case Op.CAPTURE:
{
final int refno = op.getData();
if (con.match != null) {
if (refno > 0) {
dataStack.push(con.match.getBeginning(refno));
con.match.setBeginning(refno, offset);
}
else {
final int index = -refno;
dataStack.push(con.match.getEnd(index));