| /*============================================================================= |
| Copyright (c) 2001-2014 Joel de Guzman |
| Copyright (c) 2001-2011 Hartmut Kaiser |
| |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| ==============================================================================*/ |
| #if !defined(BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM) |
| #define BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM |
| |
| #include <iosfwd> |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| namespace boost { namespace spirit { namespace x3 |
| { |
| struct unused_type |
| { |
| unused_type() = default; |
| |
| template <typename T> |
| unused_type(T const&) |
| { |
| } |
| |
| template <typename T> |
| unused_type const& |
| operator=(T const&) const |
| { |
| return *this; |
| } |
| |
| template <typename T> |
| unused_type& |
| operator=(T const&) |
| { |
| return *this; |
| } |
| |
| // unused_type can also masquerade as an empty context (see context.hpp) |
| |
| template <typename ID> |
| unused_type get(ID) const |
| { |
| return {}; |
| } |
| |
| friend std::ostream& operator<<(std::ostream& out, unused_type const&) |
| { |
| return out; |
| } |
| |
| friend std::istream& operator>>(std::istream& in, unused_type&) |
| { |
| return in; |
| } |
| }; |
| |
| constexpr auto unused = unused_type{}; |
| }}} |
| |
| #endif |
