69 lines
3.2 KiB
C
69 lines
3.2 KiB
C
|
/* 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 "atn/DecisionEventInfo.h"
|
||
|
|
#include "support/BitSet.h"
|
||
|
|
|
||
|
|
namespace antlr4 {
|
||
|
|
namespace atn {
|
||
|
|
|
||
|
|
/// <summary>
|
||
|
|
/// 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).
|
||
|
|
///
|
||
|
|
/// <para>
|
||
|
|
/// 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.
|
||
|
|
/// <seealso cref="ATNConfig#reachesIntoOuterContext"/> is 0 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.</para>
|
||
|
|
///
|
||
|
|
/// <para>
|
||
|
|
/// 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 <seealso cref="PredictionMode#SLL"/>, which in turn means
|
||
|
|
/// they cannot use the two-stage parsing strategy to improve parsing performance
|
||
|
|
/// for that input.</para>
|
||
|
|
/// </summary>
|
||
|
|
/// <seealso cref= ParserATNSimulator#reportAmbiguity </seealso>
|
||
|
|
/// <seealso cref= ANTLRErrorListener#reportAmbiguity
|
||
|
|
///
|
||
|
|
/// @since 4.3 </seealso>
|
||
|
|
class ANTLR4CPP_PUBLIC AmbiguityInfo : public DecisionEventInfo {
|
||
|
|
public:
|
||
|
|
/// The set of alternative numbers for this decision event that lead to a valid parse.
|
||
|
|
antlrcpp::BitSet ambigAlts;
|
||
|
|
|
||
|
|
/// <summary>
|
||
|
|
/// Constructs a new instance of the <seealso 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>
|
||
|
|
AmbiguityInfo(size_t decision, ATNConfigSet *configs, const antlrcpp::BitSet &ambigAlts, TokenStream *input,
|
||
|
|
size_t startIndex, size_t stopIndex, bool fullCtx);
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace atn
|
||
|
|
} // namespace antlr4
|