/*
 * [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.runtime;

import org.antlr.v4.runtime.atn.ATNConfigSet;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.misc.Nullable;

/** Indicates that the parser could not decide which of two or more paths
 *  to take based upon the remaining input. It tracks the starting token
 *  of the offending input and also knows where the parser was
 *  in the various paths when the error. Reported by reportNoViableAlternative()
 */
public class NoViableAltException extends RecognitionException {
	/** Which configurations did we try at input.index() that couldn't match input.LT(1)? */
	@Nullable
	private final ATNConfigSet deadEndConfigs;

	/** The token object at the start index; the input stream might
	 * 	not be buffering tokens so get a reference to it. (At the
	 *  time the error occurred, of course the stream needs to keep a
	 *  buffer all of the tokens but later we might not have access to those.)
	 */
	@NotNull
	private final Token startToken;

	public NoViableAltException(@NotNull Parser recognizer) { // LL(1) error
		this(recognizer,
			 recognizer.getInputStream(),
			 recognizer.getCurrentToken(),
			 recognizer.getCurrentToken(),
			 null,
			 recognizer._ctx);
	}

	public NoViableAltException(@NotNull Parser recognizer,
								@NotNull TokenStream input,
								@NotNull Token startToken,
								@NotNull Token offendingToken,
								@Nullable ATNConfigSet deadEndConfigs,
								@NotNull ParserRuleContext ctx)
	{
		super(recognizer, input, ctx);
		this.deadEndConfigs = deadEndConfigs;
		this.startToken = startToken;
		this.setOffendingToken(offendingToken);
	}

	@NotNull
	public Token getStartToken() {
		return startToken;
	}

	@Nullable
	public ATNConfigSet getDeadEndConfigs() {
		return deadEndConfigs;
	}

}