code: public void initialize(CharSequence input, int begin, int end) {
      this.input = input;
      this.send = end;
      this.matcher.reset(input).region(begin, end);
      this.index = begin;
      advance();
    }
docs: Initialize parser with a new string.
  
  @param input New string to parse.
  @param begin Begin
  @param end End