if ( expr instanceof IScriptExpression )
if ( expr != null  )
	private static void testDependencyCycle( ExprManager exprManager ) throws DataException	{		List result = new ArrayList( );		Iterator it = exprManager.getColumnNames( ).iterator( );		while ( it.hasNext( ) )		{			String name = it.next( ).toString( );			Node n = new Node( name );			IBaseExpression expr = exprManager.getExpr( name );			if ( expr instanceof IScriptExpression )			{				String exprText = ( (IScriptExpression) expr ).getText( );				try				{					List l = ExpressionUtil.extractColumnExpressions( exprText );					for ( int j = 0; j < l.size( ); j++ )					{						n.addChild( new Node( ( (IColumnBinding) l.get( j ) ).getResultSetColumnName( ) ) );					}				}				catch ( BirtException e )				{					throw new DataException( e.getLocalizedMessage( ) );				}			}			result.add( n );		}		Node[] source = new Node[result.size( )];		for ( int i = 0; i < source.length; i++ )		{			source[i] = (Node) result.get( i );		}		validateNodes( source );	}