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51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
/*
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@copyright Louis Dionne 2014
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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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*/
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#include <boost/hana/assert.hpp>
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#include <boost/hana/core/convert.hpp>
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#include <boost/hana/detail/constexpr.hpp>
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#include <boost/hana/tuple.hpp>
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using namespace boost::hana;
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//! [is_convertible]
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struct Person { };
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struct Employee : Person { };
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static_assert(is_convertible<Employee, Person>{}, "");
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static_assert(!is_convertible<Person, Employee>{}, "");
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static_assert(is_convertible<int, float>{}, "");
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//! [is_convertible]
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//! [to]
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template <typename X, typename Y, typename Z>
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struct Triple {
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X first;
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Y second;
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Z third;
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};
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BOOST_HANA_CONSTEXPR_LAMBDA auto triple = [](auto x, auto y, auto z) {
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return Triple<decltype(x), decltype(y), decltype(z)>{x, y, z};
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};
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namespace boost { namespace hana {
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template <typename X, typename Y, typename Z>
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struct to_impl<Tuple, Triple<X, Y, Z>> {
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static constexpr auto apply(Triple<X, Y, Z> xs) {
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return tuple(xs.first, xs.second, xs.third);
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}
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};
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}}
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int main() {
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BOOST_HANA_CONSTEXPR_CHECK(
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to<Tuple>(triple(1, '2', 3.3)) == tuple(1, '2', 3.3)
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);
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}
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//! [to]
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