[rules-users] Constraints over Lists

[Wolfgang Laun]

On 22/01/2013, Phani Saripalli <saripalli.phani at gmail.com> wrote:
> Hi, I have a query reg. writing constraints over lists.

The combination of dialect "mvel" and DRL functions appears to cause
an exception, due to a bug (in 5.5.0).

Below is code that works although I doubt whether neqq implements what
I guess that you think it should.

-W

function boolean isDefined(Object ob) {
    return ob != null;
}
function boolean neqq(List l1, List l2) {
    return l1 != l2;
}

declare Project
@typesafe (false)
        list1 : List
        list2 : List
end

rule kickoff
salience 999999
when
then
    insert( new Project() );
    insert( new Project() );
end

rule " Config rule "
no-loop true
when
    P : Project()
then
    modify(P) {
       setList1( Arrays.asList(10, 15, 20, 25) ),
       setList2( Arrays.asList(11, 2, 3, 4, 5, 10, 9, 8, 7) )
    };
end

rule "listEq1"
when
   P : Project()
   eval( isDefined(P.list1)
         &&
         neqq(P.getList1(), new ArrayList(Arrays.asList(1, 2, 3))))
then
     System.out.println("Lists are not equal - 1");
end

rule "listEq2"
when
    P : Project()
   eval( isDefined(P.getList1()) && isDefined(P.getList2())
         && neqq(P.getList1(), P.getList2() ) )
then
    System.out.println("Lists are not equal - 2");
end