/*
** Function to index a table.
** Receives the table at `t' and the key at top.
*/
const TObject *luaV_gettable (lua_State *L, StkId t) {
Closure *tm;
int tg;
if (ttype(t) == LUA_TTABLE && /* `t' is a table? */
((tg = hvalue(t)->htag) == LUA_TTABLE || /* with default tag? */
luaT_gettm(L, tg, TM_GETTABLE) == NULL)) { /* or no TM? */
/* do a primitive get */
const TObject *h = luaH_get(L, hvalue(t), L->top-1);
/* result is no nil or there is no `index' tag method? */
if (ttype(h) != LUA_TNIL || ((tm=luaT_gettm(L, tg, TM_INDEX)) == NULL))
return h; /* return result */
/* else call `index' tag method */
}
else { /* try a `gettable' tag method */
tm = luaT_gettmbyObj(L, t, TM_GETTABLE);
}
if (tm != NULL) { /* is there a tag method? */
luaD_checkstack(L, 2);
*(L->top+1) = *(L->top-1); /* key */
*L->top = *t; /* table */
clvalue(L->top-1) = tm; /* tag method */
ttype(L->top-1) = LUA_TFUNCTION;
L->top += 2;
luaD_call(L, L->top - 3, 1);
return L->top - 1; /* call result */
}
else { /* no tag method */
luaG_typeerror(L, t, "index");
return NULL; /* to avoid warnings */
}
}
static void marktagmethods (lua_State *L, GCState *st) {
int e;
for (e=0; e<TM_N; e++) {
int t;
for (t=0; t<=L->last_tag; t++) {
Closure *cl = luaT_gettm(L, t, e);
if (cl) markclosure(st, cl);
}
}
}
static const char *travtagmethods (lua_State *L, const TObject *o) {
if (ttype(o) == LUA_TFUNCTION) {
int e;
for (e=0; e<TM_N; e++) {
int t;
for (t=0; t<=L->last_tag; t++)
if (clvalue(o) == luaT_gettm(L, t, e))
return luaT_eventname[e];
}
}
return NULL;
}
static int call_binTM (lua_State *L, StkId top, TMS event) {
/* try first operand */
Closure *tm = luaT_gettmbyObj(L, top-2, event);
L->top = top;
if (tm == NULL) {
tm = luaT_gettmbyObj(L, top-1, event); /* try second operand */
if (tm == NULL) {
tm = luaT_gettm(L, 0, event); /* try a `global' method */
if (tm == NULL)
return 0; /* error */
}
}
lua_pushstring(L, luaT_eventname[event]);
luaD_callTM(L, tm, 3, 1);
return 1;
}
/*
** Receives table at `t', key at `key' and value at top.
*/
void luaV_settable (lua_State *L, StkId t, StkId key) {
int tg;
if (ttype(t) == LUA_TTABLE && /* `t' is a table? */
((tg = hvalue(t)->htag) == LUA_TTABLE || /* with default tag? */
luaT_gettm(L, tg, TM_SETTABLE) == NULL)) /* or no TM? */
*luaH_set(L, hvalue(t), key) = *(L->top-1); /* do a primitive set */
else { /* try a `settable' tag method */
Closure *tm = luaT_gettmbyObj(L, t, TM_SETTABLE);
if (tm != NULL) {
luaD_checkstack(L, 3);
*(L->top+2) = *(L->top-1);
*(L->top+1) = *key;
*(L->top) = *t;
clvalue(L->top-1) = tm;
ttype(L->top-1) = LUA_TFUNCTION;
L->top += 3;
luaD_call(L, L->top - 4, 0); /* call `settable' tag method */
}
else /* no tag method... */
luaG_typeerror(L, t, "index");
}
}
static void init_entry (lua_State *L, int tag) {
int i;
for (i=0; i<TM_N; i++)
luaT_gettm(L, tag, i) = NULL;
L->TMtable[tag].collected = NULL;
}
