Chris@102: /*=============================================================================
Chris@102:     Copyright (c) 2001-2014 Joel de Guzman
Chris@102:     http://spirit.sourceforge.net/
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_CONTEXT_JAN_4_2012_1215PM)
Chris@102: #define BOOST_SPIRIT_X3_CONTEXT_JAN_4_2012_1215PM
Chris@102: 
Chris@102: #if defined(_MSC_VER)
Chris@102: #pragma once
Chris@102: #endif
Chris@102: 
Chris@102: #include <boost/spirit/home/x3/support/unused.hpp>
Chris@102: #include <boost/mpl/identity.hpp>
Chris@102: 
Chris@102: namespace boost { namespace spirit { namespace x3
Chris@102: {
Chris@102:     template <typename ID, typename T, typename Next = unused_type>
Chris@102:     struct context
Chris@102:     {
Chris@102:         context(T& val, Next const& next)
Chris@102:             : val(val), next(next) {}
Chris@102: 
Chris@102:         template <typename ID_, typename Unused = void>
Chris@102:         struct get_result
Chris@102:         {
Chris@102:             typedef typename Next::template get_result<ID_>::type type;
Chris@102:         };
Chris@102: 
Chris@102:         template <typename Unused>
Chris@102:         struct get_result<mpl::identity<ID>, Unused>
Chris@102:         {
Chris@102:             typedef T& type;
Chris@102:         };
Chris@102: 
Chris@102:         T& get(mpl::identity<ID>) const
Chris@102:         {
Chris@102:             return val;
Chris@102:         }
Chris@102: 
Chris@102:         template <typename ID_>
Chris@102:         typename Next::template get_result<ID_>::type
Chris@102:         get(ID_ id) const
Chris@102:         {
Chris@102:             return next.get(id);
Chris@102:         }
Chris@102: 
Chris@102:         T& val;
Chris@102:         Next const& next;
Chris@102:     };
Chris@102: 
Chris@102:     template <typename ID, typename T>
Chris@102:     struct context<ID, T, unused_type>
Chris@102:     {
Chris@102:         context(T& val)
Chris@102:             : val(val) {}
Chris@102: 
Chris@102:         context(T& val, unused_type)
Chris@102:             : val(val) {}
Chris@102: 
Chris@102:         template <typename ID_, typename Unused = void>
Chris@102:         struct get_result
Chris@102:         {
Chris@102:             typedef unused_type type;
Chris@102:         };
Chris@102: 
Chris@102:         template <typename Unused>
Chris@102:         struct get_result<mpl::identity<ID>, Unused>
Chris@102:         {
Chris@102:             typedef T& type;
Chris@102:         };
Chris@102: 
Chris@102:         T& get(mpl::identity<ID>) const
Chris@102:         {
Chris@102:             return val;
Chris@102:         }
Chris@102: 
Chris@102:         template <typename ID_>
Chris@102:         unused_type
Chris@102:         get(ID_) const
Chris@102:         {
Chris@102:             return unused;
Chris@102:         }
Chris@102: 
Chris@102:         T& val;
Chris@102:     };
Chris@102: 
Chris@102:     template <typename Tag, typename Context>
Chris@102:     inline auto
Chris@102:     get(Context const& context)
Chris@102:         -> decltype(context.get(mpl::identity<Tag>()))
Chris@102:     {
Chris@102:         return context.get(mpl::identity<Tag>());
Chris@102:     }
Chris@102: 
Chris@102:     template <typename ID, typename T, typename Next>
Chris@102:     inline context<ID, T, Next> make_context(T& val, Next const& next)
Chris@102:     {
Chris@102:         return context<ID, T, Next>(val, next);
Chris@102:     }
Chris@102: 
Chris@102:     template <typename ID, typename T>
Chris@102:     inline context<ID, T> make_context(T& val)
Chris@102:     {
Chris@102:         return context<ID, T>(val);
Chris@102:     }
Chris@102:     
Chris@102:     namespace detail
Chris@102:     {
Chris@102:         template <typename ID, typename T, typename Next, typename FoundVal>
Chris@102:         inline Next const&
Chris@102:         make_unique_context(T& val, Next const& next, FoundVal&)
Chris@102:         {
Chris@102:             return next;
Chris@102:         }
Chris@102:         
Chris@102:         template <typename ID, typename T, typename Next>
Chris@102:         inline context<ID, T, Next>
Chris@102:         make_unique_context(T& val, Next const& next, unused_type)
Chris@102:         {
Chris@102:             return context<ID, T, Next>(val, next);
Chris@102:         }
Chris@102:     }
Chris@102:     
Chris@102:     template <typename ID, typename T, typename Next>
Chris@102:     inline auto
Chris@102:     make_unique_context(T& val, Next const& next)
Chris@102:     {
Chris@102:         return detail::make_unique_context<ID>(val, next, x3::get<ID>(next));
Chris@102:     }
Chris@102: }}}
Chris@102: 
Chris@102: #endif