1 // Copyright Daniel Wallin, David Abrahams 2005. Use, modification and

     2 // distribution is subject to the Boost Software License, Version 1.0. (See

     3 // accompanying file LICENSE_1_0.txt or copy at

     4 // http://www.boost.org/LICENSE_1_0.txt)

     5 

     6 #ifndef YESNO_050328_HPP

     7 #define YESNO_050328_HPP

     8 

     9 #include <boost/mpl/bool.hpp>

    10 

    11 namespace boost { namespace parameter { namespace aux {

    12 

    13 // types used with the "sizeof trick" to capture the results of

    14 // overload resolution at compile-time.

    15 typedef char yes_tag;

    16 typedef char (&no_tag)[2];

    17 

    18 // mpl::true_ and mpl::false_ are not distinguishable by sizeof(),

    19 // so we pass them through these functions to get a type that is.

    20 yes_tag to_yesno(mpl::true_);

    21 no_tag to_yesno(mpl::false_);

    22 

    23 }}} // namespace boost::parameter::aux

    24 

    25 #endif // YESNO_050328_HPP

    26