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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.
*/
#pragma once
#include "BaseErrorListener.h"
namespace antlr4 {
/// <summary>
/// This implementation of <seealso cref="ANTLRErrorListener"/> can be used to
/// identify certain potential correctness and performance problems in grammars.
/// "Reports" are made by calling <seealso cref="Parser#notifyErrorListeners"/>
/// with the appropriate message.
///
/// <ul>
/// <li><b>Ambiguities</b>: These are cases where more than one path through the
/// grammar can match the input.</li>
/// <li><b>Weak context sensitivity</b>: These are cases where full-context
/// prediction resolved an SLL conflict to a unique alternative which equaled
/// the minimum alternative of the SLL conflict.</li> <li><b>Strong (forced)
/// context sensitivity</b>: These are cases where the full-context prediction
/// resolved an SLL conflict to a unique alternative, <em>and</em> the minimum
/// alternative of the SLL conflict was found to not be a truly viable
/// alternative. Two-stage parsing cannot be used for inputs where this
/// situation occurs.</li>
/// </ul>
///
/// @author Sam Harwell
/// </summary>
class ANTLR4CPP_PUBLIC DiagnosticErrorListener : public BaseErrorListener {
/// <summary>
/// When {@code true}, only exactly known ambiguities are reported.
/// </summary>
protected:
const bool exactOnly;
/// <summary>
/// Initializes a new instance of <seealso cref="DiagnosticErrorListener"/>
/// which only reports exact ambiguities.
/// </summary>
public:
DiagnosticErrorListener();
/// <summary>
/// Initializes a new instance of <seealso cref="DiagnosticErrorListener"/>,
/// specifying whether all ambiguities or only exact ambiguities are reported.
/// </summary>
/// <param name="exactOnly"> {@code true} to report only exact ambiguities,
/// otherwise
/// {@code false} to report all ambiguities. </param>
DiagnosticErrorListener(bool exactOnly);
virtual void reportAmbiguity(Parser* recognizer, const dfa::DFA& dfa,
size_t startIndex, size_t stopIndex, bool exact,
const antlrcpp::BitSet& ambigAlts,
atn::ATNConfigSet* configs) override;
virtual void reportAttemptingFullContext(
Parser* recognizer, const dfa::DFA& dfa, size_t startIndex,
size_t stopIndex, const antlrcpp::BitSet& conflictingAlts,
atn::ATNConfigSet* configs) override;
virtual void reportContextSensitivity(Parser* recognizer, const dfa::DFA& dfa,
size_t startIndex, size_t stopIndex,
size_t prediction,
atn::ATNConfigSet* configs) override;
protected:
virtual std::string getDecisionDescription(Parser* recognizer,
const dfa::DFA& dfa);
/// <summary>
/// Computes the set of conflicting or ambiguous alternatives from a
/// configuration set, if that information was not already provided by the
/// parser.
/// </summary>
/// <param name="reportedAlts"> The set of conflicting or ambiguous
/// alternatives, as reported by the parser. </param> <param name="configs">
/// The conflicting or ambiguous configuration set. </param> <returns> Returns
/// {@code reportedAlts} if it is not {@code null}, otherwise returns the set
/// of alternatives represented in {@code configs}. </returns>
virtual antlrcpp::BitSet getConflictingAlts(
const antlrcpp::BitSet& reportedAlts, atn::ATNConfigSet* configs);
};
} // namespace antlr4
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