Function findindex

lua/ltable.c:171–193

** returns the index of a `key' for table traversals. First goes all ** elements in the array part, then elements in the hash part. The ** beginning of a traversal is signalled by -1. */

** beginning of a traversal is signalled by -1.
*/
static int findindex (lua_State *L, Table *t, StkId key) {
  int i;
  if (ttisnil(key)) return -1;  /* first iteration */
  i = arrayindex(key);
  if (0 < i && i <= t->sizearray)  /* is `key' inside array part? */
    return i-1;  /* yes; that's the index (corrected to C) */
  else {
    Node *n = mainposition(t, key);
    do {  /* check whether `key' is somewhere in the chain */
      /* key may be dead already, but it is ok to use it in `next' */
      if (luaO_rawequalObj(key2tval(n), key) ||
            (ttype(gkey(n)) == LUA_TDEADKEY && iscollectable(key) &&
             gcvalue(gkey(n)) == gcvalue(key))) {
        i = cast_int(n - gnode(t, 0));  /* key index in hash table */
        /* hash elements are numbered after array ones */
        return i + t->sizearray;
      }
      else n = gnext(n);
    } while (n);
    luaG_runerror(L, "invalid key to " LUA_QL("next"));  /* key not found */
    return 0;  /* to avoid warnings */
  }
}


int luaH_next (lua_State *L, Table *t, StkId key) {