stats.numDecisionEvents++;
int startingLookaheadIndex = parser.getTokenStream().index();
TokenStream input = parser.getTokenStream();
if ( dump ) System.out.println("enterDecision canBacktrack="+couldBacktrack+" "+ decisionNumber +
" backtrack depth " + backtrackDepth +
" @ " + input.get(input.index()) +
" rule " +locationDescription());
String g = (String) currentGrammarFileName.peek();
DecisionDescriptor descriptor = decisions.get(g, decisionNumber);
if ( descriptor == null ) {
descriptor = new DecisionDescriptor();