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
*
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/
package org.eclipse.birt.data.engine.impl;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import org.eclipse.birt.core.data.DataTypeUtil;
import org.eclipse.birt.core.data.ExpressionUtil;
import org.eclipse.birt.core.data.IColumnBinding;
import org.eclipse.birt.core.exception.BirtException;
import org.eclipse.birt.data.engine.api.IComputedColumn;
import org.eclipse.birt.data.engine.api.IScriptExpression;
import org.eclipse.birt.data.engine.core.DataException;
import org.eclipse.birt.data.engine.executor.transform.TransformationConstants;
import org.eclipse.birt.data.engine.expression.CompiledExpression;
import org.eclipse.birt.data.engine.expression.ExpressionCompilerUtil;
import org.eclipse.birt.data.engine.i18n.ResourceConstants;
import org.eclipse.birt.data.engine.odi.IResultClass;
import org.eclipse.birt.data.engine.odi.IResultObject;
import org.eclipse.birt.data.engine.odi.IResultObjectEvent;
import org.eclipse.birt.data.engine.script.ScriptEvalUtil;
import org.mozilla.javascript.Context;
/**
 * One of implementation of IResultObjectEvent interface. Used to calculate the
 * computed columns value in the time window from fetching data to do
 * grouping/sorting data.
 */
public class ComputedColumnHelper implements IResultObjectEvent