default.c

clips源代码

      else if (theConstraints->minValue->type == INTEGER)
        { return(EnvAddDouble(theEnv,(double) ValueToLong(theConstraints->minValue->value))); }
      else if (theConstraints->maxValue->type == FLOAT)
        { return(theConstraints->maxValue->value); }
      else if (theConstraints->maxValue->type == INTEGER)
        { return(EnvAddDouble(theEnv,(double) ValueToLong(theConstraints->maxValue->value))); }
     }

   /*======================================*/
   /* Use the standard default value (such */
   /* as nil if symbols are allowed).      */
   /*======================================*/

   return(standardDefault);
  }

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

/**********************************************/
/* ParseDefault: Parses a default value list. */
/**********************************************/
globle struct expr *ParseDefault(
  void *theEnv,
  char *readSource,
  int multifield,
  int dynamic,
  int evalStatic,
  int *noneSpecified,
  int *deriveSpecified,
  int *error)
  {
   struct expr *defaultList = NULL, *lastDefault = NULL;
   struct expr *newItem, *tmpItem;
   struct token theToken;
   DATA_OBJECT theValue;
   CONSTRAINT_RECORD *rv;
   int specialVarCode;

   *noneSpecified = FALSE;
   *deriveSpecified = FALSE;

   SavePPBuffer(theEnv," ");
   GetToken(theEnv,readSource,&theToken);

   /*===================================================*/
   /* Read the items contained in the default attribute */
   /* until a closing right parenthesis is encountered. */
   /*===================================================*/

   while (theToken.type != RPAREN)
     {
      /*========================================*/
      /* Get the next item in the default list. */
      /*========================================*/

      newItem = ParseAtomOrExpression(theEnv,readSource,&theToken);
      if (newItem == NULL)
        {
         ReturnExpression(theEnv,defaultList);
         *error = TRUE;
         return(NULL);
        }

      /*===========================================================*/
      /* Check for invalid variable usage. With the expection of   */
      /* ?NONE for the default attribute, local variables may not  */
      /* be used within the default or default-dynamic attributes. */
      /*===========================================================*/

      if ((newItem->type == SF_VARIABLE) || (newItem->type == MF_VARIABLE))
        {
         if (strcmp(ValueToString(newItem->value),"NONE") == 0)
           { specialVarCode = 0; }
         else if (strcmp(ValueToString(newItem->value),"DERIVE") == 0)
           { specialVarCode = 1; }
         else
           { specialVarCode = -1; }

         if ((dynamic) ||
             (newItem->type == MF_VARIABLE) ||
             (specialVarCode == -1) ||
             ((specialVarCode != -1) && (defaultList != NULL)))
           {
            if (dynamic) SyntaxErrorMessage(theEnv,"default-dynamic attribute");
            else SyntaxErrorMessage(theEnv,"default attribute");
            ReturnExpression(theEnv,newItem);
            ReturnExpression(theEnv,defaultList);
            *error = TRUE;
            return(NULL);
           }

         ReturnExpression(theEnv,newItem);

         /*============================================*/
         /* Check for the closing right parenthesis of */
         /* the default or default dynamic attribute.  */
         /*============================================*/

         GetToken(theEnv,readSource,&theToken);

         if (theToken.type != RPAREN)
           {
            if (dynamic) SyntaxErrorMessage(theEnv,"default-dynamic attribute");
            else SyntaxErrorMessage(theEnv,"default attribute");
            PPBackup(theEnv);
            SavePPBuffer(theEnv," ");
            SavePPBuffer(theEnv,theToken.printForm);
            *error = TRUE;
           }

         if (specialVarCode == 0)
           *noneSpecified = TRUE;
         else
           *deriveSpecified = TRUE;
         return(NULL);
        }

      /*====================================================*/
      /* Look to see if any variables have been used within */
      /* expressions contained within the default list.     */
      /*====================================================*/

      if (ExpressionContainsVariables(newItem,FALSE) == TRUE)
        {
         ReturnExpression(theEnv,defaultList);
         ReturnExpression(theEnv,newItem);
         *error = TRUE;
         if (dynamic) SyntaxErrorMessage(theEnv,"default-dynamic attribute");
         else SyntaxErrorMessage(theEnv,"default attribute");
         return(NULL);
        }

      /*============================================*/
      /* Add the default value to the default list. */
      /*============================================*/

      if (lastDefault == NULL)
        { defaultList = newItem; }
      else
        { lastDefault->nextArg = newItem; }
      lastDefault = newItem;

      /*=======================================*/
      /* Begin parsing the next default value. */
      /*=======================================*/

      SavePPBuffer(theEnv," ");
      GetToken(theEnv,readSource,&theToken);
     }

   /*=====================================*/
   /* Fix up pretty print representation. */
   /*=====================================*/

   PPBackup(theEnv);
   PPBackup(theEnv);
   SavePPBuffer(theEnv,")");

   /*=========================================*/
   /* A single field slot's default attribute */
   /* must contain a single value.            */
   /*=========================================*/

   if (multifield == FALSE)
     {
      if (defaultList == NULL)
        { *error = TRUE; }
      else if (defaultList->nextArg != NULL)
        { *error = TRUE; }
      else
        {
         rv = ExpressionToConstraintRecord(theEnv,defaultList);
         rv->multifieldsAllowed = FALSE;
         if (UnmatchableConstraint(rv)) *error = TRUE;
         RemoveConstraint(theEnv,rv);
        }

      if (*error)
        {
         PrintErrorID(theEnv,"DEFAULT",1,TRUE);
         EnvPrintRouter(theEnv,WERROR,"The default value for a single field slot must be a single field value\n");
         ReturnExpression(theEnv,defaultList);
         return(NULL);
        }
     }

   /*=======================================================*/
   /* If the dynamic-default attribute is not being parsed, */
   /* evaluate the expressions to make the default value.   */
   /*=======================================================*/

   if (dynamic || (! evalStatic) || (defaultList == NULL)) return(defaultList);

   tmpItem = defaultList;
   newItem = defaultList;

   defaultList = NULL;

   while (newItem != NULL)
     {
      SetEvaluationError(theEnv,FALSE);
      if (EvaluateExpression(theEnv,newItem,&theValue)) *error = TRUE;

      if ((theValue.type == MULTIFIELD) &&
          (multifield == FALSE) &&
          (*error == FALSE))
        {
         PrintErrorID(theEnv,"DEFAULT",1,TRUE);
         EnvPrintRouter(theEnv,WERROR,"The default value for a single field slot must be a single field value\n");
         *error = TRUE;
        }

      if (*error)
        {
         ReturnExpression(theEnv,tmpItem);
         ReturnExpression(theEnv,defaultList);
         *error = TRUE;
         return(NULL);
        }

      lastDefault = ConvertValueToExpression(theEnv,&theValue);

      defaultList = AppendExpressions(defaultList,lastDefault);

      newItem = newItem->nextArg;
     }

   ReturnExpression(theEnv,tmpItem);

   /*==========================*/
   /* Return the default list. */
   /*==========================*/

   return(defaultList);
  }

#endif /* (! RUN_TIME) && (! BLOAD_ONLY) */