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/LL1OptionalBlockSingleAlt.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.runtime.atn.DecisionState;
import org.antlr.v4.runtime.misc.IntervalSet;
import org.antlr.v4.tool.ast.GrammarAST;

import java.util.List;

/** (A B C)? */
public class LL1OptionalBlockSingleAlt extends LL1Choice {
	@ModelElement public SrcOp expr;
	@ModelElement public List<SrcOp> followExpr; // might not work in template if size>1

	public LL1OptionalBlockSingleAlt(OutputModelFactory factory,
									 GrammarAST blkAST,
									 List<CodeBlockForAlt> alts)
	{
		super(factory, blkAST, alts);
		this.decision = ((DecisionState)blkAST.atnState).decision;

		/** Lookahead for each alt 1..n */
//		IntervalSet[] altLookSets = LinearApproximator.getLL1LookaheadSets(dfa);
		IntervalSet[] altLookSets = factory.getGrammar().decisionLOOK.get(decision);
		altLook = getAltLookaheadAsStringLists(altLookSets);
		IntervalSet look = altLookSets[0];
		IntervalSet followLook = altLookSets[1];

		IntervalSet expecting = look.or(followLook);
		this.error = getThrowNoViableAlt(factory, blkAST, expecting);

		expr = addCodeForLookaheadTempVar(look);
		followExpr = factory.getLL1Test(followLook, blkAST);
	}
}

⏎ org/antlr/v4/codegen/model/LL1OptionalBlockSingleAlt.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

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