public override void EnterRule(string grammarFileName, string ruleName)
{
//System.out.println("enterRule "+grammarFileName+":"+ruleName);
ruleLevel++;
stats.numRuleInvocations++;
uniqueRules.Add(grammarFileName + ":" + ruleName, true);
stats.maxRuleInvocationDepth = Math.Max(stats.maxRuleInvocationDepth, ruleLevel);
currentGrammarFileName.Push(grammarFileName);
currentRuleName.Push(ruleName);
}