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/util/sort/DimensionSortEvalHelper.java
public DimensionSortEvalHelper( Scriptable parentScope,
			ICubeQueryDefinition queryDefn, ISortDefinition sortDefinition )
			throws DataException
	{
		assert sortDefinition != null;
		Context cx = Context.enter( );
		try
		{
			initialize( parentScope, queryDefn, sortDefinition, cx );
		}
		finally
		{
			Context.exit( );
		}
	}
	/**
	 * 
	 * @param parentScope
	 * @param queryDefn
	 * @param sortDefinition
	 * @param cx
	 * @throws DataException
	 */
	protected void initialize( Scriptable parentScope,
			ICubeQueryDefinition queryDefn, ISortDefinition sortDefinition,
			Context cx ) throws DataException
	{
		super.init( parentScope, queryDefn, cx, sortDefinition.getExpression( ) );
		this.sortDefinition = sortDefinition;
	}