/**************************************************************************************
* 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.expression;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.epl.core.ViewResourceCallback;
import com.espertech.esper.event.EventAdapterService;
import com.espertech.esper.util.JavaClassHelper;
import com.espertech.esper.view.ViewCapDataWindowAccess;
import com.espertech.esper.view.window.RandomAccessByIndexGetter;
import com.espertech.esper.view.window.RelativeAccessByEventNIndexMap;
import java.util.Collection;
import java.util.Map;
/**
* Represents the 'prev' previous event function in an expression node tree.
*/
public class ExprPreviousNode extends ExprNodeBase implements ViewResourceCallback, ExprEvaluator, ExprEvaluatorEnumeration
{
private static final long serialVersionUID = 0L;
private final PreviousType previousType;
private Class resultType;
private int streamNumber;
private Integer constantIndexNumber;
private boolean isConstantIndex;
private transient EventType enumerationMethodType;
private transient ExprPreviousEval evaluator;
public ExprPreviousNode(PreviousType previousType)
{
this.previousType = previousType;
}
public ExprEvaluator getExprEvaluator()
{
return this;
}
public Map<String, Object> getEventType() {
return null;
}
public void validate(ExprValidationContext validationContext) throws ExprValidationException
{
if ((this.getChildNodes().size() > 2) || (this.getChildNodes().isEmpty()))
{
throw new ExprValidationException("Previous node must have 1 or 2 child nodes");
}
// add constant of 1 for previous index
if (this.getChildNodes().size() == 1)
{
if (previousType == PreviousType.PREV) {
this.getChildNodes().add(0, new ExprConstantNodeImpl(1));
}
else {
this.getChildNodes().add(0, new ExprConstantNodeImpl(0));
}
}
// the row recognition patterns allows "prev(prop, index)", we switch index the first position
if (this.getChildNodes().get(1) instanceof ExprConstantNode)
{
ExprNode first = this.getChildNodes().get(0);
ExprNode second = this.getChildNodes().get(1);
this.getChildNodes().clear();
this.getChildNodes().add(second);
this.getChildNodes().add(first);
}
// Determine if the index is a constant value or an expression to evaluate
if (this.getChildNodes().get(0).isConstantResult())
{
ExprNode constantNode = this.getChildNodes().get(0);
Object value = constantNode.getExprEvaluator().evaluate(null, false, validationContext.getExprEvaluatorContext());
if (!(value instanceof Number))
{
throw new ExprValidationException("Previous function requires an integer index parameter or expression");
}
Number valueNumber = (Number) value;
if (JavaClassHelper.isFloatingPointNumber(valueNumber))
{
throw new ExprValidationException("Previous function requires an integer index parameter or expression");
}
constantIndexNumber = valueNumber.intValue();
isConstantIndex = true;
}
// Determine stream number
if (this.getChildNodes().get(1) instanceof ExprIdentNode) {
ExprIdentNode identNode = (ExprIdentNode) this.getChildNodes().get(1);
streamNumber = identNode.getStreamId();
resultType = JavaClassHelper.getBoxedType(this.getChildNodes().get(1).getExprEvaluator().getType());
}
else if (this.getChildNodes().get(1) instanceof ExprStreamUnderlyingNode) {
ExprStreamUnderlyingNode streamNode = (ExprStreamUnderlyingNode) this.getChildNodes().get(1);
streamNumber = streamNode.getStreamId();
resultType = JavaClassHelper.getBoxedType(this.getChildNodes().get(1).getExprEvaluator().getType());
enumerationMethodType = validationContext.getStreamTypeService().getEventTypes()[streamNode.getStreamId()];
}
else
{
throw new ExprValidationException("Previous function requires an event property as parameter");
}
if (previousType == PreviousType.PREVCOUNT) {
resultType = Long.class;
}
if (previousType == PreviousType.PREVWINDOW) {
resultType = JavaClassHelper.getArrayType(resultType);
}
if (validationContext.getViewResourceDelegate() == null)
{
throw new ExprValidationException("Previous function cannot be used in this context");
}
// Request a callback that provides the required access
if (!validationContext.getViewResourceDelegate().requestCapability(streamNumber, new ViewCapDataWindowAccess(), this))
{
throw new ExprValidationException("Previous function requires a single data window view onto the stream");
}
}
public PreviousType getPreviousType()
{
return previousType;
}
public Class getType()
{
return resultType;
}
public boolean isConstantResult()
{
return false;
}
public Collection<EventBean> evaluateGetROCollectionEvents(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context) {
if (!isNewData) {
return null;
}
return evaluator.evaluateGetCollEvents(eventsPerStream, context);
}
public EventBean evaluateGetEventBean(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context) {
if (!isNewData) {
return null;
}
return evaluator.evaluateGetEventBean(eventsPerStream, context);
}
public Collection evaluateGetROCollectionScalar(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context) {
if (!isNewData) {
return null;
}
return evaluator.evaluateGetCollScalar(eventsPerStream, context);
}
public EventType getEventTypeCollection(EventAdapterService eventAdapterService) throws ExprValidationException {
if (previousType == PreviousType.PREV || previousType == PreviousType.PREVTAIL) {
return null;
}
return enumerationMethodType;
}
public EventType getEventTypeSingle(EventAdapterService eventAdapterService, String statementId) throws ExprValidationException {
if (previousType == PreviousType.PREV || previousType == PreviousType.PREVTAIL) {
return enumerationMethodType;
}
return null;
}
public Class getComponentTypeCollection() throws ExprValidationException {
if (resultType.isArray()) {
return resultType.getComponentType();
}
return resultType;
}
public Object evaluate(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext)
{
if (!isNewData) {
return null;
}
return evaluator.evaluate(eventsPerStream, exprEvaluatorContext);
}
public String toExpressionString()
{
StringBuilder buffer = new StringBuilder();
buffer.append(previousType.toString().toLowerCase());
buffer.append("(");
if ((previousType == PreviousType.PREVCOUNT || previousType == PreviousType.PREVWINDOW)) {
buffer.append(this.getChildNodes().get(1).toExpressionString());
}
else {
buffer.append(this.getChildNodes().get(0).toExpressionString());
buffer.append(", ");
buffer.append(this.getChildNodes().get(1).toExpressionString());
}
buffer.append(')');
return buffer.toString();
}
@Override
public int hashCode()
{
return previousType != null ? previousType.hashCode() : 0;
}
public boolean equalsNode(ExprNode node)
{
if (node == null || getClass() != node.getClass())
{
return false;
}
ExprPreviousNode that = (ExprPreviousNode) node;
if (previousType != that.previousType)
{
return false;
}
return true;
}
public void setViewResource(Object resource)
{
RandomAccessByIndexGetter randomAccessGetter = null;
RelativeAccessByEventNIndexMap relativeAccessGetter = null;
if (resource instanceof RandomAccessByIndexGetter)
{
randomAccessGetter = (RandomAccessByIndexGetter) resource;
}
else if (resource instanceof RelativeAccessByEventNIndexMap)
{
relativeAccessGetter = (RelativeAccessByEventNIndexMap) resource;
}
else
{
throw new IllegalArgumentException("View resource " + resource.getClass() + " not recognized by expression node");
}
if (previousType == PreviousType.PREVWINDOW) {
evaluator = new ExprPreviousEvalWindow(streamNumber, this.getChildNodes().get(1).getExprEvaluator(), resultType.getComponentType(),
randomAccessGetter, relativeAccessGetter);
}
else if (previousType == PreviousType.PREVCOUNT) {
evaluator = new ExprPreviousEvalCount(streamNumber, randomAccessGetter, relativeAccessGetter);
}
else {
evaluator = new ExprPreviousEvalPrev(streamNumber, this.getChildNodes().get(0).getExprEvaluator(), this.getChildNodes().get(1).getExprEvaluator(),
randomAccessGetter, relativeAccessGetter, isConstantIndex, constantIndexNumber, previousType == PreviousType.PREVTAIL);
}
}
}