77 lines
1.9 KiB
C++
77 lines
1.9 KiB
C++
//---------------------------------------------------------------------------//
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// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_FUNCTIONAL_GET_HPP
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#define BOOST_COMPUTE_FUNCTIONAL_GET_HPP
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#include <cstddef>
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#include <boost/compute/types/fundamental.hpp>
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#include <boost/compute/type_traits/scalar_type.hpp>
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namespace boost {
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namespace compute {
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namespace detail {
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// meta-function returning the result type for get<N>()
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template<size_t N, class Arg>
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struct get_result_type
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{
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typedef typename scalar_type<Arg>::type type;
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};
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template<size_t N, class Arg, class T>
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struct invoked_get
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{
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typedef typename get_result_type<N, T>::type result_type;
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invoked_get(const Arg &arg)
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: m_arg(arg)
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{
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}
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Arg m_arg;
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};
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} // end detail namespace
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/// Returns the \c N'th element of an aggregate type (e.g. scalarN,
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/// pair, tuple, etc.).
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///
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/// \see \ref field "field<T>"
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template<size_t N>
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struct get
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{
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/// \internal_
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template<class> struct result;
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/// \internal_
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template<class F, class Arg>
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struct result<F(Arg)>
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{
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typedef typename detail::get_result_type<N, Arg>::type type;
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};
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template<class Arg>
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detail::invoked_get<
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N, Arg, typename boost::remove_cv<typename Arg::result_type>::type
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> operator()(const Arg &arg) const
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{
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typedef typename boost::remove_cv<typename Arg::result_type>::type T;
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return detail::invoked_get<N, Arg, T>(arg);
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}
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};
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_FUNCTIONAL_GET_HPP
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