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
/*******************************************************************************
 * Copyright (c) 2004, 2005 Actuate Corporation. All rights reserved. This
 * program and the accompanying materials are made available under the terms of
 * the Eclipse Public License v1.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: Actuate Corporation - initial API and implementation
 ******************************************************************************/
package org.eclipse.birt.data.engine.expression;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.birt.data.engine.api.IBaseExpression;
import org.eclipse.birt.data.engine.api.IConditionalExpression;
import org.eclipse.birt.data.engine.api.IScriptExpression;
import org.eclipse.birt.data.engine.core.DataException;
import org.eclipse.birt.data.engine.executor.BaseQuery;
import org.eclipse.birt.data.engine.executor.transform.IComputedColumnsState;
import org.eclipse.birt.data.engine.executor.transform.IExpressionProcessor;
import org.eclipse.birt.data.engine.executor.transform.ResultSetPopulator;
import org.eclipse.birt.data.engine.impl.DataSetRuntime;
import org.eclipse.birt.data.engine.impl.aggregation.AggregateTable;
import org.eclipse.birt.data.engine.impl.aggregation.JSAggrValueObject;
import org.eclipse.birt.data.engine.odi.IResultIterator;
import org.eclipse.birt.data.engine.odi.IQuery.GroupSpec;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Scriptable;
/**
 * This class handles the compilation of ROM JavaScript expressions of the