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/*=============================================================================
Copyright (c) 2005-2011 Joel de Guzman
Copyright (c) 2005-2006 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(BOOST_FUSION_DEQUE_AT_IMPL_09122006_2017)
#define BOOST_FUSION_DEQUE_AT_IMPL_09122006_2017
#include <boost/fusion/container/deque/detail/keyed_element.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/equal_to.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/add_reference.hpp>
namespace boost { namespace fusion {
struct deque_tag;
namespace extension
{
template<typename T>
struct at_impl;
template<>
struct at_impl<deque_tag>
{
template<typename Sequence, typename N>
struct apply
{
typedef typename Sequence::next_up next_up;
typedef typename Sequence::next_down next_down;
BOOST_MPL_ASSERT_RELATION(next_down::value, !=, next_up::value);
typedef mpl::plus<next_down, mpl::int_<1> > offset;
typedef mpl::int_<mpl::plus<N, offset>::value> adjusted_index;
typedef typename detail::keyed_element_value_at<Sequence, adjusted_index>::type element_type;
typedef typename add_reference<
typename mpl::eval_if<
is_const<Sequence>,
add_const<element_type>,
mpl::identity<element_type> >::type>::type type;
static type call(Sequence& seq)
{
return seq.get(adjusted_index());
}
};
};
}
}}
#endif
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