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[toc] / antlr4-cpp-runtime-4.9.2-source / runtime / src / atn / AmbiguityInfo.h

diff --git a/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/AmbiguityInfo.h b/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/AmbiguityInfo.h
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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 "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