luabind/adopt_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_ADOPT_POLICY_HPP_INCLUDED
  25 #define LUABIND_ADOPT_POLICY_HPP_INCLUDED
  26
  27 #include <luabind/config.hpp>
  28 #include <luabind/detail/policy.hpp>
  29 #include <luabind/detail/implicit_cast.hpp>
  30
  31 namespace luabind { namespace detail
  32 {
  33         template<class Direction = lua_to_cpp>
  34         struct adopt_pointer
  35         {
  36                 template<class T>
  37                 T* apply(lua_State* L, by_pointer<T>, int index)
  38                 {
  39                         // preconditions:
  40                         //      lua_isuserdata(L, index);
  41                         // getmetatable().__lua_class is true
  42                         // object_rep->flags() & object_rep::constant == 0
  43
  44                         int offset = 0;
  45                         object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, index));
  46                         assert((obj != 0) && "internal error, please report");
  47                         const class_rep* crep = obj->crep();
  48
  49                         int steps = implicit_cast(crep, LUABIND_TYPEID(T), offset);
  50                         (void)steps;
  51
  52                         assert((steps >= 0) && "adopt_pointer used with type that cannot be converted");
  53                         obj->remove_ownership();
  54                         T* ptr = reinterpret_cast<T*>(obj->ptr(offset));
  55
  56                         return ptr;
  57                 }
  58
  59                 template<class T>
  60                 static int match(lua_State* L, by_pointer<T>, int index)
  61                 {
  62                         object_rep* obj = is_class_object(L, index);
  63                         if (obj == 0) return -1;
  64                         // cannot cast a constant object to nonconst
  65                         if (obj->flags() & object_rep::constant) return -1;
  66                         if (!(obj->flags() & object_rep::owner)) return -1;
  67                         int d;
  68                         return implicit_cast(obj->crep(), LUABIND_TYPEID(T), d);
  69                 }
  70
  71                 template<class T>
  72                 void converter_postcall(lua_State*, T, int) {}
  73         };
  74
  75         template<>
  76         struct adopt_pointer<cpp_to_lua>
  77         {
  78                 template<class T>
  79                 void apply(lua_State* L, T* ptr)
  80                 {
  81                         if (ptr == 0)
  82                         {
  83                                 lua_pushnil(L);
  84                                 return;
  85                         }
  86
  87                         // if there is a back_reference, then the
  88                         // ownership will be removed from the
  89                         // back reference and put on the lua stack.
  90                         if (back_reference<T>::move(L, ptr))
  91                         {
  92                                 object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, -1));
  93                                 obj->set_flags(obj->flags() | object_rep::owner);
  94                                 return;
  95                         }
  96
  97                         class_registry* registry = class_registry::get_registry(L);
  98                         class_rep* crep = registry->find_class(LUABIND_TYPEID(T));
  99
 100 /*                      // create the struct to hold the object
 101                         void* obj = lua_newuserdata(L, sizeof(object_rep));
 102                         // we send 0 as destructor since we know it will never be called
 103                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);*/
 104
 105                         void* obj;
 106                         void* held;
 107
 108                         boost::tie(obj,held) = crep->allocate(L);
 109
 110                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);
 111
 112                         // set the meta table
 113                         detail::getref(L, crep->metatable_ref());
 114                         lua_setmetatable(L, -2);
 115                 }
 116         };
 117
 118         template<int N>
 119 //      struct adopt_policy : converter_policy_tag
 120         struct adopt_policy : conversion_policy<N>
 121         {
 122 //              BOOST_STATIC_CONSTANT(int, index = N);
 123
 124                 static void precall(lua_State*, const index_map&) {}
 125                 static void postcall(lua_State*, const index_map&) {}
 126
 127                 struct only_accepts_nonconst_pointers {};
 128
 129                 template<class T, class Direction>
 130                 struct generate_converter
 131                 {
 132                         typedef luabind::detail::is_nonconst_pointer<T> is_nonconst_p;
 133                         typedef typename boost::mpl::if_<is_nonconst_p, adopt_pointer<Direction>, only_accepts_nonconst_pointers>::type type;
 134                 };
 135         };
 136
 137 }}
 138
 139 namespace luabind
 140 {
 141         template<int N>
 142         detail::policy_cons<detail::adopt_policy<N>, detail::null_type>
 143         adopt(boost::arg<N>) { return detail::policy_cons<detail::adopt_policy<N>, detail::null_type>(); }
 144 }
 145
 146 #endif // LUABIND_ADOPT_POLICY_HPP_INCLUDE
 147