64 lines
1.8 KiB
C++
64 lines
1.8 KiB
C++
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/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#if !defined(FUSION_EMPTY_09162005_0335)
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#define FUSION_EMPTY_09162005_0335
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#include <boost/fusion/support/config.hpp>
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#include <boost/fusion/sequence/intrinsic_fwd.hpp>
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#include <boost/fusion/sequence/intrinsic/size.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/fusion/support/tag_of.hpp>
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namespace boost { namespace fusion
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{
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// Special tags:
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struct sequence_facade_tag;
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struct mpl_sequence_tag; // mpl sequence tag
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namespace extension
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{
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template <typename Tag>
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struct empty_impl
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{
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template <typename Sequence>
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struct apply
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: mpl::bool_<(result_of::size<Sequence>::value == 0)>
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{};
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};
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template <>
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struct empty_impl<sequence_facade_tag>
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{
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template <typename Sequence>
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struct apply : Sequence::template empty<Sequence> {};
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};
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template <>
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struct empty_impl<mpl_sequence_tag>;
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}
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namespace result_of
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{
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template <typename Sequence>
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struct empty
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: extension::empty_impl<typename detail::tag_of<Sequence>::type>::
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template apply<Sequence>
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{};
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}
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template <typename Sequence>
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BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
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inline typename result_of::empty<Sequence>::type
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empty(Sequence const&)
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{
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typedef typename result_of::empty<Sequence>::type result;
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return result();
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}
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}}
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#endif
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