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/tool/ANTLRToolListener.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.tool;

/** Defines behavior of object able to handle error messages from ANTLR including
 *  both tool errors like "can't write file" and grammar ambiguity warnings.
 *  To avoid having to change tools that use ANTLR (like GUIs), I am
 *  wrapping error data in Message objects and passing them to the listener.
 *  In this way, users of this interface are less sensitive to changes in
 *  the info I need for error messages.
 */
public interface ANTLRToolListener {
	public void info(String msg);
	public void error(ANTLRMessage msg);
	public void warning(ANTLRMessage msg);
}

⏎ org/antlr/v4/tool/ANTLRToolListener.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