jadex.rules.state.javaimpl.OAVLongIdGenerator Maven / Gradle / Ivy
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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.
package jadex.rules.state.javaimpl;
import java.util.LinkedHashMap;
import java.util.Map;
import jadex.rules.state.IOAVState;
import jadex.rules.state.OAVObjectType;
/**
* Id generator based on long values.
*/
public class OAVLongIdGenerator implements IOAVIdGenerator
{
//-------- attributes --------
/** The id counter. */
protected long nextid;
/** The flag indicating if content ids should be produced. */
protected boolean iscontentid;
//-------- constructor --------
/**
* Create a new id generator.
*/
public OAVLongIdGenerator()
{
this(false);
}
/**
* Create a new id generator.
*/
public OAVLongIdGenerator(boolean iscontentid)
{
nextid = Long.MIN_VALUE;
this.iscontentid = iscontentid;
}
//-------- methods --------
/**
* Create a unique id.
* @param state The state.
* @param type The object type.
* @return The new id.
*/
public Object createId(IOAVState state, OAVObjectType type)
{
long start = nextid;
Object ret = iscontentid? new OAVContentId(nextid++): new OAVObjectId(nextid++);
if(state.containsObject(ret))
System.out.println("Warning, id overflow.");
while(state.containsObject(ret) && nextid!=start)
ret = new OAVObjectId(nextid++);
if(state.containsObject(ret))
throw new RuntimeException("No free id available.");
return ret;
}
/**
* Test if an object is an id.
* @param state The state.
* @param type The object type.
* @return The new id.
*/
public boolean isId(Object id)
{
return id!=null && id instanceof OAVObjectId;
}
/**
* Main for testing.
* @param args
*/
public static void main(String[] args)
{
IOAVState state = OAVStateFactory.createOAVState(null);
OAVLongIdGenerator gen = new OAVLongIdGenerator();
for(long i=0;; i++)
{
Object id = gen.createId(state, null);
if(i%1000000==0)
System.out.println(i+": "+id);
}
}
//-------- helper classes --------
/**
* An id for an OAV object.
*/
private static class OAVObjectId
{
//-------- attributes --------
/** The id value. */
protected long id;
//-------- constructors --------
/**
* Create an OAV object id with the given id value.
* @param id The id value.
*/
public OAVObjectId(long id)
{
this.id = id;
}
//-------- methods --------
/**
* Create a string representation of this OAV object id.
*/
public String toString()
{
return "OAVObjectId("+id+")";
}
/**
* Test if two id's are equal.
* @param id The OAV object id to compare to.
* /
public boolean equals(Object id)
{
return id instanceof OAVObjectId && this.id==((OAVObjectId)id).id;
}*/
/**
* Return the hashcode for this id.
* @return The hashcode for this id.
* /
public int hashCode()
{
// Taken from java.lang.Long
// Todo: is this useful?
return (int)(id ^ (id >>> 32));
}*/
}
/**
* An id for an OAV object.
*/
private static class OAVContentId extends OAVObjectId implements IOAVContentId
{
//-------- attributes --------
/** The content map. */
protected Map content;
//-------- constructors --------
/**
* Create an OAV object id with the given id value.
* @param id The id value.
*/
public OAVContentId(long id)
{
super(id);
this.content = new LinkedHashMap();
}
//-------- methods --------
/**
* Get the content.
* @return The content.
*/
public Map getContent()
{
return content;
}
}
}