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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