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- /*=============================================================================
- Copyright (c) 2001-2011 Joel de Guzman
- Copyright (c) 2006 Dan Marsden
- Distributed under the Boost Software License, Version 1.0. (See accompanying
- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- ==============================================================================*/
- #if !defined(FUSION_AT_IMPL_20060124_1933)
- #define FUSION_AT_IMPL_20060124_1933
- #include <boost/fusion/support/config.hpp>
- #include <boost/fusion/container/vector.hpp>
- #include <boost/fusion/sequence/intrinsic/at.hpp>
- #include <boost/fusion/container/vector/convert.hpp>
- #include <boost/fusion/algorithm/transformation/transform.hpp>
- #include <boost/type_traits/remove_reference.hpp>
- #include <boost/type_traits/is_reference.hpp>
- #include <boost/mpl/assert.hpp>
- #include <boost/fusion/support/unused.hpp>
- #include <boost/mpl/eval_if.hpp>
- #include <boost/mpl/identity.hpp>
- #include <boost/type_traits/is_same.hpp>
- namespace boost { namespace fusion
- {
- struct zip_view_tag;
- namespace detail
- {
- template<typename N>
- struct poly_at
- {
- template<typename T>
- struct result;
- template<typename N1, typename SeqRef>
- struct result<poly_at<N1>(SeqRef)>
- : mpl::eval_if<is_same<SeqRef, unused_type const&>,
- mpl::identity<unused_type>,
- result_of::at<typename remove_reference<SeqRef>::type, N> >
- {
- BOOST_MPL_ASSERT((is_reference<SeqRef>));
- };
- template<typename Seq>
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- typename result<poly_at(Seq&)>::type
- operator()(Seq& seq) const
- {
- return fusion::at<N>(seq);
- }
- template<typename Seq>
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- typename result<poly_at(Seq const&)>::type
- operator()(Seq const& seq) const
- {
- return fusion::at<N>(seq);
- }
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- unused_type operator()(unused_type const&) const
- {
- return unused_type();
- }
- };
- }
- namespace extension
- {
- template<typename Tag>
- struct at_impl;
- template<>
- struct at_impl<zip_view_tag>
- {
- template<typename Seq, typename N>
- struct apply
- {
- typedef typename result_of::as_vector<
- typename result_of::transform<
- typename Seq::sequences, detail::poly_at<N> >::type>::type type;
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- static type
- call(Seq& seq)
- {
- return type(
- fusion::transform(seq.sequences_, detail::poly_at<N>()));
- }
- };
- };
- }
- }}
- #endif
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