可以使用ANTLR v4中的Visitor模式来实现列出给定规则的下一个可能规则。

我们需要实现一个Visitor类，该类将遍历语法树并记录给定规则的下一个可能规则。具体实现方法如下：

public class NextPossibleRuleVisitor extends YourGrammarBaseVisitor> {
    private String currentRule;

    public NextPossibleRuleVisitor(String currentRule) {
        this.currentRule = currentRule;
    }

    @Override
    public Set visitRuleAtom(YourGrammarParser.RuleAtomContext ctx) {
        if (ctx.atom() != null && ctx.atom().getText().equals(currentRule)) {
            // found the current rule, add the next possible rules to the result set
            YourGrammarParser.SuperRuleContext superRuleContext = (YourGrammarParser.SuperRuleContext) ctx.parent;
            YourGrammarParser.RuleAltListContext altListContext = superRuleContext.ruleBlock().ruleAltList();
            int nextAlt = altListContext.altNumber + 1;
            if (nextAlt < altListContext.labeledAlt().size()) {
                YourGrammarParser.LabeledAltContext labeledAltContext = altListContext.labeledAlt().get(nextAlt);
                YourGrammarParser.RuleAltListContext nextRuleAltListContext;
                if (labeledAltContext.block() != null) {
                    // if the next rule is a rule block
                    nextRuleAltListContext = labeledAltContext.block().ruleAltList();
                } else {
                    // if the next rule is a rule reference
                    nextRuleAltListContext = labeledAltContext.ruleRef().ruleAltList();
                }
                Set nextPossibleRules = nextRuleAltListContext.accept(this);
                return nextPossibleRules;
            }
        }
        return super.visitRuleAtom(ctx);
    }

    @Override
    public Set visitAtom(YourGrammarParser.AtomContext ctx) {
        if (ctx.ruleref() != null && ctx.ruleref().getText().equals(currentRule)) {
            // found the current rule, add the next possible rules to the result set
            YourGrammarParser.RuleAltListContext nextRuleAltListContext = ctx.ruleref().ruleAltList();
            Set nextPossibleRules = nextRuleAltListContext.accept(this);
            return nextPossibleRules;
        }
        return super.visitAtom(ctx);
    }

    @Override
    public Set visitNotSet(YourGrammarParser.NotSetContext ctx) {
        // exclude the not set rule from possible next rules
        return Collections.emptySet();
    }

    @Override
    public Set visitRuleBlock(YourGrammarParser.RuleBlockContext