How to implement FlexLexer.reset

Hi, I'm making a custom language plugin and I'm new to writing IntelliJ
plugins. I've generated a baby stage JFlex lexer and implemented all
methods of FlexLexer interface except reset(ChatSequence, int, int,
int). I looked at the _HtmlLexer in the IntelliJ source but some
variables such as zzBufferArray and zzPushbackPos don't exist in the
generated Java file I got. Could anyone help me on this? Thanks :)