ecency-mobile/ios/Pods/boost-for-react-native/boost/compute/functional/get.hpp

77 lines
1.9 KiB
C++

//---------------------------------------------------------------------------//
// 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