Bug 201019 [Automation][Regression]Exception is thrown when running reportdesign
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/adapter/ExpressionUtil.java
switch ( ce.getOperator( ) )
		{
			case IConditionalExpression.OP_TOP_N :
				prefix = "Total.isTopN";
				break;
			case IConditionalExpression.OP_TOP_PERCENT :
				prefix = "Total.isTopNPercent";
				break;
			case IConditionalExpression.OP_BOTTOM_N :
				prefix = "Total.isBottomN";
				break;
			case IConditionalExpression.OP_BOTTOM_PERCENT :
				prefix = "Total.isBottomNPercent";
				break;
		}
		
		if( prefix != null )
		{
			ce = new ConditionalExpression( prefix+"("
					+ ce.getExpression( ).getText( ) + "," +
					( (IScriptExpression) ce.getOperand1( ) ).getText( ) + ")",
					IConditionalExpression.OP_TRUE );
		}
		return ce;
	}
	/**
	 * @param result
	 * @param key
	 * @throws EngineException 
	 */