34 lines
962 B
C++
34 lines
962 B
C++
/*!
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@file
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Defines `boost::hana::Foldable`.
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@copyright Louis Dionne 2013-2016
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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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#ifndef BOOST_HANA_CONCEPT_FOLDABLE_HPP
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#define BOOST_HANA_CONCEPT_FOLDABLE_HPP
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#include <boost/hana/fwd/concept/foldable.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/default.hpp>
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#include <boost/hana/core/tag_of.hpp>
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#include <boost/hana/detail/integral_constant.hpp>
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#include <boost/hana/fold_left.hpp>
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#include <boost/hana/unpack.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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template <typename T>
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struct Foldable
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: hana::integral_constant<bool,
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!is_default<fold_left_impl<typename tag_of<T>::type>>::value ||
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!is_default<unpack_impl<typename tag_of<T>::type>>::value
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>
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{ };
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_CONCEPT_FOLDABLE_HPP
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