Antlr4.Runtime.Sharpen.BitSet.Cardinality C# (CSharp) Метод

        public int Cardinality()
        {
            return GetBitCount(_data);
        }

 public BitSet GetAncestors(int rule)
 {
     BitSet ancestors = new BitSet();
     ancestors.Or(parents[rule]);
     while (true)
     {
         int cardinality = ancestors.Cardinality();
         for (int i = ancestors.NextSetBit(0); i >= 0; i = ancestors.NextSetBit(i + 1))
         {
             ancestors.Or(parents[i]);
         }
         if (ancestors.Cardinality() == cardinality)
         {
             // nothing changed
             break;
         }
     }
     return ancestors;
 }