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- // (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
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