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/codegen/target/JavaTarget.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.codegen.target;

import org.antlr.v4.codegen.CodeGenerator;
import org.antlr.v4.codegen.Target;
import org.stringtemplate.v4.STGroup;
import org.stringtemplate.v4.StringRenderer;

import java.util.*;

public class JavaTarget extends Target {
	/**
	 * The Java target can cache the code generation templates.
	 */
	private static final ThreadLocal<STGroup> targetTemplates = new ThreadLocal<STGroup>();

	protected static final HashSet<String> reservedWords = new HashSet<>(Arrays.asList(
		"abstract", "assert", "boolean", "break", "byte", "case", "catch",
		"char", "class", "const", "continue", "default", "do", "double", "else",
		"enum", "extends", "false", "final", "finally", "float", "for", "goto",
		"if", "implements", "import", "instanceof", "int", "interface",
		"long", "native", "new", "null", "package", "private", "protected",
		"public", "return", "short", "static", "strictfp", "super", "switch",
		"synchronized", "this", "throw", "throws", "transient", "true", "try",
		"void", "volatile", "while",

		// misc
		"rule", "parserRule"
	));

	public JavaTarget(CodeGenerator gen) {
		super(gen);
	}

	@Override
    public Set<String> getReservedWords() {
		return reservedWords;
	}

	@Override
	public int getSerializedATNSegmentLimit() {
		// 65535 is the class file format byte limit for a UTF-8 encoded string literal
		// 3 is the maximum number of bytes it takes to encode a value in the range 0-0xFFFF
		return 65535 / 3;
	}

	@Override
	protected STGroup loadTemplates() {
		STGroup result = targetTemplates.get();
		if (result == null) {
			result = super.loadTemplates();
			result.registerRenderer(String.class, new JavaStringRenderer(), true);
			targetTemplates.set(result);
		}

		return result;
	}

	protected static class JavaStringRenderer extends StringRenderer {

		@Override
		public String toString(Object o, String formatString, Locale locale) {
			if ("java-escape".equals(formatString)) {
				// 5C is the hex code for the \ itself
				return ((String)o).replace("\\u", "\\u005Cu");
			}

			return super.toString(o, formatString, locale);
		}
	}

	@Override
	public boolean isATNSerializedAsInts() {
		return false;
	}
}

⏎ org/antlr/v4/codegen/target/JavaTarget.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