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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;

import jadex.rules.rulesystem.AbstractAgenda;
import jadex.rules.rulesystem.IPatternMatcherFunctionality;
import jadex.rules.rulesystem.IPatternMatcherState;
import jadex.rules.rulesystem.IRule;
import jadex.rules.rulesystem.IRulebase;
import jadex.rules.rulesystem.IRulebaseListener;
import jadex.rules.rulesystem.rete.nodes.ReteMemory;
import jadex.rules.rulesystem.rete.nodes.ReteNode;
import jadex.rules.state.IOAVState;

import java.util.Iterator;

/**
 *  The static (reusable) part of a Rete matcher (i.e. the Rete network).
 */
public class RetePatternMatcherFunctionality 
	implements IPatternMatcherFunctionality, IRulebaseListener, Cloneable
{
	//-------- attributes --------
	
	/** The rulebase. */
	protected IRulebase rulebase;
	
	/** The rete node. */
	protected ReteNode node;
	
	//-------- constructors --------
	
	/**
	 *  Create a new Rete pattern matcher functionality.
	 */
	public RetePatternMatcherFunctionality(IRulebase rulebase)
	{
		this.rulebase = rulebase;
		this.node = new ReteNode();
		
		// Build existing rules of the rulebase.
		for(Iterator it=rulebase.getRules().iterator(); it.hasNext(); )
			node.addRule((IRule)it.next());
		
		node.setInited(true);

		rulebase.addRulebaseListener(this);
	}
	
	/**
	 *  Get the rulebase.
	 *  @return The rulebase.
	 */
	public IRulebase getRulebase()
	{
		return rulebase;
	}
	
	/**
	 * 
	 * /
	public void setRulebase(IRulebase rulebase)
	{
		// Remove listener from old rulebase
		if(this.rulebase!=null)
			this.rulebase.removeRulebaseListener(this);
		
		// Create executeable rules for new rulebase
		this.rulebase = rulebase;
		this.node = new ReteNode();
		for(Iterator it=rulebase.getRules().iterator(); it.hasNext(); )
			node.addRule((IRule)it.next());
		
		// Track rulebase changes
		rulebase.addRulebaseListener(this);
	}*/
	
	//-------- IRulebaseListener interface --------
	
	/**
	 *  Notification when a rule has been added.
	 *  @param rule The added rule.
	 */
	public void ruleAdded(IRule rule)
	{
		node.addRule(rule);
	}
	
	/**
	 *  Notification when a rule has been removed.
	 *  @param rule The removed rule.
	 */
	public void ruleRemoved(IRule rule)
	{
		node.removeRule(rule);
	}
	
	//-------- IPatternMatcherFunctionality interface --------
	
	/**
	 *  Create a pattern matcher instance for a given state.
	 */
	public IPatternMatcherState createMatcherState(IOAVState state, AbstractAgenda agenda)
	{
		return new RetePatternMatcherState(node, state, new ReteMemory(state), agenda);
	}

	//-------- methods --------
	
	/**
	 *  Get the Rete node.
	 */
	public ReteNode	getReteNode()
	{
		return node;
	}
	
	//-------- cloneable --------
	
	/**
	 *  Clone this object.
	 *  @return A clone of this object.
	 */
	public Object clone()
	{
		RetePatternMatcherFunctionality ret = null;
		
		try
		{	
			ret = (RetePatternMatcherFunctionality)super.clone();
			ret.rulebase = (IRulebase)rulebase.clone();
			ret.rulebase.addRulebaseListener(ret);
			ret.node = (ReteNode)node.clone();
		}
		catch(CloneNotSupportedException exception)
		{
			throw new RuntimeException("Cloning not supported: "+this);
		}
		
		return ret;
	}
}