Bug 124610 Add a filter on a boolean computed column will cause error.
Description: Add a filter on a boolean computed column will cause error. Steps to reproduce: 1. New a BIRT sample data source and a dataset from table "orders" 2. Create a computed column with name="yes/no", type = any(no boolean for choose), value= if(row[1]%2==0){ true; }else{ false; } 3. Drag the dataset from Data Explorer to Layout 4. Select the table, click Filters tab in Property Editor. 5. Click Add button. 6. Select yes/no as Expression, Is True as Operator. 7. Save and preview. Expected result: Filter works. Actual result: Error0 : data.engine.ConvertToDataTypeError ( 1 time(s) ) detail : org.eclipse.birt.data.engine.core.DataException: can not be converted to class java.lang.Boolean.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/script/ScriptEvalUtil.java
operator,
				ExprTextAndValue.newInstance( "", op1 ),
				ExprTextAndValue.newInstance( "", op2 ) );
	}
	
	/**
	 * Most objects should already be formatted to the same type by method
	 * formatToComparable at this point if neither of them is null. This method
	 * will therefore be terminated pretty soon except for calling from method
	 * between with weird parameters like obj:String, op1:Double and op2:Date.
	 * 
	 * @param obj1
	 * @param obj2
	 * @return -1,0 and 1 standing for <,= and > respectively
	 * @throws DataException
	 */
	private static int compare( Object obj1, Object obj2 ) throws DataException
	{
	    if (obj1 == null || obj2 == null) 
	    {
            
	        if (obj1 == null && obj2 != null)
                return -1;
            else if (obj1 != null && obj2 == null)
                return 1;
            else
                return 0;
        }
	    
		try