WrapperEventBean.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.event;

import com.espertech.esper.collection.Pair;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.client.EventPropertyGetter;
import com.espertech.esper.client.PropertyAccessException;

import java.util.Map;

/**
 * Event bean that wraps another event bean adding additional properties.
 * <p>
 * This can be useful for classes for which the statement adds derived values retaining the original class.
 * <p>
 * The event type of such events is always {@link WrapperEventType}. Additional properties are stored in a
 * Map.
 */
public class WrapperEventBean implements EventBean, DecoratingEventBean
{
	private final EventBean theEvent;
	private final Map<String, Object> map;
	private final EventType eventType;

    /**
     * Ctor.
     * @param theEvent is the wrapped event
     * @param properties is zero or more property values that embellish the wrapped event
     * @param eventType is the {@link WrapperEventType}.
     */
    public WrapperEventBean(EventBean theEvent, Map<String, Object> properties, EventType eventType)
	{
		this.theEvent = theEvent;
		this.map = properties;
		this.eventType = eventType;
    }

	public Object get(String property) throws PropertyAccessException
	{
        EventPropertyGetter getter = eventType.getGetter(property);
        if (getter == null)
        {
            throw new PropertyAccessException("Property named '" + property + "' is not a valid property name for this type");
        }
        return eventType.getGetter(property).get(this);
	}

	public EventType getEventType()
	{
		return eventType;
	}

	public Object getUnderlying()
	{
        // If wrapper is simply for the underlyingg with no additional properties, then return the underlying type
        if (map.isEmpty())
        {
            return theEvent.getUnderlying();
        }
        else
        {
            return new Pair<Object, Map>(theEvent.getUnderlying(), map);
        }
    }

    /**
     * Returns the underlying map storing the additional properties, if any.
     * @return event property map
     */
    public Map getUnderlyingMap()
    {
        return map;
    }

    public Map<String, Object> getDecoratingProperties()
    {
        return map;
    }

    public EventBean getUnderlyingEvent()
    {
        return theEvent;
    }

    public String toString()
	{
        return "WrapperEventBean " +
        "[event=" + theEvent + "] " +
        "[properties=" + map + "]";
	}

    public Object getFragment(String propertyExpression)
    {
        EventPropertyGetter getter = eventType.getGetter(propertyExpression);
        if (getter == null)
        {
            throw new PropertyAccessException("Property named '" + propertyExpression + "' is not a valid property name for this type");
        }
        return getter.getFragment(this);
    }
}