Antlr.Runtime.BitSet.Remove C# (CSharp) Method

        public void Remove( int el )
        {
            int n = WordNumber( el );
            if ( n < _bits.Length )
            {
                _bits[n] &= ~BitMask( el );
            }
        }

        // what is exact? it seems to only add sets from above on stack
        // if EOR is in set i.  When it sees a set w/o EOR, it stops adding.
        // Why would we ever want them all?  Maybe no viable alt instead of
        // mismatched token?
        protected virtual BitSet CombineFollows(bool exact)
        {
            int    top       = state._fsp;
            BitSet followSet = new BitSet();

            for (int i = top; i >= 0; i--)
            {
                BitSet localFollowSet = (BitSet)state.following[i];

                /*
                 * System.out.println("local follow depth "+i+"="+
                 *                 localFollowSet.toString(getTokenNames())+")");
                 */
                followSet.OrInPlace(localFollowSet);
                if (exact)
                {
                    // can we see end of rule?
                    if (localFollowSet.Member(TokenTypes.EndOfRule))
                    {
                        // Only leave EOR in set if at top (start rule); this lets
                        // us know if have to include follow(start rule); i.e., EOF
                        if (i > 0)
                        {
                            followSet.Remove(TokenTypes.EndOfRule);
                        }
                    }
                    else
                    { // can't see end of rule, quit
                        break;
                    }
                }
            }
            return(followSet);
        }