Bug 188038 Need know which measure ComputedColumnHandle aggregate on.
GUI need to show the measure name ont the data item in the aggregation cell.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/olap/util/OlapExpressionCompiler.java
if( expr == null )
			return new HashSet();
		
		Set result = new HashSet();
		Context cx = Context.enter();
		CompilerEnvirons ce = new CompilerEnvirons();
		Parser p = new Parser( ce, cx.getErrorReporter( ) );
		ScriptOrFnNode tree = p.parse( expr.getText( ), null, 0 );
		
		populateDimLevels( tree, result, bindings, onlyFromDirectReferenceExpr );
		return result;
	}
	
	/**
	 * 
	 * @param n
	 * @param result
	 * @param bindings
	 * @param onlyFromDirectReferenceExpr
	 * @throws DataException
	 */
	private static void populateDimLevels( Node n, Set result, List bindings, boolean onlyFromDirectReferenceExpr ) throws DataException
	{
		if ( n == null )
			return;
		if ( onlyFromDirectReferenceExpr )
		{
			if ( n.getType( ) == Token.SCRIPT )
			{
				if ( n.getFirstChild( ) == null