luabind/detail/ref.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_REF_HPP_INCLUDED
  25 #define LUABIND_REF_HPP_INCLUDED
  26
  27 #include <luabind/config.hpp>
  28
  29 namespace luabind { namespace detail
  30 {
  31
  32         // based on luaL_ref from lauxlib.c in lua distribution
  33         inline int ref(lua_State *L)
  34         {
  35                 int ref;
  36                 if (lua_isnil(L, -1))
  37                 {
  38                         lua_pop(L, 1);  /* remove from stack */
  39                         return LUA_REFNIL;  /* `nil' has a unique fixed reference */
  40                 }
  41
  42                 lua_rawgeti(L, LUA_REGISTRYINDEX, 0);  /* get first free element */
  43                 ref = (int)lua_tonumber(L, -1);  /* ref = t[0] */
  44                 lua_pop(L, 1);  /* remove it from stack */
  45                 if (ref != 0)
  46                 {  /* any free element? */
  47                         lua_rawgeti(L, LUA_REGISTRYINDEX, ref);  /* remove it from list */
  48                         lua_rawseti(L, LUA_REGISTRYINDEX, 0);  /* (that is, t[0] = t[ref]) */
  49                 }
  50                 else
  51                 {  /* no free elements */
  52                         lua_pushliteral(L, "n");
  53                         lua_pushvalue(L, -1);
  54                         lua_rawget(L, LUA_REGISTRYINDEX);  /* get t.n */
  55                         ref = (int)lua_tonumber(L, -1) + 1;  /* ref = t.n + 1 */
  56                         lua_pop(L, 1);  /* pop t.n */
  57                         lua_pushnumber(L, ref);
  58                         lua_rawset(L, LUA_REGISTRYINDEX);  /* t.n = t.n + 1 */
  59                 }
  60                 lua_rawseti(L, LUA_REGISTRYINDEX, ref);
  61                 return ref;
  62         }
  63
  64         inline void unref(lua_State *L, int ref)
  65         {
  66                 if (ref >= 0)
  67                 {
  68                         lua_rawgeti(L, LUA_REGISTRYINDEX, 0);
  69                         lua_rawseti(L, LUA_REGISTRYINDEX, ref);  /* t[ref] = t[0] */
  70                         lua_pushnumber(L, ref);
  71                         lua_rawseti(L, LUA_REGISTRYINDEX, 0);  /* t[0] = ref */
  72                 }
  73         }
  74
  75         inline void getref(lua_State* L, int r)
  76         {
  77                 lua_rawgeti(L, LUA_REGISTRYINDEX, r);
  78         }
  79
  80 }}
  81
  82 #endif // LUABIND_REF_HPP_INCLUDED