Chris@102: /*=============================================================================
Chris@102:     Copyright (c) 2001-2014 Joel de Guzman
Chris@102:     Copyright (c) 2001-2011 Hartmut Kaiser
Chris@102: 
Chris@102:     Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@102:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102: ==============================================================================*/
Chris@102: #if !defined(BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM)
Chris@102: #define BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM
Chris@102: 
Chris@102: #if defined(_MSC_VER)
Chris@102: #pragma once
Chris@102: #endif
Chris@102: 
Chris@102: #include <ostream>
Chris@102: #include <istream>
Chris@102: #include <boost/mpl/identity.hpp>
Chris@102: 
Chris@102: #if defined(BOOST_MSVC)
Chris@102: # pragma warning(push)
Chris@102: # pragma warning(disable: 4522) // multiple assignment operators specified warning
Chris@102: #endif
Chris@102: 
Chris@102: ///////////////////////////////////////////////////////////////////////////////
Chris@102: namespace boost { namespace spirit { namespace x3
Chris@102: {
Chris@102:     struct unused_type
Chris@102:     {
Chris@102:         unused_type()
Chris@102:         {
Chris@102:         }
Chris@102: 
Chris@102:         template <typename T>
Chris@102:         unused_type(T const&)
Chris@102:         {
Chris@102:         }
Chris@102: 
Chris@102:         template <typename T>
Chris@102:         unused_type const&
Chris@102:         operator=(T const&) const
Chris@102:         {
Chris@102:             return *this;
Chris@102:         }
Chris@102: 
Chris@102:         template <typename T>
Chris@102:         unused_type&
Chris@102:         operator=(T const&)
Chris@102:         {
Chris@102:             return *this;
Chris@102:         }
Chris@102: 
Chris@102:         unused_type const&
Chris@102:         operator=(unused_type const&) const
Chris@102:         {
Chris@102:             return *this;
Chris@102:         }
Chris@102: 
Chris@102:         unused_type&
Chris@102:         operator=(unused_type const&)
Chris@102:         {
Chris@102:             return *this;
Chris@102:         }
Chris@102: 
Chris@102:         // unused_type can also masquerade as an empty context (see context.hpp)
Chris@102: 
Chris@102:         template <typename ID>
Chris@102:         struct get_result : mpl::identity<unused_type> {};
Chris@102: 
Chris@102:         template <typename ID>
Chris@102:         unused_type get(ID) const
Chris@102:         {
Chris@102:             return unused_type();
Chris@102:         }
Chris@102:     };
Chris@102: 
Chris@102:     unused_type const unused = unused_type();
Chris@102: 
Chris@102:     inline std::ostream& operator<<(std::ostream& out, unused_type const&)
Chris@102:     {
Chris@102:         return out;
Chris@102:     }
Chris@102: 
Chris@102:     inline std::istream& operator>>(std::istream& in, unused_type&)
Chris@102:     {
Chris@102:         return in;
Chris@102:     }
Chris@102: }}}
Chris@102: 
Chris@102: #if defined(BOOST_MSVC)
Chris@102: # pragma warning(pop)
Chris@102: #endif
Chris@102: 
Chris@102: #endif