72 lines
1.9 KiB
C++
72 lines
1.9 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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struct NoDefault {
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NoDefault() = delete;
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explicit constexpr NoDefault(int) { }
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};
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struct NoDefault_nonempty {
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NoDefault_nonempty() = delete;
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explicit constexpr NoDefault_nonempty(int k) : i(k) { }
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int i;
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};
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struct DefaultOnly {
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DefaultOnly() = default;
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DefaultOnly(DefaultOnly const&) = delete;
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DefaultOnly(DefaultOnly&&) = delete;
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};
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struct NonConstexprDefault {
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NonConstexprDefault() { }
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};
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int main() {
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{
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hana::pair<float, short*> p;
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BOOST_HANA_RUNTIME_CHECK(hana::first(p) == 0.0f);
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BOOST_HANA_RUNTIME_CHECK(hana::second(p) == nullptr);
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}
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// make sure it also works constexpr
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{
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constexpr hana::pair<float, short*> p;
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static_assert(hana::first(p) == 0.0f, "");
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static_assert(hana::second(p) == nullptr, "");
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}
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// make sure the default constructor is not instantiated when the
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// members of the pair are not default-constructible
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{
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using Pair1 = hana::pair<NoDefault, NoDefault>;
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Pair1 p1{NoDefault{1}, NoDefault{2}}; (void)p1;
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static_assert(!std::is_default_constructible<Pair1>{}, "");
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using Pair2 = hana::pair<NoDefault_nonempty, NoDefault_nonempty>;
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Pair2 p2{NoDefault_nonempty{1}, NoDefault_nonempty{2}}; (void)p2;
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static_assert(!std::is_default_constructible<Pair2>{}, "");
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}
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// make sure it works when only the default constructor is defined
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{
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hana::pair<DefaultOnly, DefaultOnly> p;
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(void)p;
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}
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{
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hana::pair<NonConstexprDefault, NonConstexprDefault> p;
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(void)p;
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}
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}
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