com/intendico/gorite/ConditionGoal.java

   1 /*********************************************************************
   2 Copyright 2012, Ralph Ronnquist.
   3
   4 This file is part of GORITE.
   5
   6 GORITE is free software: you can redistribute it and/or modify it
   7 under the terms of the Lesser GNU General Public License as published
   8 by the Free Software Foundation, either version 3 of the License, or
   9 (at your option) any later version.
  10
  11 GORITE is distributed in the hope that it will be useful, but WITHOUT
  12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  14 License for more details.
  15
  16 You should have received a copy of the Lesser GNU General Public
  17 License along with GORITE.  If not, see <http://www.gnu.org/licenses/>.
  18 **********************************************************************/
  19
  20 package com.intendico.gorite;
  21
  22 import com.intendico.data.Query;
  23 import com.intendico.data.Ref;
  24
  25 import java.util.HashSet;
  26 import java.util.Iterator;
  27 import java.util.Vector;
  28
  29 /**
  30  * A ConditionGoal is achieved by achieving any sub goal, which are
  31  * attempted in sequence. The goal fails when and if all sub goals
  32  * have been attempted and failed.
  33  */
  34 public class ConditionGoal extends Goal {
  35
  36     /**
  37      * Constructor.
  38      */
  39     public ConditionGoal(String n,Goal [] sg) {
  40         super( n, sg );
  41     }
  42
  43     /**
  44      * Convenience constructor without sub goals.
  45      */
  46     public ConditionGoal(String n) {
  47         this( n, null );
  48     }
  49
  50     /**
  51      * Creates and returns an instance object for achieving
  52      * a ConditionGoal.
  53      */
  54     public Instance instantiate(String head,Data d) {
  55         return new ConditionInstance( head );
  56     }
  57
  58     /**
  59      * Implements sequential, conditional sub goal execution
  60      * attempt. I.e., if a sub goal fails, then try next, otherwise
  61      * succeed.
  62      */
  63     public class ConditionInstance extends Instance {
  64
  65         /**
  66          * Constructor.
  67          */
  68         public ConditionInstance(String h) {
  69             super( h );
  70         }
  71
  72         /**
  73          * Next sub goal index.
  74          */
  75         public int index = 0;
  76
  77         /**
  78          * Current ongoing Instance.
  79          */
  80         public Instance ongoing = null;
  81
  82         /**
  83          * Cancels this execution by propagating the cancel call to
  84          * all sub goals.
  85          */
  86         public void cancel() {
  87             super.cancel();
  88             if ( ongoing != null )
  89                 ongoing.cancel();
  90         }
  91
  92         /**
  93          * Instantiates and performs sub goals in sequence, until the
  94          * first one that does not fail. If a sub goal fails, then
  95          * that is caught, and the next sub goal in sequence is
  96          * instantiated and performed.
  97          */
  98         public States action(String head,Data d)
  99             throws LoopEndException, ParallelEndException {
 100             Goal [] subgoals = getGoalSubgoals();
 101             if ( subgoals == null )
 102                 return States.FAILED;
 103             while ( index < subgoals.length ) {
 104                 if ( ongoing == null ) {
 105                     ongoing = subgoals[ index ].instantiate(
 106                         head + "." + index, d );
 107                 }
 108                 States s = ongoing.perform( d );
 109                 if ( s != States.FAILED )
 110                     return s;
 111                 index += 1;
 112                 ongoing = null;
 113             }
 114             return States.FAILED;
 115         }
 116     }
 117 }