1 // Copyright Daniel Wallin, David Abrahams 2005. 2 // Distributed under the Boost Software License, Version 1.0. 3 // (See accompanying file LICENSE_1_0.txt or copy at 4 // http://www.boost.org/LICENSE_1_0.txt) 5 6 #ifndef BOOST_PARAMETER_AUX_YESNO_HPP 7 #define BOOST_PARAMETER_AUX_YESNO_HPP 8 9 namespace boost { namespace parameter { namespace aux { 10 11 // types used with the "sizeof trick" to capture the results of 12 // overload resolution at compile-time. 13 typedef char yes_tag; 14 typedef char (&no_tag)[2]; 15 }}} // namespace boost::parameter::aux 16 17 #include <boost/mpl/bool.hpp> 18 19 namespace boost { namespace parameter { namespace aux { 20 21 // mpl::true_ and mpl::false_ are not distinguishable by sizeof(), 22 // so we pass them through these functions to get a type that is. 23 ::boost::parameter::aux::yes_tag to_yesno(::boost::mpl::true_); 24 ::boost::parameter::aux::no_tag to_yesno(::boost::mpl::false_); 25 }}} // namespace boost::parameter::aux 26 27 #include <boost/parameter/config.hpp> 28 29 #if defined(BOOST_PARAMETER_CAN_USE_MP11) 30 #include <boost/mp11/integral.hpp> 31 32 namespace boost { namespace parameter { namespace aux { 33 34 // mp11::mp_true and mp11::mp_false are not distinguishable by sizeof(), 35 // so we pass them through these functions to get a type that is. 36 ::boost::parameter::aux::yes_tag to_yesno(::boost::mp11::mp_true); 37 ::boost::parameter::aux::no_tag to_yesno(::boost::mp11::mp_false); 38 }}} // namespace boost::parameter::aux 39 40 #endif // BOOST_PARAMETER_CAN_USE_MP11 41 #endif // include guard 42 43