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/model/LL1OptionalBlock.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.model;

import org.antlr.v4.codegen.OutputModelFactory;
import org.antlr.v4.tool.ast.GrammarAST;

import java.util.List;

/** An optional block is just an alternative block where the last alternative
 *  is epsilon. The analysis takes care of adding to the empty alternative.
 *
 *  (A | B | C)?
 */
public class LL1OptionalBlock extends LL1AltBlock {
	public LL1OptionalBlock(OutputModelFactory factory, GrammarAST blkAST, List<CodeBlockForAlt> alts) {
		super(factory, blkAST, alts);
	}
}

⏎ org/antlr/v4/codegen/model/LL1OptionalBlock.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