In the following, if the text cursor is in the middle of '()', and you enter ')',
then you either get '())' or '()'. It seems that if you are in for(...), then you get '())' otherwise you get '()'

        public boolean startsWith(String s)
        {
            if(buf.size() < s.length())
                return false;
            int idx = 0;
            for(Iterator<Integer> it = buf.iterator();
                    it.hasNext() && idx < s.length(); idx++) {
                Integer i = it.next();
            }

            return idx == s.length();
        }