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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 java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

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

/**
 *  Node memory for not nodes. 
 */
public class NotMemory	extends BetaMemory
{
	//-------- attributes --------
	
	/** The mappings (lefttuple -> {rightvalues}). */
	protected Map mappings;
	
	/** The delay flag. */
	protected boolean	delay;

	//-------- constructors --------
	
	/**
	 *  Create a new not memory.
	 */
	public NotMemory(IOAVState state)
	{
		super(state);
		this.mappings = new LinkedHashMap();
	}

	//-------- methods --------

	/**
	 *  Add a mapping for the key to the memory.
	 *  Multiples mappings for the same key will be stored in a set.
	 */
	public void	addMapping(IOAVState state, Tuple key, Object value)
	{
		Set	values	= (Set)mappings.get(key);
		if(values==null)
		{
			values	= state.isJavaIdentity() ? (Set)new MixedIdentityHashSet(state) : new HashSet();
			mappings.put(key, values);
		}

		values.add(value);
	}
	
	/**
	 *  Remove a mapping for the key from the memory.
	 *  The value will be stored in a set.
	 */
	public boolean	removeMapping(Tuple key, Object value)
	{
		boolean	ret	= false;
		Set	values	= (Set)mappings.get(key);
		if(values!=null)
			ret	= values.remove(value);
		return ret;
	}

	/**
	 *  Remove all mappings of the tuple from memory
	 */
	public void	removeMappings(Tuple key)
	{
		mappings.remove(key);
	}

	/**
	 *  Get the mappings for a given key.
	 */
	public Set	getMappings(Tuple key)
	{
		return mappings.containsKey(key) ? (Set)mappings.get(key) : Collections.EMPTY_SET;
	}
	
	/**
	 *  Get the size of the memory.
	 *  @return The size.
	 */
	public int size()
	{
		int ret = super.size();
		for(Iterator it=mappings.keySet().iterator(); it.hasNext();)
		{
			Collection c = (Collection)mappings.get(it.next());
			ret += c.size();
		}
		return ret;
	}
	
	/**
	 *  Set the delay flag.
	 */
	public void	setDelay(boolean delay)
	{
		this.delay	= delay;
	}
	
	/**
	 *  Get the delay flag.
	 */
	public boolean	isDelay()
	{
		return delay;
	}
	
	/**
	 *  Get the string representation.
	 *  @return The string representation. 
	 */
	public String toString()
	{
		String ret = super.toString();
		ret	= ret.substring(0, ret.length()-1);
		ret	+= ", mappings=";
		ret	+= mappings;
		ret	+= ")";
		ret	+= ", delay=";
		ret	+= delay;
		return ret;
	}
}