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
try
		{
			int exprType = COMPUTED_COLUMN_EXPR;
			int currentGroupLevel = 0;
			ExpressionInfo exprInfo;
			MultiPassExpressionCompiler helper = this.getMultiPassCompilerHelper( );
			helper.setDataSetMode( isDataSetMode );
			for ( int i = 0; i < iccState.getCount( ); i++ )
			{
				if ( iccState.isValueAvailable( i ) )
				{
					helper.addAvailableCmpColumn( iccState.getName( i ) );
				}
			}
			for ( int i = 0; i < iccState.getCount( ); i++ )
			{
				if ( !iccState.isValueAvailable( i ) )
				{
					IBaseExpression baseExpression = iccState.getExpression( i );
					String name = iccState.getName( i );
					if ( useResultSetMeta
							&& name.matches( "\\Q_{$TEMP_GROUP_\\E\\d*\\Q$}_\\E" ) )
					{
						exprType = GROUP_COLUMN_EXPR;
						
						currentGroupLevel = getCurrentGroupLevel( name,
								currentGroupLevel,
								rsPopulator.getQuery( ) );
						iccState.setValueAvailable( i );
					}