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The ANTLR 4 grammar compiler.
There is a newer version: 4.13.2
/*
 * [The "BSD license"]
 *  Copyright (c) 2012 Terence Parr
 *  Copyright (c) 2012 Sam Harwell
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.antlr.v4.tool;

import org.antlr.runtime.RecognitionException;
import org.antlr.v4.Tool;
import org.antlr.v4.runtime.misc.MultiMap;
import org.antlr.v4.tool.ast.GrammarRootAST;

/** */
public class LexerGrammar extends Grammar {
	public static final String DEFAULT_MODE_NAME = "DEFAULT_MODE";

	/** The grammar from which this lexer grammar was derived (if implicit) */
    public Grammar implicitLexerOwner;

	/** DEFAULT_MODE rules are added first due to grammar syntax order */
	public MultiMap modes;

	public LexerGrammar(Tool tool, GrammarRootAST ast) {
		super(tool, ast);
	}

	public LexerGrammar(String grammarText) throws RecognitionException {
		super(grammarText);
	}

	public LexerGrammar(String grammarText, ANTLRToolListener listener) throws RecognitionException {
		super(grammarText, listener);
	}

	public LexerGrammar(String fileName, String grammarText, ANTLRToolListener listener) throws RecognitionException {
		super(fileName, grammarText, listener);
	}

	@Override
	public boolean defineRule(Rule r) {
		if (!super.defineRule(r)) {
			return false;
		}

		if ( modes==null ) modes = new MultiMap();
		modes.map(r.mode, r);
		return true;
	}

	@Override
	public boolean undefineRule(Rule r) {
		if (!super.undefineRule(r)) {
			return false;
		}

		boolean removed = modes.get(r.mode).remove(r);
		assert removed;
		return true;
	}
}