Function luaH_getint

3rd/lua-5.4.3/src/ltable.c:719–741

** Search function for integers. If integer is inside 'alimit', get it ** directly from the array part. Otherwise, if 'alimit' is not equal to ** the real size of the array, key still can be in the array part. In ** this case, try to avoid a call to 'luaH_realasize' when key is just ** one more than the limit (so that it can be incremented without ** changing the real size of the array). */

** changing the real size of the array).
*/
const TValue *luaH_getint (Table *t, lua_Integer key) {
  if (l_castS2U(key) - 1u < t->alimit)  /* 'key' in [1, t->alimit]? */
    return &t->array[key - 1];
  else if (!limitequalsasize(t) &&  /* key still may be in the array part? */
           (l_castS2U(key) == t->alimit + 1 ||
            l_castS2U(key) - 1u < luaH_realasize(t))) {
    t->alimit = cast_uint(key);  /* probably '#t' is here now */
    return &t->array[key - 1];
  }
  else {
    Node *n = hashint(t, key);
    for (;;) {  /* check whether 'key' is somewhere in the chain */
      if (keyisinteger(n) && keyival(n) == key)
        return gval(n);  /* that's it */
      else {
        int nx = gnext(n);
        if (nx == 0) break;
        n += nx;
      }
    }
    return &absentkey;
  }
}


/*