boost/type_traits/conditional.hpp

0001 //  (C) Copyright John Maddock 2010.
0002 //  Use, modification and distribution are subject to the Boost Software License,
0003 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0004 //  http://www.boost.org/LICENSE_1_0.txt).
0005 //
0006 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
0007
0008
0009 #ifndef BOOST_TT_CONDITIONAL_HPP_INCLUDED
0010 #define BOOST_TT_CONDITIONAL_HPP_INCLUDED
0011
0012 #include <boost/config.hpp>
0013
0014 namespace boost {
0015
0016 template <bool b, class T, class U> struct conditional { typedef T type; };
0017 template <class T, class U> struct conditional<false, T, U> { typedef U type; };
0018
0019 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
0020
0021    template <bool b, class T, class U> using conditional_t = typename conditional<b, T, U>::type;
0022
0023 #endif
0024
0025 } // namespace boost
0026
0027
0028 #endif // BOOST_TT_CONDITIONAL_HPP_INCLUDED