Bug 123727 the 'Top N' and 'Buttom N' do not work
Description: the 'Top N' and 'Buttom N' do not work Steps to reproduce: 1. new a report 2. new a datasource and a dataset 3. creat a report parameter, 4. drag a chart to the layout, In chart dialogue, click the 'select data' tab and click the button 'filters'. 5. set two filters condition, one is used the 'Top N' function and the other used the report parameter. 6. save and preview Actual result: NO data are displayed. Expect result: The data displayed according to the 'Top N' and 'Input Parameters'
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/script/NEvaluator.java
{
	public static final String BOTTOM_INSTANCE = "BOTTOM";
	public static final String TOP_INSTANCE = "TOP";
	private static String currentInstance = null;
	private static Object[] valueList; 
	private static int[] rowIdList;
	private static int firstPassRowNumberCounter = 0;
	private static int secondPassRowNumberCounter = 0;
	private static int qualifiedRowCounter = 0;
	
	private static int N = -1;
	private static NEvaluator instance = null;
	
	/**
	 * Return the instance of NEvaluagor according to the given instanceName.
	 * @param instanceName
	 * @return
	 */
	public static NEvaluator getInstance( String instanceName )
	{
		if ( instance == null
				|| ( currentInstance == null || !currentInstance.equalsIgnoreCase( instanceName ) ) )