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 boost::mpl::bool_<false> is_value_converter;
  39                 typedef adopt_pointer type;
  40
  41                 template<class T>
  42                 T* apply(lua_State* L, by_pointer<T>, int index)
  43                 {
  44                         // preconditions:
  45                         //      lua_isuserdata(L, index);
  46                         // getmetatable().__lua_class is true
  47                         // object_rep->flags() & object_rep::constant == 0
  48
  49                         int offset = 0;
  50                         object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, index));
  51                         assert((obj != 0) && "internal error, please report");
  52                         const class_rep* crep = obj->crep();
  53
  54                         int steps = implicit_cast(crep, LUABIND_TYPEID(T), offset);
  55                         (void)steps;
  56
  57                         assert((steps >= 0) && "adopt_pointer used with type that cannot be converted");
  58                         obj->remove_ownership();
  59                         T* ptr = reinterpret_cast<T*>(obj->ptr(offset));
  60
  61                         return ptr;
  62                 }
  63
  64                 template<class T>
  65                 static int match(lua_State* L, by_pointer<T>, int index)
  66                 {
  67                         object_rep* obj = is_class_object(L, index);
  68                         if (obj == 0) return -1;
  69                         // cannot cast a constant object to nonconst
  70                         if (obj->flags() & object_rep::constant) return -1;
  71                         if (!(obj->flags() & object_rep::owner)) return -1;
  72                         int d;
  73                         return implicit_cast(obj->crep(), LUABIND_TYPEID(T), d);
  74                 }
  75
  76                 template<class T>
  77                 void converter_postcall(lua_State*, T, int) {}
  78         };
  79
  80         template<>
  81         struct adopt_pointer<cpp_to_lua>
  82         {
  83                 typedef boost::mpl::bool_<false> is_value_converter;
  84                 typedef adopt_pointer type;
  85
  86                 template<class T>
  87                 void apply(lua_State* L, T* ptr)
  88                 {
  89                         if (ptr == 0)
  90                         {
  91                                 lua_pushnil(L);
  92                                 return;
  93                         }
  94
  95                         // if there is a back_reference, then the
  96                         // ownership will be removed from the
  97                         // back reference and put on the lua stack.
  98                         if (luabind::move_back_reference(L, ptr))
  99                         {
 100                                 object_rep* obj = static_cast<object_rep*>(lua_touserdata(L, -1));
 101                                 obj->set_flags(obj->flags() | object_rep::owner);
 102                                 return;
 103                         }
 104
 105                         class_registry* registry = class_registry::get_registry(L);
 106                         class_rep* crep = registry->find_class(LUABIND_TYPEID(T));
 107
 108 /*                      // create the struct to hold the object
 109                         void* obj = lua_newuserdata(L, sizeof(object_rep));
 110                         // we send 0 as destructor since we know it will never be called
 111                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);*/
 112
 113                         void* obj;
 114                         void* held;
 115
 116                         boost::tie(obj,held) = crep->allocate(L);
 117
 118                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);
 119
 120                         // set the meta table
 121                         detail::getref(L, crep->metatable_ref());
 122                         lua_setmetatable(L, -2);
 123                 }
 124         };
 125
 126         template<int N>
 127 //      struct adopt_policy : converter_policy_tag
 128         struct adopt_policy : conversion_policy<N>
 129         {
 130 //              BOOST_STATIC_CONSTANT(int, index = N);
 131
 132                 static void precall(lua_State*, const index_map&) {}
 133                 static void postcall(lua_State*, const index_map&) {}
 134
 135                 struct only_accepts_nonconst_pointers {};
 136
 137                 template<class T, class Direction>
 138                 struct apply
 139                 {
 140                         typedef luabind::detail::is_nonconst_pointer<T> is_nonconst_p;
 141                         typedef typename boost::mpl::if_<is_nonconst_p, adopt_pointer<Direction>, only_accepts_nonconst_pointers>::type type;
 142                 };
 143         };
 144
 145 }}
 146
 147 namespace luabind
 148 {
 149         template<int N>
 150         detail::policy_cons<detail::adopt_policy<N>, detail::null_type>
 151         adopt(LUABIND_PLACEHOLDER_ARG(N))
 152         {
 153                 return detail::policy_cons<detail::adopt_policy<N>, detail::null_type>();
 154         }
 155 }
 156
 157 #endif // LUABIND_ADOPT_POLICY_HPP_INCLUDE
 158