forked from boostorg/fusion
60 lines
2.0 KiB
C++
60 lines
2.0 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Copyright (c) 2005-2006 Dan Marsden
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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(BOOST_FUSION_DEQUE_AT_IMPL_09122006_2017)
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#define BOOST_FUSION_DEQUE_AT_IMPL_09122006_2017
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#include <boost/fusion/container/deque/detail/keyed_element.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/equal_to.hpp>
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#include <boost/mpl/assert.hpp>
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#include <boost/mpl/identity.hpp>
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#include <boost/type_traits/is_const.hpp>
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#include <boost/type_traits/add_const.hpp>
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#include <boost/type_traits/add_reference.hpp>
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namespace boost { namespace fusion {
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struct deque_tag;
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namespace extension
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{
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template<typename T>
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struct at_impl;
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template<>
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struct at_impl<deque_tag>
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{
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template<typename Sequence, typename N>
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struct apply
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{
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typedef typename Sequence::next_up next_up;
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typedef typename Sequence::next_down next_down;
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BOOST_MPL_ASSERT_RELATION(next_down::value, !=, next_up::value);
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typedef mpl::plus<next_down, mpl::int_<1> > offset;
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typedef mpl::int_<mpl::plus<N, offset>::value> adjusted_index;
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typedef typename detail::keyed_element_value_at<Sequence, adjusted_index>::type element_type;
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typedef typename add_reference<
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typename mpl::eval_if<
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is_const<Sequence>,
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add_const<element_type>,
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mpl::identity<element_type> >::type>::type type;
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static type call(Sequence& seq)
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{
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return seq.get(adjusted_index());
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}
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};
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};
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}
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}}
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#endif
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