OutputProcessViewBase.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.view;

import com.espertech.esper.client.EventType;
import com.espertech.esper.core.service.UpdateDispatchView;
import com.espertech.esper.epl.core.ResultSetProcessor;
import com.espertech.esper.epl.join.base.JoinExecutionStrategy;
import com.espertech.esper.epl.join.base.JoinSetIndicator;
import com.espertech.esper.view.View;
import com.espertech.esper.view.Viewable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.Collections;
import java.util.List;

public abstract class OutputProcessViewBase implements View, JoinSetIndicator, OutputProcessViewTerminable
{
    private static final Log log = LogFactory.getLog(OutputProcessViewBase.class);

    protected final ResultSetProcessor resultSetProcessor;
    protected JoinExecutionStrategy joinExecutionStrategy;
    protected UpdateDispatchView childView;
    protected Viewable parentView;

    protected OutputProcessViewBase(ResultSetProcessor resultSetProcessor) {
        this.resultSetProcessor = resultSetProcessor;
    }

    public Viewable getParent() {
        return parentView;
    }

    public void setParent(Viewable parent) {
        this.parentView = parent;
    }

    public View addView(View view) {
        if (childView != null)
        {
            throw new IllegalStateException("Child view has already been supplied");
        }
        childView = (UpdateDispatchView) view;
        return this;
    }

    public List<View> getViews() {
        if (childView == null) {
            return Collections.emptyList();
        }
        return Collections.<View>singletonList(childView);
    }

    public void removeAllViews()
    {
        childView = null;
    }

    public boolean removeView(View view) {
        if (view != childView)
        {
            throw new IllegalStateException("Cannot remove child view, view has not been supplied");
        }
        childView = null;
        return true;
    }

    public boolean hasViews() {
        return childView != null;
    }

    public EventType getEventType()
    {
        EventType eventType = resultSetProcessor.getResultEventType();
        if (eventType != null)
        {
            return eventType;
        }
        return parentView.getEventType();
    }

    /**
     * For joins, supplies the join execution strategy that provides iteration over statement results.
     * @param joinExecutionStrategy executes joins including static (non-continuous) joins
     */
    public void setJoinExecutionStrategy(JoinExecutionStrategy joinExecutionStrategy)
    {
        this.joinExecutionStrategy = joinExecutionStrategy;
    }
}