/*
 * 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.runtime.atn;

import org.antlr.v4.runtime.TokenStream;

This is the base class for gathering detailed information about prediction events which occur during parsing. Note that we could record the parser call stack at the time this event occurred but in the presence of left recursive rules, the stack is kind of meaningless. It's better to look at the individual configurations for their individual stacks. Of course that is a PredictionContext object not a parse tree node and so it does not have information about the extent (start...stop) of the various subtrees. Examining the stack tops of all configurations provide the return states for the rule invocations. From there you can get the enclosing rule. 
Since:
4.3/**
 * This is the base class for gathering detailed information about prediction
 * events which occur during parsing.
 *
 * Note that we could record the parser call stack at the time this event
 * occurred but in the presence of left recursive rules, the stack is kind of
 * meaningless. It's better to look at the individual configurations for their
 * individual stacks. Of course that is a {@link PredictionContext} object
 * not a parse tree node and so it does not have information about the extent
 * (start...stop) of the various subtrees. Examining the stack tops of all
 * configurations provide the return states for the rule invocations.
 * From there you can get the enclosing rule.
 *
 * @since 4.3
 */
public class DecisionEventInfo {
	
The invoked decision number which this event is related to.
See Also:
decisionToState.decisionToState/**
	 * The invoked decision number which this event is related to.
	 *
	 * @see ATN#decisionToState
	 */
	public final int decision;

	
The configuration set containing additional information relevant to the prediction state when the current event occurred, or null if no additional information is relevant or available. /**
	 * The configuration set containing additional information relevant to the
	 * prediction state when the current event occurred, or {@code null} if no
	 * additional information is relevant or available.
	 */
	public final ATNConfigSet configs;

	
The input token stream which is being parsed.
/**
	 * The input token stream which is being parsed.
	 */
	public final TokenStream input;

	
The token index in the input stream at which the current prediction was
originally invoked.
/**
	 * The token index in the input stream at which the current prediction was
	 * originally invoked.
	 */
	public final int startIndex;

	
The token index in the input stream at which the current event occurred.
/**
	 * The token index in the input stream at which the current event occurred.
	 */
	public final int stopIndex;

	
true if the current event occurred during LL prediction; otherwise, false if the input occurred during SLL prediction. /**
	 * {@code true} if the current event occurred during LL prediction;
	 * otherwise, {@code false} if the input occurred during SLL prediction.
	 */
	public final boolean fullCtx;

	public DecisionEventInfo(int decision,
							 ATNConfigSet configs,
							 TokenStream input, int startIndex, int stopIndex,
							 boolean fullCtx)
	{
		this.decision = decision;
		this.fullCtx = fullCtx;
		this.stopIndex = stopIndex;
		this.input = input;
		this.startIndex = startIndex;
		this.configs = configs;
	}
}