default.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            */
   /*                                                     */
   /*               DEFAULT ATTRIBUTE MODULE              */
   /*******************************************************/

/*************************************************************/
/* Purpose: Provides functions for parsing the default       */
/*   attribute and determining default values based on       */
/*   slot constraints.                                       */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*      Brian Donnell                                        */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*************************************************************/

#define _DEFAULT_SOURCE_

#include "setup.h"

#include <stdio.h>
#define _CLIPS_STDIO_
#if ANSI_COMPILER
#include <stdlib.h>
#endif
#include <string.h>

#include "constant.h"
#include "constrnt.h"
#include "cstrnchk.h"
#include "multifld.h"
#include "inscom.h"
#include "exprnpsr.h"
#include "scanner.h"
#include "router.h"
#include "factmngr.h"
#include "cstrnutl.h"

#include "default.h"

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

#if ANSI_COMPILER
   static VOID                    *FindDefaultValue(int,CONSTRAINT_RECORD *,VOID *);
#else
   static VOID                    *FindDefaultValue();
#endif

/********************************************************/
/* DeriveDefaultFromConstraints: Returns an appropriate */
/*   default value for the supplied constraints.        */
/********************************************************/
globle VOID DeriveDefaultFromConstraints(constraints,theDefault,multifield)
  CONSTRAINT_RECORD *constraints;
  DATA_OBJECT *theDefault;
  int multifield;
  {
   short theType;
   long minFields; /* 6.04 Bug Fix */
   VOID *theValue;
   
   /*=============================================================*/
   /* If no constraints are specified, then use the symbol nil as */
   /* a default for single field slots and a multifield of length */
   /* 0 as a default for multifield slots.                        */
   /*=============================================================*/
          
   if (constraints == NULL) 
     { 
      if (multifield)
        {
         SetpType(theDefault,MULTIFIELD);
         SetpDOBegin(theDefault,1);
         SetpDOEnd(theDefault,0);
         SetpValue(theDefault,(VOID *) CreateMultifield(0L));
        }
      else
        {
         theDefault->type = SYMBOL;
         theDefault->value = AddSymbol("nil");
        }
        
      return;
     }
   
   /*=========================================*/
   /* Determine the default's type and value. */
   /*=========================================*/
   
   if (constraints->anyAllowed || constraints->symbolsAllowed)
     { 
      theType = SYMBOL;
      theValue = FindDefaultValue(SYMBOL,constraints,AddSymbol("nil"));
     }
   
   else if (constraints->stringsAllowed)
     { 
      theType = STRING;
      theValue = FindDefaultValue(STRING,constraints,AddSymbol(""));
     }
   
   else if (constraints->integersAllowed)
     { 
      theType = INTEGER;
      theValue = FindDefaultValue(INTEGER,constraints,AddLong(0L));
     }
   
   else if (constraints->floatsAllowed)
     { 
      theType = FLOAT;
      theValue = FindDefaultValue(FLOAT,constraints,AddDouble(0.0));
     }   
#if OBJECT_SYSTEM   
   else if (constraints->instanceNamesAllowed)
     { 
      theType = INSTANCE_NAME;
      theValue = FindDefaultValue(INSTANCE_NAME,constraints,AddSymbol("nil"));
     }
  
   else if (constraints->instanceAddressesAllowed)
     { 
      theType = INSTANCE_ADDRESS;
      theValue = (VOID *) &DummyInstance;
     }
#endif 
#if DEFTEMPLATE_CONSTRUCT
   else if (constraints->factAddressesAllowed)
     { 
      theType = FACT_ADDRESS;
      theValue = (VOID *) &DummyFact;
     }
#endif
   else if (constraints->externalAddressesAllowed)
     { 
      theType = EXTERNAL_ADDRESS;
      theValue = NULL;
     }
     
   else
     {
      theType = SYMBOL;
      theValue = AddSymbol("nil");
     }
     
   /*=========================================================*/
   /* If the default is for a multifield slot, then create a  */
   /* multifield default value that satisfies the cardinality */
   /* constraints for the slot. The default value for a       */
   /* multifield slot is a multifield of length 0.            */
   /*=========================================================*/
   
   if (multifield)
     {
      if (constraints->minFields == NULL) minFields = 0;
      else if (constraints->minFields->value == NegativeInfinity) minFields = 0;
      else minFields = ValueToLong(constraints->minFields->value);
      
      SetpType(theDefault,MULTIFIELD);
      SetpDOBegin(theDefault,1);
      SetpDOEnd(theDefault,minFields);
      SetpValue(theDefault,(VOID *) CreateMultifield(minFields));
      
      for (; minFields > 0; minFields--)
        {
         SetMFType(GetpValue(theDefault),minFields,theType);
         SetMFValue(GetpValue(theDefault),minFields,theValue);
        }
     }
   else
     {
      theDefault->type = theType;
      theDefault->value = theValue;
     }
  }

/***********************************************************************/
/* FindDefaultValue: Searches the list of restriction values for a     */
/*   constraint to find a default value of the specified type. For     */
/*   example, if the attribute (allowed-symbols on off) was specified, */
/*   then the symbol "on" would be used as a default value rather than */
/*   the symbol "nil". For integers and floats, the range attribute is */
/*   also used to select a suitable default value. If a minimum value  */
/*   was specified, then this value is used first followed by the      */
/*   maximum value.                                                    */
/************************************************************************/
static VOID *FindDefaultValue(theType,theConstraints,standardDefault)
  int theType;
  CONSTRAINT_RECORD *theConstraints;
  VOID *standardDefault;
  {
   struct expr *theList;
   
   /*=====================================================*/
   /* Look on the the allowed values list to see if there */
   /* is a value of the requested type. Return the first  */
   /* value found of the requested type.                  */
   /*=====================================================*/
   
   theList = theConstraints->restrictionList;
   while (theList != NULL)
     {
      if (theList->type == theType) return(theList->value);
      theList = theList->nextArg;
     }
   
   /*=============================================================*/
   /* If no specific values were available for the default value, */
   /* and the type requested is a float or integer, then use the  */
   /* range attribute to select a default value.                  */
   /*=============================================================*/
   
   if (theType == INTEGER)
     {
      if (theConstraints->minValue->type == INTEGER)
        { return(theConstraints->minValue->value); }
      else if (theConstraints->minValue->type == FLOAT)
        { return(AddLong((long) ValueToDouble(theConstraints->minValue->value))); }
      else if (theConstraints->maxValue->type == INTEGER)
        { return(theConstraints->maxValue->value); }
      else if (theConstraints->maxValue->type == FLOAT)
        { return(AddLong((long) ValueToDouble(theConstraints->maxValue->value))); }
     }
   else if (theType == FLOAT)
     {
      if (theConstraints->minValue->type == FLOAT)
        { return(theConstraints->minValue->value); }
      else if (theConstraints->minValue->type == INTEGER)