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#getReachesIntoOuterContext is 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.
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, ParserErrorListener#reportAmbiguity
| Modifier and Type | Field and Description |
|---|---|
| private final BitSet | ambigAlts
The set of alternative numbers for this decision event that lead to a valid parse. |
| Access | Constructor and Description |
|---|---|
| public | AmbiguityInfo(int
The decision number decision, SimulatorState The final simulator state identifying the ambiguous
alternatives for the current input state, BitSet The set of alternatives in the decision that lead to a valid parse.
The predicted alt is the min(ambigAlts) ambigAlts, TokenStream The input token stream input, int The start index for the current prediction startIndex, int The index at which the ambiguity was identified during
prediction stopIndex)Constructs a new instance of the |
| Modifier and Type | Method and Description |
|---|---|
| public BitSet |
| ambigAlts | back to summary |
|---|---|
| private final BitSet ambigAlts The set of alternative numbers for this decision event that lead to a valid parse. | |
| AmbiguityInfo | back to summary |
|---|---|
| public AmbiguityInfo(int decision, SimulatorState state, BitSet ambigAlts, TokenStream input, int startIndex, int stopIndex) Constructs a new instance of the
| |
| getAmbiguousAlternatives | back to summary |
|---|---|
| public BitSet getAmbiguousAlternatives() Gets the set of alternatives in the decision that lead to a valid parse.
| |