common/lqt_common.cpp

   1 /*
   2  * Copyright (c) 2007-2008 Mauro Iazzi
   3  *
   4  * Permission is hereby granted, free of charge, to any person
   5  * obtaining a copy of this software and associated documentation
   6  * files (the "Software"), to deal in the Software without
   7  * restriction, including without limitation the rights to use,
   8  * copy, modify, merge, publish, distribute, sublicense, and/or sell
   9  * copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following
  11  * conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be
  14  * included in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  18  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  20  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  21  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  22  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  */
  26
  27 #include "lqt_common.hpp"
  28 #include <iostream>
  29 #include <cstdlib>
  30 #include <cstring>
  31
  32 static void lqtL_getenumtable (lua_State *L) {
  33     lua_getfield(L, LUA_REGISTRYINDEX, LQT_ENUMS);
  34     if (lua_isnil(L, -1)) {
  35         lua_pop(L, 1);
  36         lua_newtable(L);
  37         lua_pushvalue(L, -1);
  38         lua_setfield(L, LUA_REGISTRYINDEX, LQT_ENUMS);
  39     }
  40 }
  41
  42 static void lqtL_getpointertable (lua_State *L) {
  43     lua_getfield(L, LUA_REGISTRYINDEX, LQT_POINTERS); // (1) get storage for pointers
  44     if (lua_isnil(L, -1)) { // (1) if there is not
  45         lua_pop(L, 1); // (0) pop the nil value
  46         lua_newtable(L); // (1) create a new one
  47         lua_newtable(L); // (2) create an empty metatable
  48         lua_pushstring(L, "v"); // (3) push the mode value: weak values are enough
  49         lua_setfield(L, -2, "__mode"); // (2) set the __mode field
  50         lua_setmetatable(L, -2); // (1) set it as the metatable
  51         lua_pushvalue(L, -1); // (2) duplicate the new pointer table
  52         lua_setfield(L, LUA_REGISTRYINDEX, LQT_POINTERS); // (1) put one copy as storage
  53     }
  54 }
  55
  56 static void lqtL_getreftable (lua_State *L) {
  57     lua_getfield(L, LUA_REGISTRYINDEX, LQT_REFS); // (1) get storage for pointers
  58     if (lua_isnil(L, -1)) { // (1) if there is not
  59         lua_pop(L, 1); // (0) pop the nil value
  60         lua_newtable(L); // (1) create a new one
  61         lua_newtable(L); // (2) create an empty metatable
  62         lua_pushstring(L, "v"); // (3) push the mode value: weak values are enough
  63         lua_setfield(L, -2, "__mode"); // (2) set the __mode field
  64         lua_setmetatable(L, -2); // (1) set it as the metatable
  65         lua_pushvalue(L, -1); // (2) duplicate the new pointer table
  66         lua_setfield(L, LUA_REGISTRYINDEX, LQT_REFS); // (1) put one copy as storage
  67     }
  68 }
  69
  70 void * lqtL_getref (lua_State *L, size_t sz, bool weak) {
  71     void *ret = NULL;
  72     lqtL_getreftable(L); // (1)
  73     ret = lua_newuserdata(L, sz); // (2)
  74     /*
  75        lua_newtable(L); // (3)
  76        lua_getglobal(L, "DEBUG"); // (4)
  77        lua_setfield(L, -2, "__gc"); // (3)
  78        lua_setmetatable(L, -2); // (2)
  79        */
  80     if (weak) {
  81         lua_rawseti(L, -2, 1+lua_objlen(L, -2)); // (1)
  82     } else {
  83         lua_pushinteger(L, 1+lua_objlen(L, -2)); // (3)
  84         lua_settable(L, -3); // (1)
  85     }
  86     lua_pop(L, 1);
  87     return ret;
  88 }
  89
  90 bool * lqtL_toboolref (lua_State *L, int index) {
  91     bool tmp = lua_toboolean(L, index);
  92     bool *ret = (bool*)lqtL_getref(L, sizeof(bool), true);
  93     *ret = tmp;
  94     return ret;
  95 }
  96
  97 int * lqtL_tointref (lua_State *L, int index) {
  98     int tmp = lua_tointeger(L, index);
  99     int *ret = (int*)lqtL_getref(L, sizeof(int), false);
 100     *ret = tmp;
 101     return ret;
 102 }
 103
 104 void lqtL_pusharguments (lua_State *L, char **argv) {
 105     int i = 0;
 106     lua_newtable(L);
 107     for (i=0;*argv /* fix the maximum number? */;argv++,i++) {
 108         lua_pushstring(L, *argv);
 109         lua_rawseti(L, -2, i+1);
 110     }
 111     return;
 112 }
 113
 114 char ** lqtL_toarguments (lua_State *L, int index) {
 115     char ** ret = (char**)lqtL_getref(L, sizeof(char*)*(lua_objlen(L, index)+1), false);
 116     const char *str = NULL;
 117     size_t strlen = 0;
 118     int i = 0;
 119     for (i=0;;i++) {
 120         lua_rawgeti(L, index, i+1);
 121         if (!lua_isstring(L, -1)) {
 122             str = NULL; strlen = 0;
 123             ret[i] = NULL;
 124             lua_pop(L, 1);
 125             break;
 126         } else {
 127             str = lua_tolstring(L, -1, &strlen);
 128             ret[i] = (char*)lqtL_getref(L, sizeof(char)*(strlen+1), false);
 129             strncpy(ret[i], str, strlen+1);
 130             lua_pop(L, 1);
 131         }
 132     }
 133     return ret;
 134 }
 135
 136 static int lqtL_createenum (lua_State *L, lqt_Enum e[], const char *n) {
 137     luaL_Reg empty[] = { { 0, 0 } };
 138     lqt_Enum *l = e;
 139     lqtL_getenumtable(L); // (1)
 140     lua_newtable(L); // (2)
 141     lua_pushvalue(L, -1); // (3)
 142     lua_setfield(L, -3, n); // (2)
 143     while ( (l->name!=0) ) { // (2)
 144         lua_pushstring(L, l->name); // (3)
 145         lua_pushinteger(L, l->value); // (4)
 146         lua_settable(L, -3); // (2)
 147         lua_pushinteger(L, l->value); // (3)
 148         lua_pushstring(L, l->name); // (4)
 149         lua_settable(L, -3); // (2)
 150         l++; // (2)
 151     }
 152     lua_pop(L, 2); // (0)
 153     l = e;
 154     luaL_register(L, n, empty); // (1)
 155     while ( (l->name!=0) ) { // (1)
 156         lua_pushstring(L, l->name); // (2)
 157         lua_pushinteger(L, l->value); // (3)
 158         lua_settable(L, -3); // (1)
 159         lua_pushinteger(L, l->value); // (2)
 160         lua_pushstring(L, l->name); // (3)
 161         lua_settable(L, -3); // (1)
 162         l++; // (1)
 163     }
 164     lua_pop(L, 1); // (0)
 165     return 0;
 166 }
 167
 168 int lqtL_createenumlist (lua_State *L, lqt_Enumlist list[]) {
 169     while (list->enums!=0 && list->name!=0) {
 170         lqtL_createenum(L, list->enums, list->name); // (0)
 171         list++;
 172     }
 173     return 0;
 174 }
 175
 176 static int lqtL_gcfunc (lua_State *L) {
 177     if (!lua_isuserdata(L, 1) && lua_islightuserdata(L, 1)) return 0;
 178     lua_getfenv(L, 1); // (1)
 179     if (!lua_istable(L, -1)) {
 180         lua_pop(L, 1); // (0)
 181         return 0;
 182     }
 183     lua_getfield(L, -1, "__gc"); // (2)
 184     lua_remove(L, -2); // (1)
 185     if (!lua_isfunction(L, -1)) {
 186         lua_pop(L, 1); // (0)
 187         return 0;
 188     }
 189     lua_pushvalue(L, 1); // (2)
 190     if (lqtL_pcall(L, 1, 0, 0)) { // (-2;+1/+0)
 191         // (1)
 192         return lua_error(L);
 193     }
 194     return 0; // (+0)
 195 }
 196
 197 static int lqtL_newindexfunc (lua_State *L) {
 198     lua_settop(L, 3); // (=3)
 199     if (!lua_isuserdata(L, 1) && lua_islightuserdata(L, 1)) return 0;
 200     lua_getfenv(L, 1); // (+1)
 201     if (!lua_istable(L, -1)) {
 202         lua_pop(L, 1); // (+0)
 203         return 0;
 204     }
 205     lua_remove(L, 1); // (+0)
 206     lua_insert(L, 1); // (+0)
 207     lua_rawset(L, 1); // (-2)
 208     return 0;
 209 }
 210 static int lqtL_indexfunc (lua_State *L) {
 211     int i = 1;
 212     if (lua_isuserdata(L, 1) && !lua_islightuserdata(L, 1)) {
 213         lua_getfenv(L, 1); // (1)
 214         lua_pushvalue(L, 2); // (2)
 215         lua_gettable(L, -2); // (2)
 216         if (!lua_isnil(L, -1)) {
 217             lua_remove(L, -2);
 218             return 1;
 219         }
 220         lua_pop(L, 2); // (0)
 221     }
 222     lua_pushnil(L); // (+1)
 223     while (!lua_isnone(L, lua_upvalueindex(i))) { // (+1)
 224         lua_pop(L, 1); // (+0)
 225         lua_pushvalue(L, 2); // (+1)
 226         if (i==1) {
 227             lua_rawget(L, lua_upvalueindex(i)); // (+1)
 228         } else {
 229             lua_gettable(L, lua_upvalueindex(i)); // (+1)
 230         }
 231         if (!lua_isnil(L, -1)) break;
 232         i++;
 233     }
 234     return 1; // (+1)
 235 }
 236
 237 static int lqtL_pushindexfunc (lua_State *L, const char *name, lqt_Base *bases) {
 238     int upnum = 1;
 239     luaL_newmetatable(L, name); // (1)
 240     while (bases->basename!=NULL) {
 241         luaL_newmetatable(L, bases->basename); // (upnum)
 242         upnum++;
 243         bases++;
 244     }
 245     lua_pushcclosure(L, lqtL_indexfunc, upnum); // (1)
 246     return 1;
 247 }
 248
 249 static int lqtL_ctor_helper(lua_State*L) {
 250     lua_getfield(L, 1, "new");
 251     lua_replace(L, 1);
 252     lua_call(L, lua_gettop(L)-1, LUA_MULTRET);
 253     return lua_gettop(L);
 254 }
 255
 256 static int lqtL_local_ctor(lua_State*L) {
 257     lua_pushvalue(L, lua_upvalueindex(1)); // (+1)
 258     lua_getfield(L, -1, "new"); // (+2)
 259     lua_insert(L, 1); // (+2)
 260     lua_pop(L, 1); // (+1)
 261     lua_call(L, lua_gettop(L)-1, LUA_MULTRET); // (X)
 262     lua_getfield(L, 1, "delete"); // (X+1)
 263     lua_setfield(L, 1, "__gc"); // (X)
 264     return lua_gettop(L);
 265 }
 266
 267 int lqtL_createclass (lua_State *L, const char *name, luaL_Reg *mt, lqt_Base *bases) {
 268     int len = 0;
 269     char *new_name = NULL;
 270     lqt_Base *bi = bases;
 271     luaL_newmetatable(L, name); // (1)
 272     luaL_register(L, NULL, mt); // (1)
 273     // setup offsets
 274     lua_pushstring(L, name); // (2) FIXME: remove
 275     lua_pushinteger(L, 0); // (3) FIXME: remove
 276     lua_settable(L, -3); // (1) FIXME: remove
 277     while (bi->basename!=NULL) {
 278         lua_pushstring(L, bi->basename); // (2) FIXME: remove
 279         lua_pushinteger(L, bi->offset); // (3) FIXME: remove
 280         lua_settable(L, -3); // (1) FIXME: remove
 281         bi++;
 282     }
 283     // set metafunctions
 284     lqtL_pushindexfunc(L, name, bases); // (2)
 285     lua_setfield(L, -2, "__index"); // (1)
 286     lua_pushcfunction(L, lqtL_newindexfunc); // (2)
 287     lua_setfield(L, -2, "__newindex"); // (1)
 288     lua_pushcfunction(L, lqtL_gcfunc); // (2)
 289     lua_setfield(L, -2, "__gc"); // (1)
 290
 291     // set it as its own metatable
 292     lua_pushvalue(L, -1); // (2)
 293     lua_setmetatable(L, -2); // (1)
 294     lua_pop(L, 1); // (0)
 295     len = strlen(name);
 296     new_name = (char*)malloc(len*sizeof(char));
 297     strncpy(new_name, name, len);
 298     new_name[len-1] = '\0';
 299     luaL_register(L, new_name, mt); // (1)
 300     free(new_name);
 301     new_name = NULL;
 302     lua_newtable(L); // (2)
 303     lua_pushcfunction(L, lqtL_ctor_helper); // (3)
 304     lua_setfield(L, -2, "__call"); // (2)
 305     lua_setmetatable(L, -2); // (1)
 306     lua_pushvalue(L, -1); // (2)
 307     lua_pushcclosure(L, lqtL_local_ctor, 1); // (2)
 308     lua_setfield(L, -2, "new_local");
 309     lua_pop(L, 1); // (0)
 310     /*
 311        lua_pushlstring(L, name, strlen(name)-1); // (1)
 312        lua_newtable(L); // (2)
 313        luaL_newmetatable(L, name); // (3)
 314        lua_setmetatable(L, -2); // (2)
 315     // don't register again but use metatable
 316     //luaL_register(L, NULL, mt); // (2)
 317     lua_settable(L, LUA_GLOBALSINDEX); // (0)
 318     */
 319     return 0;
 320 }
 321
 322     bool lqtL_isinteger (lua_State *L, int i) {
 323         if (lua_type(L, i)==LUA_TNUMBER)
 324             return lua_tointeger(L, i)==lua_tonumber(L, i);
 325         else
 326             return false;
 327     }
 328 bool lqtL_isnumber (lua_State *L, int i) {
 329     return lua_type(L, i)==LUA_TNUMBER;
 330 }
 331 bool lqtL_isstring (lua_State *L, int i) {
 332     return lua_type(L, i)==LUA_TSTRING;
 333 }
 334 bool lqtL_isboolean (lua_State *L, int i) {
 335     return lua_type(L, i)==LUA_TBOOLEAN;
 336 }
 337 bool lqtL_missarg (lua_State *L, int index, int n) {
 338     bool ret = true;
 339     int i = 0;
 340     for (i=index;i<index+n;i++) {
 341         if (!lua_isnoneornil(L, i)) {
 342             ret = false;
 343             break;
 344         }
 345     }
 346     return ret;
 347 }
 348
 349 static void CS(lua_State *L) {
 350     std::cerr << "++++++++++" << std::endl;
 351     for (int i=1;i<=lua_gettop(L);i++) {
 352         std::cerr << luaL_typename(L, i) << " " << lua_touserdata(L, i) << std::endl;
 353     }
 354     std::cerr << "----------" << std::endl;
 355 }
 356
 357 static void lqtL_ensurepointer (lua_State *L, const void *p) { // (+1)
 358     lqtL_getpointertable(L); // (1)
 359     lua_pushlightuserdata(L, const_cast<void*>(p)); // (2)
 360     lua_gettable(L, -2); // (2)
 361     if (lua_isnil(L, -1)) { // (2)
 362         lua_pop(L, 1); // (1)
 363         const void **pp = static_cast<const void**>(lua_newuserdata(L, sizeof(void*))); // (2)
 364         *pp = p; // (2)
 365         lua_newtable(L); // (3)
 366         lua_setfenv(L, -2); // (2)
 367         lua_pushlightuserdata(L, const_cast<void*>(p)); // (3)
 368         lua_pushvalue(L, -2); // (4)
 369         lua_settable(L, -4); // (2)
 370     } else {
 371         //const void **pp = static_cast<const void**>(lua_touserdata(L, -1)); // (2)
 372         //if (pp!=NULL) *pp = p; // (2)
 373     }
 374     // (2)
 375     lua_remove(L, -2); // (1)
 376 }
 377
 378 void lqtL_register (lua_State *L, const void *p) { // (+0)
 379     lqtL_ensurepointer(L, p);
 380     lua_pop(L, 1);
 381 }
 382
 383 void lqtL_unregister (lua_State *L, const void *p) {
 384     lqtL_getpointertable(L); // (1)
 385     lua_pushlightuserdata(L, const_cast<void*>(p)); // (2)
 386     lua_gettable(L, -2); // (2)
 387     if (lua_isuserdata(L, -1)) {
 388         const void **pp = static_cast<const void**>(lua_touserdata(L, -1)); // (2)
 389         *pp = 0;
 390     }
 391     lua_pop(L, 1); // (1)
 392     lua_pushlightuserdata(L, const_cast<void*>(p)); // (2)
 393     lua_pushnil(L); // (3)
 394     lua_settable(L, -3); // (1)
 395     lua_pop(L, 1); // (0)
 396 }
 397
 398 void lqtL_pushudata (lua_State *L, const void *p, const char *name) {
 399     bool already = false;
 400     lqtL_ensurepointer(L, p); // (1)
 401     if (lua_getmetatable(L, -1)) {
 402         // (2)
 403         lua_pop(L, 1); // (1)
 404         lua_getfield(L, -1, name); // (2)
 405         already = lua_toboolean(L, -1); // (2)
 406         lua_pop(L, 1); // (1)
 407     } else {
 408         // (1)
 409     }
 410     if (!already) {
 411         luaL_newmetatable(L, name); // (2)
 412         lua_setmetatable(L, -2); // (1)
 413     }
 414     return;
 415 }
 416
 417 void lqtL_passudata (lua_State *L, const void *p, const char *name) {
 418     lqtL_pushudata(L, p, name);
 419     // FIXME: these should be added, but it is not safe for now
 420     lua_getfield(L, -1, "delete");
 421     lua_setfield(L, -2, "__gc");
 422     return;
 423 }
 424
 425 void lqtL_copyudata (lua_State *L, const void *p, const char *name) {
 426     luaL_newmetatable(L, name);
 427     lua_pushstring(L, "new");
 428     lua_rawget(L, -2);
 429     if (lua_isnil(L, -1)) {
 430         std::cerr << "cannot copy " << name << std::endl;
 431         lua_pop(L, 2);
 432         lua_pushnil(L);
 433     } else {
 434         lua_remove(L, -2);
 435         lqtL_pushudata(L, p, name);
 436         if (lqtL_pcall(L, 1, 1, 0)) {
 437             std::cerr << "error copying " << name << std::endl;
 438             lua_pop(L, 1);
 439             lua_pushnil(L);
 440         }
 441         // Enable autodeletion for copied stuff
 442         lua_getfield(L, -1, "delete");
 443         lua_setfield(L, -2, "__gc");
 444     }
 445     return;
 446 }
 447
 448 void *lqtL_toudata (lua_State *L, int index, const char *name) {
 449     void *ret = 0;
 450     if (!lqtL_testudata(L, index, name)) return 0;
 451     void **pp = static_cast<void**>(lua_touserdata(L, index));
 452     ret = *pp;
 453     lua_getfield(L, index, name);
 454     ret = (void*)(lua_tointeger(L, -1) + (char*)ret);
 455     lua_pop(L, 1);
 456     return ret;
 457 }
 458
 459 void lqtL_eraseudata (lua_State *L, int index, const char *name) {
 460     void *ret = 0;
 461     if (name!=NULL && !lqtL_testudata(L, index, name)) return;
 462     void **pp = static_cast<void**>(lua_touserdata(L, index));
 463     void *p = *pp;
 464     *pp = 0;
 465     lqtL_getpointertable(L); // (1)
 466     lua_pushlightuserdata(L, p); // (2)
 467     lua_pushnil(L); // (3)
 468     lua_settable(L, -3); // (1)
 469     lua_pop(L, 1);
 470     return;
 471 }
 472
 473 bool lqtL_testudata (lua_State *L, int index, const char *name) {
 474     if (!lua_isuserdata(L, index) || lua_islightuserdata(L, index)) return false;
 475     lua_getfield(L, index, name);
 476     if (lua_isnil(L, -1)) {
 477         lua_pop(L, 1);
 478         return false;
 479     }
 480     lua_pop(L, 1);
 481     return true;
 482 }
 483
 484 void lqtL_pushenum (lua_State *L, int value, const char *name) {
 485     lqtL_getenumtable(L);
 486     lua_getfield(L, -1, name);
 487     lua_remove(L, -2);
 488     if (!lua_istable(L, -1)) {
 489         lua_pop(L, 1);
 490         lua_pushnil(L);
 491         return;
 492     }
 493     lua_pushnumber(L, value);
 494     lua_gettable(L, -2);
 495     lua_remove(L, -2);
 496 }
 497
 498 bool lqtL_isenum (lua_State *L, int index, const char *name) {
 499     bool ret = false;
 500     if (!lua_isstring(L, index)) return false;
 501     lqtL_getenumtable(L);
 502     lua_getfield(L, -1, name);
 503     if (!lua_istable(L, -1)) {
 504         lua_pop(L, 2);
 505         return false;
 506     }
 507     lua_remove(L, -2);
 508     lua_pushvalue(L, index);
 509     lua_gettable(L, -2);
 510     ret = !lua_isnil(L, -1);
 511     lua_pop(L, 2);
 512     return ret;
 513 }
 514
 515 int lqtL_toenum (lua_State *L, int index, const char *name) {
 516     int ret = -1;
 517     // index = LQT_TOPOSITIVE(L, index);
 518     lqtL_getenumtable(L); // (1)
 519     lua_getfield(L, -1, name); // (2)
 520     if (lua_isnil(L, -1)) {
 521         lua_pop(L, 2); //(0)
 522         return 0;
 523     }
 524     lua_pushvalue(L, index); // (3)
 525     lua_gettable(L, -2); // (3)
 526     if (lqtL_isinteger(L, -1)) {
 527         ret = lua_tointeger(L, -1); // (3)
 528     } else {
 529         ret = lua_tointeger(L, index); // (3)
 530     }
 531     lua_pop(L, 3); // (0)
 532     return ret;
 533 }
 534
 535 int lqtL_getflags (lua_State *L, int index, const char *name) {
 536     int ret = 0;
 537     int eindex = 0;
 538     int i = 1;
 539     if (lqtL_isinteger(L, index)) return lua_tointeger(L, index);
 540     if (!lua_istable(L, index)) return 0;
 541     lqtL_getenumtable(L); // (1)
 542     lua_getfield(L, -1, name); // (2)
 543     if (!lua_istable(L, -1)) {
 544         // (2)
 545         lua_pop(L, 2);
 546         return 0;
 547     }
 548     // (2)
 549     lua_remove(L, -2); // (1)
 550     eindex = lua_gettop(L);
 551     for (i=1;;i++) { // (1)
 552         lua_rawgeti(L, index, i); // (2)
 553         if (lua_type(L, -1)!=LUA_TSTRING) {
 554             lua_pop(L, 1); // (1)
 555             break;
 556         } else {
 557             lua_gettable(L, eindex); // (2)
 558             ret = ret | (int)lua_tointeger(L, -1);
 559             lua_pop(L, 1); // (1)
 560         }
 561     }
 562     // (1)
 563     lua_pop(L, 1); // (0)
 564     return ret;
 565 }
 566
 567 void lqtL_pushflags (lua_State *L, int index, const char *name) {
 568     // TODO
 569     lua_pushnil(L);
 570     return;
 571 }
 572
 573 int lqtL_touintarray (lua_State *L) {
 574     uint *p = NULL;
 575     size_t i = 0;
 576     size_t n, nb;
 577     n = lua_objlen(L, -1);
 578     nb = (n + 1) * sizeof(uint);
 579     p = (uint*)lua_newuserdata(L, nb);
 580     for (i=1;i<=n;i++) {
 581         lua_rawgeti(L, -2, i);
 582         p[i-1] = lua_tointeger(L, -1);
 583         lua_pop(L, 1);
 584     }
 585     lua_remove(L, -2);
 586     p[n] = 0;
 587     return 1;
 588 }
 589
 590 int lqtL_pcall_debug_default (lua_State *L, int narg, int nres, int err) {
 591     int status = 0;
 592     std::cerr << "entering a pcall" << std::endl;
 593     status = lua_pcall(L, narg, nres, err);
 594     std::cerr << "pcall finished with status " << status << std::endl;
 595     return status;
 596 }
 597
 598 int lqtL_pcall_debug (lua_State *L, int narg, int nres, int err) {
 599     int status = 0;
 600     lua_getfield(L, LUA_REGISTRYINDEX, LQT_PCALL);
 601     lqt_PCallPtr pcall = (lqt_PCallPtr)lua_touserdata(L, -1);
 602     lua_pop(L, 1);
 603     if (pcall) {
 604         status = pcall(L, narg, nres, err);
 605     } else {
 606         status = lqtL_pcall_debug_default(L, narg, nres, err);
 607     }
 608     return status;
 609 }
 610
 611
 612