Function luaV_settable

third-party/lua-5.2.4/src/lvm.c:136–172

void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {
  int loop;
  for (loop = 0; loop < MAXTAGLOOP; loop++) {
    const TValue *tm;
    if (ttistable(t)) {  /* `t' is a table? */
      Table *h = hvalue(t);
      TValue *oldval = cast(TValue *, luaH_get(h, key));
      /* if previous value is not nil, there must be a previous entry
         in the table; moreover, a metamethod has no relevance */
      if (!ttisnil(oldval) ||
         /* previous value is nil; must check the metamethod */
         ((tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL &&
         /* no metamethod; is there a previous entry in the table? */
         (oldval != luaO_nilobject ||
         /* no previous entry; must create one. (The next test is
            always true; we only need the assignment.) */
         (oldval = luaH_newkey(L, h, key), 1)))) {
        /* no metamethod and (now) there is an entry with given key */
        setobj2t(L, oldval, val);  /* assign new value to that entry */
        invalidateTMcache(h);
        luaC_barrierback(L, obj2gco(h), val);
        return;
      }
      /* else will try the metamethod */
    }
    else  /* not a table; check metamethod */
      if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
        luaG_typeerror(L, t, "index");
    /* there is a metamethod */
    if (ttisfunction(tm)) {
      callTM(L, tm, t, key, val, 0);
      return;
    }
    t = tm;  /* else repeat with 'tm' */
  }
  luaG_runerror(L, "loop in settable");
}


static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,