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/LeftRecursiveRuleFunction.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.CodeGenerator;
import org.antlr.v4.codegen.OutputModelFactory;
import org.antlr.v4.codegen.model.decl.RuleContextDecl;
import org.antlr.v4.codegen.model.decl.RuleContextListDecl;
import org.antlr.v4.codegen.model.decl.StructDecl;
import org.antlr.v4.parse.ANTLRParser;
import org.antlr.v4.runtime.misc.Pair;
import org.antlr.v4.tool.LeftRecursiveRule;
import org.antlr.v4.tool.Rule;
import org.antlr.v4.tool.ast.GrammarAST;

public class LeftRecursiveRuleFunction extends RuleFunction {
	public LeftRecursiveRuleFunction(OutputModelFactory factory, LeftRecursiveRule r) {
		super(factory, r);

		CodeGenerator gen = factory.getGenerator();
		// Since we delete x=lr, we have to manually add decls for all labels
		// on left-recur refs to proper structs
		for (Pair<GrammarAST,String> pair : r.leftRecursiveRuleRefLabels) {
			GrammarAST idAST = pair.a;
			String altLabel = pair.b;
			String label = idAST.getText();
			GrammarAST rrefAST = (GrammarAST)idAST.getParent().getChild(1);
			if ( rrefAST.getType() == ANTLRParser.RULE_REF ) {
				Rule targetRule = factory.getGrammar().getRule(rrefAST.getText());
				String ctxName = gen.getTarget().getRuleFunctionContextStructName(targetRule);
				RuleContextDecl d;
				if (idAST.getParent().getType() == ANTLRParser.ASSIGN) {
					d = new RuleContextDecl(factory, label, ctxName);
				}
				else {
					d = new RuleContextListDecl(factory, label, ctxName);
				}

				StructDecl struct = ruleCtx;
				if ( altLabelCtxs!=null ) {
					StructDecl s = altLabelCtxs.get(altLabel);
					if ( s!=null ) struct = s; // if alt label, use subctx
				}
				struct.addDecl(d); // stick in overall rule's ctx
			}
		}
	}
}

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