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/RuleContextWithAltNum.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;

import org.antlr.v4.runtime.atn.ATN;

/** A handy class for use with
 *
 *  options {contextSuperClass=org.antlr.v4.runtime.RuleContextWithAltNum;}
 *
 *  that provides a backing field / impl for the outer alternative number
 *  matched for an internal parse tree node.
 *
 *  I'm only putting into Java runtime as I'm certain I'm the only one that
 *  will really every use this.
 */
public class RuleContextWithAltNum extends ParserRuleContext {
	public int altNum;
	public RuleContextWithAltNum() { altNum = ATN.INVALID_ALT_NUMBER; }

	public RuleContextWithAltNum(ParserRuleContext parent, int invokingStateNumber) {
		super(parent, invokingStateNumber);
	}
	@Override public int getAltNumber() { return altNum; }
	@Override public void setAltNumber(int altNum) { this.altNum = altNum; }
}

⏎ org/antlr/v4/runtime/RuleContextWithAltNum.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