public function yypushstate($state)
    {
        if ($this->yyTraceFILE) {
             fprintf($this->yyTraceFILE, "%sState push %s\n", $this->yyTracePrompt, isset($this->state_name[$this->_yy_state]) ? $this->state_name[$this->_yy_state] : $this->_yy_state);
        }