Bug 182895 Support sort on Level attribute.
Currently in OLAP engine we only support sort on level key value. We should go ahead to support sort on level attribute value.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/olap/data/impl/aggregation/sort/AggregationSortHelper.java
{
	private int index;
	private IDiskArray base;
	private IDiskArray aggrValues;
	WrapperedDiskArray( IDiskArray base, IDiskArray aggrValues )
	{
		this.base = base;
		this.aggrValues = aggrValues;
		this.index = 0;
	}
	/**
	 * 
	 * @return
	 * @throws IOException
	 */
	private Object getCurrentBaseRow( ) throws IOException
	{
		return this.base.get( this.index );
	}
	/**
	 * 
	 * @return
	 * @throws IOException
	 */
	private Object getCurrentKeyRow( ) throws IOException
	{
		return this.aggrValues.get( this.index );
	}