if accept state, what ttype do we match or alt do we predict? This is set to {@link ATN#INVALID_ALT_NUMBER} when {@link #predicates}{@code !=null} or {@link #requiresFullContext}.
See Implementation
if accept state, what ttype do we match or alt do we predict? This is set to {@link ATN#INVALID_ALT_NUMBER} when {@link #predicates}{@code !=null} or {@link #requiresFullContext}.