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/Lexer.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.codegen.Target;
import org.antlr.v4.tool.Grammar;
import org.antlr.v4.tool.LexerGrammar;
import org.antlr.v4.tool.Rule;

import java.util.*;

public class Lexer extends Recognizer {
	public final Collection<String> channelNames;
	public final Map<String, Integer> escapedChannels;
	public final LexerFile file;
	public final Collection<String> modes;
	public final Collection<String> escapedModeNames;

	@ModelElement public LinkedHashMap<Rule, RuleActionFunction> actionFuncs =
		new LinkedHashMap<Rule, RuleActionFunction>();

	public Lexer(OutputModelFactory factory, LexerFile file) {
		super(factory);
		this.file = file; // who contains us?

		Grammar g = factory.getGrammar();
		Target target = factory.getGenerator().getTarget();

		escapedChannels = new LinkedHashMap<>();
		channelNames = new ArrayList<>();
		for (String key : g.channelNameToValueMap.keySet()) {
			Integer value = g.channelNameToValueMap.get(key);
			escapedChannels.put(target.escapeIfNeeded(key), value);
			channelNames.add(key);
		}

		modes = ((LexerGrammar)g).modes.keySet();
		escapedModeNames = new ArrayList<>(modes.size());
		for (String mode : modes) {
			escapedModeNames.add(target.escapeIfNeeded(mode));
		}
	}
}

⏎ org/antlr/v4/codegen/model/Lexer.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