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-rw-r--r--boost/compute/functional/get.hpp76
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+//---------------------------------------------------------------------------//
+// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
+//
+// 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
+//
+// See http://boostorg.github.com/compute for more information.
+//---------------------------------------------------------------------------//
+
+#ifndef BOOST_COMPUTE_FUNCTIONAL_GET_HPP
+#define BOOST_COMPUTE_FUNCTIONAL_GET_HPP
+
+#include <cstddef>
+
+#include <boost/compute/types/fundamental.hpp>
+#include <boost/compute/type_traits/scalar_type.hpp>
+
+namespace boost {
+namespace compute {
+namespace detail {
+
+// meta-function returning the result type for get<N>()
+template<size_t N, class Arg>
+struct get_result_type
+{
+ typedef typename scalar_type<Arg>::type type;
+};
+
+template<size_t N, class Arg, class T>
+struct invoked_get
+{
+ typedef typename get_result_type<N, T>::type result_type;
+
+ invoked_get(const Arg &arg)
+ : m_arg(arg)
+ {
+ }
+
+ Arg m_arg;
+};
+
+} // end detail namespace
+
+/// Returns the \c N'th element of an aggregate type (e.g. scalarN,
+/// pair, tuple, etc.).
+///
+/// \see \ref field "field<T>"
+template<size_t N>
+struct get
+{
+ /// \internal_
+ template<class> struct result;
+
+ /// \internal_
+ template<class F, class Arg>
+ struct result<F(Arg)>
+ {
+ typedef typename detail::get_result_type<N, Arg>::type type;
+ };
+
+ template<class Arg>
+ detail::invoked_get<
+ N, Arg, typename boost::remove_cv<typename Arg::result_type>::type
+ > operator()(const Arg &arg) const
+ {
+ typedef typename boost::remove_cv<typename Arg::result_type>::type T;
+
+ return detail::invoked_get<N, Arg, T>(arg);
+ }
+};
+
+} // end compute namespace
+} // end boost namespace
+
+#endif // BOOST_COMPUTE_FUNCTIONAL_GET_HPP