getUniqueAlt static method
Returns the unique alternative predicted by all alternative subsets in
altsets
. If no such alternative exists, this method returns
{@link ATN#INVALID_ALT_NUMBER}.
@param altsets a collection of alternative subsets
Implementation
static int getUniqueAlt(List<BitSet> altsets) {
final all = getAlts(altsets);
if (all.cardinality == 1) return all.nextset(0);
return ATN.INVALID_ALT_NUMBER;
}