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51 lines
1.6 KiB
C++
51 lines
1.6 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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//////////////////////////////////////////////////////////////////////////////
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// Important: Keep this file in sync with the Overview in the README
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//////////////////////////////////////////////////////////////////////////////
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#include <boost/hana/detail/assert.hpp>
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#include <boost/hana/foreign.hpp>
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#include <boost/hana/functional/compose.hpp>
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#include <boost/hana/integral.hpp>
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#include <boost/hana/tuple.hpp>
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#include <boost/hana/type.hpp>
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#include <string>
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#include <type_traits>
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using namespace boost::hana;
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struct President { std::string name; };
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struct Car { std::string name; };
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struct City { std::string name; };
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auto name = [](auto x) { return x.name; };
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int main() {
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// Heterogeneous sequences for value-level metaprogramming.
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auto stuff = tuple(President{"Obama"}, Car{"Toyota"}, City{"Quebec"});
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BOOST_HANA_RUNTIME_ASSERT(reverse(fmap(name, stuff)) == tuple("Quebec", "Toyota", "Obama"));
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// No compile-time information is lost (the assertion is done at compile-time).
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BOOST_HANA_CONSTANT_ASSERT(length(stuff) == int_<3>);
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// Type-level metaprogramming works too.
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auto types = fmap(compose(metafunction<std::add_pointer>, decltype_), stuff);
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static_assert(std::is_same<
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decltype(head(types))::type, President*
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>{}, "");
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static_assert(std::is_same<
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decltype(at(int_<1>, types))::type, Car*
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>{}, "");
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static_assert(std::is_same<
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decltype(last(types))::type, City*
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>{}, "");
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}
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