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Jadex Rules is a small lightweight rule engine, which currently employs the well-known Rete algorithm for highly efficient rule matching. Jadex rules is therefore similar to other rule engines like JESS and Drools. Despite the similarities there are also important differences between these systems: * Jadex Rules is very small and intended to be used as component of other software. Even though rules can be specified in a Java dialect as well as (a small variation of) the CLIPS language its primary usage is on the API level. Jadex Rules is currently the core component of the Jadex BDI reasoning engine. * Jadex Rules cleanly separates between state and rule representation. This allows the state implementation as well as the matcher to be flexibly exchanged. Some experiments have e.g. been conducted with a Jena representation. Regarding the matcher, it is planned to support also the Treat algorithm, which has a lower memory footprint than Rete. * Jadex Rules pays close attention to rule debugging. The state as well as the rete engine can be observed at runtime. The rule debugger provides functionalities to execute a rule program stepwise and also use rule breakpoints to stop the execution at those points.

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package jadex.rules.rulesystem.rete.nodes;

import jadex.commons.SReflect;
import jadex.commons.collection.SCollection;

import java.util.HashMap;

/**
 *  Abstract super class for all kinds of nodes.
 */
public abstract class AbstractNode implements INode
{	
	//-------- attributes --------
	
	/** The node id. */
	protected int nodeid;
	
	//-------- constructors --------

	/**
	 *  Create a new node.
	 */
	public AbstractNode(int nodeid)
	{
		this.nodeid = nodeid;
	}
	
	//-------- methods --------
	
	/**
	 *  Get the nodeid.
	 *  @return The nodeid.
	 */
	public int getNodeId()
	{
		return nodeid;
	}

	/**
	 *  Get the hashcode.
	 *  @return The hash code.
	 */
	public int hashCode()
	{
		return nodeid;
	}

	/**
	 *  Test for equality.
	 *  @return True, if equal.
	 */
	public boolean equals(Object obj)
	{
		return (obj instanceof INode) && ((INode)obj).getNodeId()==nodeid;
	}

	/**
	 *  Get the string representation.
	 *  @return The string representation. 
	 */
	public String toString()
	{
		return toString("");
	}
	
	/**
	 *  Customizable string representation.
	 *  The given string will be inserted.
	 */
	protected String	toString(String insert)
	{
		return SReflect.getInnerClassName(this.getClass())
			+ "(id="+nodeid
			+ insert
//			+ ", relevants="+getRelevantAttributes()
			+ ")";
	}

	//-------- cloneable --------
	
	/** The thread local. */
	protected static ThreadLocal clones = new ThreadLocal();
	
	/**
	 *  Clone this object.
	 *  @return A clone of this object.
	 */
	public Object clone()
	{
		Object ret = null;
	
		boolean creator = false;
		HashMap cls = (HashMap)clones.get();
		if(cls==null)
		{
			cls = SCollection.createHashMap();
			clones.set(cls);
			creator = true;
		}
		else
		{
			ret = cls.get(this);
		}
	
		if(ret==null)
		{
			try
			{
				ret = super.clone();
			}
			catch(CloneNotSupportedException exception)
			{
				throw new RuntimeException("Cloning not supported: "+this);
			}
	
			// Save the clone immediately to make it accessible for other elements.
			cls.put(this, ret);
	
			doClone(ret);
		}

		// Delete clones hashmap if element was creator.
		if(creator)
			clones.set(null);
	
		return ret;
	}
	
	/**
	 *  Do clone makes a deep clone without regarding cycles.
	 *  Method is overridden by subclasses to actually incorporate their attributes.
	 *  @param theclone The clone.
	 */
	protected abstract void doClone(Object theclone);

	//-------- debugging --------

	/**
	 *  Check the consistency of the node.
	 */
	public boolean	checkNodeConsistency(ReteMemory mem)
	{
		// Mark node as checked (for debugging).
		Object	node	= this;
		while(!(node instanceof ReteNode))
		{
			if(node instanceof IObjectConsumerNode)
			{
				node	= ((IObjectConsumerNode)node).getObjectSource();
			}
			else if(node instanceof ITupleConsumerNode)
			{
				node	= ((ITupleConsumerNode)node).getTupleSource();
			}
			else
			{
				throw new RuntimeException("Unhandled node type: "+node);
			}
		}
		((ReteNode)node).checked.add(this);

		// Empty default implementation.
		return true;
	}
}