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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.rules.rulesystem.rete.Tuple;
import jadex.rules.state.IOAVState;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;


/**
 *  The rete memory for all nodes.
 */
public class ReteMemory
{
	//-------- attributes --------
	
	/** The memory. */
	protected Map memory;
	
	/** The state. */
	protected IOAVState	state;
	
//	/** Used for logging debug output. */
//	protected List	debug;
	
	//-------- constructors --------
	
	/**
	 *  Create a new rete memory.
	 */
	public ReteMemory(IOAVState state)
	{
		this.state	= state;
		this.memory = new HashMap();
	}
	
	//-------- collection methods --------
	
	/**
	 *  Test if there is a memory for a node.
	 *  @param node The node.
	 *  @return True, if there is a memory.
	 */
	public boolean	hasNodeMemory(INode node)
	{
		return memory.containsKey(node);
	}
	
//	protected Set	empties	= new HashSet();
//	protected Set	unempties	= new HashSet();
	
	/**
	 *  Get the memory for a node.
	 *  @param node The node.
	 *  @return The memory.
	 */
	public Object getNodeMemory(INode node)
	{
		Object ret = memory.get(node);
		if(ret == null)
		{
			ret = node.createNodeMemory(state);
			memory.put(node, ret);
		}
		
//		// Debbuging code to check if node memory is created but never used.
//		else if(!unempties.contains(ret))
//		{
//			boolean	empty	= ret instanceof Collection ? ((Collection)ret).isEmpty() : ((BetaMemory)ret).size()==0;
//			if(empty)
//			{
//				empties.add(ret);
//				System.out.println("Empties: "+empties.size());
//			}
//			else
//			{
//				empties.remove(ret);
//				unempties.add(ret);
//			}
//		}
		
		return ret;
	}
	
	//-------- tuple memory methods --------
	
	/**
	 *  Get a tuple.
	 *  Returns an existing tuple from the cache, if present.
	 *  Otherwise a new one is created.
	 */
	public Tuple	getTuple(IOAVState state, Tuple left, Object right)
	{
		return new Tuple(state, left, right);
//		Tuple	ret;
//		Map	lefties	= (Map)tuplememory.get(left);
//		if(lefties==null)
//		{
//			lefties	= new WeakHashMap();
//			tuplememory.put(left, lefties);
//			ret	= new Tuple(left, right);
//			lefties.put(right, ret);
//		}
//		else
//		{
//			ret	= (Tuple)lefties.get(right);
//			if(ret==null)
//			{				
//				ret	= new Tuple(left, right);
//				lefties.put(right, ret);
//			}
//		}
//		return ret;
	}
	
	//-------- methods --------
	
	/**
	 *  Get the total memory size
	 *  @return The memory size.
	 */
	public int getTotalMemorySize()
	{
		int	size	= 0;
		for(Iterator it=memory.values().iterator(); it.hasNext(); )
		{
			Object o = it.next();
			if(o instanceof Collection)
			{
				size += ((Collection)o).size();
			}
			else if(o instanceof NotMemory)
			{
				size += ((NotMemory)o).size();
			}
			else if(o instanceof BetaMemory)
			{
				size += ((BetaMemory)o).size();
			}
		}
		return size;
	}
	
	/**
	 *  Get the string representation.
	 *  @return The string representation. 
	 */
	public String toString()
	{
		//return Srules.getInnerClassName(this.getClass())+"(values="+memory+")";
		StringBuffer ret = new StringBuffer(SReflect.getInnerClassName(this.getClass()).toString());
		ret.append(", size="+getTotalMemorySize());
		ret.append(" : \n");
		for(Iterator it=memory.keySet().iterator(); it.hasNext(); )
		{
			Object node = it.next();
			ret.append(node).append(" : ");
			ret.append(memory.get(node)).append("\n");
		}
		return ret.toString();
	}
}