Bug 189706 Enhance computed column aggregation function handling in UI.
Due to the issue discussed in 189705, current computed column aggregation builder in data set editor has bugs to extend: 1.When new a computed column, the aggregation argument field cannot be correctly set. 2.The argument field cannot be correct grayed out when user select a aggregation function without arguments 3.The available aggregation function list is incomprehensive 4.Some aggregation function cannot be set to model(say, weightedAve).
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/expression/ExpressionProcessor.java
helper.reSetPassLevelFlag( );
				}
			}
			calculate( helper );
		}
		finally
		{
			Context.exit( );
		}
	}
	
	/**
	 * 
	 * @param exprArray
	 * @param arrayType
	 * @param rsPopulator
	 * @param dataSetRuntime
	 * @param useResultSetMeta
	 * @param isDataSetMode
	 * @throws DataException
	 */
	public void evaluateMultiPassExprOnGroup( Object[] exprArray,
			int[] currentGroupLevel, int arrayType ) throws DataException
	{
		assert exprArray != null;
		IBaseExpression baseExpression = null;
		Context context = Context.enter( );
		MultiPassExpressionCompiler helper = this.getMultiPassCompilerHelper( );
		helper.setDataSetMode( isDataSetMode );