public class AmbiguityInfo extends DecisionEventInfo
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.
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.
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
PredictionMode.SLL, which in turn means
they cannot use the two-stage parsing strategy to improve parsing performance
for that input.
ParserATNSimulator.reportAmbiguity(org.antlr.v4.runtime.dfa.DFA, org.antlr.v4.runtime.dfa.DFAState, int, int, boolean, java.util.BitSet, org.antlr.v4.runtime.atn.ATNConfigSet),
ANTLRErrorListener.reportAmbiguity(org.antlr.v4.runtime.Parser, org.antlr.v4.runtime.dfa.DFA, int, int, boolean, java.util.BitSet, org.antlr.v4.runtime.atn.ATNConfigSet)
|Modifier and Type||Field and Description|
The set of alternative numbers for this decision event that lead to a valid parse.
|Constructor and Description|
Constructs a new instance of the
public BitSet ambigAlts
public AmbiguityInfo(int decision, ATNConfigSet configs, BitSet ambigAlts, TokenStream input, int startIndex, int stopIndex, boolean fullCtx)
AmbiguityInfoclass with the specified detailed ambiguity information.
decision- The decision number
configs- The final configuration set identifying the ambiguous alternatives for the current input
ambigAlts- The set of alternatives in the decision that lead to a valid parse. The predicted alt is the min(ambigAlts)
input- The input token stream
startIndex- The start index for the current prediction
stopIndex- The index at which the ambiguity was identified during prediction
trueif the ambiguity was identified during LL prediction; otherwise,
falseif the ambiguity was identified during SLL prediction
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