luabind/return_reference_to_policy.hpp

   1 // Copyright (c) 2003 Daniel Wallin and Arvid Norberg
   2
   3 // Permission is hereby granted, free of charge, to any person obtaining a
   4 // copy of this software and associated documentation files (the "Software"),
   5 // to deal in the Software without restriction, including without limitation
   6 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
   7 // and/or sell copies of the Software, and to permit persons to whom the
   8 // Software is furnished to do so, subject to the following conditions:
   9
  10 // The above copyright notice and this permission notice shall be included
  11 // in all copies or substantial portions of the Software.
  12
  13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
  14 // ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
  15 // TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
  16 // PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
  17 // SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
  18 // ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  19 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
  21 // OR OTHER DEALINGS IN THE SOFTWARE.
  22
  23 #ifndef LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED
  24 #define LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED
  25
  26 namespace luabind { namespace detail
  27 {
  28         template<class T>
  29         struct return_reference_to_converter;
  30
  31         template<>
  32         struct return_reference_to_converter<cpp_to_lua>
  33         {
  34                 template<class T>
  35                 void apply(lua_State* L, const T&)
  36                 {
  37                         lua_pushnil(L);
  38                 }
  39         };
  40
  41         template<int N>
  42         struct return_reference_to_policy : conversion_policy<0>
  43         {
  44                 static void precall(lua_State*, const index_map&) {}
  45                 static void postcall(lua_State* L, const index_map& indices)
  46                 {
  47                         int result_index = indices[0];
  48                         int ref_to_index = indices[N];
  49
  50                         lua_pushvalue(L, ref_to_index);
  51                         lua_replace(L, result_index);
  52                 }
  53
  54                 template<class T, class Direction>
  55                 struct apply
  56                 {
  57                         typedef return_reference_to_converter<Direction> type;
  58                 };
  59         };
  60 }}
  61
  62 namespace luabind
  63 {
  64         template<int N>
  65         detail::policy_cons<detail::return_reference_to_policy<N>, detail::null_type>
  66         return_reference_to(LUABIND_PLACEHOLDER_ARG(N))
  67         {
  68                 return detail::policy_cons<detail::return_reference_to_policy<N>, detail::null_type>();
  69         }
  70 }
  71
  72 #endif // LUABIND_RETURN_REFERENCE_TO_POLICY_HPP_INCLUDED
  73