// Copyright (c) 2003 Daniel Wallin and Arvid Norberg

// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
// ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED
#define LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED

#include <luabind/detail/policy.hpp>    // for index_map, policy_cons, etc

#include <luabind/lua_include.hpp>      // for lua_State, lua_pushnil, etc

namespace luabind { namespace detail
{
    struct cpp_to_lua;
    struct null_type;

    template<class T>
    struct return_reference_to_converter;

    template<>
    struct return_reference_to_converter<cpp_to_lua>
    {
        template<class T>
        void apply(lua_State* L, const T&)
        {
            lua_pushnil(L);
        }
    };

    template<int N>
    struct return_reference_to_policy : conversion_policy<0>
    {
        static void precall(lua_State*, const index_map&) {}
        static void postcall(lua_State* L, const index_map& indices)
        {
            int result_index = indices[0];
            int ref_to_index = indices[N];

            lua_pushvalue(L, ref_to_index);
            lua_replace(L, result_index);
        }

        template<class T, class Direction>
        struct apply
        {
            typedef return_reference_to_converter<Direction> type;
        };
    };
}}

namespace luabind
{
    template<int N>
    detail::policy_cons<detail::return_reference_to_policy<N>, detail::null_type>
    return_reference_to(LUABIND_PLACEHOLDER_ARG(N))
    {
        return detail::policy_cons<detail::return_reference_to_policy<N>, detail::null_type>();
    }
}

#endif // LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED
