src/ltm.c

   1 /*
   2 ** $Id: ltm.c,v 1.25 1999/05/21 19:41:49 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   int e = luaL_findstring(name, list);
  27   if (e < 0)
  28     luaL_verror("`%.50s' is not a valid event name", name);
  29   return e;
  30 }
  31
  32
  33
  34 /* events in LUA_T_NIL are all allowed, since this is used as a
  35 *  'placeholder' for "default" fallbacks
  36 */
  37 static char luaT_validevents[NUM_TAGS][IM_N] = { /* ORDER LUA_T, ORDER IM */
  38 {1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1},  /* LUA_T_USERDATA */
  39 {1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_NUMBER */
  40 {1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},  /* LUA_T_STRING */
  41 {0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},  /* LUA_T_ARRAY */
  42 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_PROTO */
  43 {1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0},  /* LUA_T_CPROTO */
  44 {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}   /* LUA_T_NIL */
  45 };
  46
  47 static int luaT_validevent (int t, int e) {  /* ORDER LUA_T */
  48   return (t < LUA_T_NIL) ?  1 : luaT_validevents[-t][e];
  49 }
  50
  51
  52 static void init_entry (int tag) {
  53   int i;
  54   for (i=0; i<IM_N; i++)
  55     ttype(luaT_getim(tag, i)) = LUA_T_NIL;
  56 }
  57
  58
  59 void luaT_init (void) {
  60   int t;
  61   L->last_tag = -(NUM_TAGS-1);
  62   luaM_growvector(L->IMtable, 0, NUM_TAGS, struct IM, arrEM, MAX_INT);
  63   for (t=L->last_tag; t<=0; t++)
  64     init_entry(t);
  65 }
  66
  67
  68 int lua_newtag (void) {
  69   --L->last_tag;
  70   luaM_growvector(L->IMtable, -(L->last_tag), 1, struct IM, arrEM, MAX_INT);
  71   init_entry(L->last_tag);
  72   return L->last_tag;
  73 }
  74
  75
  76 static void checktag (int tag) {
  77   if (!(L->last_tag <= tag && tag <= 0))
  78     luaL_verror("%d is not a valid tag", tag);
  79 }
  80
  81 void luaT_realtag (int tag) {
  82   if (!(L->last_tag <= tag && tag < LUA_T_NIL))
  83     luaL_verror("tag %d was not created by `newtag'", tag);
  84 }
  85
  86
  87 int lua_copytagmethods (int tagto, int tagfrom) {
  88   int e;
  89   checktag(tagto);
  90   checktag(tagfrom);
  91   for (e=0; e<IM_N; e++) {
  92     if (luaT_validevent(tagto, e))
  93       *luaT_getim(tagto, e) = *luaT_getim(tagfrom, e);
  94   }
  95   return tagto;
  96 }
  97
  98
  99 int luaT_effectivetag (TObject *o) {
 100   int t;
 101   switch (t = ttype(o)) {
 102     case LUA_T_ARRAY:
 103       return o->value.a->htag;
 104     case LUA_T_USERDATA: {
 105       int tag = o->value.ts->u.d.tag;
 106       return (tag >= 0) ? LUA_T_USERDATA : tag;
 107     }
 108     case LUA_T_CLOSURE:
 109       return o->value.cl->consts[0].ttype;
 110 #ifdef DEBUG
 111     case LUA_T_PMARK: case LUA_T_CMARK:
 112     case LUA_T_CLMARK: case LUA_T_LINE:
 113       LUA_INTERNALERROR("invalid type");
 114 #endif
 115     default:
 116       return t;
 117   }
 118 }
 119
 120
 121 TObject *luaT_gettagmethod (int t, char *event) {
 122   int e = luaI_checkevent(event, luaT_eventname);
 123   checktag(t);
 124   if (luaT_validevent(t, e))
 125     return luaT_getim(t,e);
 126   else
 127     return &luaO_nilobject;
 128 }
 129
 130
 131 void luaT_settagmethod (int t, char *event, TObject *func) {
 132   TObject temp;
 133   int e = luaI_checkevent(event, luaT_eventname);
 134   checktag(t);
 135   if (!luaT_validevent(t, e))
 136     luaL_verror("cannot change tag method `%.20s' for type `%.20s'%.20s",
 137                 luaT_eventname[e], luaO_typenames[-t],
 138                 (t == LUA_T_ARRAY || t == LUA_T_USERDATA) ? " with default tag"
 139                                                           : "");
 140   temp = *func;
 141   *func = *luaT_getim(t,e);
 142   *luaT_getim(t, e) = temp;
 143 }
 144
 145
 146 char *luaT_travtagmethods (int (*fn)(TObject *)) {  /* ORDER IM */
 147   int e;
 148   for (e=IM_GETTABLE; e<=IM_FUNCTION; e++) {
 149     int t;
 150     for (t=0; t>=L->last_tag; t--)
 151       if (fn(luaT_getim(t,e)))
 152         return luaT_eventname[e];
 153   }
 154   return NULL;
 155 }
 156
 157
 158 /*
 159 * ===================================================================
 160 * compatibility with old fallback system
 161 */
 162 #ifdef LUA_COMPAT2_5
 163
 164 #include "lapi.h"
 165 #include "lstring.h"
 166
 167 static void errorFB (void)
 168 {
 169   lua_Object o = lua_getparam(1);
 170   if (lua_isstring(o))
 171     fprintf(stderr, "lua: %s\n", lua_getstring(o));
 172   else
 173     fprintf(stderr, "lua: unknown error\n");
 174 }
 175
 176
 177 static void nilFB (void) { }
 178
 179
 180 static void typeFB (void) {
 181   lua_error("unexpected type");
 182 }
 183
 184
 185 static void fillvalids (IMS e, TObject *func) {
 186   int t;
 187   for (t=LUA_T_NIL; t<=LUA_T_USERDATA; t++)
 188     if (luaT_validevent(t, e))
 189       *luaT_getim(t, e) = *func;
 190 }
 191
 192
 193 void luaT_setfallback (void) {
 194   static char *oldnames [] = {"error", "getglobal", "arith", "order", NULL};
 195   TObject oldfunc;
 196   lua_CFunction replace;
 197   char *name = luaL_check_string(1);
 198   lua_Object func = lua_getparam(2);
 199   luaL_arg_check(lua_isfunction(func), 2, "function expected");
 200   switch (luaL_findstring(name, oldnames)) {
 201     case 0: {  /* old error fallback */
 202       TObject *em = &(luaS_new("_ERRORMESSAGE")->u.s.globalval);
 203       oldfunc = *em;
 204       *em = *luaA_Address(func);
 205       replace = errorFB;
 206       break;
 207     }
 208     case 1:  /* old getglobal fallback */
 209       oldfunc = *luaT_getim(LUA_T_NIL, IM_GETGLOBAL);
 210       *luaT_getim(LUA_T_NIL, IM_GETGLOBAL) = *luaA_Address(func);
 211       replace = nilFB;
 212       break;
 213     case 2: {  /* old arith fallback */
 214       int i;
 215       oldfunc = *luaT_getim(LUA_T_NUMBER, IM_POW);
 216       for (i=IM_ADD; i<=IM_UNM; i++)  /* ORDER IM */
 217         fillvalids(i, luaA_Address(func));
 218       replace = typeFB;
 219       break;
 220     }
 221     case 3: {  /* old order fallback */
 222       int i;
 223       oldfunc = *luaT_getim(LUA_T_NIL, IM_LT);
 224       for (i=IM_LT; i<=IM_GE; i++)  /* ORDER IM */
 225         fillvalids(i, luaA_Address(func));
 226       replace = typeFB;
 227       break;
 228     }
 229     default: {
 230       int e;
 231       if ((e = luaL_findstring(name, luaT_eventname)) >= 0) {
 232         oldfunc = *luaT_getim(LUA_T_NIL, e);
 233         fillvalids(e, luaA_Address(func));
 234         replace = (e == IM_GC || e == IM_INDEX) ? nilFB : typeFB;
 235       }
 236       else {
 237         luaL_verror("`%.50s' is not a valid fallback name", name);
 238         replace = NULL;  /* to avoid warnings */
 239       }
 240     }
 241   }
 242   if (oldfunc.ttype != LUA_T_NIL)
 243     luaA_pushobject(&oldfunc);
 244   else
 245     lua_pushcfunction(replace);
 246 }
 247 #endif
 248