| 1 | // Copyright Louis Dionne 2013-2022 |
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| 2 | // Distributed under the Boost Software License, Version 1.0. |
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| 3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) |
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| 4 | |
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| 5 | #include <boost/hana/assert.hpp> |
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| 6 | #include <boost/hana/config.hpp> |
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| 7 | #include <boost/hana/first.hpp> |
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| 8 | #include <boost/hana/pair.hpp> |
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| 9 | #include <boost/hana/second.hpp> |
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| 10 | |
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| 11 | #include <utility> |
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| 12 | namespace hana = boost::hana; |
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| 13 | |
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| 14 | |
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| 15 | struct MoveOnly { |
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| 16 | int data_; |
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| 17 | MoveOnly(MoveOnly const&) = delete; |
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| 18 | MoveOnly& operator=(MoveOnly const&) = delete; |
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| 19 | MoveOnly(int data = 1) : data_(data) { } |
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| 20 | MoveOnly(MoveOnly&& x) : data_(x.data_) { x.data_ = 0; } |
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| 21 | |
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| 22 | MoveOnly& operator=(MoveOnly&& x) |
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| 23 | { data_ = x.data_; x.data_ = 0; return *this; } |
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| 24 | |
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| 25 | bool operator==(const MoveOnly& x) const { return data_ == x.data_; } |
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| 26 | }; |
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| 27 | |
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| 28 | struct MoveOnlyDerived : MoveOnly { |
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| 29 | MoveOnlyDerived(MoveOnlyDerived&&) = default; |
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| 30 | MoveOnlyDerived(int data = 1) : MoveOnly(data) { } |
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| 31 | }; |
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| 32 | |
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| 33 | constexpr auto in_constexpr_context(int a, short b) { |
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| 34 | hana::pair<int, short> p1(a, b); |
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| 35 | hana::pair<int, short> p2; |
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| 36 | hana::pair<double, long> p3; |
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| 37 | p2 = std::move(p1); |
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| 38 | p3 = std::move(p2); |
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| 39 | return p3; |
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| 40 | } |
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| 41 | |
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| 42 | int main() { |
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| 43 | // from pair<T, U> to pair<T, U> |
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| 44 | { |
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| 45 | hana::pair<MoveOnly, short> p1(MoveOnly{3}, 4); |
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| 46 | hana::pair<MoveOnly, short> p2; |
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| 47 | p2 = std::move(p1); |
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| 48 | BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3}); |
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| 49 | BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4); |
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| 50 | } |
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| 51 | |
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| 52 | // from pair<T, U> to pair<V, W> |
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| 53 | { |
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| 54 | hana::pair<MoveOnlyDerived, short> p1(MoveOnlyDerived{3}, 4); |
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| 55 | hana::pair<MoveOnly, long> p2; |
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| 56 | p2 = std::move(p1); |
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| 57 | BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3}); |
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| 58 | BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4); |
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| 59 | } |
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| 60 | |
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| 61 | // make sure that also works in a constexpr context |
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| 62 | // (test fails under GCC <= 6 due to buggy constexpr) |
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| 63 | #if BOOST_HANA_CONFIG_GCC >= BOOST_HANA_CONFIG_VERSION(7, 0, 0) |
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| 64 | { |
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| 65 | constexpr auto p = in_constexpr_context(3, 4); |
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| 66 | static_assert(hana::first(p) == 3, "" ); |
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| 67 | static_assert(hana::second(p) == 4, "" ); |
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| 68 | } |
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| 69 | #endif |
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| 70 | } |
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| 71 | |
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