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Diffstat (limited to 'boost/hof/detail/result_type.hpp')
| -rw-r--r-- | boost/hof/detail/result_type.hpp | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/boost/hof/detail/result_type.hpp b/boost/hof/detail/result_type.hpp new file mode 100644 index 0000000000..ce570baab6 --- /dev/null +++ b/boost/hof/detail/result_type.hpp @@ -0,0 +1,43 @@ +/*============================================================================= + Copyright (c) 2016 Paul Fultz II + result_type.hpp + 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) +==============================================================================*/ + +#ifndef BOOST_HOF_GUARD_RESULT_TYPE_HPP +#define BOOST_HOF_GUARD_RESULT_TYPE_HPP + +#include <boost/hof/detail/holder.hpp> +#include <utility> + +namespace boost { namespace hof { namespace detail { + +template<class F, class=void> +struct function_result_type +{}; + +template<class F> +struct function_result_type<F, typename holder< + typename F::result_type +>::type> +{ + typedef typename F::result_type result_type; +}; + +template<class F, class G, class=void> +struct compose_function_result_type +: function_result_type<F> +{}; + +template<class F, class G> +struct compose_function_result_type<F, G, typename holder< + decltype(std::declval<F>()(std::declval<typename G::result_type>())) +>::type> +{ + typedef decltype(std::declval<F>()(std::declval<typename G::result_type>())) result_type; +}; + +}}} // namespace boost::hof + +#endif |