boost/function_types/result_type.hpp

0001
0002 // (C) Copyright Tobias Schwinger
0003 //
0004 // Use modification and distribution are subject to the boost Software License,
0005 // Version 1.0. (See http://www.boost.org/LICENSE_1_0.txt).
0006
0007 //------------------------------------------------------------------------------
0008
0009 #ifndef BOOST_FT_RESULT_TYPE_HPP_INCLUDED
0010 #define BOOST_FT_RESULT_TYPE_HPP_INCLUDED
0011
0012 #include <boost/blank.hpp>
0013 #include <boost/mpl/if.hpp>
0014
0015 #include <boost/mpl/aux_/lambda_support.hpp>
0016
0017 #include <boost/mpl/at.hpp>
0018
0019 #include <boost/function_types/is_callable_builtin.hpp>
0020 #include <boost/function_types/components.hpp>
0021
0022 namespace boost
0023 {
0024   namespace function_types
0025   {
0026     template< typename T > struct result_type;
0027
0028     namespace detail
0029     {
0030       template<typename T> struct result_type_impl
0031         : mpl::at_c
0032           < typename function_types::components<T>::types, 0 >
0033       { };
0034     }
0035
0036     template<typename T> struct result_type
0037       : mpl::if_
0038         < function_types::is_callable_builtin<T>
0039         , detail::result_type_impl<T>, boost::blank
0040         >::type
0041     {
0042       BOOST_MPL_AUX_LAMBDA_SUPPORT(1,result_type,(T))
0043     };
0044   }
0045 }
0046
0047 #endif
0048