ANTLR print used tokens

gistfile1.txt

package com.facebook.presto.sql.parser;

import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.atn.ATN;
import org.antlr.v4.runtime.atn.ATNState;
import org.antlr.v4.runtime.atn.NotSetTransition;
import org.antlr.v4.runtime.atn.Transition;
import org.antlr.v4.runtime.misc.IntervalSet;
import org.testng.annotations.Test;

public class TestTokens
{
    @Test
    public void testUnusedTokens()
    {
        IntervalSet tokens = new IntervalSet();

        ATN atn = SqlBaseParser._ATN;
        for (ATNState state : atn.states) {
            for (Transition transition : state.getTransitions()) {
                IntervalSet label = transition.label();
                if (label != null) {
                    if (transition instanceof NotSetTransition) {
                        label = label.complement(IntervalSet.of(Token.MIN_USER_TOKEN_TYPE, atn.maxTokenType));
                    }
                    tokens.addAll(label);
                }
            }
        }

        for (Integer token : tokens.toSet()) {
            String name = SqlBaseLexer.VOCABULARY.getDisplayName(token);
            System.out.println(name);
        }
    }
}