src/ltm.c

   1 /*
   2 ** $Id: ltm.c,v 1.16 1998/06/18 16:57:03 roberto Exp $
   3 ** Tag methods
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdio.h>
   9 #include <string.h>
  10
  11 #include "lauxlib.h"
  12 #include "lmem.h"
  13 #include "lobject.h"
  14 #include "lstate.h"
  15 #include "ltm.h"
  16
  17
  18 char *luaT_eventname[] = {  /* ORDER IM */
  19   "gettable", "settable", "index", "getglobal", "setglobal", "add",
  20   "sub", "mul", "div", "pow", "unm", "lt", "le", "gt", "ge",
  21   "concat", "gc", "function", NULL
  22 };
  23
  24
  25 static int luaI_checkevent (char *name, char *list[])
  26 {
  27   int e = luaL_findstring(name, list);
  28   if (e < 0)
  29     luaL_verror("`%.50s' is not a valid event name", name);
  30   return e;
  31 }
  32
  33
  34
  35 /* events in LUA_T_NIL are all allowed, since this is used as a
  36 *  'placeholder' for "default" fallbacks
  37 */
  38 static char validevents[NUM_TAGS][IM_N] = { /* ORDER LUA_T, ORDER IM */
  39 {1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1},  /* LUA_T_USERDATA */
  40 {1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_NUMBER */
  41 {1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_STRING */
  42 {0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},  /* LUA_T_ARRAY */
  43 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_PROTO */
  44 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_CPROTO */
  45 {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}   /* LUA_T_NIL */
  46 };
  47
  48
  49 static int validevent (int t, int e)
  50 { /* ORDER LUA_T */
  51   return (t < LUA_T_NIL) ?  1 : validevents[-t][e];
  52 }
  53
  54
  55 static void init_entry (int tag)
  56 {
  57   int i;
  58   for (i=0; i<IM_N; i++)
  59     ttype(luaT_getim(tag, i)) = LUA_T_NIL;
  60 }
  61
  62
  63 void luaT_init (void)
  64 {
  65   int t;
  66   L->IMtable_size = NUM_TAGS*2;
  67   L->last_tag = -(NUM_TAGS-1);
  68   L->IMtable = luaM_newvector(L->IMtable_size, struct IM);
  69   for (t=L->last_tag; t<=0; t++)
  70     init_entry(t);
  71 }
  72
  73
  74 int lua_newtag (void)
  75 {
  76   --L->last_tag;
  77   if ((-L->last_tag) >= L->IMtable_size)
  78     L->IMtable_size = luaM_growvector(&L->IMtable, L->IMtable_size,
  79                                    struct IM, memEM, MAX_INT);
  80   init_entry(L->last_tag);
  81   return L->last_tag;
  82 }
  83
  84
  85 static void checktag (int tag)
  86 {
  87   if (!(L->last_tag <= tag && tag <= 0))
  88     luaL_verror("%d is not a valid tag", tag);
  89 }
  90
  91 void luaT_realtag (int tag)
  92 {
  93   if (!(L->last_tag <= tag && tag < LUA_T_NIL))
  94     luaL_verror("tag %d is not result of `newtag'", tag);
  95 }
  96
  97
  98 int lua_copytagmethods (int tagto, int tagfrom)
  99 {
 100   int e;
 101   checktag(tagto);
 102   checktag(tagfrom);
 103   for (e=0; e<IM_N; e++) {
 104     if (validevent(tagto, e))
 105       *luaT_getim(tagto, e) = *luaT_getim(tagfrom, e);
 106   }
 107   return tagto;
 108 }
 109
 110
 111 int luaT_efectivetag (TObject *o)
 112 {
 113   int t;
 114   switch (t = ttype(o)) {
 115     case LUA_T_ARRAY:
 116       return o->value.a->htag;
 117     case LUA_T_USERDATA: {
 118       int tag = o->value.ts->u.d.tag;
 119       return (tag >= 0) ? LUA_T_USERDATA : tag;
 120     }
 121     case LUA_T_CLOSURE:
 122       return o->value.cl->consts[0].ttype;
 123 #ifdef DEBUG
 124     case LUA_T_PMARK: case LUA_T_CMARK:
 125     case LUA_T_CLMARK: case LUA_T_LINE:
 126       LUA_INTERNALERROR("invalid type");
 127 #endif
 128     default:
 129       return t;
 130   }
 131 }
 132
 133
 134 TObject *luaT_gettagmethod (int t, char *event)
 135 {
 136   int e = luaI_checkevent(event, luaT_eventname);
 137   checktag(t);
 138   if (validevent(t, e))
 139     return luaT_getim(t,e);
 140   else
 141     return &luaO_nilobject;
 142 }
 143
 144
 145 void luaT_settagmethod (int t, char *event, TObject *func)
 146 {
 147   TObject temp = *func;
 148   int e = luaI_checkevent(event, luaT_eventname);
 149   checktag(t);
 150   if (!validevent(t, e))
 151     luaL_verror("settagmethod: cannot change tag method `%.20s' for tag %d",
 152                 luaT_eventname[e], t);
 153   *func = *luaT_getim(t,e);
 154   *luaT_getim(t, e) = temp;
 155 }
 156
 157
 158 char *luaT_travtagmethods (int (*fn)(TObject *))
 159 {
 160   int e;
 161   if (fn(&L->errorim))
 162     return "error";
 163   for (e=IM_GETTABLE; e<=IM_FUNCTION; e++) {  /* ORDER IM */
 164     int t;
 165     for (t=0; t>=L->last_tag; t--)
 166       if (fn(luaT_getim(t,e)))
 167         return luaT_eventname[e];
 168   }
 169   return NULL;
 170 }
 171
 172
 173 /*
 174 * ===================================================================
 175 * compatibility with old fallback system
 176 */
 177 #ifdef LUA_COMPAT2_5
 178
 179 #include "lapi.h"
 180
 181 static void errorFB (void)
 182 {
 183   lua_Object o = lua_getparam(1);
 184   if (lua_isstring(o))
 185     fprintf(stderr, "lua: %s\n", lua_getstring(o));
 186   else
 187     fprintf(stderr, "lua: unknown error\n");
 188 }
 189
 190
 191 static void nilFB (void) { }
 192
 193
 194 static void typeFB (void)
 195 {
 196   lua_error("unexpected type");
 197 }
 198
 199
 200 static void fillvalids (IMS e, TObject *func)
 201 {
 202   int t;
 203   for (t=LUA_T_NIL; t<=LUA_T_USERDATA; t++)
 204     if (validevent(t, e))
 205       *luaT_getim(t, e) = *func;
 206 }
 207
 208
 209 void luaT_setfallback (void)
 210 {
 211   static char *oldnames [] = {"error", "getglobal", "arith", "order", NULL};
 212   TObject oldfunc;
 213   lua_CFunction replace;
 214   char *name = luaL_check_string(1);
 215   lua_Object func = lua_getparam(2);
 216   luaL_arg_check(lua_isfunction(func), 2, "function expected");
 217   switch (luaL_findstring(name, oldnames)) {
 218     case 0:  /* old error fallback */
 219       oldfunc = L->errorim;
 220       L->errorim = *luaA_Address(func);
 221       replace = errorFB;
 222       break;
 223     case 1:  /* old getglobal fallback */
 224       oldfunc = *luaT_getim(LUA_T_NIL, IM_GETGLOBAL);
 225       *luaT_getim(LUA_T_NIL, IM_GETGLOBAL) = *luaA_Address(func);
 226       replace = nilFB;
 227       break;
 228     case 2: {  /* old arith fallback */
 229       int i;
 230       oldfunc = *luaT_getim(LUA_T_NUMBER, IM_POW);
 231       for (i=IM_ADD; i<=IM_UNM; i++)  /* ORDER IM */
 232         fillvalids(i, luaA_Address(func));
 233       replace = typeFB;
 234       break;
 235     }
 236     case 3: {  /* old order fallback */
 237       int i;
 238       oldfunc = *luaT_getim(LUA_T_NIL, IM_LT);
 239       for (i=IM_LT; i<=IM_GE; i++)  /* ORDER IM */
 240         fillvalids(i, luaA_Address(func));
 241       replace = typeFB;
 242       break;
 243     }
 244     default: {
 245       int e;
 246       if ((e = luaL_findstring(name, luaT_eventname)) >= 0) {
 247         oldfunc = *luaT_getim(LUA_T_NIL, e);
 248         fillvalids(e, luaA_Address(func));
 249         replace = (e == IM_GC || e == IM_INDEX) ? nilFB : typeFB;
 250       }
 251       else {
 252         luaL_verror("`%.50s' is not a valid fallback name", name);
 253         replace = NULL;  /* to avoid warnings */
 254       }
 255     }
 256   }
 257   if (oldfunc.ttype != LUA_T_NIL)
 258     luaA_pushobject(&oldfunc);
 259   else
 260     lua_pushcfunction(replace);
 261 }
 262 #endif
 263