/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* 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.agg.access;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.expression.core.ExprEvaluator;
import com.espertech.esper.epl.expression.core.ExprEvaluatorContext;
import java.util.Collection;
import java.util.Collections;
/**
* Represents the aggregation accessor that provides the result for the "first" and "last" aggregation function with index.
*/
public class AggregationAccessorFirstLastIndexWEval implements AggregationAccessor {
private final int streamNum;
private final ExprEvaluator childNode;
private final EventBean[] eventsPerStream;
private final ExprEvaluator indexNode;
private final int constant;
private final boolean isFirst;
/**
* Ctor.
*
* @param streamNum stream id
* @param childNode expression
* @param indexNode index expression
* @param constant constant index
* @param isFirst true if returning first, false for returning last
*/
public AggregationAccessorFirstLastIndexWEval(int streamNum, ExprEvaluator childNode, ExprEvaluator indexNode, int constant, boolean isFirst) {
this.streamNum = streamNum;
this.childNode = childNode;
this.indexNode = indexNode;
this.eventsPerStream = new EventBean[streamNum + 1];
this.constant = constant;
this.isFirst = isFirst;
}
public Object getValue(AggregationState state, EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) {
EventBean bean = getBean(state);
if (bean == null) {
return null;
}
this.eventsPerStream[streamNum] = bean;
return childNode.evaluate(this.eventsPerStream, true, null);
}
public Collection<EventBean> getEnumerableEvents(AggregationState state, EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) {
EventBean bean = getBean(state);
if (bean == null) {
return null;
}
return Collections.singletonList(bean);
}
public Collection<Object> getEnumerableScalar(AggregationState state, EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) {
Object value = getValue(state, eventsPerStream, isNewData, exprEvaluatorContext);
if (value == null) {
return null;
}
return Collections.singletonList(value);
}
public EventBean getEnumerableEvent(AggregationState state, EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) {
return getBean(state);
}
private EventBean getBean(AggregationState state) {
EventBean bean;
int index = constant;
if (index == -1) {
Object result = indexNode.evaluate(null, true, null);
if ((result == null) || (!(result instanceof Integer))) {
return null;
}
index = (Integer) result;
}
if (isFirst) {
bean = ((AggregationStateLinear) state).getFirstNthValue(index);
} else {
bean = ((AggregationStateLinear) state).getLastNthValue(index);
}
return bean;
}
}