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
  51                         assert((steps >= 0) && "adopt_pointer used with type that cannot be converted");
  52                         obj->remove_ownership();
  53                         T* ptr = reinterpret_cast<T*>(obj->ptr(offset));
  54
  55                         return ptr;
  56                 }
  57
  58                 template<class T>
  59                 static int match(lua_State* L, by_pointer<T>, int index)
  60                 {
  61                         object_rep* obj = is_class_object(L, index);
  62                         if (obj == 0) return -1;
  63                         // cannot cast a constant object to nonconst
  64                         if (obj->flags() & object_rep::constant) return -1;
  65                         if (!(obj->flags() & object_rep::owner)) return -1;
  66                         int d;
  67                         return implicit_cast(obj->crep(), LUABIND_TYPEID(T), d);
  68                 }
  69
  70                 template<class T>
  71                 void converter_postcall(lua_State*, T, int) {}
  72         };
  73
  74         template<>
  75         struct adopt_pointer<cpp_to_lua>
  76         {
  77                 template<class T>
  78                 void apply(lua_State* L, T* ptr)
  79                 {
  80                         if (ptr == 0)
  81                         {
  82                                 lua_pushnil(L);
  83                                 return;
  84                         }
  85
  86                         class_registry* registry = class_registry::get_registry(L);
  87                         class_rep* crep = registry->find_class(LUABIND_TYPEID(T));
  88
  89 /*                      // create the struct to hold the object
  90                         void* obj = lua_newuserdata(L, sizeof(object_rep));
  91                         // we send 0 as destructor since we know it will never be called
  92                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);*/
  93
  94                         void* obj;
  95                         void* held;
  96
  97                         boost::tie(obj,held) = crep->allocate(L);
  98
  99                         new(obj) object_rep(ptr, crep, object_rep::owner, delete_s<T>::apply);
 100
 101                         // set the meta table
 102                         detail::getref(L, crep->metatable_ref());
 103                         lua_setmetatable(L, -2);
 104                 }
 105         };
 106
 107         template<int N>
 108 //      struct adopt_policy : converter_policy_tag
 109         struct adopt_policy : conversion_policy<N>
 110         {
 111 //              BOOST_STATIC_CONSTANT(int, index = N);
 112
 113                 static void precall(lua_State*, const index_map&) {}
 114                 static void postcall(lua_State*, const index_map&) {}
 115
 116                 struct only_accepts_nonconst_pointers {};
 117
 118                 template<class T, class Direction>
 119                 struct generate_converter
 120                 {
 121                         typedef luabind::detail::is_nonconst_pointer<T> is_nonconst_p;
 122                         typedef typename boost::mpl::if_<is_nonconst_p, adopt_pointer<Direction>, only_accepts_nonconst_pointers>::type type;
 123                 };
 124         };
 125
 126 }}
 127
 128 namespace luabind
 129 {
 130         template<int N>
 131         detail::policy_cons<detail::adopt_policy<N>, detail::null_type>
 132         adopt(boost::arg<N>) { return detail::policy_cons<detail::adopt_policy<N>, detail::null_type>(); }
 133 }
 134
 135 #endif // LUABIND_ADOPT_POLICY_HPP_INCLUDE
 136