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