altNumber property
For rule associated with this parse tree internal node, return the outer alternative number used to match the input. Default implementation does not compute nor store this alt num. Create a subclass of ParserRuleContext with backing field and set option contextSuperClass. to set it.
Implementation
int get altNumber => ATN.INVALID_ALT_NUMBER;
Set the outer alternative number for this context node. Default implementation does nothing to avoid backing field overhead for trees that don't need it. Create a subclass of ParserRuleContext with backing field and set option contextSuperClass.
Implementation
set altNumber(int altNumber) {}