factbld.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 there is an upper level above the new node, then */
   /* place the new node as the first child in the upper  */
   /* level's nextLevel (child) link.                     */
   /*=====================================================*/
   
   if (upperLevel != NULL)
     {
      newNode->rightNode = upperLevel->nextLevel;
      if (upperLevel->nextLevel != NULL)
        { upperLevel->nextLevel->leftNode = newNode; }
      upperLevel->nextLevel = newNode;
      return(newNode);
     }
   
   /*=====================================================*/
   /* Since there is no upper level above the new node,   */
   /* (i.e. the new node is being added to the highest    */
   /* level in the pattern network), the new node becomes */
   /* the first node visited in the pattern network.      */
   /*=====================================================*/
     
   newNode->rightNode = CurrentDeftemplate->patternNetwork;
   if (CurrentDeftemplate->patternNetwork != NULL)
     { CurrentDeftemplate->patternNetwork->leftNode = newNode; }
     
   CurrentDeftemplate->patternNetwork = newNode;
   return(newNode);
  }

/*************************************************************/
/* DetachFactPattern: Removes a pattern node and all of its  */
/*   parent nodes from the pattern network. Nodes are only   */
/*   removed if they are no longer shared (i.e. a pattern    */
/*   node that has more than one child node is shared). A    */
/*   pattern from a rule is typically removed by removing    */
/*   the bottom most pattern node used by the pattern and    */
/*   then removing any parent nodes which are not shared by  */
/*   other patterns.                                         */
/*                                                           */
/*   Example:                                                */
/*     Patterns (a b c d) and (a b e f) would be represented */
/*     by the pattern net shown on the left.  If (a b c d)   */
/*     was detached, the resultant pattern net would be the  */
/*     one shown on the right.                               */
/*                                                           */
/*           a                  a                            */
/*           |                  |                            */
/*           b                  b                            */
/*           |                  |                            */
/*           c--e               e                            */
/*           |  |               |                            */
/*           d  f               f                            */
/*                                                           */
/*************************************************************/
static VOID DetachFactPattern(thePattern)
  struct patternNodeHeader *thePattern;
  {
   struct factPatternNode *patternPtr;
   struct factPatternNode *upperLevel;
   
   /*=====================================================*/
   /* Get rid of any matches stored in the alpha memory.  */
   /*=====================================================*/
   
   patternPtr = (struct factPatternNode *) thePattern;
   ClearPatternMatches(patternPtr);

   /*=====================================================*/
   /* If there are no joins entered from this pattern, then */
   /* the pattern node is no longer a stop node. Also if  */
   /* the pattern has a next level pointer, then it can   */
   /* not be removed since other patterns make use of it. */
   /*=====================================================*/
    
   if (patternPtr->header.entryJoin == NULL) patternPtr->header.stopNode = CLIPS_FALSE;
   if (patternPtr->nextLevel != NULL) return;
   
   /*==============================================================*/
   /* Loop until all appropriate pattern nodes have been detached. */
   /*==============================================================*/

   upperLevel = patternPtr;
   while (upperLevel != NULL)
     {
      if ((upperLevel->leftNode == NULL) &&
          (upperLevel->rightNode == NULL))
        {
         /*===============================================*/
         /* Pattern node is the only node on this level.  */
         /* Remove it and continue detaching other nodes  */
         /* above this one, because no other patterns are */
         /* dependent upon this node.                     */
         /*===============================================*/

         patternPtr = upperLevel;
         upperLevel = patternPtr->lastLevel;
         
         if (upperLevel == NULL) 
           { FindAndSetDeftemplatePatternNetwork(patternPtr,NULL); }
         else 
           {
            upperLevel->nextLevel = NULL;
            if (upperLevel->header.stopNode) upperLevel = NULL;
           }

         RemoveHashedExpression(patternPtr->networkTest);
         rtn_struct(factPatternNode,patternPtr);
        }
      else if (upperLevel->leftNode != NULL)
        {
         /*====================================================*/
         /* Pattern node has another pattern node which must   */
         /* be checked preceding it.  Remove the pattern node, */
         /* but do not detach any nodes above this one.        */
         /*====================================================*/

         patternPtr = upperLevel;
         upperLevel->leftNode->rightNode = upperLevel->rightNode;
         if (upperLevel->rightNode != NULL)
           { upperLevel->rightNode->leftNode = upperLevel->leftNode; }

         RemoveHashedExpression(patternPtr->networkTest);
         rtn_struct(factPatternNode,patternPtr);
         upperLevel = NULL;
        }
      else
        {
         /*====================================================*/
         /* Pattern node has no pattern node preceding it, but */
         /* does have one succeeding it. Remove the pattern    */
         /* node, but do not detach any nodes above this one.  */
         /*====================================================*/

         patternPtr = upperLevel;
         upperLevel = upperLevel->lastLevel;
         if (upperLevel == NULL)
           { FindAndSetDeftemplatePatternNetwork(patternPtr,patternPtr->rightNode); }
         else
           { upperLevel->nextLevel = patternPtr->rightNode; }
         patternPtr->rightNode->leftNode = NULL;

         RemoveHashedExpression(patternPtr->networkTest);
         rtn_struct(factPatternNode,patternPtr);
         upperLevel = NULL;
        }
     }
  }
  
/***********************************************************/
/* FindAndSetDeftemplatePatternNetwork: When a deftemplate */
/*   pattern is detached from the fact pattern network, it */
/*   is not possible to directly detach the link from the  */
/*   deftemplate to the pattern network (it is a one way   */
/*   link). Therefore if the top most pointer to a         */
/*   deftemplates pattern network must be changed, it is   */
/*   necessary to search the list of deftemplates to find  */
/*   the appropriate one to modify.                        */
/***********************************************************/
static VOID FindAndSetDeftemplatePatternNetwork(rootNode,newRootNode)
  struct factPatternNode *rootNode;
  struct factPatternNode *newRootNode;
  {
   struct deftemplate *theDeftemplate;
   struct defmodule *theModule;
   
   /*=======================================================*/
   /* Save the current module since we will be changing it. */
   /*=======================================================*/
   
   SaveCurrentModule();
   
   /*=======================================================*/
   /* Loop through every module looking for the deftemplate */
   /* associated with the specified root node.              */
   /*=======================================================*/
    
   for (theModule = (struct defmodule *) GetNextDefmodule(NULL);
        theModule != NULL;
        theModule = (struct defmodule *) GetNextDefmodule(theModule))
     {
      /*======================================================*/
      /* Set the current module to the module being examined. */
      /*======================================================*/
      
      SetCurrentModule((VOID *) theModule);
      
      /*======================================================*/
      /* Loop through every deftemplate in the current module */
      /* searching for the deftemplate associated with the    */
      /* specified root node.                                 */
      /*======================================================*/
      
      for (theDeftemplate = (struct deftemplate *) GetNextDeftemplate(NULL);
           theDeftemplate != NULL;
           theDeftemplate = (struct deftemplate *) GetNextDeftemplate(theDeftemplate))
        {
         /*===========================================================*/
         /* When the associated deftemplate is found, change its root */
         /* node from the current value to the new value. Restore the */
         /* current module before leaving this routine.               */
         /*===========================================================*/
         
         if (theDeftemplate->patternNetwork == rootNode)
           {
            RestoreCurrentModule();
            theDeftemplate->patternNetwork = newRootNode;
            return;
           }
        }
     }
     
   /*========================================================*/
   /* If the deftemplate wasn't found, then we're presumably */
   /* we're in the the middle of a clear and the deftemplate */
   /* has already been deleted so there's no need to update  */
   /* the links to the fact pattern network.                 */
   /*========================================================*/
   
   RestoreCurrentModule();
  }
              
/***************************************************************/
/* ClearPatternMatches: Clears the fact list of all pointers   */
/*   which point to a specific pattern.  The pointers are used */
/*   to remember which patterns were matched by a fact to      */
/*   make retraction easier.  When a rule is excised, the      */
/*   pointers need to be removed.                              */
/***************************************************************/
static VOID ClearPatternMatches(patternPtr)
  struct factPatternNode *patternPtr;
  {
   struct fact *theFact;
   struct patternMatch *lastMatch, *theMatch;

   /*===========================================*/
   /* Loop through every fact in the fact list. */
   /*===========================================*/

   for (theFact = (struct fact *) GetNextFact(NULL);
        theFact != NULL;
        theFact = (struct fact *) GetNextFact(theFact))
     {
      /*========================================*/
      /* Loop through every match for the fact. */
      /*========================================*/
      
      lastMatch = NULL;
      theMatch = (struct patternMatch *) theFact->list;

      while (theMatch != NULL)
        {
         /*================================================*/
         /* If the match is for the pattern being deleted, */
         /* then remove the match.                         */
         /*================================================*/
         
         if (theMatch->matchingPattern == (struct patternNodeHeader *) patternPtr)
           {
            if (lastMatch == NULL)
              {
               /*=====================================*/
               /* Remove the first match of the fact. */
               /*=====================================*/
               
               theFact->list = (VOID *) theMatch->next;
               rtn_struct(patternMatch,theMatch);
               theMatch = (struct patternMatch *) theFact->list;
              }
            else
             {
               /*===================================*/
               /* Remove a match for the fact which */
               /* follows the first match.          */
               /*===================================*/
               
              lastMatch->next = theMatch->next;
              rtn_struct(patternMatch,theMatch);
              theMatch = lastMatch->next;
             }
           }
           
         /*====================================================*/
         /* If the match is not for the pattern being deleted, */
         /* then move on to the next match for the fact.       */
         /*====================================================*/
         
         else
          {
           lastMatch = theMatch;
           theMatch = theMatch->next;
          }
       }
    }
  }
  
#endif /* (! RUN_TIME) && (! BLOAD_ONLY) */
  
#endif /* DEFTEMPLATE_CONSTRUCT && DEFRULE_CONSTRUCT */