extnfunc.c

clips源代码

      lastPtr = fhPtr;
     }

   return(FALSE);
  }

/***************************************************************************/
/* AddFunctionParser: Associates a specialized expression parsing function */
/*   with the function entry for a function which was defined using        */
/*   DefineFunction. When this function is parsed, the specialized parsing */
/*   function will be called to parse the arguments of the function. Only  */
/*   user and system defined functions can have specialized parsing        */
/*   routines. Generic functions and deffunctions can not have specialized */
/*   parsing routines.                                                     */
/***************************************************************************/
globle int AddFunctionParser(
  void *theEnv,
  char *functionName,
  struct expr *(*fpPtr)(void *,struct expr *,char *))
  {
   struct FunctionDefinition *fdPtr;

   fdPtr = FindFunction(theEnv,functionName);
   if (fdPtr == NULL)
     {
      EnvPrintRouter(theEnv,WERROR,"Function parsers can only be added for existing functions.\n");
      return(0);
     }
   fdPtr->restrictions = NULL;
   fdPtr->parser = fpPtr;
   fdPtr->overloadable = FALSE;

   return(1);
  }

/*********************************************************************/
/* RemoveFunctionParser: Removes a specialized expression parsing    */
/*   function (if it exists) from the function entry for a function. */
/*********************************************************************/
globle int RemoveFunctionParser(
  void *theEnv,
  char *functionName)
  {
   struct FunctionDefinition *fdPtr;

   fdPtr = FindFunction(theEnv,functionName);
   if (fdPtr == NULL)
     {
      EnvPrintRouter(theEnv,WERROR,"Function parsers can only be removed from existing functions.\n");
      return(0);
     }

   fdPtr->parser = NULL;

   return(1);
  }

/*****************************************************************/
/* FuncSeqOvlFlags: Makes a system function overloadable or not, */
/* i.e. can the function be a method for a generic function.     */
/*****************************************************************/
globle int FuncSeqOvlFlags(
  void *theEnv,
  char *functionName,
  int seqp,
  int ovlp)
  {
   struct FunctionDefinition *fdPtr;

   fdPtr = FindFunction(theEnv,functionName);
   if (fdPtr == NULL)
     {
      EnvPrintRouter(theEnv,WERROR,"Only existing functions can be marked as using sequence expansion arguments/overloadable or not.\n");
      return(FALSE);
     }
   fdPtr->sequenceuseok = (short) (seqp ? TRUE : FALSE);
   fdPtr->overloadable = (short) (ovlp ? TRUE : FALSE);
   return(TRUE);
  }

#endif

/*********************************************************/
/* GetArgumentTypeName: Returns a descriptive string for */
/*   a function argument type (used by DefineFunction2). */
/*********************************************************/
globle char *GetArgumentTypeName(
  int theRestriction)
  {
   switch ((char) theRestriction)
     {
      case 'a':
        return("external address");

      case 'e':
        return("instance address, instance name, or symbol");

      case 'd':
      case 'f':
        return("float");

      case 'g':
        return("integer, float, or symbol");

      case 'h':
        return("instance address, instance name, fact address, integer, or symbol");

      case 'j':
        return("symbol, string, or instance name");

      case 'k':
        return("symbol or string");

      case 'i':
      case 'l':
        return("integer");

      case 'm':
        return("multifield");

      case 'n':
        return("integer or float");

      case 'o':
        return("instance name");

      case 'p':
        return("instance name or symbol");

      case 'q':
        return("multifield, symbol, or string");

      case 's':
        return("string");

      case 'w':
        return("symbol");

      case 'x':
        return("instance address");

      case 'y':
        return("fact-address");

      case 'z':
        return("fact-address, integer, or symbol");

      case 'u':
        return("non-void return value");
     }

   return("unknown argument type");
  }

/***************************************************/
/* GetNthRestriction: Returns the restriction type */
/*   for the nth parameter of a function.          */
/***************************************************/
globle int GetNthRestriction(
  struct FunctionDefinition *theFunction,
  int position)
  {
   int defaultRestriction = (int) 'u';
   size_t theLength;
   int i = 2;

   /*===========================================================*/
   /* If no restrictions at all are specified for the function, */
   /* then return 'u' to indicate that any value is suitable as */
   /* an argument to the function.                              */
   /*===========================================================*/

   if (theFunction == NULL) return(defaultRestriction);

   if (theFunction->restrictions == NULL) return(defaultRestriction);

   /*===========================================================*/
   /* If no type restrictions are specified for the function,   */
   /* then return 'u' to indicate that any value is suitable as */
   /* an argument to the function.                              */
   /*===========================================================*/

   theLength = strlen(theFunction->restrictions);

   if (theLength < 3) return(defaultRestriction);

   /*==============================================*/
   /* Determine the functions default restriction. */
   /*==============================================*/

   defaultRestriction = (int) theFunction->restrictions[i];

   if (defaultRestriction == '*') defaultRestriction = (int) 'u';

   /*=======================================================*/
   /* If the requested position does not have a restriction */
   /* specified, then return the default restriction.       */
   /*=======================================================*/

   if (theLength < (size_t) (position + 3)) return(defaultRestriction);

   /*=========================================================*/
   /* Return the restriction specified for the nth parameter. */
   /*=========================================================*/

   return((int) theFunction->restrictions[position + 2]);
  }

/*************************************************/
/* GetFunctionList: Returns the ListOfFunctions. */
/*************************************************/
globle struct FunctionDefinition *GetFunctionList(
  void *theEnv)
  {
   return(ExternalFunctionData(theEnv)->ListOfFunctions);
  }

/**************************************************************/
/* InstallFunctionList: Sets the ListOfFunctions and adds all */
/*   the function entries to the FunctionHashTable.           */
/**************************************************************/
globle void InstallFunctionList(
  void *theEnv,
  struct FunctionDefinition *value)
  {
   int i;
   struct FunctionHash *fhPtr, *nextPtr;

   if (ExternalFunctionData(theEnv)->FunctionHashtable != NULL)
     {
      for (i = 0; i < SIZE_FUNCTION_HASH; i++)
        {
         fhPtr = ExternalFunctionData(theEnv)->FunctionHashtable[i];
         while (fhPtr != NULL)
           {
            nextPtr = fhPtr->next;
            rtn_struct(theEnv,FunctionHash,fhPtr);
            fhPtr = nextPtr;
           }
         ExternalFunctionData(theEnv)->FunctionHashtable[i] = NULL;
        }
     }

   ExternalFunctionData(theEnv)->ListOfFunctions = value;

   while (value != NULL)
     {
      AddHashFunction(theEnv,value);
      value = value->next;
     }
  }

/********************************************************/
/* FindFunction: Returns a pointer to the corresponding */
/*   FunctionDefinition structure if a function name is */
/*   in the function list, otherwise returns NULL.      */
/********************************************************/
globle struct FunctionDefinition *FindFunction(
  void *theEnv,
  char *functionName)
  {
   struct FunctionHash *fhPtr;
   unsigned hashValue;
   SYMBOL_HN *findValue;

   if (ExternalFunctionData(theEnv)->FunctionHashtable == NULL) return(NULL);
   
   hashValue = HashSymbol(functionName,SIZE_FUNCTION_HASH);

   findValue = (SYMBOL_HN *) FindSymbolHN(theEnv,functionName);

   for (fhPtr = ExternalFunctionData(theEnv)->FunctionHashtable[hashValue];
        fhPtr != NULL;
        fhPtr = fhPtr->next)
     {
      if (fhPtr->fdPtr->callFunctionName == findValue)
        { return(fhPtr->fdPtr); }
     }

   return(NULL);
  }

/*********************************************************/
/* InitializeFunctionHashTable: Purpose is to initialize */
/*   the function hash table to NULL.                    */
/*********************************************************/
static void InitializeFunctionHashTable(
  void *theEnv)
  {
   int i;

   ExternalFunctionData(theEnv)->FunctionHashtable = (struct FunctionHash **)
                       gm2(theEnv,(int) sizeof (struct FunctionHash *) *
                           SIZE_FUNCTION_HASH);

   for (i = 0; i < SIZE_FUNCTION_HASH; i++) ExternalFunctionData(theEnv)->FunctionHashtable[i] = NULL;
  }

/****************************************************************/
/* AddHashFunction: Adds a function to the function hash table. */
/****************************************************************/
static void AddHashFunction(
  void *theEnv,
  struct FunctionDefinition *fdPtr)
  {
   struct FunctionHash *newhash, *temp;
   unsigned hashValue;

   if (ExternalFunctionData(theEnv)->FunctionHashtable == NULL) InitializeFunctionHashTable(theEnv);

   newhash = get_struct(theEnv,FunctionHash);
   newhash->fdPtr = fdPtr;

   hashValue = HashSymbol(fdPtr->callFunctionName->contents,SIZE_FUNCTION_HASH);

   temp = ExternalFunctionData(theEnv)->FunctionHashtable[hashValue];
   ExternalFunctionData(theEnv)->FunctionHashtable[hashValue] = newhash;
   newhash->next = temp;
  }

/*************************************************/
/* GetMinimumArgs: Returns the minimum number of */
/*   arguments expected by an external function. */
/*************************************************/
globle int GetMinimumArgs(
  struct FunctionDefinition *theFunction)
  {
   char theChar[2], *restrictions;

   restrictions = theFunction->restrictions;
   if (restrictions == NULL) return(-1);

   theChar[0] = restrictions[0];
   theChar[1] = '\0';

   if (isdigit(theChar[0]))
     { return atoi(theChar); }
   else if (theChar[0] == '*')
     { return(-1); }
   
   return(-1); 
  }
  
/*************************************************/
/* GetMaximumArgs: Returns the maximum number of */
/*   arguments expected by an external function. */
/*************************************************/
globle int GetMaximumArgs(
  struct FunctionDefinition *theFunction)
  {
   char theChar[2], *restrictions;

   restrictions = theFunction->restrictions;
   if (restrictions == NULL) return(-1);
   if (restrictions[0] == '\0') return(-1);

   theChar[0] = restrictions[1];
   theChar[1] = '\0';

   if (isdigit(theChar[0]))
     { return atoi(theChar); }
   else if (theChar[0] == '*')
     { return(-1); }
   
   return(-1); 
  }