common/luaobject.c

   1 /*
   2  * luaobject.c - useful functions for handling Lua objects
   3  *
   4  * Copyright © 2009 Julien Danjou <julien@danjou.info>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  */
  21
  22 #include "common/luaobject.h"
  23
  24 /** Setup the object system at startup.
  25  * \param L The Lua VM state.
  26  */
  27 void
  28 luaA_object_setup(lua_State *L)
  29 {
  30     /* Push identification string */
  31     lua_pushliteral(L, LUAA_OBJECT_REGISTRY_KEY);
  32     /* Create an empty table */
  33     lua_newtable(L);
  34     /* Create an empty metatable */
  35     lua_newtable(L);
  36     /* Set this empty table as the registry metatable.
  37      * It's used to store the number of reference on stored objects. */
  38     lua_setmetatable(L, -2);
  39     /* Register table inside registry */
  40     lua_rawset(L, LUA_REGISTRYINDEX);
  41 }
  42
  43 /** Increment a object reference in its store table.
  44  * \param L The Lua VM state.
  45  * \param tud The table index on the stack.
  46  * \param oud The object index on the stack.
  47  * \return A pointer to the object.
  48  */
  49 void *
  50 luaA_object_incref(lua_State *L, int tud, int oud)
  51 {
  52     /* Get pointer value of the item */
  53     void *pointer = (void *) lua_topointer(L, oud);
  54
  55     /* Not reference able. */
  56     if(!pointer)
  57     {
  58         lua_remove(L, oud);
  59         return NULL;
  60     }
  61
  62     /* Push the pointer (key) */
  63     lua_pushlightuserdata(L, pointer);
  64     /* Push the data (value) */
  65     lua_pushvalue(L, oud < 0 ? oud - 1 : oud);
  66     /* table.lightudata = data */
  67     lua_rawset(L, tud < 0 ? tud - 2 : tud);
  68
  69     /* refcount++ */
  70
  71     /* Get the metatable */
  72     lua_getmetatable(L, tud);
  73     /* Push the pointer (key) */
  74     lua_pushlightuserdata(L, pointer);
  75     /* Get the number of references */
  76     lua_rawget(L, -2);
  77     /* Get the number of references and increment it */
  78     int count = lua_tonumber(L, -1) + 1;
  79     lua_pop(L, 1);
  80     /* Push the pointer (key) */
  81     lua_pushlightuserdata(L, pointer);
  82     /* Push count (value) */
  83     lua_pushinteger(L, count);
  84     /* Set metatable[pointer] = count */
  85     lua_rawset(L, -3);
  86     /* Pop metatable */
  87     lua_pop(L, 1);
  88
  89     /* Remove referenced item */
  90     lua_remove(L, oud);
  91
  92     return pointer;
  93 }
  94
  95 /** Decrement a object reference in its store table.
  96  * \param L The Lua VM state.
  97  * \param tud The table index on the stack.
  98  * \param oud The object index on the stack.
  99  * \return A pointer to the object.
 100  */
 101 void
 102 luaA_object_decref(lua_State *L, int tud, void *pointer)
 103 {
 104     if(!pointer)
 105         return;
 106
 107     /* First, refcount-- */
 108     /* Get the metatable */
 109     lua_getmetatable(L, tud);
 110     /* Push the pointer (key) */
 111     lua_pushlightuserdata(L, pointer);
 112     /* Get the number of references */
 113     lua_rawget(L, -2);
 114     /* Get the number of references and decrement it */
 115     int count = lua_tonumber(L, -1) - 1;
 116     lua_pop(L, 1);
 117     /* Push the pointer (key) */
 118     lua_pushlightuserdata(L, pointer);
 119     /* Hasn't the ref reached 0? */
 120     if(count)
 121         lua_pushinteger(L, count);
 122     else
 123         /* Yup, delete it, set nil as value */
 124         lua_pushnil(L);
 125     /* Set meta[pointer] = count/nil */
 126     lua_rawset(L, -3);
 127     /* Pop metatable */
 128     lua_pop(L, 1);
 129
 130     /* Wait, no more ref? */
 131     if(!count)
 132     {
 133         /* Yes? So remove it from table */
 134         lua_pushlightuserdata(L, pointer);
 135         /* Push nil as value */
 136         lua_pushnil(L);
 137         /* table[pointer] = nil */
 138         lua_rawset(L, tud < 0 ? tud - 2 : tud);
 139     }
 140 }
 141
 142 int
 143 luaA_settype(lua_State *L, lua_class_t *lua_class)
 144 {
 145     lua_pushlightuserdata(L, lua_class);
 146     lua_rawget(L, LUA_REGISTRYINDEX);
 147     lua_setmetatable(L, -2);
 148     return 1;
 149 }
 150
 151 /** Add a signal to an object.
 152  * \param L The Lua VM state.
 153  * \param oud The object index on the stack.
 154  * \param name The name of the signal.
 155  * \param ud The index of function to call when signal is emitted.
 156  */
 157 void
 158 luaA_object_add_signal(lua_State *L, int oud,
 159                        const char *name, int ud)
 160 {
 161     luaA_checkfunction(L, ud);
 162     lua_object_t *obj = lua_touserdata(L, oud);
 163     signal_add(&obj->signals, name, luaA_object_ref_item(L, oud, ud));
 164 }
 165
 166 /** Remove a signal to an object.
 167  * \param L The Lua VM state.
 168  * \param oud The object index on the stack.
 169  * \param name The name of the signal.
 170  * \param ud The index of function to call when signal is emitted.
 171  */
 172 void
 173 luaA_object_remove_signal(lua_State *L, int oud,
 174                           const char *name, int ud)
 175 {
 176     luaA_checkfunction(L, ud);
 177     lua_object_t *obj = lua_touserdata(L, oud);
 178     void *ref = (void *) lua_topointer(L, ud);
 179     signal_remove(&obj->signals, name, ref);
 180     luaA_object_unref_item(L, oud, ref);
 181     lua_remove(L, ud);
 182 }
 183
 184 void
 185 signal_object_emit(lua_State *L, signal_array_t *arr, const char *name, int nargs)
 186 {
 187     signal_t *sigfound = signal_array_getbyid(arr,
 188                                               a_strhash((const unsigned char *) name));
 189
 190     if(sigfound)
 191     {
 192         int nbfunc = sigfound->sigfuncs.len;
 193         luaL_checkstack(L, lua_gettop(L) + nbfunc + nargs + 1, "too much signal");
 194         /* Push all functions and then execute, because this list can change
 195          * while executing funcs. */
 196         foreach(func, sigfound->sigfuncs)
 197             luaA_object_push(L, (void *) *func);
 198
 199         for(int i = 0; i < nbfunc; i++)
 200         {
 201             /* push all args */
 202             for(int j = 0; j < nargs; j++)
 203                 lua_pushvalue(L, - nargs - nbfunc + i);
 204             /* push first function */
 205             lua_pushvalue(L, - nargs - nbfunc + i);
 206             /* remove this first function */
 207             lua_remove(L, - nargs - nbfunc - 1 + i);
 208             luaA_dofunction(L, nargs, 0);
 209         }
 210     }
 211     /* remove args */
 212     lua_pop(L, nargs);
 213 }
 214
 215 /** Emit a signal to an object.
 216  * \param L The Lua VM state.
 217  * \param oud The object index on the stack.
 218  * \param name The name of the signal.
 219  * \param nargs The number of arguments to pass to the called functions.
 220  */
 221 void
 222 luaA_object_emit_signal(lua_State *L, int oud,
 223                         const char *name, int nargs)
 224 {
 225     int oud_abs = luaA_absindex(L, oud);
 226     lua_object_t *obj = lua_touserdata(L, oud);
 227     if(!obj)
 228         luaL_error(L, "trying to emit signal on non-object");
 229     signal_t *sigfound = signal_array_getbyid(&obj->signals,
 230                                               a_strhash((const unsigned char *) name));
 231     if(sigfound)
 232     {
 233         int nbfunc = sigfound->sigfuncs.len;
 234         luaL_checkstack(L, lua_gettop(L) + nbfunc + nargs + 2, "too much signal");
 235         /* Push all functions and then execute, because this list can change
 236          * while executing funcs. */
 237         foreach(func, sigfound->sigfuncs)
 238             luaA_object_push_item(L, oud_abs, (void *) *func);
 239
 240         for(int i = 0; i < nbfunc; i++)
 241         {
 242             /* push object */
 243             lua_pushvalue(L, oud_abs);
 244             /* push all args */
 245             for(int j = 0; j < nargs; j++)
 246                 lua_pushvalue(L, - nargs - nbfunc - 1 + i);
 247             /* push first function */
 248             lua_pushvalue(L, - nargs - nbfunc - 1 + i);
 249             /* remove this first function */
 250             lua_remove(L, - nargs - nbfunc - 2 + i);
 251             luaA_dofunction(L, nargs + 1, 0);
 252         }
 253     }
 254     lua_pop(L, nargs);
 255 }
 256
 257 int
 258 luaA_object_add_signal_simple(lua_State *L)
 259 {
 260     luaA_object_add_signal(L, 1, luaL_checkstring(L, 2), 3);
 261     return 0;
 262 }
 263
 264 int
 265 luaA_object_remove_signal_simple(lua_State *L)
 266 {
 267     luaA_object_remove_signal(L, 1, luaL_checkstring(L, 2), 3);
 268     return 0;
 269 }
 270
 271 int
 272 luaA_object_emit_signal_simple(lua_State *L)
 273 {
 274     luaA_object_emit_signal(L, 1, luaL_checkstring(L, 2), lua_gettop(L) - 2);
 275     return 0;
 276 }
 277
 278 int
 279 luaA_object_tostring(lua_State *L)
 280 {
 281     lua_class_t *lua_class = luaA_class_get(L, 1);
 282     lua_pushfstring(L, "%s: %p", lua_class->name, luaA_checkudata(L, 1, lua_class));
 283     return 1;
 284 }
 285
 286 /** Garbage collect a Lua object.
 287  * \param L The Lua VM state.
 288  * \return The number of elements pushed on stack.
 289  */
 290 int
 291 luaA_object_gc(lua_State *L)
 292 {
 293     lua_object_t *item = lua_touserdata(L, 1);
 294     signal_array_wipe(&item->signals);
 295     return 0;
 296 }
 297
 298 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80