boost/type_traits/add_const.hpp

0001
0002 //  (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes, Howard
0003 //  Hinnant & John Maddock 2000.
0004 //  Use, modification and distribution are subject to the Boost Software License,
0005 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0006 //  http://www.boost.org/LICENSE_1_0.txt).
0007 //
0008 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
0009
0010 #ifndef BOOST_TT_ADD_CONST_HPP_INCLUDED
0011 #define BOOST_TT_ADD_CONST_HPP_INCLUDED
0012
0013 #include <boost/type_traits/detail/config.hpp>
0014
0015 namespace boost {
0016
0017 // * convert a type T to const type - add_const<T>
0018 // this is not required since the result is always
0019 // the same as "T const", but it does suppress warnings
0020 // from some compilers:
0021
0022 #if defined(BOOST_MSVC)
0023 // This bogus warning will appear when add_const is applied to a
0024 // const volatile reference because we can't detect const volatile
0025 // references with MSVC6.
0026 #   pragma warning(push)
0027 #   pragma warning(disable:4181) // warning C4181: qualifier applied to reference type ignored
0028 #endif
0029
0030    template <class T> struct add_const
0031    {
0032       typedef T const type;
0033    };
0034
0035 #if defined(BOOST_MSVC)
0036 #   pragma warning(pop)
0037 #endif
0038
0039    template <class T> struct add_const<T&>
0040    {
0041       typedef T& type;
0042    };
0043
0044 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
0045
0046    template <class T> using add_const_t = typename add_const<T>::type;
0047
0048 #endif
0049
0050 } // namespace boost
0051
0052 #endif // BOOST_TT_ADD_CONST_HPP_INCLUDED