Bug 201030 NPE throws out when preview the attached report design
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/script/ScriptEvalUtil.java
* @return
		 */
		private static Object[] isComparable( Object obj, int operator,
				ExprTextAndValue[] operands )
		{
			if ( needFormat( obj, operator, operands ) )
				return formatToComparable( obj, operands );
			return null;
		}
		/**
		 * 
		 * @param obj
		 * @param operator
		 * @param ops
		 * @return
		 */
		private static boolean needFormat( Object obj, int operator,
				ExprTextAndValue[] ops )
		{
			if ( operator < IConditionalExpression.OP_EQ ||
					( operator > IConditionalExpression.OP_NOT_BETWEEN && operator < IConditionalExpression.OP_IN ) ||
					obj == null || ops.length == 0 )
				return false;
			
			else if ( ( operator == IConditionalExpression.OP_BETWEEN || operator == IConditionalExpression.OP_NOT_BETWEEN ) &&
					ops.length < 2 )
				return false;
			return true;
		}