57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
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///////////////////////////////////////////////////////////////////////////////
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/// \file at.hpp
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/// Proto callables Fusion at
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//
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// Copyright 2010 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_PROTO_FUNCTIONAL_FUSION_AT_HPP_EAN_11_27_2010
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#define BOOST_PROTO_FUNCTIONAL_FUSION_AT_HPP_EAN_11_27_2010
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#include <boost/type_traits/add_const.hpp>
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#include <boost/type_traits/remove_const.hpp>
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#include <boost/type_traits/remove_reference.hpp>
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#include <boost/fusion/include/at.hpp>
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#include <boost/proto/proto_fwd.hpp>
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namespace boost { namespace proto { namespace functional
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{
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/// \brief A PolymorphicFunctionObject type that invokes the
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/// \c fusion::at() accessor on its argument.
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///
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/// A PolymorphicFunctionObject type that invokes the
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/// \c fusion::at() accessor on its argument.
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struct at
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Seq, typename N>
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struct result<This(Seq, N)>
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: fusion::result_of::at<
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typename boost::remove_reference<Seq>::type
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, typename boost::remove_const<typename boost::remove_reference<N>::type>::type
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>
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{};
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template<typename Seq, typename N>
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typename fusion::result_of::at<Seq, N>::type
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operator ()(Seq &seq, N const & BOOST_PROTO_DISABLE_IF_IS_CONST(Seq)) const
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{
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return fusion::at<N>(seq);
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}
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template<typename Seq, typename N>
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typename fusion::result_of::at<Seq const, N>::type
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operator ()(Seq const &seq, N const &) const
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{
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return fusion::at<N>(seq);
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}
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};
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}}}
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#endif
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