luabind/detail/make_instance.hpp

   1 // Copyright Daniel Wallin 2009. Use, modification and distribution is
   2 // subject to the Boost Software License, Version 1.0. (See accompanying
   3 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   4
   5 #ifndef LUABIND_DETAIL_MAKE_INSTANCE_090310_HPP
   6 # define LUABIND_DETAIL_MAKE_INSTANCE_090310_HPP
   7
   8 # include <boost/type_traits/is_polymorphic.hpp>
   9 # include <luabind/detail/inheritance.hpp>
  10 # include <luabind/detail/object_rep.hpp>
  11
  12 namespace luabind { namespace detail {
  13
  14 template <class T>
  15 std::pair<class_id, void*> get_dynamic_class_aux(
  16     lua_State* L, T const* p, mpl::true_)
  17 {
  18     lua_pushstring(L, "__luabind_class_id_map");
  19     lua_rawget(L, LUA_REGISTRYINDEX);
  20
  21     class_id_map& class_ids = *static_cast<class_id_map*>(
  22         lua_touserdata(L, -1));
  23
  24     lua_pop(L, 1);
  25
  26     return std::make_pair(
  27         class_ids.get_local(typeid(*p))
  28       , dynamic_cast<void*>(const_cast<T*>(p))
  29     );
  30 }
  31
  32 template <class T>
  33 std::pair<class_id, void*> get_dynamic_class_aux(
  34     lua_State*, T const* p, mpl::false_)
  35 {
  36     return std::make_pair(registered_class<T>::id, (void*)p);
  37 }
  38
  39 template <class T>
  40 std::pair<class_id, void*> get_dynamic_class(lua_State* L, T* p)
  41 {
  42     return get_dynamic_class_aux(L, p, boost::is_polymorphic<T>());
  43 }
  44
  45 template <class T>
  46 class_rep* get_pointee_class(class_map const& classes, T*)
  47 {
  48     return classes.get(registered_class<T>::id);
  49 }
  50
  51 template <class P>
  52 class_rep* get_pointee_class(lua_State* L, P const& p, class_id dynamic_id)
  53 {
  54     lua_pushstring(L, "__luabind_class_map");
  55     lua_rawget(L, LUA_REGISTRYINDEX);
  56
  57     class_map const& classes = *static_cast<class_map*>(
  58         lua_touserdata(L, -1));
  59
  60     lua_pop(L, 1);
  61
  62     class_rep* cls = classes.get(dynamic_id);
  63
  64     if (!cls)
  65         cls = get_pointee_class(classes, get_pointer(p));
  66
  67     return cls;
  68 }
  69
  70 // Create an appropriate instance holder for the given pointer like object.
  71 template <class P>
  72 void make_instance(lua_State* L, P p)
  73 {
  74     std::pair<class_id, void*> dynamic = get_dynamic_class(L, get_pointer(p));
  75
  76     class_rep* cls = get_pointee_class(L, p, dynamic.first);
  77
  78     if (!cls)
  79     {
  80         throw std::runtime_error("Trying to use unregistered class");
  81     }
  82
  83     object_rep* instance = push_new_instance(L, cls);
  84
  85     typedef pointer_holder<P> holder_type;
  86
  87     void* storage = instance->allocate(sizeof(holder_type));
  88
  89     try
  90     {
  91         new (storage) holder_type(p, dynamic.first, dynamic.second);
  92     }
  93     catch (...)
  94     {
  95         instance->deallocate(storage);
  96         lua_pop(L, 1);
  97         throw;
  98     }
  99
 100     instance->set_instance(static_cast<holder_type*>(storage));
 101 }
 102
 103 }} // namespace luabind::detail
 104
 105 #endif // LUABIND_DETAIL_MAKE_INSTANCE_090310_HPP