luabind/dependency_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
  24 #ifndef LUABIND_DEPENDENCY_POLICY_HPP_INCLUDED
  25 #define LUABIND_DEPENDENCY_POLICY_HPP_INCLUDED
  26
  27 #include <luabind/config.hpp>
  28 #include <luabind/detail/policy.hpp>
  29
  30 namespace luabind { namespace detail
  31 {
  32         // makes A dependent on B, meaning B will outlive A.
  33         // internally A stores a reference to B
  34         template<int A, int B>
  35         struct dependency_policy
  36         {
  37                 static void postcall(lua_State* L, const index_map& indices)
  38                 {
  39                         int nurse_index = indices[A];
  40                         int patient = indices[B];
  41
  42                         object_rep* nurse = static_cast<object_rep*>(lua_touserdata(L, nurse_index));
  43                         assert((nurse != 0) && "internal error, please report"); // internal error
  44
  45                         nurse->add_dependency(L, patient);
  46                 }
  47         };
  48
  49 }}
  50
  51 namespace luabind
  52 {
  53         // most absurd workaround of all time?
  54         namespace detail
  55         {
  56                 template<int N>
  57                 struct size_char_array
  58                 {
  59                         char storage[N + 2];
  60                 };
  61
  62                 template<int N>
  63                 size_char_array<N> deduce_size(boost::arg<N>);
  64
  65                 template<class T>
  66                 struct get_index_workaround
  67                 {
  68                         static T t;
  69                         BOOST_STATIC_CONSTANT(int, value = sizeof(deduce_size(t)) - 2);
  70                 };
  71         }
  72
  73         template<class A, class B>
  74         detail::policy_cons<detail::dependency_policy<detail::get_index_workaround<A>::value, detail::get_index_workaround<B>::value>, detail::null_type>       dependency(A,B) { return detail::policy_cons<detail::dependency_policy<detail::get_index_workaround<A>::value, detail::get_index_workaround<B>::value>, detail::null_type>(); }
  75
  76         template<class A>
  77         detail::policy_cons<detail::dependency_policy<0, detail::get_index_workaround<A>::value>, detail::null_type>
  78         return_internal_reference(A)
  79         { return detail::policy_cons<detail::dependency_policy<0, detail::get_index_workaround<A>::value>, detail::null_type>(); }
  80 }
  81
  82 #endif // LUABIND_DEPENDENCY_POLICY_HPP_INCLUDED
  83