crstrtgy.c

一套美国国家宇航局人工智能中心NASA的专家系统工具源代码

      if (actPtr->salience > salience)
        {
         lastAct = actPtr;
         actPtr = actPtr->next;
        }
      else if (actPtr->salience < salience)
        { return(lastAct); }
      else if (randomID > actPtr->randomID)
        {
         lastAct = actPtr;
         actPtr = actPtr->next;
        }
      else if (randomID < actPtr->randomID)
       { return(lastAct); }
      else if (timetag > actPtr->timetag)
        {
         lastAct = actPtr;
         actPtr = actPtr->next;
        }
      else
       { return(lastAct); }
     }

   /*===========================================*/
   /* Return the insertion point in the agenda. */
   /*===========================================*/
   
   return(lastAct);
  }

/******************************************************************/
/* SortPartialMatch: Copies a partial match and then sorts the    */
/*   fact-indices in the copied partial match in ascending order. */
/******************************************************************/
static struct partialMatch *SortPartialMatch(binds)
  struct partialMatch *binds;
  {
   struct partialMatch *nbinds;
   struct alphaMatch *temp;
   int flag, j, k;

   /*=================*/
   /* Copy the array. */
   /*=================*/

   nbinds = CopyPartialMatch(binds,0,0);

   /*=================*/
   /* Sort the array. */
   /*=================*/

   for (flag = CLIPS_TRUE, k = binds->bcount - 1;
        flag == CLIPS_TRUE;
        k--)
     {
      flag = CLIPS_FALSE;
      for (j = 0 ; j < k ; j++)
        {
         if ((nbinds->binds[j].gm.theMatch->matchingItem != NULL) &&
             (nbinds->binds[j + 1].gm.theMatch->matchingItem != NULL))
           {
            if (nbinds->binds[j].gm.theMatch->matchingItem->timeTag < 
                nbinds->binds[j + 1].gm.theMatch->matchingItem->timeTag)
              {
               temp = nbinds->binds[j].gm.theMatch;
               nbinds->binds[j].gm.theMatch = nbinds->binds[j+1].gm.theMatch;
               nbinds->binds[j+1].gm.theMatch = temp;
               flag = CLIPS_TRUE;
              }
           }
        }
     }

   /*===================*/
   /* Return the array. */
   /*===================*/

   return(nbinds);
  }

/**************************************************************************/
/* ComparePartialMatches: Compares two activations using the lex conflict */
/*   resolution strategy to determine which activation should be placed   */
/*   first on the agenda. This lexicographic comparison function is used  */
/*   for both the lex and mea strategies.                                 */
/**************************************************************************/
static int ComparePartialMatches(actPtr,newActivation)
  ACTIVATION *actPtr, *newActivation;
  {
   int cCount, oCount, mCount, i;

   /*=================================================*/
   /* If the activation already on the agenda doesn't */
   /* have a set of sorted timetags, then create one. */
   /*=================================================*/
   
   if (actPtr->sortedBasis == NULL)
     { actPtr->sortedBasis = SortPartialMatch(actPtr->basis); }

   /*==============================================================*/
   /* Determine the number of timetags in each of the activations. */
   /* The number of timetags to be compared is the lessor of these */
   /* two numbers.                                                 */
   /*==============================================================*/
   
   cCount = newActivation->sortedBasis->bcount;
   oCount = actPtr->sortedBasis->bcount;
   if (oCount > cCount) mCount = cCount;
   else mCount = oCount;

   /*===========================================================*/
   /* Compare the sorted timetags one by one until there are no */
   /* more timetags to compare or the timetags being compared   */
   /* are not equal. If the timetags aren't equal, then the     */
   /* activation containing the larger timetag is placed before */
   /* the activation containing the smaller timetag.            */
   /*===========================================================*/
   
   for (i = 0 ; i < mCount ; i++)
     {
      if ((actPtr->sortedBasis->binds[i].gm.theMatch->matchingItem != NULL) &&
          (newActivation->sortedBasis->binds[i].gm.theMatch->matchingItem != NULL))
        {
         if (newActivation->sortedBasis->binds[i].gm.theMatch->matchingItem->timeTag <
             actPtr->sortedBasis->binds[i].gm.theMatch->matchingItem->timeTag)
           { return(LESS_THAN); }
         else if (newActivation->sortedBasis->binds[i].gm.theMatch->matchingItem->timeTag >
                  actPtr->sortedBasis->binds[i].gm.theMatch->matchingItem->timeTag)
           { return(GREATER_THAN); }
        }
      else if (newActivation->sortedBasis->binds[i].gm.theMatch->matchingItem != NULL)
        { return(GREATER_THAN); }
      else if (actPtr->sortedBasis->binds[i].gm.theMatch->matchingItem != NULL)
        { return(LESS_THAN); }
     }

   /*==========================================================*/
   /* If the sorted timetags are identical up to the number of */
   /* timetags contained in the smaller partial match, then    */
   /* the activation containing more timetags should be        */
   /* placed before the activation containing fewer timetags.  */
   /*==========================================================*/
   
   if (cCount < oCount) return(LESS_THAN);
   else if (cCount > oCount) return(GREATER_THAN);

   /*=========================================================*/
   /* If the sorted partial matches for both activations are  */
   /* identical (containing the same number and values of     */
   /* timetags), then the activation associated with the rule */
   /* having the highest complexity is placed before the      */
   /* other partial match.                                    */
   /*=========================================================*/
   
   if (newActivation->theRule->complexity < actPtr->theRule->complexity)
     { return(LESS_THAN); }
   else if (newActivation->theRule->complexity > actPtr->theRule->complexity) 
     { return(GREATER_THAN); }

   /*================================================*/
   /* The two partial matches are equal for purposes */
   /* of placement on the agenda for the lex and mea */
   /* conflict resolution strategies.                */
   /*================================================*/
   
   return(EQUAL);
  }

/*************************************/
/* SetStrategy: C access routine for */
/*   the set-strategy command.       */
/*************************************/
globle int SetStrategy(value)
  int value;
  {
   int oldStrategy;

   oldStrategy = Strategy;
   Strategy = value;

   if (oldStrategy != Strategy) ReorderAgenda(NULL);

   return(oldStrategy);
  }

/*************************************/
/* GetStrategy: C access routine for */
/*   the get-strategy command.       */
/*************************************/
globle int GetStrategy()
  {
   return(Strategy);
  }

/********************************************/
/* GetStrategyCommand: CLIPS access routine */
/*   for the get-strategy command.          */
/********************************************/
globle SYMBOL_HN *GetStrategyCommand()
  {
   ArgCountCheck("get-strategy",EXACTLY,0);

   return((SYMBOL_HN *) AddSymbol(GetStrategyName(GetStrategy())));
  }

/********************************************/
/* SetStrategyCommand: CLIPS access routine */
/*   for the set-strategy command.          */
/********************************************/
globle SYMBOL_HN *SetStrategyCommand()
  {
   DATA_OBJECT argPtr;
   char *argument;
   int oldStrategy = Strategy;
   
   /*=====================================================*/
   /* Check for the correct number and type of arguments. */
   /*=====================================================*/
   
   if (ArgCountCheck("set-strategy",EXACTLY,1) == -1)
     { return((SYMBOL_HN *) AddSymbol(GetStrategyName(GetStrategy()))); }

   if (ArgTypeCheck("set-strategy",1,SYMBOL,&argPtr) == CLIPS_FALSE)
     { return((SYMBOL_HN *) AddSymbol(GetStrategyName(GetStrategy()))); }

   argument = DOToString(argPtr);

   /*=============================================*/
   /* Set the strategy to the specified strategy. */
   /*=============================================*/
   
   if (strcmp(argument,"depth") == 0)
     { SetStrategy(DEPTH_STRATEGY); }
   else if (strcmp(argument,"breadth") == 0)
     { SetStrategy(BREADTH_STRATEGY); }
   else if (strcmp(argument,"lex") == 0)
     { SetStrategy(LEX_STRATEGY); }
   else if (strcmp(argument,"mea") == 0)
     { SetStrategy(MEA_STRATEGY); }
   else if (strcmp(argument,"complexity") == 0)
     { SetStrategy(COMPLEXITY_STRATEGY); }
   else if (strcmp(argument,"simplicity") == 0)
     { SetStrategy(SIMPLICITY_STRATEGY); }
   else if (strcmp(argument,"random") == 0)
     { SetStrategy(RANDOM_STRATEGY); }
   else
     {
      ExpectedTypeError1("set-strategy",1,
      "symbol with value depth, breadth, lex, mea, complexity, simplicity, or random");
      return((SYMBOL_HN *) AddSymbol(GetStrategyName(GetStrategy())));
     }

   /*=======================================*/
   /* Return the old value of the strategy. */
   /*=======================================*/
   
   return((SYMBOL_HN *) AddSymbol(GetStrategyName(oldStrategy)));
  }
  
/**********************************************************/
/* GetStrategyName: Given the integer value corresponding */
/*   to a specified strategy, return a character string   */
/*   of the strategy's name.                              */
/**********************************************************/
static char *GetStrategyName(strategy)
  int strategy;
  {
   char *sname;

   switch (strategy)
     {
      case DEPTH_STRATEGY:
        sname = "depth";
        break;
      case BREADTH_STRATEGY:
        sname = "breadth";
        break;
      case LEX_STRATEGY:
        sname = "lex";
        break;
      case MEA_STRATEGY:
        sname = "mea";
        break;
      case COMPLEXITY_STRATEGY:
        sname = "complexity";
        break;
      case SIMPLICITY_STRATEGY:
        sname = "simplicity";
        break;
      case RANDOM_STRATEGY:
        sname = "random";
        break;
      default:
        sname = "unknown";
        break;
     }

   return(sname);
  }
#endif /* CONFLICT_RESOLUTION_STRATEGIES */
  
#endif /* DEFRULE_CONSTRUCT */