extnfunc.c

NASA 开发使用的一个专家系统

   /*******************************************************/
   /*      "C" Language Integrated Production System      */
   /*                                                     */
   /*             CLIPS Version 6.05  04/09/97            */
   /*                                                     */
   /*               EXTERNAL FUNCTION MODULE              */
   /*******************************************************/

/*************************************************************/
/* Purpose: Routines for adding new user or system defined   */
/*   functions.                                              */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*      Brian L. Donnell                                     */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*************************************************************/

#define _EXTNFUNC_SOURCE_

#include "setup.h"

#include <ctype.h>

#include "constant.h"
#include "router.h"
#include "clipsmem.h"
#include "evaluatn.h"

#include "extnfunc.h"

/***************************************/
/* LOCAL INTERNAL FUNCTION DEFINITIONS */
/***************************************/

#if ANSI_COMPILER
   static VOID                    AddHashFunction(struct FunctionDefinition *);
   static VOID                    InitializeFunctionHashTable(void);
#else
   static VOID                    AddHashFunction();
   static VOID                    InitializeFunctionHashTable();
#endif
   
/***************************************/
/* LOCAL INTERNAL VARIABLE DEFINITIONS */
/***************************************/

   static struct FunctionDefinition     *ListOfFunctions = NULL;
   static struct FunctionHash          **FunctionHashtable;

#if (! RUN_TIME)

/************************************************************/
/* DefineFunction: Used to define a system or user external */
/*   function so that CLIPS can access it.                  */
/************************************************************/
globle int DefineFunction(name,returnType,pointer,actualName)
  char *name, *actualName;
  int returnType;
  int (*pointer)(VOID_ARG);
  {
   return(DefineFunction2(name,returnType,pointer,actualName,NULL));
  }

/*************************************************************/
/* DefineFunction2: Used to define a system or user external */
/*   function so that CLIPS can access it. Allows argument   */
/*   restrictions to be attached to the function.            */
/*   Return types are:                                       */
/*     a - external address                                  */
/*     b - boolean integer (converted to symbol)             */
/*     c - character (converted to symbol)                   */
/*     d - double precision float                            */
/*     f - single precision float (converted to double)      */
/*     i - integer (converted to long integer)               */
/*     j - unknown (symbol, string,                          */
/*                  or instance name by convention)          */
/*     k - unknown (symbol or string by convention)          */
/*     l - long integer                                      */
/*     m - unknown (multifield by convention)                */
/*     n - unknown (integer or float by convention)          */
/*     o - instance name                                     */
/*     s - string                                            */
/*     u - unknown                                           */
/*     v - void                                              */
/*     w - symbol                                            */
/*     x - instance address                                  */
/*************************************************************/
globle int DefineFunction2(name,returnType,pointer,actualName,restrictions)
  char *name, *actualName;
  int returnType;
  int (*pointer)(VOID_ARG);
  char *restrictions;
  {
   struct FunctionDefinition *newFunction;

   if ( (returnType != 'a') &&
        (returnType != 'b') &&
        (returnType != 'c') &&
        (returnType != 'd') &&
        (returnType != 'f') &&
        (returnType != 'i') &&
        (returnType != 'j') &&
        (returnType != 'k') &&
        (returnType != 'l') &&
        (returnType != 'm') &&
        (returnType != 'n') &&
#if OBJECT_SYSTEM
        (returnType != 'o') &&
#endif
        (returnType != 's') &&
        (returnType != 'u') &&
        (returnType != 'v') &&
#if OBJECT_SYSTEM
        (returnType != 'x') &&
#endif
        (returnType != 'w') )
     { return(0); }

   newFunction = get_struct(FunctionDefinition);
   newFunction->callFunctionName = (SYMBOL_HN *) AddSymbol(name);
   newFunction->returnValueType = (char) returnType;
   newFunction->functionPointer = pointer;
   newFunction->next = GetFunctionList();
   newFunction->actualFunctionName = actualName;
   if (restrictions != NULL)
     {
      if (((int) (strlen(restrictions)) < 2) ? TRUE : 
          ((! isdigit(restrictions[0]) && (restrictions[0] != '*')) ||
           (! isdigit(restrictions[1]) && (restrictions[1] != '*'))))
        restrictions = NULL;
     }
   newFunction->restrictions = restrictions;
   newFunction->parser = NULL;
   newFunction->overloadable = CLIPS_TRUE;
   newFunction->sequenceuseok = CLIPS_TRUE;

   IncrementSymbolCount(newFunction->callFunctionName);
   ListOfFunctions = newFunction;
   AddHashFunction(newFunction);

   return(1);
  }

/***************************************************************************/
/* 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(functionName,fpPtr)
  char *functionName;
#if ANSI_COMPILER
  struct expr *(*fpPtr)(struct expr *,char *);
#else
  struct expr *(*fpPtr)();
#endif
  {
   struct FunctionDefinition *fdPtr;

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

   return(1);
  }

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

   fdPtr = FindFunction(functionName);
   if (fdPtr == NULL)
     {
      PrintCLIPS(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(functionName,seqp,ovlp)
  char *functionName;
  int seqp,ovlp;
  {
   struct FunctionDefinition *fdPtr;

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

#endif

/*********************************************************/
/* GetArgumentTypeName: Returns a descriptive string for */
/*   a function argument type (used by DefineFunction2). */
/*********************************************************/