rulelhs.c

clips源代码

   /*******************************************************/
   /*      "C" Language Integrated Production System      */
   /*                                                     */
   /*             CLIPS Version 6.22  06/15/04            */
   /*                                                     */
   /*             DEFRULE LHS PARSING MODULE              */
   /*******************************************************/

/*************************************************************/
/* Purpose: Coordinates parsing of the LHS conditional       */
/*   elements of a rule.                                     */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*************************************************************/

#define _RULELHS_SOURCE_

#include "setup.h"

#if (! RUN_TIME) && (! BLOAD_ONLY) &&  DEFRULE_CONSTRUCT

#include <stdio.h>
#define _STDIO_INCLUDED_
#include <string.h>

#include "agenda.h"
#include "argacces.h"
#include "constant.h"
#include "constrct.h"
#include "constrnt.h"
#include "cstrnchk.h"
#include "envrnmnt.h"
#include "exprnpsr.h"
#include "memalloc.h"
#include "pattern.h"
#include "reorder.h"
#include "router.h"
#include "ruledef.h"
#include "scanner.h"
#include "symbol.h"

#include "rulelhs.h"

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

   static struct lhsParseNode    *RuleBodyParse(void *,char *,struct token *,char *,int *);
   static void                    DeclarationParse(void *,char *,char *,int *);
   static struct lhsParseNode    *LHSPattern(void *,char *,int,char *,int *,int,
                                             struct token *,char *);
   static struct lhsParseNode    *ConnectedPatternParse(void *,char *,struct token *,int *);
   static struct lhsParseNode    *GroupPatterns(void *,char *,int,char *,int *);
   static struct lhsParseNode    *TestPattern(void *,char *,int *);
   static struct lhsParseNode    *AssignmentParse(void *,char *,SYMBOL_HN *,int *);
   static void                    TagLHSLogicalNodes(struct lhsParseNode *);
   static struct lhsParseNode    *SimplePatternParse(void *,char *,struct token *,int *);
   static void                    ParseSalience(void *,char *,char *,int *);
   static void                    ParseAutoFocus(void *,char *,int *);

/*******************************************************************/
/* ParseRuleLHS: Coordinates all the actions necessary for parsing */
/*   the LHS of a rule including the reordering of pattern         */
/*   conditional elements to conform with the KB Rete topology.    */
/*******************************************************************/
globle struct lhsParseNode *ParseRuleLHS(
  void *theEnv,
  char *readSource,
  struct token *theToken,
  char *ruleName,
  int *error)
  {
   struct lhsParseNode *theLHS;
   int result;
   
   *error = FALSE;

   /*========================================*/
   /* Initialize salience parsing variables. */
   /*========================================*/

   PatternData(theEnv)->GlobalSalience = 0;
   PatternData(theEnv)->GlobalAutoFocus = FALSE;
   PatternData(theEnv)->SalienceExpression = NULL;

   /*============================*/
   /* Set the indentation depth. */
   /*============================*/

   SetIndentDepth(theEnv,3);

   /*=====================================================*/
   /* Get the raw representation for the LHS of the rule. */
   /*=====================================================*/

   theLHS = RuleBodyParse(theEnv,readSource,theToken,ruleName,error);

   if (*error) return(NULL);

   /*====================================================*/
   /* Reorder the raw representation so that it consists */
   /* of at most a single top level OR CE containing one */
   /* or more AND CEs.                                   */
   /*====================================================*/

   theLHS = ReorderPatterns(theEnv,theLHS,&result);

   /*================================*/
   /* Return the LHS representation. */
   /*================================*/

   return(theLHS);
  }

/*********************************************************/
/* RuleBodyParse: Parses the LHS of a rule, but does not */
/*   reorder any of the LHS patterns to conform with the */
/*   KB Rete Topology.                                   */
/*                                                       */
/* <rule-body> ::= [<declaration>]                       */
/*                 <conditional-element>*                */
/*                 =>                                    */
/*********************************************************/
static struct lhsParseNode *RuleBodyParse(
  void *theEnv,
  char *readSource,
  struct token *theToken,
  char *ruleName,
  int *error)
  {
   struct lhsParseNode *theNode, *otherNodes;

   /*=============================*/
   /* Set the error return value. */
   /*=============================*/

   *error = FALSE;

   /*==================================================*/
   /* If we're already at the separator, "=>", between */
   /* the LHS and RHS, then the LHS is empty.          */
   /*==================================================*/

   if ((theToken->type == SYMBOL) ?
       (strcmp(ValueToString(theToken->value),"=>") == 0) : FALSE)
     { return(NULL); }

   /*===========================================*/
   /* Parse the first pattern as a special case */
   /* (the declare statement is allowed).       */
   /*===========================================*/

   theNode = LHSPattern(theEnv,readSource,SYMBOL,"=>",error,TRUE,theToken,ruleName);

   if (*error == TRUE)
     {
      ReturnLHSParseNodes(theEnv,theNode);
      return(NULL);
     }

   PPCRAndIndent(theEnv);

   /*======================================*/
   /* Parse the other patterns in the LHS. */
   /*======================================*/

   otherNodes = GroupPatterns(theEnv,readSource,SYMBOL,"=>",error);

   if (*error == TRUE)
     {
      ReturnLHSParseNodes(theEnv,theNode);
      return(NULL);
     }

   /*================================================*/
   /* Construct the final LHS by combining the first */
   /* pattern with the remaining patterns.           */
   /*================================================*/

   if (theNode == NULL)
     { theNode = otherNodes; }
   else
     { theNode->bottom = otherNodes; }

   /*=======================*/
   /* Return the final LHS. */
   /*=======================*/

   return(theNode);
  }

/********************************************************/
/* DeclarationParse: Parses a defrule declaration.      */
/*                                                      */
/* <declaration> ::= (declare <rule-property>+)         */
/*                                                      */
/* <rule-property> ::= (salience <integer-expression>)  */
/* <rule-property> ::= (auto-focus TRUE | FALSE)        */
/********************************************************/
static void DeclarationParse(
  void *theEnv,
  char *readSource,
  char *ruleName,
  int *error)
  {
   struct token theToken;
   struct expr *packPtr;
   int notDone = TRUE;
   int salienceParsed = FALSE, autoFocusParsed = FALSE;

   /*===========================*/
   /* Next token must be a '('. */
   /*===========================*/

   SavePPBuffer(theEnv," ");

   GetToken(theEnv,readSource,&theToken);
   if (theToken.type != LPAREN)
     {
      SyntaxErrorMessage(theEnv,"declare statement");
      *error = TRUE;
      return;
     }

   /*==========================================*/
   /* Continue parsing until there are no more */
   /* valid rule property declarations.        */
   /*==========================================*/

   while (notDone)
     {
      /*=============================================*/
      /* The name of a rule property must be symbol. */
      /*=============================================*/

      GetToken(theEnv,readSource,&theToken);
      if (theToken.type != SYMBOL)
        {
         SyntaxErrorMessage(theEnv,"declare statement");
         *error = TRUE;
        }

      /*==============================================*/
      /* Parse a salience declaration if encountered. */
      /*==============================================*/

      else if (strcmp(ValueToString(theToken.value),"salience") == 0)
        {
         if (salienceParsed)
           {
            AlreadyParsedErrorMessage(theEnv,"salience declaration",NULL);
            *error = TRUE;
           }
         else
           {
            ParseSalience(theEnv,readSource,ruleName,error);
            salienceParsed = TRUE;
           }
        }

      /*=================================================*/
      /* Parse an auto-focus declaration if encountered. */
      /* A global flag is used to indicate if the        */
      /* auto-focus feature for a rule was parsed.       */
      /*=================================================*/

      else if (strcmp(ValueToString(theToken.value),"auto-focus") == 0)
        {
         if (autoFocusParsed)
           {
            AlreadyParsedErrorMessage(theEnv,"auto-focus declaration",NULL);
            *error = TRUE;
           }
         else
           {
            ParseAutoFocus(theEnv,readSource,error);
            autoFocusParsed = TRUE;
           }
         }

       /*==========================================*/
       /* Otherwise the symbol does not correspond */
       /* to a valid rule property.                */
       /*==========================================*/

       else
        {
         SyntaxErrorMessage(theEnv,"declare statement");
         *error = TRUE;
        }

      /*=====================================*/
      /* Return if an error was encountered. */
      /*=====================================*/

      if (*error)
        {
         ReturnExpression(theEnv,PatternData(theEnv)->SalienceExpression);
         PatternData(theEnv)->SalienceExpression = NULL;
         return;
        }

      /*=======================================*/
      /* Both the salience and auto-focus rule */
      /* properties are closed with a ')'.     */
      /*=======================================*/

      GetToken(theEnv,readSource,&theToken);
      if (theToken.type != RPAREN)
        {
         PPBackup(theEnv);
         SavePPBuffer(theEnv," ");
         SavePPBuffer(theEnv,theToken.printForm);
         ReturnExpression(theEnv,PatternData(theEnv)->SalienceExpression);
         PatternData(theEnv)->SalienceExpression = NULL;
         SyntaxErrorMessage(theEnv,"declare statement");
         *error = TRUE;
         return;
        }

      /*=============================================*/
      /* The declare statement is closed with a ')'. */
      /*=============================================*/

      GetToken(theEnv,readSource,&theToken);
      if (theToken.type == RPAREN) notDone = FALSE;
      else if (theToken.type != LPAREN)
        {
         ReturnExpression(theEnv,PatternData(theEnv)->SalienceExpression);
         PatternData(theEnv)->SalienceExpression = NULL;
         SyntaxErrorMessage(theEnv,"declare statement");
         *error = TRUE;
         return;
        }
      else
        {
         PPBackup(theEnv);
         SavePPBuffer(theEnv," (");
        }
     }

   /*==========================================*/
   /* Return the value of the salience through */
   /* the global variable SalienceExpression.  */
   /*==========================================*/

   packPtr = PackExpression(theEnv,PatternData(theEnv)->SalienceExpression);
   ReturnExpression(theEnv,PatternData(theEnv)->SalienceExpression);
   PatternData(theEnv)->SalienceExpression = packPtr;
   return;
  }

/************************************************************/
/* ParseSalience: Parses the rest of a defrule salience     */
/*   declaration once the salience keyword has been parsed. */
/************************************************************/
static void ParseSalience(
  void *theEnv,
  char *readSource,
  char *ruleName,
  int *error)
  {
   int salience;
   DATA_OBJECT salienceValue;

   /*==============================*/
   /* Get the salience expression. */
   /*==============================*/

   SavePPBuffer(theEnv," ");

   PatternData(theEnv)->SalienceExpression = ParseAtomOrExpression(theEnv,readSource,NULL);
   if (PatternData(theEnv)->SalienceExpression == NULL)
     {
      *error = TRUE;
      return;
     }

   /*============================================================*/
   /* Evaluate the expression and determine if it is an integer. */
   /*============================================================*/

   SetEvaluationError(theEnv,FALSE);
   if (EvaluateExpression(theEnv,PatternData(theEnv)->SalienceExpression,&salienceValue))
     {
      SalienceInformationError(theEnv,"defrule",ruleName);
      *error = TRUE;
      return;
     }

   if (salienceValue.type != INTEGER)
     {
      SalienceNonIntegerError(theEnv);
      *error = TRUE;
      return;