| |
| // (C) Copyright Tobias Schwinger |
| // |
| // Use modification and distribution are subject to the boost Software License, |
| // Version 1.0. (See http://www.boost.org/LICENSE_1_0.txt). |
| |
| //------------------------------------------------------------------------------ |
| |
| // Metafunction to compute optimal parameter type for argument forwarding. |
| |
| // This header is not an FT example in itself -- it's used by some of them to |
| // optimize argument forwarding. |
| // |
| // For more details see 'fast_mem_fn.hpp' in this directory or the documentation |
| // of the CallTraits utility [1]. |
| // |
| // |
| // References |
| // ========== |
| // |
| // [1] http://www.boost.org/libs/utility/call_traits.htm |
| |
| #ifndef BOOST_UTILITY_PARAM_TYPE_HPP_INCLUDED |
| #define BOOST_UTILITY_PARAM_TYPE_HPP_INCLUDED |
| |
| #include <boost/config.hpp> |
| |
| #include <boost/type_traits/add_const.hpp> |
| #include <boost/type_traits/add_reference.hpp> |
| |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/identity.hpp> |
| |
| #include <boost/mpl/aux_/lambda_support.hpp> |
| // #include <boost/type_traits/detail/template_arity_spec.hpp> |
| |
| // namespace boost |
| namespace example |
| { |
| namespace mpl = boost::mpl; |
| |
| // namespace utility |
| // { |
| namespace param_type_detail |
| { |
| template<typename T> |
| struct by_ref_cond |
| { |
| typedef by_ref_cond type; |
| BOOST_STATIC_CONSTANT(bool,value = sizeof(void*) < sizeof(T)); |
| }; |
| |
| template<typename T> |
| struct add_ref_to_const |
| : boost::add_reference< typename boost::add_const<T>::type > |
| { }; |
| } |
| |
| template<typename T> |
| struct param_type |
| : mpl::eval_if< param_type_detail::by_ref_cond<T> |
| , param_type_detail::add_ref_to_const<T>, mpl::identity<T> > |
| { |
| BOOST_MPL_AUX_LAMBDA_SUPPORT(1,param_type,(T)) |
| }; |
| // } |
| // BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1,utility::param_type) |
| } |
| |
| #endif |
| |