/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package com.espertech.esper.epl.variable;
import com.espertech.esper.collection.SingleEventIterator;
import com.espertech.esper.core.StatementResultService;
import com.espertech.esper.event.EventAdapterService;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.view.ViewSupport;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* View for handling create-variable syntax.
* <p>
* The view posts to listeners when a variable changes, if it has subviews.
* <p>
* The view returns the current variable value for the iterator.
* <p>
* The event type for such posted events is a single field Map with the variable value.
*/
public class CreateVariableView extends ViewSupport implements VariableChangeCallback
{
private static final Log log = LogFactory.getLog(CreateVariableView.class);
private final EventAdapterService eventAdapterService;
private final VariableReader reader;
private final EventType eventType;
private final String variableName;
private final StatementResultService statementResultService;
/**
* Ctor.
* @param eventAdapterService for creating events
* @param variableService for looking up variables
* @param variableName is the name of the variable to create
* @param statementResultService for coordinating on whether insert and remove stream events should be posted
*/
public CreateVariableView(EventAdapterService eventAdapterService, VariableService variableService, String variableName, StatementResultService statementResultService)
{
this.eventAdapterService = eventAdapterService;
this.variableName = variableName;
this.statementResultService = statementResultService;
reader = variableService.getReader(variableName);
Map<String, Object> variableTypes = new HashMap<String, Object>();
variableTypes.put(variableName, reader.getType());
eventType = eventAdapterService.createAnonymousMapType(variableTypes);
}
public void update(Object newValue, Object oldValue)
{
if (statementResultService.isMakeNatural() || statementResultService.isMakeSynthetic())
{
Map<String, Object> valuesOld = new HashMap<String, Object>();
valuesOld.put(variableName, oldValue);
EventBean eventOld = eventAdapterService.adaptorForTypedMap(valuesOld, eventType);
Map<String, Object> valuesNew = new HashMap<String, Object>();
valuesNew.put(variableName, newValue);
EventBean eventNew = eventAdapterService.adaptorForTypedMap(valuesNew, eventType);
this.updateChildren(new EventBean[] {eventNew}, new EventBean[] {eventOld});
}
}
public void update(EventBean[] newData, EventBean[] oldData)
{
throw new UnsupportedOperationException("Update not supported");
}
public EventType getEventType()
{
return eventType;
}
public Iterator<EventBean> iterator()
{
Object value = reader.getValue();
Map<String, Object> values = new HashMap<String, Object>();
values.put(variableName, value);
EventBean event = eventAdapterService.adaptorForTypedMap(values, eventType);
return new SingleEventIterator(event);
}
}