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, ANTLRErrorListener#reportAmbiguity
| Modifier and Type | Field and Description |
|---|---|
| public 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, ATNConfigSet The final configuration set identifying the ambiguous
alternatives for the current input configs, 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, boolean true if the ambiguity was identified during LL
prediction; otherwise, false if the ambiguity was identified
during SLL predictionConstructs a new instance of the |
| ambigAlts | back to summary |
|---|---|
| public 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, ATNConfigSet configs, BitSet ambigAlts, TokenStream input, int startIndex, int stopIndex, boolean fullCtx) Constructs a new instance of the
| |