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/* 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.
*/
using Antlr4.Runtime;
using Antlr4.Runtime.Atn;
using Antlr4.Runtime.Sharpen;
namespace Antlr4.Runtime.Atn
{
/// <summary>This class represents profiling event information for an ambiguity.</summary>
/// <remarks>
/// This class represents profiling event information for an ambiguity.
/// Ambiguities are decisions where a particular input resulted in an SLL
/// conflict, followed by LL prediction also reaching a conflict state
/// (indicating a true ambiguity in the grammar).
/// <p>
/// This event may be reported during SLL prediction in cases where the
/// conflicting SLL configuration set provides sufficient information to
/// determine that the SLL conflict is truly an ambiguity. For example, if none
/// of the ATN configurations in the conflicting SLL configuration set have
/// traversed a global follow transition (i.e.
/// <see cref="ATNConfig.reachesIntoOuterContext"/>
/// is
/// <see langword="false"/>
/// for all
/// configurations), then the result of SLL prediction for that input is known to
/// be equivalent to the result of LL prediction for that input.</p>
/// <p>
/// In some cases, the minimum represented alternative in the conflicting LL
/// configuration set is not equal to the minimum represented alternative in the
/// conflicting SLL configuration set. Grammars and inputs which result in this
/// scenario are unable to use
/// <see cref="PredictionMode.SLL"/>
/// , which in turn means
/// they cannot use the two-stage parsing strategy to improve parsing performance
/// for that input.</p>
/// </remarks>
/// <seealso cref="ParserATNSimulator.ReportAmbiguity(Antlr4.Runtime.Dfa.DFA, Antlr4.Runtime.Dfa.DFAState, int, int, bool, Antlr4.Runtime.Sharpen.BitSet, ATNConfigSet)"/>
/// <seealso cref="Antlr4.Runtime.IParserErrorListener.ReportAmbiguity(Antlr4.Runtime.Parser, Antlr4.Runtime.Dfa.DFA, int, int, bool, Antlr4.Runtime.Sharpen.BitSet, ATNConfigSet)"/>
/// <since>4.3</since>
public class AmbiguityInfo : DecisionEventInfo
{
/** The set of alternative numbers for this decision event that lead to a valid parse. */
public BitSet ambigAlts;
/// <summary>
/// Constructs a new instance of the
/// <see cref="AmbiguityInfo"/>
/// class with the
/// specified detailed ambiguity information.
/// </summary>
/// <param name="decision">The decision number</param>
/// <param name="configs">The final configuration set identifying the ambiguous
/// alternatives for the current input
/// </param>
/// <param name="ambigAlts">The set of alternatives in the decision that lead to a valid parse.
/// The predicted alt is the min(ambigAlts)
/// </param>
/// <param name="input">The input token stream</param>
/// <param name="startIndex">The start index for the current prediction</param>
/// <param name="stopIndex">
/// The index at which the ambiguity was identified during
/// prediction
/// </param>
/// <param name="fullCtx">@code true} if the ambiguity was identified during LL
/// prediction; otherwise, {@code false} if the ambiguity was identified
/// during SLL prediction
/// </param>
public AmbiguityInfo(int decision,
ATNConfigSet configs,
BitSet ambigAlts,
ITokenStream input, int startIndex, int stopIndex,
bool fullCtx)
: base(decision, configs, input, startIndex, stopIndex, fullCtx)
{
this.ambigAlts = ambigAlts;
}
}
}