globlpsr.c

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   /* Check for import/export conflicts from the construct definition. */
   /*==================================================================*/
     
#if DEFMODULE_CONSTRUCT
   if (FindImportExportConflict("defglobal",((struct defmodule *) GetCurrentModule()),ValueToString(variableName)))
     {
      ImportExportConflictMessage("defglobal",ValueToString(variableName),NULL,NULL);
      *defglobalError = CLIPS_TRUE;
      return(CLIPS_FALSE);
     }
#endif

   /*==============================*/
   /* The next token must be an =. */
   /*==============================*/

   GetToken(readSource,theToken);
   if (strcmp(theToken->printForm,"=") != 0)
     {
      SyntaxErrorMessage("defglobal");
      *defglobalError = CLIPS_TRUE;
      return(CLIPS_FALSE);
     }

   SavePPBuffer(" ");

   /*======================================================*/
   /* Parse the expression to be assigned to the variable. */
   /*======================================================*/

   assignPtr = ParseAtomOrExpression(readSource,NULL);
   if (assignPtr == NULL)
     {
      *defglobalError = CLIPS_TRUE;
      return(CLIPS_FALSE);
     }

   /*==========================*/
   /* Evaluate the expression. */
   /*==========================*/

   SetEvaluationError(CLIPS_FALSE);
   if (EvaluateExpression(assignPtr,&assignValue))
     {
      ReturnExpression(assignPtr);
      *defglobalError = CLIPS_TRUE;
      return(CLIPS_FALSE);
     }

   SavePPBuffer(")");
   
   /*======================================*/
   /* Add the variable to the global list. */
   /*======================================*/

   AddDefglobal(variableName,&assignValue,assignPtr);
   
   /*==================================================*/
   /* Return TRUE to indicate that the global variable */
   /* definition was successfully parsed.              */
   /*==================================================*/
   
   return(CLIPS_TRUE);
  }

/*********************************************************/
/* AddDefglobal: Adds a defglobal to the current module. */
/*********************************************************/
static VOID AddDefglobal(name,vPtr,ePtr)
  SYMBOL_HN *name;
  DATA_OBJECT_PTR vPtr;
  struct expr *ePtr;
  {
   struct defglobal *defglobalPtr;
   BOOLEAN new = CLIPS_FALSE;
#if DEBUGGING_FUNCTIONS
   int GlobalHadWatch = CLIPS_FALSE;
#endif

   /*========================================================*/
   /* If the defglobal is already defined, then use the old  */
   /* data structure and substitute new values. If it hasn't */
   /* been defined, then create a new data structure.        */
   /*========================================================*/

   defglobalPtr = QFindDefglobal(name);
   if (defglobalPtr == NULL)
     {
      new = CLIPS_TRUE;
      defglobalPtr = get_struct(defglobal);
     }
   else
     {
      DeinstallConstructHeader(&defglobalPtr->header);
#if DEBUGGING_FUNCTIONS
      GlobalHadWatch = defglobalPtr->watch;
#endif
     }

   /*===========================================*/
   /* Remove the old values from the defglobal. */
   /*===========================================*/

   if (new == CLIPS_FALSE)
     {
      ValueDeinstall(&defglobalPtr->current);
      if (defglobalPtr->current.type == MULTIFIELD)
        { ReturnMultifield(defglobalPtr->current.value); }
      
      RemoveHashedExpression(defglobalPtr->initial);
     }

   /*=======================================*/
   /* Copy the new values to the defglobal. */
   /*=======================================*/

   defglobalPtr->current.type = vPtr->type;
   if (vPtr->type != MULTIFIELD) defglobalPtr->current.value = vPtr->value;
   else DuplicateMultifield(&defglobalPtr->current,vPtr);
   ValueInstall(&defglobalPtr->current);

   defglobalPtr->initial = AddHashedExpression(ePtr);
   ReturnExpression(ePtr);
   ChangeToGlobals = CLIPS_TRUE;

   /*=================================*/
   /* Restore the old watch value to  */
   /* the defglobal if redefined.     */
   /*=================================*/
   
#if DEBUGGING_FUNCTIONS
   defglobalPtr->watch = GlobalHadWatch ? CLIPS_TRUE : WatchGlobals;
#endif

   /*======================================*/
   /* Save the name and pretty print form. */
   /*======================================*/
   
   defglobalPtr->header.name = name;
   IncrementSymbolCount(name);

   SavePPBuffer("\n");
   if (GetConserveMemory() == CLIPS_TRUE)
     { defglobalPtr->header.ppForm = NULL; }
   else
     { defglobalPtr->header.ppForm = CopyPPBuffer(); }
     
   defglobalPtr->inScope = CLIPS_TRUE;

   /*=============================================*/
   /* If the defglobal was redefined, we're done. */
   /*=============================================*/

   if (new == CLIPS_FALSE) return;

   /*===================================*/
   /* Copy the defglobal variable name. */
   /*===================================*/

   defglobalPtr->busyCount = 0;
   defglobalPtr->header.whichModule = (struct defmoduleItemHeader *)
                               GetModuleItem(NULL,FindModuleItem("defglobal")->moduleIndex);

   /*=============================================*/
   /* Add the defglobal to the list of defglobals */
   /* for the current module.                     */
   /*=============================================*/
      
   AddConstructToModule(&defglobalPtr->header);
  }
  
/*****************************************************************/
/* ReplaceGlobalVariable: Replaces a global variable found in an */
/*   expression with the appropriate primitive data type which   */
/*   can later be used to retrieve the global variable's value.  */
/*****************************************************************/
globle BOOLEAN ReplaceGlobalVariable(ePtr)
  struct expr *ePtr;
  {
   struct defglobal *theGlobal;
   int count;
   
   /*=================================*/
   /* Search for the global variable. */
   /*=================================*/
   
   theGlobal = (struct defglobal *) 
               FindImportedConstruct("defglobal",NULL,ValueToString(ePtr->value),
                                     &count,CLIPS_TRUE,NULL);
               
   /*=============================================*/
   /* If it wasn't found, print an error message. */
   /*=============================================*/
   
   if (theGlobal == NULL)
     {
      GlobalReferenceErrorMessage(ValueToString(ePtr->value));
      return(CLIPS_FALSE);
     }
     
   /*========================================================*/
   /* The current implementation of the defmodules shouldn't */
   /* allow a construct to be defined which would cause an   */
   /* ambiguous reference, but we'll check for it anyway.    */
   /*========================================================*/
   
   if (count > 1) 
     {
      AmbiguousReferenceErrorMessage("defglobal",ValueToString(ePtr->value));
      return(CLIPS_FALSE);
     }

   /*==============================================*/
   /* Replace the symbolic reference of the global */
   /* variable with a direct pointer reference.    */
   /*==============================================*/
   
   ePtr->type = DEFGLOBAL_PTR;
   ePtr->value = (VOID *) theGlobal;

   return(CLIPS_TRUE);
  }

/*****************************************************************/
/* GlobalReferenceErrorMessage: Prints an error message when a   */
/*   symbolic reference to a global variable cannot be resolved. */
/*****************************************************************/
globle VOID GlobalReferenceErrorMessage(variableName)
  char *variableName;
  {
   PrintErrorID("GLOBLPSR",1,CLIPS_TRUE);
   PrintCLIPS(WERROR,"\nGlobal variable ?*");
   PrintCLIPS(WERROR,variableName);
   PrintCLIPS(WERROR,"* was referenced, but is not defined.\n");
  }
  
#endif /* (! RUN_TIME) && (! BLOAD_ONLY) */

#endif /* DEFGLOBAL_CONSTRUCT */