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 #include <boost/mpl/bool.hpp>
  31 #include <luabind/back_reference_fwd.hpp>
  32
  33 namespace luabind { namespace detail
  34 {
  35         template<class Direction = lua_to_cpp>
  36         struct adopt_pointer
  37         {
  38                 typedef adopt_pointer type;
  39
  40                 template<class T>
  41                 T* apply(lua_State* L, by_pointer<T>, int index)
  42                 {
  43                         // preconditions:
  44                         //      lua_isuserdata(L, index);
  45                         // getmetatable().__lua_class is true
  46                         // object_rep->flags() & object_rep::constant == 0
  47
  48                         int offset = 0;
  49                         object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, index));
  50                         assert((obj != 0) && "internal error, please report");
  51                         const class_rep* crep = obj->crep();
  52
  53                         int steps = implicit_cast(crep, LUABIND_TYPEID(T), offset);
  54                         (void)steps;
  55
  56                         assert((steps >= 0) && "adopt_pointer used with type that cannot be converted");
  57                         obj->remove_ownership();
  58                         T* ptr = reinterpret_cast<T*>(obj->ptr(offset));
  59
  60                         return ptr;
  61                 }
  62
  63                 template<class T>
  64                 static int match(lua_State* L, by_pointer<T>, int index)
  65                 {
  66                         object_rep* obj = is_class_object(L, index);
  67                         if (obj == 0) return -1;
  68                         // cannot cast a constant object to nonconst
  69                         if (obj->flags() & object_rep::constant) return -1;
  70                         if (!(obj->flags() & object_rep::owner)) return -1;
  71                         int d;
  72                         return implicit_cast(obj->crep(), LUABIND_TYPEID(T), d);
  73                 }
  74
  75                 template<class T>
  76                 void converter_postcall(lua_State*, T, int) {}
  77         };
  78
  79         template<>
  80         struct adopt_pointer<cpp_to_lua>
  81         {
  82                 typedef adopt_pointer type;
  83
  84                 template<class T>
  85                 void apply(lua_State* L, T* ptr)
  86                 {
  87                         if (ptr == 0)
  88                         {
  89                                 lua_pushnil(L);
  90                                 return;
  91                         }
  92
  93                         // if there is a back_reference, then the
  94                         // ownership will be removed from the
  95                         // back reference and put on the lua stack.
  96                         if (luabind::move_back_reference(L, ptr))
  97                         {
  98                                 object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, -1));
  99                                 obj->set_flags(obj->flags() | object_rep::owner);
 100                                 return;
 101                         }
 102
 103                         class_registry* registry = class_registry::get_registry(L);
 104                         class_rep* crep = registry->find_class(LUABIND_TYPEID(T));
 105
 106 /*                      // create the struct to hold the object
 107                         void* obj = lua_newuserdata(L, sizeof(object_rep));
 108                         // we send 0 as destructor since we know it will never be called
 109                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);*/
 110
 111                         void* obj;
 112                         void* held;
 113
 114                         boost::tie(obj,held) = crep->allocate(L);
 115
 116                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);
 117
 118                         // set the meta table
 119                         detail::getref(L, crep->metatable_ref());
 120                         lua_setmetatable(L, -2);
 121                 }
 122         };
 123
 124         template<int N>
 125 //      struct adopt_policy : converter_policy_tag
 126         struct adopt_policy : conversion_policy<N>
 127         {
 128 //              BOOST_STATIC_CONSTANT(int, index = N);
 129
 130                 static void precall(lua_State*, const index_map&) {}
 131                 static void postcall(lua_State*, const index_map&) {}
 132
 133                 struct only_accepts_nonconst_pointers {};
 134
 135                 template<class T, class Direction>
 136                 struct apply
 137                 {
 138                         typedef luabind::detail::is_nonconst_pointer<T> is_nonconst_p;
 139                         typedef typename boost::mpl::if_<is_nonconst_p, adopt_pointer<Direction>, only_accepts_nonconst_pointers>::type type;
 140                 };
 141         };
 142
 143 }}
 144
 145 namespace luabind
 146 {
 147         template<int N>
 148         detail::policy_cons<detail::adopt_policy<N>, detail::null_type>
 149         adopt(LUABIND_PLACEHOLDER_ARG(N))
 150         {
 151                 return detail::policy_cons<detail::adopt_policy<N>, detail::null_type>();
 152         }
 153 }
 154
 155 #endif // LUABIND_ADOPT_POLICY_HPP_INCLUDE
 156