ResultSetAggregateAllIterator.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.core;

import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Iterator for aggregation results that aggregate all rows.
 */
public class ResultSetAggregateAllIterator implements Iterator<EventBean>
{
    private final Iterator<EventBean> sourceIterator;
    private final ResultSetProcessorAggregateAll resultSetProcessor;
    private EventBean nextResult;
    private final EventBean[] eventsPerStream;
    private ExprEvaluatorContext exprEvaluatorContext;

    /**
     * Ctor.
     * @param sourceIterator is the parent iterator
     * @param resultSetProcessor for getting outgoing rows
     * @param exprEvaluatorContext context for expression evalauation
     */
    public ResultSetAggregateAllIterator(Iterator<EventBean> sourceIterator, ResultSetProcessorAggregateAll resultSetProcessor, ExprEvaluatorContext exprEvaluatorContext)
    {
        this.sourceIterator = sourceIterator;
        this.resultSetProcessor = resultSetProcessor;
        eventsPerStream = new EventBean[1];
        this.exprEvaluatorContext = exprEvaluatorContext;
    }

    public boolean hasNext()
    {
        if (nextResult != null)
        {
            return true;
        }
        findNext();
        if (nextResult != null)
        {
            return true;
        }
        return false;
    }

    public EventBean next()
    {
        if (nextResult != null)
        {
            EventBean result = nextResult;
            nextResult = null;
            return result;
        }
        findNext();
        if (nextResult != null)
        {
            EventBean result = nextResult;
            nextResult = null;
            return result;
        }
        throw new NoSuchElementException();
    }

    private void findNext()
    {
        while (sourceIterator.hasNext())
        {
            EventBean candidate = sourceIterator.next();
            eventsPerStream[0] = candidate;

            Boolean pass = true;
            if (resultSetProcessor.getOptionalHavingNode() != null)
            {
                pass = (Boolean) resultSetProcessor.getOptionalHavingNode().evaluate(eventsPerStream, true, exprEvaluatorContext);
            }
            if (!pass)
            {
                continue;
            }

            nextResult = resultSetProcessor.getSelectExprProcessor().process(eventsPerStream, true, true, exprEvaluatorContext);

            break;
        }
    }

    public void remove()
    {
        throw new UnsupportedOperationException();
    }
}