#pragma once

#ifndef PACK_ARGS_LIMIT
#define PACK_ARGS_LIMIT 10
#endif

#include <boost/config.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/enum.hpp>
#include <boost/preprocessor/facilities/empty.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/mpl/if.hpp>
#include <boost/fusion/sequence/intrinsic/at.hpp>
#include <boost/fusion/sequence/intrinsic/size.hpp>
#include <boost/type_traits/is_const.hpp>

namespace detail_
{

template<class Derived, class Sequence, class Result, int N>
struct pack_args_forward
{
};

template<class Derived, class Sequence, class Result, int N>
struct pack_args_forwardconst
{
};

#define PP_AT_C(z, n, text) typename boost::fusion::result_of::at_c<Sequence, n>::type BOOST_PP_CAT(text, n)

#define PP_PACK_ARGS_N(z, n, text) \
template<class Derived, class Sequence, class Result> \
struct BOOST_PP_CAT(pack_args_forward, text) <Derived, Sequence, Result, n> \
{ \
	Result operator() (BOOST_PP_ENUM(n, PP_AT_C, a) ) text \
	{ \
		return (*(static_cast<Derived*>(this))).on_packed_args(Sequence(BOOST_PP_ENUM_PARAMS(n, a))); \
	} \
};

BOOST_PP_REPEAT(PACK_ARGS_LIMIT, PP_PACK_ARGS_N, BOOST_PP_EMPTY())
BOOST_PP_REPEAT(PACK_ARGS_LIMIT, PP_PACK_ARGS_N, const)

#undef PP_PACK_ARGS_N
#undef PP_AT_C

struct pack_args_n
{
	template<class Derived, class Sequence, class Result>
	struct pack_args : public pack_args_forward<Derived, Sequence, Result, boost::fusion::result_of::size<Sequence>::value>
	{
		
	};
};

struct pack_args_n_const
{
	template<class Derived, class Sequence, class Result>
	struct pack_args : public pack_args_forwardconst<Derived, Sequence, Result, boost::fusion::result_of::size<Sequence>::value>
	{

	};
};

} // namespace detail

template<class Derived, class Sequence, class Result>
struct pack_args : public 
	boost::mpl::if_c
	<
		boost::is_const<Derived>::value, 
		detail_::pack_args_n_const,
		detail_::pack_args_n
	>::type::pack_args<Derived, Sequence, Result>
{
	typedef Result result_type;
	typedef Sequence sequence_type;
};