58 lines
1.8 KiB
C++
58 lines
1.8 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/at.hpp>
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#include <boost/hana/bool.hpp>
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#include <boost/hana/first.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/pair.hpp>
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#include <boost/hana/second.hpp>
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#include <boost/hana/tuple.hpp>
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#include <type_traits>
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#include <utility>
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namespace hana = boost::hana;
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// In GitHub issue #331, we noticed that `first` and `second` could sometimes
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// return the wrong member in case of nested pairs. This is due to the way we
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// inherit from base classes to enable EBO. We also check for `basic_tuple`,
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// because both are implemented similarly.
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int main() {
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{
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using Nested = hana::pair<hana::int_<1>, hana::int_<2>>;
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using Pair = hana::pair<hana::int_<0>, Nested>;
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Pair pair{};
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auto a = hana::first(pair);
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static_assert(std::is_same<decltype(a), hana::int_<0>>{}, "");
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auto b = hana::second(pair);
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static_assert(std::is_same<decltype(b), Nested>{}, "");
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}
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{
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using Nested = hana::basic_tuple<hana::int_<1>, hana::int_<2>>;
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using Tuple = hana::basic_tuple<hana::int_<0>, Nested>;
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Tuple tuple{};
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auto a = hana::at_c<0>(tuple);
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static_assert(std::is_same<decltype(a), hana::int_<0>>{}, "");
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auto b = hana::at_c<1>(tuple);
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static_assert(std::is_same<decltype(b), Nested>{}, "");
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}
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// Original test case submitted by Vittorio Romeo
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{
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hana::pair<hana::int_<1>, hana::bool_<false>> p{};
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auto copy = hana::make_pair(hana::int_c<0>, p);
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auto move = hana::make_pair(hana::int_c<0>, std::move(p));
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copy = move; // copy assign
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copy = std::move(move); // move assign
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}
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}
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