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/DefaultToolListener.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;

import org.antlr.v4.Tool;
import org.stringtemplate.v4.ST;

/** */
public class DefaultToolListener implements ANTLRToolListener {
	public Tool tool;

	public DefaultToolListener(Tool tool) { this.tool = tool; }

	@Override
	public void info(String msg) {
		if (tool.errMgr.formatWantsSingleLineMessage()) {
			msg = msg.replace('\n', ' ');
		}
		System.out.println(msg);
	}

	@Override
	public void error(ANTLRMessage msg) {
		ST msgST = tool.errMgr.getMessageTemplate(msg);
		String outputMsg = msgST.render();
		if (tool.errMgr.formatWantsSingleLineMessage()) {
			outputMsg = outputMsg.replace('\n', ' ');
		}
		System.err.println(outputMsg);
	}

	@Override
	public void warning(ANTLRMessage msg) {
		ST msgST = tool.errMgr.getMessageTemplate(msg);
		String outputMsg = msgST.render();
		if (tool.errMgr.formatWantsSingleLineMessage()) {
			outputMsg = outputMsg.replace('\n', ' ');
		}
		System.err.println(outputMsg);
	}
}

⏎ org/antlr/v4/tool/DefaultToolListener.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