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 Runtime 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/runtime/misc/LogManager.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.runtime.misc;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class LogManager {
    protected static class Record {
		long timestamp;
		StackTraceElement location;
		String component;
		String msg;
		public Record() {
			timestamp = System.currentTimeMillis();
			location = new Throwable().getStackTrace()[0];
		}

		@Override
		public String toString() {
            StringBuilder buf = new StringBuilder();
            buf.append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS").format(new Date(timestamp)));
            buf.append(" ");
            buf.append(component);
            buf.append(" ");
            buf.append(location.getFileName());
            buf.append(":");
            buf.append(location.getLineNumber());
            buf.append(" ");
            buf.append(msg);
            return buf.toString();
		}
	}

	protected List<Record> records;

	public void log(String component, String msg) {
		Record r = new Record();
		r.component = component;
		r.msg = msg;
		if ( records==null ) {
			records = new ArrayList<Record>();
		}
		records.add(r);
	}

    public void log(String msg) { log(null, msg); }

    public void save(String filename) throws IOException {
        FileWriter fw = new FileWriter(filename);
        BufferedWriter bw = new BufferedWriter(fw);
        try {
            bw.write(toString());
        }
        finally {
            bw.close();
        }
    }

    public String save() throws IOException {
        //String dir = System.getProperty("java.io.tmpdir");
        String dir = ".";
        String defaultFilename =
            dir + "/antlr-" +
            new SimpleDateFormat("yyyy-MM-dd-HH.mm.ss").format(new Date()) + ".log";
        save(defaultFilename);
        return defaultFilename;
    }

    @Override
    public String toString() {
        if ( records==null ) return "";
        String nl = System.getProperty("line.separator");
        StringBuilder buf = new StringBuilder();
        for (Record r : records) {
            buf.append(r);
            buf.append(nl);
        }
        return buf.toString();
    }

    public static void main(String[] args) throws IOException {
        LogManager mgr = new LogManager();
        mgr.log("atn", "test msg");
        mgr.log("dfa", "test msg 2");
        System.out.println(mgr);
        mgr.save();
    }
}

⏎ org/antlr/v4/runtime/misc/LogManager.java

Or download all of them as a single archive file:

File name: antlr-runtime-4.10.1-sources.jar
File size: 308953 bytes
Release date: 2022-04-15
Download 

⇒ ANTLR Tool Source Code

⇐ What Is ANTLR Parser Generator

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⇑⇑ FAQ for ANTLR Parser Generator