factmch.c

clips源代码

   /*******************************************************/
   /*      "C" Language Integrated Production System      */
   /*                                                     */
   /*             CLIPS Version 6.30  10/19/06            */
   /*                                                     */
   /*                 FACT MATCH MODULE                   */
   /*******************************************************/

/*************************************************************/
/* Purpose: Implements the algorithm for pattern matching in */
/*   the fact pattern network.                               */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*                                                           */
/* Revision History:                                         */
/*      6.23: Correction for FalseSymbol/TrueSymbol. DR0859  */
/*                                                           */
/*      6.24: Removed INCREMENTAL_RESET compilation flag.    */
/*                                                           */
/*            Renamed BOOLEAN macro type to intBool.         */
/*                                                           */
/*      6.30: Added support for hashed alpha memories.       */
/*                                                           */
/*************************************************************/

#define _FACTMCH_SOURCE_

#include <stdio.h>
#define _STDIO_INCLUDED_

#include "setup.h"

#if DEFTEMPLATE_CONSTRUCT && DEFRULE_CONSTRUCT

#include "drive.h"
#include "engine.h"
#include "envrnmnt.h"
#include "extnfunc.h"
#include "factgen.h"
#include "factrete.h"
#include "incrrset.h"
#include "memalloc.h"
#include "reteutil.h"
#include "router.h"
#include "sysdep.h"
#include "tmpltdef.h"

#include "factmch.h"

/***************************************/
/* LOCAL INTERNAL FUNCTION DEFINITIONS */
/***************************************/

   static intBool                  EvaluatePatternExpression(void *,struct factPatternNode *,struct expr *);
   static void                     TraceErrorToJoin(void *,struct factPatternNode *,int);
   static void                     ProcessFactAlphaMatch(void *,struct fact *,struct multifieldMarker *,struct factPatternNode *);
   static struct factPatternNode  *GetNextFactPatternNode(void *,int,struct factPatternNode *);
   static int                      SkipFactPatternNode(void *,struct factPatternNode *);
   static void                     ProcessMultifieldNode(void *,
                                                         struct factPatternNode *,
                                                         struct multifieldMarker *,
                                                         struct multifieldMarker *,int);
   static void                     PatternNetErrorMessage(void *,struct factPatternNode *);

/*************************************************************************/
/* FactPatternMatch: Implements the core loop for fact pattern matching. */
/*************************************************************************/
globle void FactPatternMatch(
  void *theEnv,
  struct fact *theFact,
  struct factPatternNode *patternPtr,
  int offset,
  struct multifieldMarker *markers,
  struct multifieldMarker *endMark)
  {
   int theSlotField;
   int offsetSlot;
   DATA_OBJECT theResult;
   struct factPatternNode *tempPtr;
   
   /*=========================================================*/
   /* If there's nothing left in the pattern network to match */
   /* against, then the current traversal of the pattern      */
   /* network needs to back up.                               */
   /*=========================================================*/

   if (patternPtr == NULL) return;

   /*=======================================================*/
   /* The offsetSlot variable indicates the current offset  */
   /* within the multifield slot being pattern matched.     */
   /* (Recall that a multifield wildcard or variable        */
   /* recursively iterates through all possible  bindings.) */
   /* Once a new slot starts being pattern matched, the     */
   /* offset is reset to zero.                              */
   /*=======================================================*/

   offsetSlot = patternPtr->whichSlot;

   /*================================================*/
   /* Set up some global parameters for use by the   */
   /* Rete access functions and general convenience. */
   /*================================================*/

   FactData(theEnv)->CurrentPatternFact = theFact;
   FactData(theEnv)->CurrentPatternMarks = markers;

   /*============================================*/
   /* Loop through each node in pattern network. */
   /*============================================*/

   while (patternPtr != NULL)
     {
      /*=============================================================*/
      /* Determine the position of the field we're going to pattern  */
      /* match. If this routine has been entered recursively because */
      /* of multifield wildcards or variables, then add in the       */
      /* additional offset caused by the values which match these    */
      /* multifields. This offset may be negative (if for example a  */
      /* a multifield matched a zero length value).                  */
      /*=============================================================*/

      theSlotField = patternPtr->whichField;
      if (offsetSlot == patternPtr->whichSlot)
        { theSlotField += offset; }

      /*===================================*/
      /* Determine if we want to skip this */
      /* node during an incremental reset. */
      /*===================================*/

      if (SkipFactPatternNode(theEnv,patternPtr))
        { patternPtr = GetNextFactPatternNode(theEnv,TRUE,patternPtr); }

      /*=========================================================*/
      /* If this is a single field pattern node, then determine  */
      /* if the constraints for the node have been satisfied for */
      /* the current field in the slot being examined.           */
      /*=========================================================*/

      else if (patternPtr->header.singlefieldNode)
        {
         /*==================================================*/
         /* If we're at the last slot in the pattern, make   */
         /* sure the number of fields in the fact correspond */
         /* to the number of fields required by the pattern  */
         /* based on the binding of multifield variables.    */
         /*==================================================*/

         int skipit = FALSE;
         if (patternPtr->header.endSlot &&
             ((FactData(theEnv)->CurrentPatternMarks == NULL) ?
              FALSE :
              (FactData(theEnv)->CurrentPatternMarks->where.whichSlotNumber == patternPtr->whichSlot)) &&
             (FactData(theEnv)->CurrentPatternFact->theProposition.theFields
                  [patternPtr->whichSlot].type == MULTIFIELD))
           {
            if ((patternPtr->leaveFields + theSlotField) != (int)
               ((struct multifield *) FactData(theEnv)->CurrentPatternFact->theProposition.theFields
                                      [patternPtr->whichSlot].value)->multifieldLength)
              { skipit = TRUE; }
           }

         if (skipit)
           { patternPtr = GetNextFactPatternNode(theEnv,TRUE,patternPtr); }
         else

         if (patternPtr->header.selector)
           {
            if (EvaluatePatternExpression(theEnv,patternPtr,patternPtr->networkTest->nextArg))
              {
               EvaluateExpression(theEnv,patternPtr->networkTest,&theResult);
            
               tempPtr = FindHashedPatternNode(theEnv,patternPtr,theResult.type,theResult.value);
              }
            else
              { tempPtr = NULL; }
              
            if (tempPtr != NULL)
              {
               if (tempPtr->header.stopNode)
                 { ProcessFactAlphaMatch(theEnv,theFact,markers,tempPtr); }
               
               patternPtr = GetNextFactPatternNode(theEnv,FALSE,tempPtr);
              }
            else
              { patternPtr = GetNextFactPatternNode(theEnv,TRUE,patternPtr); }
           }
         
         /*=============================================*/
         /* If the constraints are satisified, then ... */
         /*=============================================*/

         else if (EvaluatePatternExpression(theEnv,patternPtr,patternPtr->networkTest))
           {
            /*=======================================================*/
            /* If a leaf pattern node has been successfully reached, */
            /* then the pattern has been satisified. Generate an     */
            /* alpha match to store in the pattern node.             */
            /*=======================================================*/

            if (patternPtr->header.stopNode)
              { ProcessFactAlphaMatch(theEnv,theFact,markers,patternPtr); }

            /*===================================*/
            /* Move on to the next pattern node. */
            /*===================================*/

            patternPtr = GetNextFactPatternNode(theEnv,FALSE,patternPtr);
           }

         /*==============================================*/
         /* Otherwise, move on to the next pattern node. */
         /*==============================================*/

         else
           { patternPtr = GetNextFactPatternNode(theEnv,TRUE,patternPtr); }
        }

      /*======================================================*/
      /* If this is a multifield pattern node, then determine */
      /* if the constraints for the node have been satisfied  */
      /* for the current field in the slot being examined.    */
      /*======================================================*/

      else if (patternPtr->header.multifieldNode)
        {
         /*========================================================*/
         /* Determine if the multifield pattern node's constraints */
         /* are satisfied. If we've traversed to a different slot  */
         /* than the one we started this routine with, then the    */
         /* offset into the slot is reset to zero.                 */
         /*========================================================*/

         if (offsetSlot == patternPtr->whichSlot)
           { ProcessMultifieldNode(theEnv,patternPtr,markers,endMark,offset); }
         else
           { ProcessMultifieldNode(theEnv,patternPtr,markers,endMark,0); }

         /*===================================================*/
         /* Move on to the next pattern node. Since the lower */
         /* branches of the pattern network have already been */
         /* recursively processed by ProcessMultifieldNode,   */
         /* we get the next pattern node by treating this     */
         /* multifield pattern node as if it were a single    */
         /* field pattern node that failed its constraint.    */
         /*===================================================*/

         patternPtr = GetNextFactPatternNode(theEnv,TRUE,patternPtr);
        }
     }
  }

/**************************************************************/
/* ProcessMultifieldNode: Handles recursive pattern matching  */
/*  when a multifield wildcard or variable is encountered as  */
/*  a slot constraint. The pattern matching routine is called */
/*  iteratively for each possible binding of the multifield   */
/*  wildcard or variable.                                     */
/**************************************************************/
static void ProcessMultifieldNode(
  void *theEnv,
  struct factPatternNode *thePattern,
  struct multifieldMarker *markers,
  struct multifieldMarker *endMark,
  int offset)
  {
   struct multifieldMarker *newMark, *oldMark;
   int repeatCount;
   struct multifield *theSlotValue;
   DATA_OBJECT theResult;
   struct factPatternNode *tempPtr;
   intBool success;

   /*========================================*/
   /* Get a pointer to the slot value of the */
   /* multifield slot being pattern matched. */
   /*========================================*/

   theSlotValue = (struct multifield *)
     FactData(theEnv)->CurrentPatternFact->theProposition.theFields[thePattern->whichSlot].value;

   /*===============================================*/
   /* Save the value of the markers already stored. */
   /*===============================================*/