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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.rulesystem.rules.functions;
import jadex.rules.rulesystem.rete.extractors.AttributeSet;
import jadex.rules.rulesystem.rules.ILazyValue;
import jadex.rules.state.IOAVState;
/**
* Calculate the modulo between two numbers.
*/
public class Modulo implements IFunction
{
/**
* Invoke a function and return a value (optional).
* @param paramvalues The parameter values.
* @param state The state.
* @return The function value.
*/
public Object invoke(Object[] paramvalues, IOAVState state)
{
Comparable ret = null;
if(paramvalues.length != 2)
throw new RuntimeException("Modulo requires two parameters: "+paramvalues);
Object val1 = paramvalues[0] instanceof ILazyValue? ((ILazyValue)paramvalues[0]).getValue(): paramvalues[0];
Object val2 = paramvalues[1] instanceof ILazyValue? ((ILazyValue)paramvalues[1]).getValue(): paramvalues[1];
if(!(val1 instanceof Number))
throw new RuntimeException("Modulo requires Number parameters: "+paramvalues[0]);
if(!(val2 instanceof Number))
throw new RuntimeException("Modulo requires Number parameters: "+paramvalues[1]);
Number a = (Number)val1;
Number b = (Number)val2;
// todo: support long/double/...
ret = new Long(a.longValue() % b.longValue());
return ret;
}
/**
* Get the return type of this function.
*/
public Class getReturnType()
{
return Number.class;
}
/**
* Get the set of relevant attribute types.
* @return The relevant attribute types.
*/
public AttributeSet getRelevantAttributes()
{
return AttributeSet.EMPTY_ATTRIBUTESET;
}
/**
* Get the string representation.
* @return The string representation.
*/
public String toString()
{
return "%";
}
/**
* Test for equality.
*/
public boolean equals(Object obj)
{
return obj instanceof Modulo;
}
/*public static void main(String[] args)
{
double a = 7.2 % 3.5;
System.out.println(a);
}*/
}