ANTLR is a powerful parser generator for multiple programming languages including Java.

ANTLR contains 2 major modules:

• Runtime - For building and executing parsers/lexers generated in Java.
• Tool (The Parser Generator) - For generating parsers/lexers Java class.

ANTLR Tool Source Code files are provided in the distribution packge (antlr4-4.10.1.zip). You can download them at ANTLR Website.

You can also browse the source code below:

⏎ org/antlr/v4/automata/ATNVisitor.java

/*
 * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

package org.antlr.v4.automata;

import org.antlr.v4.runtime.atn.ATNState;
import org.antlr.v4.runtime.atn.Transition;

import java.util.HashSet;
import java.util.Set;

/** A simple visitor that walks everywhere it can go starting from s,
 *  without going into an infinite cycle. Override and implement
 *  visitState() to provide functionality.
 */
public class ATNVisitor {
	public void visit(ATNState s) {
		visit_(s, new HashSet<Integer>());
	}

	public void visit_(ATNState s, Set<Integer> visited) {
		if ( !visited.add(s.stateNumber) ) return;
		visited.add(s.stateNumber);

		visitState(s);
		int n = s.getNumberOfTransitions();
		for (int i=0; i<n; i++) {
			Transition t = s.transition(i);
			visit_(t.target, visited);
		}
	}

	public void visitState(ATNState s) { }
}

⏎ org/antlr/v4/automata/ATNVisitor.java

Or download all of them as a single archive file:

File name: antlr-tool-4.10.1-sources.jar
File size: 347718 bytes
Release date: 2022-04-15
Download 

⇒ Donwload antlr4-4.10.1.zip

⇐ ANTLR Runtime Source Code

⇑ Download and Review ANTLR Parser Generator

⇑⇑ FAQ for ANTLR Parser Generator