diff options
Diffstat (limited to 'boost/compute/lambda/placeholders.hpp')
-rw-r--r-- | boost/compute/lambda/placeholders.hpp | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/boost/compute/lambda/placeholders.hpp b/boost/compute/lambda/placeholders.hpp new file mode 100644 index 0000000000..5c3fe531d1 --- /dev/null +++ b/boost/compute/lambda/placeholders.hpp @@ -0,0 +1,93 @@ +//---------------------------------------------------------------------------// +// 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_LAMBDA_PLACEHOLDERS_HPP +#define BOOST_COMPUTE_LAMBDA_PLACEHOLDERS_HPP + +#include <boost/mpl/has_xxx.hpp> + +#include <boost/compute/lambda/context.hpp> +#include <boost/compute/lambda/result_of.hpp> + +namespace boost { +namespace compute { +namespace lambda { + +namespace mpl = boost::mpl; +namespace proto = boost::proto; + +// lambda placeholders +expression<proto::terminal<placeholder<0> >::type> const _1; +expression<proto::terminal<placeholder<1> >::type> const _2; +expression<proto::terminal<placeholder<2> >::type> const _3; + +namespace detail { + +BOOST_MPL_HAS_XXX_TRAIT_DEF(result_type) + +template<class T, bool HasResultType> +struct terminal_type_impl; + +template<class T> +struct terminal_type_impl<T, true> +{ + typedef typename T::result_type type; +}; + +template<class T> +struct terminal_type_impl<T, false> +{ + typedef T type; +}; + +template<class T> +struct terminal_type +{ + typedef typename terminal_type_impl<T, has_result_type<T>::value>::type type; +}; + +} // end detail namespace + +// result_of placeholders +template<class Args> +struct result_of<expression<proto::terminal<placeholder<0> >::type>, Args, proto::tag::terminal> +{ + typedef typename boost::tuples::element<0, Args>::type arg_type; + + typedef typename detail::terminal_type<arg_type>::type type; +}; + +template<class Args> +struct result_of<expression<proto::terminal<placeholder<1> >::type>, Args, proto::tag::terminal> +{ + typedef typename boost::tuples::element<1, Args>::type arg_type; + + typedef typename detail::terminal_type<arg_type>::type type; +}; + +template<class Args> +struct result_of<expression<proto::terminal<placeholder<2> >::type>, Args, proto::tag::terminal> +{ + typedef typename boost::tuples::element<2, Args>::type arg_type; + + typedef typename detail::terminal_type<arg_type>::type type; +}; + +} // end lambda namespace + +// lift lambda placeholders up to the boost::compute namespace +using lambda::_1; +using lambda::_2; +using lambda::_3; + +} // end compute namespace +} // end boost namespace + +#endif // BOOST_COMPUTE_LAMBDA_PLACEHOLDERS_HPP |