Ejemplo n.º 1
0
globle struct expr *GetRHSPattern(
  char *readSource,
  struct token *tempToken,
  int *error,
  int constantsOnly,
  int readFirstParen,
  int checkFirstParen,
  int endType)
  {
   struct expr *lastOne = NULL;
   struct expr *nextOne, *firstOne, *argHead = NULL;
   int printError, count;
   struct deftemplate *theDeftemplate;
   struct symbolHashNode *templateName;

   /*=================================================*/
   /* Get the opening parenthesis of the RHS pattern. */
   /*=================================================*/

   *error = FALSE;

   if (readFirstParen) GetToken(readSource,tempToken);

   if (checkFirstParen)
     {
      if (tempToken->type == endType) return(NULL);

      if (tempToken->type != LPAREN)
        {
         SyntaxErrorMessage("RHS patterns");
         *error = TRUE;
         return(NULL);
        }
     }

   /*======================================================*/
   /* The first field of an asserted fact must be a symbol */
   /* (but not = or : which have special significance).    */
   /*======================================================*/

   GetToken(readSource,tempToken);
   if (tempToken->type != SYMBOL)
     {
      SyntaxErrorMessage("first field of a RHS pattern");
      *error = TRUE;
      return(NULL);
     }
   else if ((strcmp(ValueToString(tempToken->value),"=") == 0) ||
            (strcmp(ValueToString(tempToken->value),":") == 0))
     {
      SyntaxErrorMessage("first field of a RHS pattern");
      *error = TRUE;
      return(NULL);
     }

   /*=========================================================*/
   /* Check to see if the relation name is a reserved symbol. */
   /*=========================================================*/

   templateName = (struct symbolHashNode *) tempToken->value;

   if (ReservedPatternSymbol(ValueToString(templateName),NULL))
     {
      ReservedPatternSymbolErrorMsg(ValueToString(templateName),"a relation name");
      *error = TRUE;
      return(NULL);
     }

   /*============================================================*/
   /* A module separator in the name is illegal in this context. */
   /*============================================================*/

   if (FindModuleSeparator(ValueToString(templateName)))
     {
      IllegalModuleSpecifierMessage();

      *error = TRUE;
      return(NULL);
     }

   /*=============================================================*/
   /* Determine if there is an associated deftemplate. If so, let */
   /* the deftemplate parsing functions parse the RHS pattern and */
   /* then return the fact pattern that was parsed.               */
   /*=============================================================*/

   theDeftemplate = (struct deftemplate *)
                    FindImportedConstruct("deftemplate",NULL,ValueToString(templateName),
                                          &count,TRUE,NULL);

   if (count > 1)
     {
      AmbiguousReferenceErrorMessage("deftemplate",ValueToString(templateName));
      *error = TRUE;
      return(NULL);
     }

   /*======================================================*/
   /* If no deftemplate exists with the specified relation */
   /* name, then create an implied deftemplate.            */
   /*======================================================*/

   if (theDeftemplate == NULL)
#if (! BLOAD_ONLY) && (! RUN_TIME)
     {
#if BLOAD || BLOAD_AND_BSAVE
      if ((Bloaded()) && (! CheckSyntaxMode))
        {
         NoSuchTemplateError(ValueToString(templateName));
         *error = TRUE;
         return(NULL);
        }
#endif
#if DEFMODULE_CONSTRUCT
      if (FindImportExportConflict("deftemplate",((struct defmodule *) GetCurrentModule()),ValueToString(templateName)))
        {
         ImportExportConflictMessage("implied deftemplate",ValueToString(templateName),NULL,NULL);
         *error = TRUE;
         return(NULL);
        }
#endif
      if (! CheckSyntaxMode)
        { theDeftemplate = CreateImpliedDeftemplate((SYMBOL_HN *) templateName,TRUE); }
     }
#else
    {
     NoSuchTemplateError(ValueToString(templateName));
     *error = TRUE;
     return(NULL);
    }
#endif

   /*=========================================*/
   /* If an explicit deftemplate exists, then */
   /* parse the fact as a deftemplate fact.   */
   /*=========================================*/

   if ((theDeftemplate != NULL) && (theDeftemplate->implied == FALSE))
     {
      firstOne = GenConstant(DEFTEMPLATE_PTR,theDeftemplate);
      firstOne->nextArg = ParseAssertTemplate(readSource,tempToken,
                                              error,endType,
                                              constantsOnly,theDeftemplate);
      if (*error)
        {
         ReturnExpression(firstOne);
         firstOne = NULL;
        }

      return(firstOne);
     }

   /*========================================*/
   /* Parse the fact as an ordered RHS fact. */
   /*========================================*/

   firstOne = GenConstant(DEFTEMPLATE_PTR,theDeftemplate);

#if (! RUN_TIME) && (! BLOAD_ONLY)
   SavePPBuffer(" ");
#endif

   while ((nextOne = GetAssertArgument(readSource,tempToken,
                                        error,endType,constantsOnly,&printError)) != NULL)
     {
      if (argHead == NULL) argHead = nextOne;
      else lastOne->nextArg = nextOne;
      lastOne = nextOne;
#if (! RUN_TIME) && (! BLOAD_ONLY)
      SavePPBuffer(" ");
#endif
     }

   /*===========================================================*/
   /* If an error occurred, set the error flag and return NULL. */
   /*===========================================================*/

   if (*error)
     {
      if (printError) SyntaxErrorMessage("RHS patterns");
      ReturnExpression(firstOne);
      ReturnExpression(argHead);
      return(NULL);
     }

   /*=====================================*/
   /* Fix the pretty print representation */
   /* of the RHS ordered fact.            */
   /*=====================================*/

#if (! RUN_TIME) && (! BLOAD_ONLY)
   PPBackup();
   PPBackup();
   SavePPBuffer(tempToken->printForm);
#endif

   /*==========================================================*/
   /* Ordered fact assertions are processed by stuffing all of */
   /* the fact's proposition (except the relation name) into a */
   /* single multifield slot.                                  */
   /*==========================================================*/

   firstOne->nextArg = GenConstant(FACT_STORE_MULTIFIELD,AddBitMap("\0",1));
   firstOne->nextArg->argList = argHead;

   /*==============================*/
   /* Return the RHS ordered fact. */
   /*==============================*/

   return(firstOne);
  }
Ejemplo n.º 2
0
static struct expr *ParseAssertSlotValues(
  char *inputSource,
  struct token *tempToken,
  struct templateSlot *slotPtr,
  int *error,
  int constantsOnly)
  {
   struct expr *nextSlot;
   struct expr *newField, *valueList, *lastValue;
   int printError;

   /*=============================*/
   /* Handle a single field slot. */
   /*=============================*/

   if (slotPtr->multislot == FALSE)
     {
      /*=====================*/
      /* Get the slot value. */
      /*=====================*/

      SavePPBuffer(" ");

      newField = GetAssertArgument(inputSource,tempToken,
                                   error,RPAREN,constantsOnly,&printError);
      if (*error)
        {
         if (printError) SyntaxErrorMessage("deftemplate pattern");
         return(NULL);
        }

      /*=================================================*/
      /* A single field slot value must contain a value. */
      /* Only a multifield slot can be empty.            */
      /*=================================================*/

      if (newField == NULL)
       {
        *error = TRUE;
        SingleFieldSlotCardinalityError(slotPtr->slotName->contents);
        return(NULL);
       }

      /*==============================================*/
      /* A function returning a multifield value can  */
      /* not be called to get the value for the slot. */
      /*==============================================*/

      if ((newField->type == FCALL) ? (ExpressionFunctionType(newField) == 'm') :
                                      (newField->type == MF_VARIABLE))
       {
        *error = TRUE;
        SingleFieldSlotCardinalityError(slotPtr->slotName->contents);
        ReturnExpression(newField);
        return(NULL);
       }

      /*============================*/
      /* Move on to the next token. */
      /*============================*/

      GetToken(inputSource,tempToken);
     }

   /*========================================*/
   /* Handle a multifield slot. Build a list */
   /* of the values stored in the slot.      */
   /*========================================*/

   else
     {
      SavePPBuffer(" ");
      valueList = GetAssertArgument(inputSource,tempToken,
                                     error,RPAREN,constantsOnly,&printError);
      if (*error)
        {
         if (printError) SyntaxErrorMessage("deftemplate pattern");
         return(NULL);
        }

      if (valueList == NULL)
        {
         PPBackup();
         PPBackup();
         SavePPBuffer(")");
        }

      lastValue = valueList;

      while (lastValue != NULL) /* (tempToken->type != RPAREN) */
        {
         if (tempToken->type == RPAREN)
           { SavePPBuffer(" "); }
         else
           {
            /* PPBackup(); */
            SavePPBuffer(" ");
            /* SavePPBuffer(tempToken->printForm); */
           }

         newField = GetAssertArgument(inputSource,tempToken,error,RPAREN,constantsOnly,&printError);
         if (*error)
           {
            if (printError) SyntaxErrorMessage("deftemplate pattern");
            ReturnExpression(valueList);
            return(NULL);
           }

         if (newField == NULL)
           {
            PPBackup();
            PPBackup();
            SavePPBuffer(")");
           }

         lastValue->nextArg = newField;
         lastValue = newField;
        }

      newField = valueList;
     }

   /*==========================================================*/
   /* Slot definition must be closed with a right parenthesis. */
   /*==========================================================*/

   if (tempToken->type != RPAREN)
     {
      SingleFieldSlotCardinalityError(slotPtr->slotName->contents);
      *error = TRUE;
      ReturnExpression(newField);
      return(NULL);
     }

   /*=========================================================*/
   /* Build and return a structure describing the slot value. */
   /*=========================================================*/

   nextSlot = GenConstant(SYMBOL,slotPtr->slotName);
   nextSlot->argList = newField;

   return(nextSlot);
  }
Ejemplo n.º 3
0
static struct expr *ModAndDupParse(
  void *theEnv,
  struct expr *top,
  char *logicalName,
  char *name)
  {
   int error = FALSE;
   struct token theToken;
   struct expr *nextOne, *tempSlot;
   struct expr *newField, *firstField, *lastField;
   int printError;
   short done;

   /*==================================================================*/
   /* Parse the fact-address or index to the modify/duplicate command. */
   /*==================================================================*/

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

   if ((theToken.type == SF_VARIABLE) || (theToken.type == GBL_VARIABLE))
     { nextOne = GenConstant(theEnv,theToken.type,theToken.value); }
   else if (theToken.type == INTEGER)
     {
      if (! TopLevelCommand(theEnv))
        {
         PrintErrorID(theEnv,"TMPLTFUN",1,TRUE);
         EnvPrintRouter(theEnv,WERROR,"Fact-indexes can only be used by ");
         EnvPrintRouter(theEnv,WERROR,name);
         EnvPrintRouter(theEnv,WERROR," as a top level command.\n");
         ReturnExpression(theEnv,top);
         return(NULL);
        }

      nextOne = GenConstant(theEnv,INTEGER,theToken.value);
     }
   else
     {
      ExpectedTypeError2(theEnv,name,1);
      ReturnExpression(theEnv,top);
      return(NULL);
     }

   nextOne->nextArg = NULL;
   nextOne->argList = NULL;
   top->argList = nextOne;
   nextOne = top->argList;

   /*=======================================================*/
   /* Parse the remaining modify/duplicate slot specifiers. */
   /*=======================================================*/

   GetToken(theEnv,logicalName,&theToken);
   while (theToken.type != RPAREN)
     {
      PPBackup(theEnv);
      SavePPBuffer(theEnv," ");
      SavePPBuffer(theEnv,theToken.printForm);

      /*=================================================*/
      /* Slot definition begins with a left parenthesis. */
      /*=================================================*/

      if (theToken.type != LPAREN)
        {
         SyntaxErrorMessage(theEnv,"duplicate/modify function");
         ReturnExpression(theEnv,top);
         return(NULL);
        }

      /*=================================*/
      /* The slot name must be a symbol. */
      /*=================================*/

      GetToken(theEnv,logicalName,&theToken);
      if (theToken.type != SYMBOL)
        {
         SyntaxErrorMessage(theEnv,"duplicate/modify function");
         ReturnExpression(theEnv,top);
         return(NULL);
        }

      /*=================================*/
      /* Check for duplicate slot names. */
      /*=================================*/

      for (tempSlot = top->argList->nextArg;
           tempSlot != NULL;
           tempSlot = tempSlot->nextArg)
        {
         if (tempSlot->value == theToken.value)
           {
            AlreadyParsedErrorMessage(theEnv,"slot ",ValueToString(theToken.value));
            ReturnExpression(theEnv,top);
            return(NULL);
           }
        }

      /*=========================================*/
      /* Add the slot name to the list of slots. */
      /*=========================================*/

      nextOne->nextArg = GenConstant(theEnv,SYMBOL,theToken.value);
      nextOne = nextOne->nextArg;

      /*====================================================*/
      /* Get the values to be stored in the specified slot. */
      /*====================================================*/

      firstField = NULL;
      lastField = NULL;
      done = FALSE;
      while (! done)
        {
         SavePPBuffer(theEnv," ");
         newField = GetAssertArgument(theEnv,logicalName,&theToken,&error,
                                      RPAREN,FALSE,&printError);

         if (error)
           {
            if (printError) SyntaxErrorMessage(theEnv,"deftemplate pattern");
            ReturnExpression(theEnv,top);
            return(NULL);
           }

         if (newField == NULL)
           { done = TRUE; }

         if (lastField == NULL)
           { firstField = newField; }
         else
           { lastField->nextArg = newField; }
         lastField = newField;
        }

      /*================================================*/
      /* Slot definition ends with a right parenthesis. */
      /*================================================*/

      if (theToken.type != RPAREN)
        {
         SyntaxErrorMessage(theEnv,"duplicate/modify function");
         ReturnExpression(theEnv,top);
         ReturnExpression(theEnv,firstField);
         return(NULL);
        }
      else
        {
         PPBackup(theEnv);
         PPBackup(theEnv);
         SavePPBuffer(theEnv,")");
        }

      nextOne->argList = firstField;

      GetToken(theEnv,logicalName,&theToken);
     }

   /*================================================*/
   /* Return the parsed modify/duplicate expression. */
   /*================================================*/

   return(top);
  }
Ejemplo n.º 4
0
globle struct expr *GetRHSPattern(
  char *readSource,
  struct token *tempToken,
  int *error,
  int constantsOnly,
  int readFirstParen,
  int checkFirstParen,
  int endType)
  {
   struct expr *lastOne = NULL;
   struct expr *nextOne, *firstOne, *argHead = NULL;
   int printError, count;
   struct deftemplate *theDeftemplate;
   struct symbolHashNode *templateName;

   /*=================================================*/
   /* Get the opening parenthesis of the RHS pattern. */
   /*=================================================*/

   *error = FALSE;

   if (readFirstParen) GetToken(readSource,tempToken);

   if (checkFirstParen)
     {
      if (tempToken->type == endType) return(NULL);

      if (tempToken->type != LPAREN)
        {
         SyntaxErrorMessage("RHS patterns");
         *error = TRUE;
         return(NULL);
        }
     }

   /*======================================================*/
   /* The first field of an asserted fact must be a symbol */
   /* (but not = or : which have special significance).    */
   /*======================================================*/

   GetToken(readSource,tempToken);
   if (tempToken->type != SYMBOL)
     {
      SyntaxErrorMessage("first field of a RHS pattern");
      *error = TRUE;
      return(NULL);
     }
   else if ((strcmp(ValueToString(tempToken->value),"=") == 0) ||
            (strcmp(ValueToString(tempToken->value),":") == 0))
     {
      SyntaxErrorMessage("first field of a RHS pattern");
      *error = TRUE;
      return(NULL);
     }

   /*=========================================================*/
   /* Check to see if the relation name is a reserved symbol. */
   /*=========================================================*/

   templateName = (struct symbolHashNode *) tempToken->value;

   if (ReservedPatternSymbol(ValueToString(templateName),NULL))
     {
      ReservedPatternSymbolErrorMsg(ValueToString(templateName),"a relation name");
      *error = TRUE;
      return(NULL);
     }

   /*============================================================*/
   /* A module separator in the name is illegal in this context. */
   /*============================================================*/

   if (FindModuleSeparator(ValueToString(templateName)))
     {
      IllegalModuleSpecifierMessage();

      *error = TRUE;
      return(NULL);
     }

   /*=============================================================*/
   /* Determine if there is an associated deftemplate. If so, let */
   /* the deftemplate parsing functions parse the RHS pattern and */
   /* then return the fact pattern that was parsed.               */
   /*=============================================================*/

   theDeftemplate = (struct deftemplate *)
                    FindImportedConstruct("deftemplate",NULL,ValueToString(templateName),
                                          &count,TRUE,NULL);

   if (count > 1)
     {
      AmbiguousReferenceErrorMessage("deftemplate",ValueToString(templateName));
      *error = TRUE;
      return(NULL);
     }

   /*======================================================*/
   /* If no deftemplate exists with the specified relation */
   /* name, then create an implied deftemplate.            */
   /*======================================================*/

   if (theDeftemplate == NULL)
#if (! BLOAD_ONLY) && (! RUN_TIME)
     {
#if BLOAD || BLOAD_AND_BSAVE
      if ((Bloaded()) && (! CheckSyntaxMode))
        {
         NoSuchTemplateError(ValueToString(templateName));
         *error = TRUE;
         return(NULL);
        }
#endif
#if DEFMODULE_CONSTRUCT
      if (FindImportExportConflict("deftemplate",((struct defmodule *) GetCurrentModule()),ValueToString(templateName)))
        {
         ImportExportConflictMessage("implied deftemplate",ValueToString(templateName),NULL,NULL);
         *error = TRUE;
         return(NULL);
        }
#endif
      if (! CheckSyntaxMode)
        { theDeftemplate = CreateImpliedDeftemplate((SYMBOL_HN *) templateName,TRUE); }
     }
#else
    {
     NoSuchTemplateError(ValueToString(templateName));
     *error = TRUE;
     return(NULL);
    }
#endif

   /*=========================================*/
   /* If an explicit deftemplate exists, then */
   /* parse the fact as a deftemplate fact.   */
   /*=========================================*/

   if ((theDeftemplate != NULL) && (theDeftemplate->implied == FALSE))
     {
      firstOne = GenConstant(DEFTEMPLATE_PTR,theDeftemplate);
#if FUZZY_DEFTEMPLATES 
      if (theDeftemplate->fuzzyTemplate != NULL)
         firstOne->nextArg = ParseAssertFuzzyFact(readSource,tempToken,
                                              error,endType,
                                              constantsOnly,theDeftemplate,
                                              TRUE);
      else
#endif

      firstOne->nextArg = ParseAssertTemplate(readSource,tempToken,
                                              error,endType,
                                              constantsOnly,theDeftemplate);
      if (*error)
        {
         ReturnExpression(firstOne);
         firstOne = NULL;
        }

#if CERTAINTY_FACTORS 
      else
        {
          /* if certaintly factors allowed then the next item after a fact
             specifier COULD be a certainty factor spec --- CF x.xxx
          */
          SavePPBuffer(" ");
          GetToken(readSource,tempToken);
          if ((tempToken->type == SYMBOL) &&
              ((strcmp(ValueToString(tempToken->value),"CF") == 0) ||
               (strcmp(ValueToString(tempToken->value),"cf") == 0))
             )
            {
              struct expr *CFexpr;
              /* expecting a certainty factor (float) expression */
              /* tokenToFloatExpression expect 1st token already read */
              SavePPBuffer(" ");
              GetToken(readSource,tempToken);
              CFexpr = tokenToFloatExpression(readSource,tempToken,error,constantsOnly);

              if (*error)
                {
                  ReturnExpression(firstOne);
                  return( NULL );
                }

              if (CFexpr->type == FLOAT) /* if constant -- check range */
                {
                  double cfval = ValueToDouble(CFexpr->value);
                  if (cfval > 1.0 || cfval < 0.0)
                    {
                      *error = TRUE;
                      ReturnExpression(CFexpr);
                      cfRangeError();
                      ReturnExpression(firstOne);
                      return( NULL );
                    }
                }

             /* store the CF expression in the argList of the DEFTEMPLATE_PTR expr */
             firstOne->argList = CFexpr;
            }
          else
            {
              /* Do an 'UnGetToken' function here to undo the lookahead for a CF.
                 Also need to PPBackup over the space added before reading the
                 potential CF expression -- UnGetToken does one PPBackup over the
                 token which was added to the PP Buffer
              */
              UnGetToken(tempToken);
              PPBackup();
            }
        }
#endif

      return(firstOne);
     }


   /*========================================*/
   /* Parse the fact as an ordered RHS fact. */
   /*========================================*/

   firstOne = GenConstant(DEFTEMPLATE_PTR,theDeftemplate);

#if FUZZY_DEFTEMPLATES
   /*=============================================*/
   /* Fuzzy facts parsed differently              */
   /*=============================================*/
   if (theDeftemplate->fuzzyTemplate != NULL)
     {
       firstOne->nextArg = ParseAssertFuzzyFact(readSource,tempToken,
                                                error,endType,
                                                constantsOnly,theDeftemplate,
                                                TRUE);
       if (*error)
         {
          ReturnExpression(firstOne);
          return(NULL);
         }
     }
   else
     { /*   --- matches } below with FUZZY_DEFTEMPLATES */

#endif   /* FUZZY_DEFTEMPLATES */


#if (! RUN_TIME) && (! BLOAD_ONLY)
   SavePPBuffer(" ");
#endif

   while ((nextOne = GetAssertArgument(readSource,tempToken,
                                        error,endType,constantsOnly,&printError)) != NULL)
     {
      if (argHead == NULL) argHead = nextOne;
      else lastOne->nextArg = nextOne;
      lastOne = nextOne;
#if (! RUN_TIME) && (! BLOAD_ONLY)
      SavePPBuffer(" ");
#endif
     }

   /*===========================================================*/
   /* If an error occurred, set the error flag and return NULL. */
   /*===========================================================*/

   if (*error)
     {
      if (printError) SyntaxErrorMessage("RHS patterns");
      ReturnExpression(firstOne);
      ReturnExpression(argHead);
      return(NULL);
     }

   /*=====================================*/
   /* Fix the pretty print representation */
   /* of the RHS ordered fact.            */
   /*=====================================*/

#if (! RUN_TIME) && (! BLOAD_ONLY)
   PPBackup();
   PPBackup();
   SavePPBuffer(tempToken->printForm);
#endif

   /*==========================================================*/
   /* Ordered fact assertions are processed by stuffing all of */
   /* the fact's proposition (except the relation name) into a */
   /* single multifield slot.                                  */
   /*==========================================================*/

   firstOne->nextArg = GenConstant(FACT_STORE_MULTIFIELD,AddBitMap("\0",1));
   firstOne->nextArg->argList = argHead;

#if FUZZY_DEFTEMPLATES 
     }  /*    --- matches else { above with FUZZY_DEFTEMPLATES */
#endif

#if CERTAINTY_FACTORS 
   /* if certaintly factors allowed then the next item after a fact
          specifier could be a certainty factor spec --- CF x.xxx
   */
#if (! RUN_TIME) && (! BLOAD_ONLY)
   SavePPBuffer(" ");
#endif
   GetToken(readSource,tempToken);
   if ((tempToken->type == SYMBOL) &&
           ((strcmp(ValueToString(tempToken->value),"CF") == 0) ||
                (strcmp(ValueToString(tempToken->value),"cf") == 0))
          )
         {
            struct expr *CFexpr;

                /* expecting a certainty factor (float) expression */
        /* tokenToFloatExpression expect 1st token already read */
#if (! RUN_TIME) && (! BLOAD_ONLY)
        SavePPBuffer(" ");
#endif
        GetToken(readSource,tempToken);
                CFexpr = tokenToFloatExpression(readSource,tempToken,error,constantsOnly);

            if (*error)
          {
            ReturnExpression(firstOne);
            return( NULL );
          }

            if (CFexpr->type == FLOAT) /* if constant -- check range */
                  {
                    double cfval = ValueToDouble(CFexpr->value);
                        if (cfval > 1.0 || cfval < 0.0)
                          {
                            *error = TRUE;
                ReturnExpression(CFexpr);
                            cfRangeError();
                ReturnExpression(firstOne);
                return( NULL );
                          }
                  }

                /* store the CF expression in the argList of the DEFTEMPLATE_PTR expr */
            firstOne->argList = CFexpr;
          }
        else
      {
            /* Do an 'UnGetToken' function here to undo the lookahead for a CF.
                   Also need to PPBackup over the space added before reading the
                   potential CF expression -- UnGetToken does one PPBackup over the
                   token which was added to the PP Buffer
                */
                UnGetToken(tempToken);
#if (! RUN_TIME) && (! BLOAD_ONLY)
        PPBackup();
#endif
      }

#endif   /* CERTAINTY_FACTORS */


   /*==============================*/
   /* Return the RHS ordered fact. */
   /*==============================*/

   return(firstOne);
  }