[rules-users] comparing an intersection of sets..

[Wolfgang Laun]

It is possible to hide the eval for computing the intersection in a DSL.

Given

public class Element {
    private String name;
    private Set<Integer> numbers;
    public Element( String name, Integer... numbers ){ ... }
    // getters...
    public boolean disjointWith( Element other ){
        Set<Integer> ownNumbers = new HashSet<Integer>( this.numbers );
        ownNumbers.retainAll( other.getNumbers() );
        return ownNumbers.isEmpty();
    }
}

and the dsl

[when]There is an element {eVar}={eVar} : Element()
[when]- called {nVar}={nVar} : name
[when]- other than {oVar}=this != {oVar}
[when]- where {eVar} is disjoint from {oVar}=eval(
{eVar}.disjointWith( {oVar} ) )
[when]- where {eVar} intersects with {oVar}=eval( !
{eVar}.disjointWith( {oVar} ) )
[then]show disjoint {n1Var} and {n2Var}=System.out.println( {n1Var} +
" and " + {n2Var} + " are disjoint.");
[then]show intersecting {n1Var} and {n2Var}=System.out.println(
{n1Var} + " and " + {n2Var} + " intersect.");

you can write the drsl

package appl.domain
expander elements.dsl

rule "find disjoint pairs"
when
    There is an element e1
    - called n1
    There is an element e2
    - called n2
    - other than e1
    - where e1 is disjoint from e2
then
	show disjoint n1 and n2
end

On 25 August 2010 16:55, mechlife <gaiamech at gmail.com> wrote:
>
> Thanks for your response.
>
> I need to use it like 1-4 times depending on what the legacy rules are setup
> on one rule but i do have thousands of rules.
> Also, a future state might be to get these imported into a tool for business
> users to start writing these and would definitely be more pleasing if they
> had an operator that they could use.
> Would you be able to point me to some resources on how to do the custom
> operator
> if the need arise.
>
> thanks again for your time.
> --
> View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/comparing-an-intersection-of-sets-tp1313555p1332184.html
> Sent from the Drools - User mailing list archive at Nabble.com.
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