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/tree/xpath/XPathElement.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.tree.xpath;

import org.antlr.v4.runtime.tree.ParseTree;

import java.util.Collection;

public abstract class XPathElement {
	protected String nodeName;
	protected boolean invert;

	/** Construct element like {@code /ID} or {@code ID} or {@code /*} etc...
	 *  op is null if just node
	 */
	public XPathElement(String nodeName) {
		this.nodeName = nodeName;
	}

	/**
	 * Given tree rooted at {@code t} return all nodes matched by this path
	 * element.
	 */
	public abstract Collection<ParseTree> evaluate(ParseTree t);

	@Override
	public String toString() {
		String inv = invert ? "!" : "";
		return getClass().getSimpleName()+"["+inv+nodeName+"]";
	}
}

⏎ org/antlr/v4/runtime/tree/xpath/XPathElement.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