EnumEvalAverageScalarLambda.java

/*
 * *************************************************************************************
 *  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.enummethod.eval;

import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.epl.expression.ExprEvaluator;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.event.arr.ObjectArrayEventBean;
import com.espertech.esper.event.arr.ObjectArrayEventType;

import java.util.Collection;

public class EnumEvalAverageScalarLambda extends EnumEvalBase implements EnumEval {

    private final ObjectArrayEventType resultEventType;

    public EnumEvalAverageScalarLambda(ExprEvaluator innerExpression, int streamCountIncoming, ObjectArrayEventType resultEventType) {
        super(innerExpression, streamCountIncoming);
        this.resultEventType = resultEventType;
    }

    public Object evaluateEnumMethod(EventBean[] eventsLambda, Collection target, boolean isNewData, ExprEvaluatorContext context) {
        double sum = 0d;
        int count = 0;
        ObjectArrayEventBean resultEvent = new ObjectArrayEventBean(new Object[1], resultEventType);

        Collection<Object> values = (Collection<Object>) target;
        for (Object next : values) {

            resultEvent.getProperties()[0] = next;
            eventsLambda[streamNumLambda] = resultEvent;

            Number num = (Number) innerExpression.evaluate(eventsLambda, isNewData, context);
            if (num == null) {
                continue;
            }
            count++;
            sum += num.doubleValue();
        }

        if (count == 0) {
            return null;
        }
        return sum / count;
    }
}