refactor IteratorReducerResultSet

 */

public final class IteratorReducerResultSet extends AbstractDelegateResultSet {

    private int resultSetIndex = 1;

    private int index = 1;

    public IteratorReducerResultSet(final ResultSetMergeContext resultSetMergeContext) throws SQLException {

        super(resultSetMergeContext.getShardingResultSets().getResultSets());

    @Override

    protected boolean afterFirstNext() throws SQLException {

        return processCurrent() || (!isOutOfIndex() && processNext());

        return processCurrent() || processNext();

    }

    private boolean processCurrent() throws SQLException {

        return getDelegate().next();

    }

    private boolean isOutOfIndex() {

        return resultSetIndex >= getResultSets().size();

    }

    private boolean processNext() throws SQLException {

        ResultSet resultSet = getResultSets().get(resultSetIndex++);

        if (index == getResultSets().size()) {

            return false;

        }

        ResultSet resultSet = getResultSets().get(index++);

        setDelegate(resultSet);

        return resultSet.next();

    }