williamr@2: //-----------------------------------------------------------------------------
williamr@2: // boost blank.hpp header file
williamr@2: // See http://www.boost.org for updates, documentation, and revision history.
williamr@2: //-----------------------------------------------------------------------------
williamr@2: //
williamr@2: // Copyright (c) 2003
williamr@2: // Eric Friedman
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: #ifndef BOOST_BLANK_HPP
williamr@2: #define BOOST_BLANK_HPP
williamr@2: 
williamr@2: #include "boost/blank_fwd.hpp"
williamr@2: 
williamr@2: #include <iosfwd> // for std::basic_ostream forward declare
williamr@2: 
williamr@2: #include "boost/detail/templated_streams.hpp"
williamr@2: #include "boost/mpl/bool.hpp"
williamr@2: #include "boost/type_traits/is_empty.hpp"
williamr@2: #include "boost/type_traits/is_pod.hpp"
williamr@2: #include "boost/type_traits/is_stateless.hpp"
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2: struct blank
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: // type traits specializations
williamr@2: //
williamr@2: 
williamr@2: template <>
williamr@2: struct is_pod< blank >
williamr@2:     : mpl::true_
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: template <>
williamr@2: struct is_empty< blank >
williamr@2:     : mpl::true_
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: template <>
williamr@2: struct is_stateless< blank >
williamr@2:     : mpl::true_
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: // relational operators
williamr@2: //
williamr@2: 
williamr@2: inline bool operator==(const blank&, const blank&)
williamr@2: {
williamr@2:     return true;
williamr@2: }
williamr@2: 
williamr@2: inline bool operator<=(const blank&, const blank&)
williamr@2: {
williamr@2:     return true;
williamr@2: }
williamr@2: 
williamr@2: inline bool operator>=(const blank&, const blank&)
williamr@2: {
williamr@2:     return true;
williamr@2: }
williamr@2: 
williamr@2: inline bool operator!=(const blank&, const blank&)
williamr@2: {
williamr@2:     return false;
williamr@2: }
williamr@2: 
williamr@2: inline bool operator<(const blank&, const blank&)
williamr@2: {
williamr@2:     return false;
williamr@2: }
williamr@2: 
williamr@2: inline bool operator>(const blank&, const blank&)
williamr@2: {
williamr@2:     return false;
williamr@2: }
williamr@2: 
williamr@2: // streaming support
williamr@2: //
williamr@2: BOOST_TEMPLATED_STREAM_TEMPLATE(E,T)
williamr@2: inline BOOST_TEMPLATED_STREAM(ostream, E,T)& operator<<(
williamr@2:       BOOST_TEMPLATED_STREAM(ostream, E,T)& out
williamr@2:     , const blank&
williamr@2:     )
williamr@2: {
williamr@2:     // (output nothing)
williamr@2:     return out;
williamr@2: }
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_BLANK_HPP