src/ref.cpp

   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 #include <algorithm>
  24 #include <luabind/config.hpp>
  25 #include <luabind/detail/ref.hpp>
  26 #include <luabind/lua_include.hpp>
  27 #include <luabind/detail/debug.hpp>
  28
  29 namespace luabind { namespace detail
  30 {
  31
  32 // most of the code in this file comes from
  33 // lauxlib.c in lua distribution
  34
  35 /******************************************************************************
  36 * Copyright (C) 1994-2003 Tecgraf, PUC-Rio.  All rights reserved.
  37 *
  38 * Permission is hereby granted, free of charge, to any person obtaining
  39 * a copy of this software and associated documentation files (the
  40 * "Software"), to deal in the Software without restriction, including
  41 * without limitation the rights to use, copy, modify, merge, publish,
  42 * distribute, sublicense, and/or sell copies of the Software, and to
  43 * permit persons to whom the Software is furnished to do so, subject to
  44 * the following conditions:
  45 *
  46 * The above copyright notice and this permission notice shall be
  47 * included in all copies or substantial portions of the Software.
  48 *
  49 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  50 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  51 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  52 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  53 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  54 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  55 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  56 ******************************************************************************/
  57
  58         enum
  59         {
  60                 // the number of reserved references
  61                 RESERVED_REFS = 2,
  62
  63                 // free list of references
  64                 FREELIST_REF = 1,
  65
  66                 // array sizes (not used here)
  67                 ARRAYSIZE_REF = 2
  68         };
  69
  70         int checkint (lua_State *L, int topop)
  71         {
  72                 int n = (int)lua_tonumber(L, -1);
  73                 if (n == 0 && !lua_isnumber(L, -1)) n = -1;
  74                 lua_pop(L, topop);
  75                 return n;
  76         }
  77
  78
  79         void getsizes (lua_State *L)
  80         {
  81                 lua_rawgeti(L, LUA_REGISTRYINDEX, ARRAYSIZE_REF);
  82                 if (lua_isnil(L, -1)) {  /* no `size' table? */
  83                         lua_pop(L, 1);  /* remove nil */
  84                         lua_newtable(L);  /* create it */
  85                         lua_pushvalue(L, -1);  /* `size' will be its own metatable */
  86                         lua_setmetatable(L, -2);
  87                         lua_pushliteral(L, "__mode");
  88                         lua_pushliteral(L, "k");
  89                         lua_rawset(L, -3);  /* metatable(N).__mode = "k" */
  90                         lua_pushvalue(L, -1);
  91                         lua_rawseti(L, LUA_REGISTRYINDEX, ARRAYSIZE_REF);  /* store in register */
  92                 }
  93         }
  94
  95         void luaL_setn (lua_State *L, int t, int n)
  96         {
  97                 lua_pushliteral(L, "n");
  98                 lua_rawget(L, t);
  99                 if (checkint(L, 1) >= 0) {  /* is there a numeric field `n'? */
 100                         lua_pushliteral(L, "n");  /* use it */
 101                         lua_pushnumber(L, n);
 102                         lua_rawset(L, t);
 103                 }
 104                 else {  /* use `sizes' */
 105                         getsizes(L);
 106                         lua_pushvalue(L, t);
 107                         lua_pushnumber(L, n);
 108                         lua_rawset(L, -3);  /* sizes[t] = n */
 109                         lua_pop(L, 1);  /* remove `sizes' */
 110                 }
 111         }
 112
 113         int luaL_getn (lua_State *L, int t)
 114         {
 115                 int n;
 116                 lua_pushliteral(L, "n");  /* try t.n */
 117                 lua_rawget(L, t);
 118                 if ((n = checkint(L, 1)) >= 0) return n;
 119                 getsizes(L);  /* else try sizes[t] */
 120                 lua_pushvalue(L, t);
 121                 lua_rawget(L, -2);
 122                 if ((n = checkint(L, 2)) >= 0) return n;
 123                 for (n = 1; ; n++) {  /* else must count elements */
 124                         lua_rawgeti(L, t, n);
 125                         if (lua_isnil(L, -1)) break;
 126                         lua_pop(L, 1);
 127                 }
 128                 lua_pop(L, 1);
 129                 return n - 1;
 130         }
 131
 132
 133         // based on luaL_ref
 134         int LUABIND_API ref(lua_State *L)
 135         {
 136                 int t = LUA_REGISTRYINDEX;
 137
 138                 int ref;
 139                 if (lua_isnil(L, -1))
 140                 {
 141                         lua_pop(L, 1);  /* remove from stack */
 142                         return LUA_REFNIL;  /* `nil' has a unique fixed reference */
 143                 }
 144
 145                 lua_rawgeti(L, t, FREELIST_REF);  /* get first free element */
 146                 ref = (int)lua_tonumber(L, -1);  /* ref = t[FREELIST_REF] */
 147                 lua_pop(L, 1);  /* remove it from stack */
 148                 if (ref != 0) {  /* any free element? */
 149                         lua_rawgeti(L, t, ref);  /* remove it from list */
 150                         lua_rawseti(L, t, FREELIST_REF);  /* (t[FREELIST_REF] = t[ref]) */
 151                 }
 152                 else {  /* no free elements */
 153                         ref = ::luabind::detail::luaL_getn(L, t);
 154                         if (ref < RESERVED_REFS)
 155                         ref = RESERVED_REFS;  /* skip reserved references */
 156                         ref++;  /* create new reference */
 157                         ::luabind::detail::luaL_setn(L, t, ref);
 158                 }
 159                 lua_rawseti(L, t, ref);
 160                 return ref;
 161         }
 162
 163         void LUABIND_API unref(lua_State *L, int ref)
 164         {
 165                 LUABIND_CHECK_STACK(L);
 166
 167                 int t = LUA_REGISTRYINDEX;
 168                 if (ref >= 0) {
 169                         lua_rawgeti(L, t, FREELIST_REF);
 170                         lua_rawseti(L, t, ref);  /* t[ref] = t[FREELIST_REF] */
 171                         lua_pushnumber(L, ref);
 172                         lua_rawseti(L, t, FREELIST_REF);  /* t[FREELIST_REF] = ref */
 173                 }
 174         }
 175
 176 }}