src/fallback.c

   1 /*
   2 ** fallback.c
   3 ** TecCGraf - PUC-Rio
   4 */
   5
   6 char *rcs_fallback="$Id: fallback.c,v 2.9 1997/06/23 18:27:53 roberto Exp $";
   7
   8 #include <stdio.h>
   9 #include <string.h>
  10
  11 #include "auxlib.h"
  12 #include "luamem.h"
  13 #include "fallback.h"
  14 #include "opcode.h"
  15 #include "lua.h"
  16 #include "table.h"
  17 #include "tree.h"
  18 #include "hash.h"
  19
  20
  21
  22 /* -------------------------------------------
  23 ** Reference routines
  24 */
  25
  26 static struct ref {
  27   TObject o;
  28   enum {LOCK, HOLD, FREE, COLLECTED} status;
  29 } *refArray = NULL;
  30 static int refSize = 0;
  31
  32 int luaI_ref (TObject *object, int lock)
  33 {
  34   int i;
  35   int oldSize;
  36   if (ttype(object) == LUA_T_NIL)
  37     return -1;   /* special ref for nil */
  38   for (i=0; i<refSize; i++)
  39     if (refArray[i].status == FREE)
  40       goto found;
  41   /* no more empty spaces */
  42   oldSize = refSize;
  43   refSize = growvector(&refArray, refSize, struct ref, refEM, MAX_WORD);
  44   for (i=oldSize; i<refSize; i++)
  45     refArray[i].status = FREE;
  46   i = oldSize;
  47  found:
  48   refArray[i].o = *object;
  49   refArray[i].status = lock ? LOCK : HOLD;
  50   return i;
  51 }
  52
  53
  54 void lua_unref (int ref)
  55 {
  56   if (ref >= 0 && ref < refSize)
  57     refArray[ref].status = FREE;
  58 }
  59
  60
  61 TObject *luaI_getref (int ref)
  62 {
  63   static TObject nul = {LUA_T_NIL, {0}};
  64   if (ref == -1)
  65     return &nul;
  66   if (ref >= 0 && ref < refSize &&
  67       (refArray[ref].status == LOCK || refArray[ref].status == HOLD))
  68     return &refArray[ref].o;
  69   else
  70     return NULL;
  71 }
  72
  73
  74 void luaI_travlock (int (*fn)(TObject *))
  75 {
  76   int i;
  77   for (i=0; i<refSize; i++)
  78     if (refArray[i].status == LOCK)
  79       fn(&refArray[i].o);
  80 }
  81
  82
  83 void luaI_invalidaterefs (void)
  84 {
  85   int i;
  86   for (i=0; i<refSize; i++)
  87     if (refArray[i].status == HOLD && !luaI_ismarked(&refArray[i].o))
  88       refArray[i].status = COLLECTED;
  89 }
  90
  91
  92 /* -------------------------------------------
  93 * Internal Methods
  94 */
  95
  96 char *luaI_eventname[] = {  /* ORDER IM */
  97   "gettable", "settable", "index", "getglobal", "setglobal", "add",
  98   "sub", "mul", "div", "pow", "unm", "lt", "le", "gt", "ge",
  99   "concat", "gc", "function",
 100   NULL
 101 };
 102
 103
 104
 105 static int luaI_checkevent (char *name, char *list[])
 106 {
 107   int e = luaI_findstring(name, list);
 108   if (e < 0)
 109     luaL_verror("`%s' is not a valid event name", name);
 110   return e;
 111 }
 112
 113
 114 struct IM *luaI_IMtable = NULL;
 115
 116 static int IMtable_size = 0;
 117 static int last_tag = LUA_T_NIL;  /* ORDER LUA_T */
 118
 119
 120 /* events in LUA_T_LINE are all allowed, since this is used as a
 121 *  'placeholder' for "default" fallbacks
 122 */
 123 static char validevents[NUM_TYPES][IM_N] = { /* ORDER LUA_T, ORDER IM */
 124 {1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1},  /* LUA_T_USERDATA */
 125 {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},  /* LUA_T_LINE */
 126 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  /* LUA_T_CMARK */
 127 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  /* LUA_T_MARK */
 128 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_CFUNCTION */
 129 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_FUNCTION */
 130 {0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},  /* LUA_T_ARRAY */
 131 {1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_STRING */
 132 {1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_NUMBER */
 133 {1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}   /* LUA_T_NIL */
 134 };
 135
 136 static int validevent (lua_Type t, int e)
 137 { /* ORDER LUA_T */
 138   return (t < LUA_T_NIL) ?  1 : validevents[-t][e];
 139 }
 140
 141
 142 static void init_entry (int tag)
 143 {
 144   int i;
 145   for (i=0; i<IM_N; i++)
 146     ttype(luaI_getim(tag, i)) = LUA_T_NIL;
 147 }
 148
 149 void luaI_initfallbacks (void)
 150 {
 151   if (luaI_IMtable == NULL) {
 152     int i;
 153     IMtable_size = NUM_TYPES+10;
 154     luaI_IMtable = newvector(IMtable_size, struct IM);
 155     for (i=LUA_T_NIL; i<=LUA_T_USERDATA; i++)
 156       init_entry(i);
 157   }
 158 }
 159
 160 int lua_newtag (void)
 161 {
 162   --last_tag;
 163   if ((-last_tag) >= IMtable_size) {
 164     luaI_initfallbacks();
 165     IMtable_size = growvector(&luaI_IMtable, IMtable_size,
 166                               struct IM, memEM, MAX_INT);
 167   }
 168   init_entry(last_tag);
 169   return last_tag;
 170 }
 171
 172
 173 static void checktag (int tag)
 174 {
 175   if (!(last_tag <= tag && tag <= 0))
 176     luaL_verror("%d is not a valid tag", tag);
 177 }
 178
 179 void luaI_realtag (int tag)
 180 {
 181   if (!(last_tag <= tag && tag < LUA_T_NIL))
 182     luaL_verror("tag %d is not result of `newtag'", tag);
 183 }
 184
 185
 186 void luaI_settag (int tag, TObject *o)
 187 {
 188   luaI_realtag(tag);
 189   switch (ttype(o)) {
 190     case LUA_T_ARRAY:
 191       o->value.a->htag = tag;
 192       break;
 193     case LUA_T_USERDATA:
 194       o->value.ts->tag = tag;
 195       break;
 196     default:
 197       luaL_verror("cannot change the tag of a %s", luaI_typenames[-ttype(o)]);
 198   }
 199 }
 200
 201
 202 int luaI_efectivetag (TObject *o)
 203 {
 204   lua_Type t = ttype(o);
 205   if (t == LUA_T_USERDATA) {
 206     int tag = o->value.ts->tag;
 207     return (tag >= 0) ? LUA_T_USERDATA : tag;
 208   }
 209   else if (t == LUA_T_ARRAY)
 210     return o->value.a->htag;
 211   else return t;
 212 }
 213
 214
 215 void luaI_gettagmethod (void)
 216 {
 217   int t = (int)luaL_check_number(1);
 218   int e = luaI_checkevent(luaL_check_string(2), luaI_eventname);
 219   checktag(t);
 220   if (validevent(t, e))
 221     luaI_pushobject(luaI_getim(t,e));
 222 }
 223
 224
 225 void luaI_settagmethod (void)
 226 {
 227   int t = (int)luaL_check_number(1);
 228   int e = luaI_checkevent(luaL_check_string(2), luaI_eventname);
 229   lua_Object func = lua_getparam(3);
 230   checktag(t);
 231   if (!validevent(t, e))
 232     luaL_verror("cannot change internal method `%s' for tag %d",
 233                 luaI_eventname[e], t);
 234   luaL_arg_check(lua_isnil(func) || lua_isfunction(func),
 235                  3, "function expected");
 236   luaI_pushobject(luaI_getim(t,e));
 237   *luaI_getim(t, e) = *luaI_Address(func);
 238 }
 239
 240
 241 static void stderrorim (void)
 242 {
 243   lua_Object s = lua_getparam(1);
 244   if (lua_isstring(s))
 245     fprintf(stderr, "lua: %s\n", lua_getstring(s));
 246 }
 247
 248 static TObject errorim = {LUA_T_CFUNCTION, {stderrorim}};
 249
 250
 251 TObject *luaI_geterrorim (void)
 252 {
 253   return &errorim;
 254 }
 255
 256 void luaI_seterrormethod (void)
 257 {
 258   lua_Object func = lua_getparam(1);
 259   luaL_arg_check(lua_isnil(func) || lua_isfunction(func),
 260                  1, "function expected");
 261   luaI_pushobject(&errorim);
 262   errorim = *luaI_Address(func);
 263 }
 264
 265 char *luaI_travfallbacks (int (*fn)(TObject *))
 266 {
 267   int e;
 268   if (fn(&errorim))
 269     return "error";
 270   for (e=IM_GETTABLE; e<=IM_FUNCTION; e++) {  /* ORDER IM */
 271     int t;
 272     for (t=0; t>=last_tag; t--)
 273       if (fn(luaI_getim(t,e)))
 274         return luaI_eventname[e];
 275   }
 276   return NULL;
 277 }
 278
 279
 280 /*
 281 * ===================================================================
 282 * compatibility with old fallback system
 283 */
 284 #if     LUA_COMPAT2_5
 285
 286 static void errorFB (void)
 287 {
 288   lua_Object o = lua_getparam(1);
 289   if (lua_isstring(o))
 290     fprintf (stderr, "lua: %s\n", lua_getstring(o));
 291   else
 292     fprintf(stderr, "lua: unknown error\n");
 293 }
 294
 295
 296 static void nilFB (void) { }
 297
 298
 299 static void typeFB (void)
 300 {
 301   lua_error("unexpected type");
 302 }
 303
 304
 305 static void fillvalids (IMS e, TObject *func)
 306 {
 307   int t;
 308   for (t=LUA_T_NIL; t<=LUA_T_USERDATA; t++)
 309     if (validevent(t, e))
 310       *luaI_getim(t, e) = *func;
 311 }
 312
 313
 314 void luaI_setfallback (void)
 315 {
 316   static char *oldnames [] = {"error", "getglobal", "arith", "order", NULL};
 317   TObject oldfunc;
 318   lua_CFunction replace;
 319   char *name = luaL_check_string(1);
 320   lua_Object func = lua_getparam(2);
 321   luaI_initfallbacks();
 322   luaL_arg_check(lua_isfunction(func), 2, "function expected");
 323   switch (luaI_findstring(name, oldnames)) {
 324     case 0:  /* old error fallback */
 325       oldfunc = errorim;
 326       errorim = *luaI_Address(func);
 327       replace = errorFB;
 328       break;
 329     case 1:  /* old getglobal fallback */
 330       oldfunc = *luaI_getim(LUA_T_NIL, IM_GETGLOBAL);
 331       *luaI_getim(LUA_T_NIL, IM_GETGLOBAL) = *luaI_Address(func);
 332       replace = nilFB;
 333       break;
 334     case 2: {  /* old arith fallback */
 335       int i;
 336       oldfunc = *luaI_getim(LUA_T_NUMBER, IM_POW);
 337       for (i=IM_ADD; i<=IM_UNM; i++)  /* ORDER IM */
 338         fillvalids(i, luaI_Address(func));
 339       replace = typeFB;
 340       break;
 341     }
 342     case 3: {  /* old order fallback */
 343       int i;
 344       oldfunc = *luaI_getim(LUA_T_LINE, IM_LT);
 345       for (i=IM_LT; i<=IM_GE; i++)  /* ORDER IM */
 346         fillvalids(i, luaI_Address(func));
 347       replace = typeFB;
 348       break;
 349     }
 350     default: {
 351       int e;
 352       if ((e = luaI_findstring(name, luaI_eventname)) >= 0) {
 353         oldfunc = *luaI_getim(LUA_T_LINE, e);
 354         fillvalids(e, luaI_Address(func));
 355         replace = (e == IM_GC || e == IM_INDEX) ? nilFB : typeFB;
 356       }
 357       else {
 358         luaL_verror("`%s' is not a valid fallback name", name);
 359         replace = NULL;  /* to avoid warnings */
 360       }
 361     }
 362   }
 363   if (oldfunc.ttype != LUA_T_NIL)
 364     luaI_pushobject(&oldfunc);
 365   else
 366     lua_pushcfunction(replace);
 367 }
 368 #endif