private static void ConstructChildPos(SyntaxTreeNode child, BitSet firstpos, BitSet lastpos, BitSet[] followpos) {
BitSet firstPosTemp = new BitSet(firstpos.Count);
BitSet lastPosTemp = new BitSet(lastpos.Count);
child.ConstructPos(firstPosTemp, lastPosTemp, followpos);
firstpos.Or(firstPosTemp);
lastpos.Or(lastPosTemp);
}