manners.groovy.drl

drools 一个开放源码的规则引擎

<?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:groovy="http://drools.org/semantics/groovy"
          xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
          xs:schemaLocation="http://drools.org/rules rules.xsd
                             http://drools.org/semantics/groovy groovy.xsd">

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

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

            <groovy:consequence>
               println "FIRE: find first seat: " + guest ;

               drools.assertObject(new org.drools.examples.manners.model.Seating(1, guest, null));

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

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

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

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

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

          <groovy:condition>
             seating.getGuest1().hasOppositeSex(guest)
          </groovy:condition>

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

          <groovy:consequence>
             println "FIRE: find seating: " + seating + " " + guest ;

             org.drools.examples.manners.model.Seating nextSeat = new org.drools.examples.manners.model.Seating(seating.getSeat2(), guest, seating);
             drools.assertObject(nextSeat);

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

          </groovy:consequence>
       </rule>

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

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

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

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

          <groovy:consequence>
             println "FIRE: try another path: " + seating ;

             org.drools.examples.manners.model.Seating prevSeat = seating.getPrevSeat();
             prevSeat.setGuest2(null);
             drools.modifyObject(prevSeat);

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

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

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

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

          <groovy:consequence>
             println "FIRE: we are done" ;

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

             int i = list.size();
             while (i > 0) {
                org.drools.examples.manners.model.Seat seat = (org.drools.examples.manners.model.Seat)list.get(i-1);
                println seat ;
                drools.assertObject(seat);
                i--;
             }

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

</rule-set>