/**************************************************************************************
* 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.core;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.core.service.StatementResultService;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.epl.expression.ExprValidationException;
import com.espertech.esper.event.NaturalEventBean;
/**
* A select expression processor that check what type of result (synthetic and natural) event is expected and
* produces.
*/
public class SelectExprResultProcessor implements SelectExprProcessor
{
private final StatementResultService statementResultService;
private final SelectExprProcessor syntheticProcessor;
private final BindProcessor bindProcessor;
private final ExprEvaluatorContext exprEvaluatorContext;
/**
* Ctor.
* @param statementResultService for awareness of listeners and subscribers handles output results
* @param syntheticProcessor is the processor generating synthetic events according to the select clause
* @param bindProcessor for generating natural object column results
* @param exprEvaluatorContext context for expression evalauation
* @throws ExprValidationException if the validation failed
*/
public SelectExprResultProcessor(StatementResultService statementResultService,
SelectExprProcessor syntheticProcessor,
BindProcessor bindProcessor,
ExprEvaluatorContext exprEvaluatorContext)
{
this.statementResultService = statementResultService;
this.syntheticProcessor = syntheticProcessor;
this.bindProcessor = bindProcessor;
this.exprEvaluatorContext = exprEvaluatorContext;
}
public EventType getResultEventType()
{
return syntheticProcessor.getResultEventType();
}
public EventBean process(EventBean[] eventsPerStream, boolean isNewData, boolean isSynthesize, ExprEvaluatorContext exprEvaluatorContext)
{
if ((isSynthesize) && (!statementResultService.isMakeNatural()))
{
return syntheticProcessor.process(eventsPerStream, isNewData, isSynthesize, exprEvaluatorContext);
}
EventBean syntheticEvent = null;
EventType syntheticEventType = null;
if (statementResultService.isMakeSynthetic() || isSynthesize)
{
syntheticEvent = syntheticProcessor.process(eventsPerStream, isNewData, isSynthesize, exprEvaluatorContext);
if (!statementResultService.isMakeNatural())
{
return syntheticEvent;
}
syntheticEventType = syntheticProcessor.getResultEventType();
}
if (!statementResultService.isMakeNatural())
{
return null; // neither synthetic nor natural required, be cheap and generate no output event
}
Object[] parameters = bindProcessor.process(eventsPerStream, isNewData, this.exprEvaluatorContext);
return new NaturalEventBean(syntheticEventType, parameters, syntheticEvent);
}
}