LeftRecursionDetector.java 文件源码

/** enclosingRule calls targetRule. Find the cycle containing
 *  the target and add the caller.  Find the cycle containing the caller
 *  and add the target.  If no cycles contain either, then create a new
 *  cycle.
 */
protected void addRulesToCycle(Rule enclosingRule, Rule targetRule) {
    //System.err.println("left-recursion to "+targetRule.name+" from "+enclosingRule.name);
    boolean foundCycle = false;
    for (Set<Rule> rulesInCycle : listOfRecursiveCycles) {
        // ensure both rules are in same cycle
        if (rulesInCycle.contains(targetRule)) {
            rulesInCycle.add(enclosingRule);
            foundCycle = true;
        }
        if (rulesInCycle.contains(enclosingRule)) {
            rulesInCycle.add(targetRule);
            foundCycle = true;
        }
    }
    if ( !foundCycle ) {
        Set<Rule> cycle = new OrderedHashSet<Rule>();
        cycle.add(targetRule);
        cycle.add(enclosingRule);
        listOfRecursiveCycles.add(cycle);
    }
}