); (void)p4;
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}
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// And also constexpr across pair types
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{
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constexpr hana::pair<int, short> p1(3, 4);
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constexpr hana::pair<double, long> p2 = p1;
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static_assert(hana::first(p2) == 3, "");
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static_assert(hana::second(p2) == 4, "");
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}
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// Make sure we don't define the copy constructor when it shouldn't be defined.
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{
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using Pair1 = hana::pair<NoCopy, NoCopy>;
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Pair1 pair1; (void)pair1;
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static_assert(!std::is_copy_constructible<Pair1>::value, "");
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using Pair2 = hana::pair<NoCopy_nonempty, NoCopy_nonempty>;
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Pair2 pair2; (void)pair2;
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static_assert(!std::is_copy_constructible<Pair2>::value, "");
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}
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}
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