* Tweak the value-stack push method to record the line number on which the current rule started.
*/
@Override
public boolean push(Object value) {
if (value instanceof PolicyNode) {
PolicyNode x = (PolicyNode) value;
int startIndex = getContext().getStartIndex();
x.setLineNumber(getContext().getInputBuffer().getPosition(startIndex).line);
}
return super.push(value);
}