Exemple #1
0
globle int CheckArgumentAgainstRestriction(
  struct expr *theExpression,
  int theRestriction)
  {
   CONSTRAINT_RECORD *cr1, *cr2, *cr3;

   /*=============================================*/
   /* Generate a constraint record for the actual */
   /* argument passed to the function.            */
   /*=============================================*/

   cr1 = ExpressionToConstraintRecord(theExpression);

   /*================================================*/
   /* Generate a constraint record based on the type */
   /* of argument expected by the function.          */
   /*================================================*/

   cr2 = ArgumentTypeToConstraintRecord(theRestriction);

   /*===============================================*/
   /* Intersect the two constraint records and then */
   /* discard them.                                 */
   /*===============================================*/

   cr3 = IntersectConstraints(cr1,cr2);

   RemoveConstraint(cr1);
   RemoveConstraint(cr2);

   /*====================================================*/
   /* If the intersection of the two constraint records  */
   /* is empty, then the argument passed to the function */
   /* doesn't satisfy the restrictions for the argument. */
   /*====================================================*/

   if (UnmatchableConstraint(cr3))
     {
      RemoveConstraint(cr3);
      return(TRUE);
     }

   /*===================================================*/
   /* The argument satisfies the function restrictions. */
   /*===================================================*/

   RemoveConstraint(cr3);
   return(FALSE);
  }
Exemple #2
0
static BOOLEAN CheckForUnmatchableConstraints(
  struct lhsParseNode *theNode,
  int whichCE)
  {
   if (GetStaticConstraintChecking() == FALSE) return(FALSE);

   if (UnmatchableConstraint(theNode->constraints))
     {
      ConstraintConflictMessage((SYMBOL_HN *) theNode->value,whichCE,
                                theNode->index,theNode->slot);
      return(TRUE);
     }

   return(FALSE);
  }
Exemple #3
0
static intBool CheckForUnmatchableConstraints(
  void *theEnv,
  struct lhsParseNode *theNode,
  int whichCE)
  {
   if (EnvGetStaticConstraintChecking(theEnv) == FALSE) return(FALSE);

   if (UnmatchableConstraint(theNode->constraints))
     {
      ConstraintConflictMessage(theEnv,(SYMBOL_HN *) theNode->value,whichCE,
                                theNode->index,theNode->slot);
      return(TRUE);
     }

   return(FALSE);
  }
Exemple #4
0
static BOOLEAN CheckArgumentForConstraintError(
  struct expr *expressionList,
  struct expr *lastOne,
  int i,
  struct FunctionDefinition *theFunction,
  struct lhsParseNode *theLHS)
  {
   int theRestriction;
   CONSTRAINT_RECORD *constraint1, *constraint2, *constraint3, *constraint4;
   struct lhsParseNode *theVariable;
   struct expr *tmpPtr;
   int rv = FALSE;

   /*=============================================================*/
   /* Skip anything that isn't a variable or isn't an argument to */
   /* a user defined function (i.e. deffunctions and generic have */
   /* no constraint information so they aren't checked).          */
   /*=============================================================*/

   if ((expressionList->type != SF_VARIABLE) || (theFunction == NULL))
     { return (rv); }

   /*===========================================*/
   /* Get the restrictions for the argument and */
   /* convert them to a constraint record.      */
   /*===========================================*/

   theRestriction = GetNthRestriction(theFunction,i);
   constraint1 = ArgumentTypeToConstraintRecord(theRestriction);

   /*================================================*/
   /* Look for the constraint record associated with */
   /* binding the variable in the LHS of the rule.   */
   /*================================================*/

   theVariable = FindVariable((SYMBOL_HN *) expressionList->value,theLHS);
   if (theVariable != NULL)
     {
      if (theVariable->type == MF_VARIABLE)
        {
         constraint2 = GetConstraintRecord();
         SetConstraintType(MULTIFIELD,constraint2);
        }
      else if (theVariable->constraints == NULL)
        { constraint2 = GetConstraintRecord(); }
      else
        { constraint2 = CopyConstraintRecord(theVariable->constraints); }
     }
   else
     { constraint2 = NULL; }

   /*================================================*/
   /* Look for the constraint record associated with */
   /* binding the variable on the RHS of the rule.   */
   /*================================================*/

   constraint3 = FindBindConstraints((SYMBOL_HN *) expressionList->value);

   /*====================================================*/
   /* Union the LHS and RHS variable binding constraints */
   /* (the variable must satisfy one or the other).      */
   /*====================================================*/

   constraint3 = UnionConstraints(constraint3,constraint2);

   /*====================================================*/
   /* Intersect the LHS/RHS variable binding constraints */
   /* with the function argument restriction constraints */
   /* (the variable must satisfy both).                  */
   /*====================================================*/

   constraint4 = IntersectConstraints(constraint3,constraint1);

   /*====================================*/
   /* Check for unmatchable constraints. */
   /*====================================*/

   if (UnmatchableConstraint(constraint4) && GetStaticConstraintChecking())
     {
      PrintErrorID("RULECSTR",3,TRUE);
      PrintRouter(WERROR,"Previous variable bindings of ?");
      PrintRouter(WERROR,ValueToString((SYMBOL_HN *) expressionList->value));
      PrintRouter(WERROR," caused the type restrictions");
      PrintRouter(WERROR,"\nfor argument #");
      PrintLongInteger(WERROR,(long int) i);
      PrintRouter(WERROR," of the expression ");
      tmpPtr = lastOne->nextArg;
      lastOne->nextArg = NULL;
      PrintExpression(WERROR,lastOne);
      lastOne->nextArg = tmpPtr;
      PrintRouter(WERROR,"\nfound in the rule's RHS to be violated.\n");

      rv = TRUE;
     }

   /*===========================================*/
   /* Free the temporarily created constraints. */
   /*===========================================*/

   RemoveConstraint(constraint1);
   RemoveConstraint(constraint2);
   RemoveConstraint(constraint3);
   RemoveConstraint(constraint4);

   /*========================================*/
   /* Return TRUE if unmatchable constraints */
   /* were detected, otherwise FALSE.        */
   /*========================================*/

   return(rv);
  }
Exemple #5
0
static BOOLEAN MultifieldCardinalityViolation(
  struct lhsParseNode *theNode)
  {
   struct lhsParseNode *tmpNode;
   struct expr *tmpMax;
   long minFields = 0;
   long maxFields = 0;
   int posInfinity = FALSE;
   CONSTRAINT_RECORD *newConstraint, *tempConstraint;

   /*================================*/
   /* A single field slot can't have */
   /* a cardinality violation.       */
   /*================================*/

   if (theNode->multifieldSlot == FALSE) return(FALSE);

   /*=============================================*/
   /* Determine the minimum and maximum number of */
   /* fields the slot could contain based on the  */
   /* slot constraints found in the pattern.      */
   /*=============================================*/

   for (tmpNode = theNode->bottom;
        tmpNode != NULL;
        tmpNode = tmpNode->right)
     {
      /*====================================================*/
      /* A single field variable increases both the minimum */
      /* and maximum number of fields by one.               */
      /*====================================================*/

      if ((tmpNode->type == SF_VARIABLE) ||
          (tmpNode->type == SF_WILDCARD))
        {
         minFields++;
         maxFields++;
        }

      /*=================================================*/
      /* Otherwise a multifield wildcard or variable has */
      /* been encountered. If it is constrained then use */
      /* minimum and maximum number of fields constraint */
      /* associated with this LHS node.                  */
      /*=================================================*/

      else if (tmpNode->constraints != NULL)
        {
         /*=======================================*/
         /* The lowest minimum of all the min/max */
         /* pairs will be the first in the list.  */
         /*=======================================*/

         if (tmpNode->constraints->minFields->value != NegativeInfinity)
           { minFields += ValueToLong(tmpNode->constraints->minFields->value); }

         /*=========================================*/
         /* The greatest maximum of all the min/max */
         /* pairs will be the last in the list.     */
         /*=========================================*/

         tmpMax = tmpNode->constraints->maxFields;
         while (tmpMax->nextArg != NULL) tmpMax = tmpMax->nextArg;
         if (tmpMax->value == PositiveInfinity)
           { posInfinity = TRUE; }
         else
           { maxFields += ValueToLong(tmpMax->value); }
        }

      /*================================================*/
      /* Otherwise an unconstrained multifield wildcard */
      /* or variable increases the maximum number of    */
      /* fields to positive infinity.                   */
      /*================================================*/

      else
        { posInfinity = TRUE; }
     }

   /*==================================================================*/
   /* Create a constraint record for the cardinality of the sum of the */
   /* cardinalities of the restrictions inside the multifield slot.    */
   /*==================================================================*/

   if (theNode->constraints == NULL) tempConstraint = GetConstraintRecord();
   else tempConstraint = CopyConstraintRecord(theNode->constraints);
   ReturnExpression(tempConstraint->minFields);
   ReturnExpression(tempConstraint->maxFields);
   tempConstraint->minFields = GenConstant(INTEGER,AddLong((long) minFields));
   if (posInfinity) tempConstraint->maxFields = GenConstant(SYMBOL,PositiveInfinity);
   else tempConstraint->maxFields = GenConstant(INTEGER,AddLong((long) maxFields));

   /*================================================================*/
   /* Determine the final cardinality for the multifield slot by     */
   /* intersecting the cardinality sum of the restrictions within    */
   /* the multifield slot with the original cardinality of the slot. */
   /*================================================================*/

   newConstraint = IntersectConstraints(theNode->constraints,tempConstraint);
   if (theNode->derivedConstraints) RemoveConstraint(theNode->constraints);
   RemoveConstraint(tempConstraint);
   theNode->constraints = newConstraint;
   theNode->derivedConstraints = TRUE;

   /*===================================================================*/
   /* Determine if the final cardinality for the slot can be satisfied. */
   /*===================================================================*/

   if (GetStaticConstraintChecking() == FALSE) return(FALSE);
   if (UnmatchableConstraint(newConstraint)) return(TRUE);

   return(FALSE);
  }
Exemple #6
0
globle struct constraintRecord *IntersectConstraints(
  void *theEnv,
  CONSTRAINT_RECORD *c1,
  CONSTRAINT_RECORD *c2)
  {
   struct constraintRecord *rv;
   int c1Changed = FALSE, c2Changed = FALSE;

   /*=================================================*/
   /* If both constraint records are NULL,then create */
   /* a constraint record that allows any value.      */
   /*=================================================*/

   if ((c1 == NULL) && (c2 == NULL))
     {
      rv = GetConstraintRecord(theEnv);
      rv->multifieldsAllowed = TRUE;
      return(rv);
     }

   /*=================================================*/
   /* If one of the constraint records is NULL, then  */
   /* the intersection is the other constraint record */
   /* (a NULL value means no constraints).            */
   /*=================================================*/

   if (c1 == NULL) return(CopyConstraintRecord(theEnv,c2));

   if (c2 == NULL) return(CopyConstraintRecord(theEnv,c1));

   /*=================================*/
   /* Create a new constraint record. */
   /*=================================*/

   rv = GetConstraintRecord(theEnv);

   /*==============================*/
   /* Intersect the allowed types. */
   /*==============================*/

   if ((c1->multifieldsAllowed != c2->multifieldsAllowed) &&
       (c1->singlefieldsAllowed != c2->singlefieldsAllowed))
     {
      rv->anyAllowed = FALSE;
      return(rv);
     }

   if (c1->multifieldsAllowed && c2->multifieldsAllowed)
     { rv->multifieldsAllowed = TRUE; }
   else
     { rv->multifieldsAllowed = FALSE; }

   if (c1->singlefieldsAllowed && c2->singlefieldsAllowed)
     { rv->singlefieldsAllowed = TRUE; }
   else
     { rv->singlefieldsAllowed = FALSE; }

   if (c1->anyAllowed && c2->anyAllowed) rv->anyAllowed = TRUE;
   else
     {
      if (c1->anyAllowed)
        {
         c1Changed = TRUE;
         SetAnyAllowedFlags(c1,FALSE);
        }
      else if (c2->anyAllowed)
        {
         c2Changed = TRUE;
         SetAnyAllowedFlags(c2,FALSE);
        }

      rv->anyAllowed = FALSE;
      rv->symbolsAllowed = (c1->symbolsAllowed && c2->symbolsAllowed);
      rv->stringsAllowed = (c1->stringsAllowed && c2->stringsAllowed);
      rv->floatsAllowed = (c1->floatsAllowed && c2->floatsAllowed);
      rv->integersAllowed = (c1->integersAllowed && c2->integersAllowed);
      rv->instanceNamesAllowed = (c1->instanceNamesAllowed && c2->instanceNamesAllowed);
      rv->instanceAddressesAllowed = (c1->instanceAddressesAllowed && c2->instanceAddressesAllowed);
      rv->externalAddressesAllowed = (c1->externalAddressesAllowed && c2->externalAddressesAllowed);
      rv->voidAllowed = (c1->voidAllowed && c2->voidAllowed);
      rv->multifieldsAllowed = (c1->multifieldsAllowed && c2->multifieldsAllowed);
      rv->factAddressesAllowed = (c1->factAddressesAllowed && c2->factAddressesAllowed);
#if FUZZY_DEFTEMPLATES
      rv->fuzzyValuesAllowed = (c1->fuzzyValuesAllowed && c2->fuzzyValuesAllowed);
#endif

      if (c1Changed) SetAnyAllowedFlags(c1,TRUE);
      if (c2Changed) SetAnyAllowedFlags(c2,TRUE);
     }

   /*=====================================*/
   /* Intersect the allowed-values flags. */
   /*=====================================*/

   if (c1->anyRestriction || c2->anyRestriction) rv->anyRestriction = TRUE;
   else
     {
      rv->anyRestriction = FALSE;
      rv->symbolRestriction = (c1->symbolRestriction || c2->symbolRestriction);
      rv->stringRestriction = (c1->stringRestriction || c2->stringRestriction);
      rv->floatRestriction = (c1->floatRestriction || c2->floatRestriction);
      rv->integerRestriction = (c1->integerRestriction || c2->integerRestriction);
      rv->classRestriction = (c1->classRestriction || c2->classRestriction);
      rv->instanceNameRestriction = (c1->instanceNameRestriction || c2->instanceNameRestriction);
#if FUZZY_DEFTEMPLATES
      rv->fuzzyValueRestriction = (c1->fuzzyValueRestriction || c2->fuzzyValueRestriction);
#endif
     }

   /*==================================================*/
   /* Intersect the allowed values list, allowed class */
   /* list, min and max values, and the range values.  */
   /*==================================================*/

   IntersectAllowedValueExpressions(theEnv,c1,c2,rv);
   IntersectAllowedClassExpressions(theEnv,c1,c2,rv);
   IntersectNumericExpressions(theEnv,c1,c2,rv,TRUE);
   IntersectNumericExpressions(theEnv,c1,c2,rv,FALSE);

   /*==========================================*/
   /* Update the allowed-values flags based on */
   /* the previous intersection for allowed,   */
   /* min and max, and range values.           */
   /*==========================================*/

   UpdateRestrictionFlags(rv);

   /*============================================*/
   /* If multifields are allowed, then intersect */
   /* the constraint record for them.            */
   /*============================================*/

   if (rv->multifieldsAllowed)
     {
      rv->multifield = IntersectConstraints(theEnv,c1->multifield,c2->multifield);
      if (UnmatchableConstraint(rv->multifield))
        { rv->multifieldsAllowed = FALSE; }
     }

   /*========================*/
   /* Return the intersected */
   /* constraint record.     */
   /*========================*/

   return(rv);
  }
Exemple #7
0
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,(char*)" ");
   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,(char*)"default-dynamic attribute");
            else SyntaxErrorMessage(theEnv,(char*)"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,(char*)"default-dynamic attribute");
            else SyntaxErrorMessage(theEnv,(char*)"default attribute");
            PPBackup(theEnv);
            SavePPBuffer(theEnv,(char*)" ");
            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,(char*)"default-dynamic attribute");
         else SyntaxErrorMessage(theEnv,(char*)"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,(char*)" ");
      GetToken(theEnv,readSource,&theToken);
     }

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

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

   /*=========================================*/
   /* 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,(char*)"DEFAULT",1,TRUE);
         EnvPrintRouter(theEnv,WERROR,(char*)"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,(char*)"DEFAULT",1,TRUE);
         EnvPrintRouter(theEnv,WERROR,(char*)"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);
  }
Exemple #8
0
static struct lhsParseNode *CheckExpression(
  void *theEnv,
  struct lhsParseNode *exprPtr,
  struct lhsParseNode *lastOne,
  int whichCE,
  struct symbolHashNode *slotName,
  int theField)
  {
   struct lhsParseNode *rv;
   int i = 1;

   while (exprPtr != NULL)
     {
      /*===============================================================*/
      /* Check that single field variables contained in the expression */
      /* were previously defined in the LHS. Also check to see if the  */
      /* variable has unmatchable constraints.                         */
      /*===============================================================*/

      if (exprPtr->type == SF_VARIABLE)
        {
         if (exprPtr->referringNode == NULL)
           {
            VariableReferenceErrorMessage(theEnv,(SYMBOL_HN *) exprPtr->value,lastOne,
                                          whichCE,slotName,theField);
            return(exprPtr);
           }
         else if ((UnmatchableConstraint(exprPtr->constraints)) &&
                  EnvGetStaticConstraintChecking(theEnv))
           {
            ConstraintReferenceErrorMessage(theEnv,(SYMBOL_HN *) exprPtr->value,lastOne,i,
                                            whichCE,slotName,theField);
            return(exprPtr);
           }
        }

      /*==================================================*/
      /* Check that multifield variables contained in the */
      /* expression were previously defined in the LHS.   */
      /*==================================================*/

      else if ((exprPtr->type == MF_VARIABLE) && (exprPtr->referringNode == NULL))
        {
         VariableReferenceErrorMessage(theEnv,(SYMBOL_HN *) exprPtr->value,lastOne,
                                       whichCE,slotName,theField);
         return(exprPtr);
        }

      /*=====================================================*/
      /* Check that global variables are referenced properly */
      /* (i.e. if you reference a global variable, it must   */
      /* already be defined by a defglobal construct).       */
      /*=====================================================*/

#if DEFGLOBAL_CONSTRUCT
      else if (exprPtr->type == GBL_VARIABLE)
        {
         int count;

         if (FindImportedConstruct(theEnv,"defglobal",NULL,ValueToString(exprPtr->value),
                                   &count,TRUE,NULL) == NULL)
           {
            VariableReferenceErrorMessage(theEnv,(SYMBOL_HN *) exprPtr->value,lastOne,
                                          whichCE,slotName,theField);
            return(exprPtr);
           }
        }
#endif

      /*============================================*/
      /* Recursively check other function calls to  */
      /* insure variables are referenced correctly. */
      /*============================================*/

      else if (((exprPtr->type == FCALL)
#if DEFGENERIC_CONSTRUCT
             || (exprPtr->type == GCALL)
#endif
#if DEFFUNCTION_CONSTRUCT
             || (exprPtr->type == PCALL)
#endif
         ) && (exprPtr->bottom != NULL))
        {
         if ((rv = CheckExpression(theEnv,exprPtr->bottom,exprPtr,whichCE,slotName,theField)) != NULL)
           { return(rv); }
        }

      /*=============================================*/
      /* Move on to the next part of the expression. */
      /*=============================================*/

      i++;
      exprPtr = exprPtr->right;
     }

   /*================================================*/
   /* Return NULL to indicate no error was detected. */
   /*================================================*/

   return(NULL);
  }