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/impl/ComputedColumnHelper.java
resultSetCCList );
		List availableCCList = new ArrayList( );
		getAvailableComputedList( getComputedNameList( dataSetCCList ),
				dataSetCCList,
				availableCCList );
		this.availableModeInstance = new ComputedColumnHelperInstance( dataSet,
				availableCCList );
		this.currentModel = TransformationConstants.DATA_SET_MODEL;
		this.allCC = new ArrayList( );
		this.allCC.addAll( dataSetCCList );
		this.allCC.addAll( resultSetCCList );
		logger.exiting( ComputedColumnHelper.class.getName( ), "ComputedColumnHelper" );
	}
	/**
	 * 
	 * @return
	 */
	private ComputedColumnHelperInstance getCurrentInstance( )
	{
		if ( this.currentModel == TransformationConstants.DATA_SET_MODEL )
			return this.dataSetInstance;
		else if ( this.currentModel == TransformationConstants.RESULT_SET_MODEL )
			return this.resultSetInstance;
		else if ( this.currentModel == TransformationConstants.PRE_CALCULATE_MODEL )
			return this.availableModeInstance;
		return null;
	}
	/*
	 * (non-Javadoc)
	 *