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/atn/PlusBlockStartState.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.atn;

/** Start of {@code (A|B|...)+} loop. Technically a decision state, but
 *  we don't use for code generation; somebody might need it, so I'm defining
 *  it for completeness. In reality, the {@link PlusLoopbackState} node is the
 *  real decision-making note for {@code A+}.
 */
public final class PlusBlockStartState extends BlockStartState {
	public PlusLoopbackState loopBackState;

	@Override
	public int getStateType() {
		return PLUS_BLOCK_START;
	}
}

⏎ org/antlr/v4/runtime/atn/PlusBlockStartState.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

⇑ Download and Review ANTLR Parser Generator

⇑⇑ FAQ for ANTLR Parser Generator