manners.drl

rule engine drools-2.0-beta-18

<?xml version="1.0" encoding="UTF-8"?>
<!--

The definition of a RuleExecutionSet is not within the scope of the JSR 94.
The implementation given in this file is written for the reference
implementation. A rule engine vendor verifying their rule engine should
modify this file to their specific needs.

Miss Manners is a program which handles the problem of finding an acceptable
seating arrangement for guests at a dinner party.  It will attempt to match
people with the same hobbies, and to seat everyone next to a member of the
opposite sex.  Manners is a small program, which has only few rules, and
employs a depth-first search approach to the problem.

-->
<rule-set name="Miss Manners"
          xmlns="http://drools.org/rules"
          xmlns:java="http://drools.org/semantics/java"
          xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
          xs:schemaLocation="http://drools.org/rules rules.xsd
                             http://drools.org/semantics/java java.xsd">

       <!--
       Initialize the root seating element.
       -->
        <rule name="find first seat" salience="40">
           <parameter identifier="context">
               <class>org.drools.jsr94.benchmark.Context</class>
           </parameter>
           <parameter identifier="guest">
               <class>org.drools.jsr94.benchmark.Guest</class>
           </parameter>

           <java:condition>
              context.isState("start")
           </java:condition>

            <java:consequence>
               import org.drools.jsr94.benchmark.drools.Seating;

               System.out.println("FIRE: find first seat: " + guest);

               drools.assertObject(new Seating(1, guest, null));

               context.setState("find_seating");
               drools.modifyObject(context);
            </java:consequence>
        </rule>

       <!--
       Find guest for empty seat.
       -->
       <rule name="find seating" salience="30">
          <parameter identifier="context">
              <class>org.drools.jsr94.benchmark.Context</class>
          </parameter>
          <parameter identifier="guest">
              <class>org.drools.jsr94.benchmark.Guest</class>
          </parameter>
          <parameter identifier="seating">
              <class>org.drools.jsr94.benchmark.drools.Seating</class>
          </parameter>

          <java:condition>
             context.isState("find_seating")
          </java:condition>

          <java:condition>
             seating.getGuest2() == null
          </java:condition>

          <java:condition>
             !seating.getTabooList().contains(guest)
          </java:condition>

          <java:condition>
             seating.getGuest1().hasOpositeSex(guest)
          </java:condition>

          <java:condition>
             seating.getGuest1().hasSameHobby(guest)
          </java:condition>

          <java:consequence>
             System.out.println("FIRE: find seating: " + seating + " " + guest);

             Seating nextSeat = new Seating(seating.getSeat2(), guest, seating);
             drools.assertObject(nextSeat);

             seating.setGuest2(guest);
             seating.getTabooList().add(guest);
             seating.setNextSeat(nextSeat);
             drools.modifyObject(seating);

          </java:consequence>
       </rule>

       <!--
       Reached dead end, try another path.
       -->
       <rule name="try another path" salience="20">
          <parameter identifier="context">
              <class>org.drools.jsr94.benchmark.Context</class>
          </parameter>
          <parameter identifier="lastSeat">
              <class>org.drools.jsr94.benchmark.LastSeat</class>
          </parameter>
          <parameter identifier="seating">
              <class>org.drools.jsr94.benchmark.drools.Seating</class>
          </parameter>

          <java:condition>
             context.isState("find_seating")
          </java:condition>

          <java:condition>
             lastSeat.getSeat() > seating.getSeat1()
          </java:condition>

          <java:condition>
             seating.getGuest2() == null
          </java:condition>

          <java:consequence>
             System.out.println("FIRE: try another path: " + seating);

             Seating prevSeat = seating.getPrevSeat();
             prevSeat.setGuest2(null);
             drools.modifyObject(prevSeat);

             drools.retractObject(seating);
          </java:consequence>
       </rule>

       <!--
       All seats are taken.
       -->
       <rule name="we are done" salience="10">
          <parameter identifier="context">
              <class>org.drools.jsr94.benchmark.Context</class>
          </parameter>
          <parameter identifier="lastSeat">
              <class>org.drools.jsr94.benchmark.LastSeat</class>
          </parameter>
          <parameter identifier="seating">
              <class>org.drools.jsr94.benchmark.drools.Seating</class>
          </parameter>

          <java:condition>
             context.isState("find_seating")
          </java:condition>

          <java:condition>
             lastSeat.getSeat() == seating.getSeat1()
          </java:condition>

          <java:consequence>
             import org.drools.jsr94.benchmark.Seat;
             import java.util.List;
             import java.util.ArrayList;

             System.out.println("FIRE: we are done");

             List list = new ArrayList();
             while(seating != null) {
                Seat seat = new Seat(seating.getSeat1(), seating.getGuest1().getName());
                seating = seating.getPrevSeat();
                list.add(seat);
             }

             for (int i = list.size(); i > 0; i--) {
                Seat seat = (Seat)list.get(i-1);
                System.out.println(seat);
                drools.assertObject(seat);
             }

             context.setState("all_done");
             drools.modifyObject(context);
          </java:consequence>
       </rule>

</rule-set>