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
{
			return ( result instanceof Date ) || ( result instanceof String );
		}
		/**
		 * To check whether the expressions are comparable. If so, they will be
		 * formatted to the comparable.For operands, only ExprTextAndValue is
		 * acceptable.
		 * 
		 * @param obj
		 * @param operator
		 * @param op1
		 * @param op2
		 * @return
		 * @throws DataException
		 */
		private static Object[] isComparable( Object obj, int operator,
				ExprTextAndValue op1, ExprTextAndValue op2 )
				throws DataException
		{
			if ( isFormatNeeded( obj, operator, op1, op2 ) )
				return formatToComparable( obj, op1, op2 );
			return null;
		}
		/**
		 * 
		 * @param obj
		 * @param operator
		 * @param op1
		 * @param op2
		 * @return