org.antlr.v4.runtime.atn.LookaheadEventInfo Maven / Gradle / Ivy

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/*
 * Copyright (c) 2012 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.runtime.atn;

import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.misc.Nullable;

/**
 * This class represents profiling event information for tracking the lookahead
 * depth required in order to make a prediction.
 *
 * @since 4.3
 */
public class LookaheadEventInfo extends DecisionEventInfo {
	/** The alternative chosen by adaptivePredict(), not necessarily
	 *  the outermost alt shown for a rule; left-recursive rules have
	 *  user-level alts that differ from the rewritten rule with a (...) block
	 *  and a (..)* loop.
	 */
	public final int predictedAlt;

	/**
	 * Constructs a new instance of the {@link LookaheadEventInfo} class with
	 * the specified detailed lookahead information.
	 *
	 * @param decision The decision number
	 * @param state The final simulator state containing the necessary
	 * information to determine the result of a prediction, or {@code null} if
	 * the final state is not available
	 * @param input The input token stream
	 * @param startIndex The start index for the current prediction
	 * @param stopIndex The index at which the prediction was finally made
	 * @param fullCtx {@code true} if the current lookahead is part of an LL
	 * prediction; otherwise, {@code false} if the current lookahead is part of
	 * an SLL prediction
	 */
	public LookaheadEventInfo(int decision, @Nullable SimulatorState state,
							  int predictedAlt,
							  @NotNull TokenStream input, int startIndex, int stopIndex,
							  boolean fullCtx)
	{
		super(decision, state, input, startIndex, stopIndex, fullCtx);
		this.predictedAlt = predictedAlt;
	}
}