williamr@2: 
williamr@2: #ifndef BOOST_MPL_VOID_HPP_INCLUDED
williamr@2: #define BOOST_MPL_VOID_HPP_INCLUDED
williamr@2: 
williamr@2: // Copyright Aleksey Gurtovoy 2001-2004
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. 
williamr@2: // (See accompanying file LICENSE_1_0.txt or copy at 
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //
williamr@2: // See http://www.boost.org/libs/mpl for documentation.
williamr@2: 
williamr@2: // $Source: /cvsroot/boost/boost/boost/mpl/void.hpp,v $
williamr@2: // $Date: 2004/09/02 15:40:42 $
williamr@2: // $Revision: 1.9 $
williamr@2: 
williamr@2: #include <boost/mpl/void_fwd.hpp>
williamr@2: #include <boost/mpl/bool.hpp>
williamr@2: #include <boost/mpl/aux_/na_spec.hpp>
williamr@2: #include <boost/mpl/aux_/config/msvc.hpp>
williamr@2: #include <boost/mpl/aux_/config/workaround.hpp>
williamr@2: 
williamr@2: BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN
williamr@2: 
williamr@2: //  [JDG Feb-4-2003] made void_ a complete type to allow it to be
williamr@2: //  instantiated so that it can be passed in as an object that can be
williamr@2: //  used to select an overloaded function. Possible use includes signaling
williamr@2: //  a zero arity functor evaluation call.
williamr@2: struct void_ { typedef void_ type; };
williamr@2: 
williamr@2: BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE
williamr@2: 
williamr@2: namespace boost { namespace mpl {
williamr@2: 
williamr@2: template< typename T >
williamr@2: struct is_void_
williamr@2:     : false_
williamr@2: {
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
williamr@2:     using false_::value;
williamr@2: #endif
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct is_void_<void_>
williamr@2:     : true_
williamr@2: {
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
williamr@2:     using true_::value;
williamr@2: #endif
williamr@2: };
williamr@2: 
williamr@2: template< typename T >
williamr@2: struct is_not_void_
williamr@2:     : true_
williamr@2: {
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
williamr@2:     using true_::value;
williamr@2: #endif
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct is_not_void_<void_>
williamr@2:     : false_
williamr@2: {
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
williamr@2:     using false_::value;
williamr@2: #endif
williamr@2: };
williamr@2: 
williamr@2: BOOST_MPL_AUX_NA_SPEC(1, is_void_)
williamr@2: BOOST_MPL_AUX_NA_SPEC(1, is_not_void_)
williamr@2: 
williamr@2: }}
williamr@2: 
williamr@2: #endif // BOOST_MPL_VOID_HPP_INCLUDED