/**************************************************************************************
* 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.view.std;
import com.espertech.esper.client.EventType;
import com.espertech.esper.epl.expression.ExprNode;
import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext;
import com.espertech.esper.core.service.StatementContext;
import com.espertech.esper.epl.expression.ExprNodeUtility;
import com.espertech.esper.view.*;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Factory for {@link MergeView} instances.
*/
public class MergeViewFactory implements ViewFactory
{
private List<ExprNode> viewParameters;
private int streamNumber;
private ExprNode[] criteriaExpressions;
private EventType eventType;
public void setViewParameters(ViewFactoryContext viewFactoryContext, List<ExprNode> expressionParameters) throws ViewParameterException
{
this.viewParameters = expressionParameters;
this.streamNumber = viewFactoryContext.getStreamNum();
}
public void attach(EventType parentEventType, StatementContext statementContext, ViewFactory optionalParentFactory, List<ViewFactory> parentViewFactories) throws ViewParameterException
{
// Find the group by view matching the merge view
GroupByViewFactoryMarker groupByViewFactory = null;
ExprNode[] unvalidated = viewParameters.toArray(new ExprNode[viewParameters.size()]);
for (ViewFactory parentView : parentViewFactories)
{
if (!(parentView instanceof GroupByViewFactoryMarker))
{
continue;
}
GroupByViewFactoryMarker candidateGroupByView = (GroupByViewFactoryMarker) parentView;
if (ExprNodeUtility.deepEquals(candidateGroupByView.getCriteriaExpressions(), unvalidated))
{
groupByViewFactory = candidateGroupByView;
}
}
if (groupByViewFactory == null)
{
throw new ViewParameterException("Groupwin view for this merge view could not be found among parent views");
}
criteriaExpressions = groupByViewFactory.getCriteriaExpressions();
// determine types of fields
Class[] fieldTypes = new Class[criteriaExpressions.length];
for (int i = 0; i < fieldTypes.length; i++)
{
fieldTypes[i] = criteriaExpressions[i].getExprEvaluator().getType();
}
// Determine the final event type that the merge view generates
// This event type is ultimatly generated by AddPropertyValueView which is added to each view branch for each
// group key.
// If the parent event type contains the merge fields, we use the same event type
boolean parentContainsMergeKeys = true;
String[] fieldNames = new String[criteriaExpressions.length];
for (int i = 0; i < criteriaExpressions.length; i++)
{
String name = criteriaExpressions[i].toExpressionString();
fieldNames[i] = name;
if (!(parentEventType.isProperty(name)))
{
parentContainsMergeKeys = false;
}
}
// If the parent view contains the fields to group by, the event type after merging stays the same
if (parentContainsMergeKeys)
{
eventType = parentEventType;
}
else
// If the parent event type does not contain the fields, such as when a statistics views is
// grouped which simply provides a map of calculated values,
// then we need to add in the merge field as an event property thus changing event types.
{
Map<String, Object> additionalProps = new HashMap<String, Object>();
for (int i = 0; i < fieldNames.length; i++)
{
additionalProps.put(fieldNames[i], fieldTypes[i]);
}
String outputEventTypeName = statementContext.getStatementId() + "_mergeview_" + streamNumber;
eventType = statementContext.getEventAdapterService().createAnonymousWrapperType(outputEventTypeName, parentEventType, additionalProps);
}
}
public View makeView(AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)
{
return new MergeView(agentInstanceViewFactoryContext, criteriaExpressions, eventType);
}
public EventType getEventType()
{
return eventType;
}
public boolean canReuse(View view)
{
if (!(view instanceof MergeView))
{
return false;
}
MergeView myView = (MergeView) view;
if (!ExprNodeUtility.deepEquals(myView.getGroupFieldNames(), criteriaExpressions))
{
return false;
}
return true;
}
}