cstrcpsr.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            */
   /*                                                     */
   /*              CONSTRUCT PARSER MODULE                */
   /*******************************************************/

/*************************************************************/
/* Purpose: Parsing routines and utilities for parsing       */
/*   constructs.                                             */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*************************************************************/

#define _CSTRCPSR_SOURCE_

#include "setup.h"

#if (! RUN_TIME) && (! BLOAD_ONLY)

#include <stdio.h>
#define _CLIPS_STDIO_

#include "router.h"
#include "watch.h"
#include "constrct.h" 
#include "prcdrpsr.h"
#include "exprnpsr.h"
#include "modulutl.h"
#include "modulpsr.h"
#include "utility.h"

#include "cstrcpsr.h"

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

#if ANSI_COMPILER
   static int                     FindConstructBeginning(char *,struct token *,int,int *);
#else
   static int                     FindConstructBeginning();
#endif

/********************************************************/
/* Load: C access routine for the load command. Returns */
/*   0 if the file couldn't be opened, -1 if the file   */
/*   was opened but an error occurred while loading     */
/*   constructs, and 1 if the file was opened and no    */
/*   errors occured while loading.                      */
/********************************************************/
globle int Load(fileName)
  char *fileName;
  {
   FILE *theFile;
   int noErrorsDetected;

   /*=======================================*/
   /* Open the file specified by file name. */
   /*=======================================*/

   if ((theFile = fopen(fileName,"r")) == NULL) return(0);
     
   /*===================================================*/
   /* Read in the constructs. Enabling fast load allows */
   /* the router system to be bypassed for quicker load */
   /* times.                                            */
   /*===================================================*/
   
   SetFastLoad(theFile);
   noErrorsDetected = LoadConstructsFromLogicalName((char *) theFile);
   SetFastLoad(NULL);

   /*=================*/
   /* Close the file. */
   /*=================*/

   fclose(theFile);
   
   /*========================================*/
   /* If no errors occurred during the load, */
   /* return 1, otherwise return -1.         */
   /*========================================*/
   
   if (noErrorsDetected) return(1);
   
   return(-1);
  }

/******************************************************************/
/* LoadConstructsFromLogicalName: Loads a set of constructs into  */
/*   the current CLIPS environment from a specified logical name. */
/******************************************************************/
globle int LoadConstructsFromLogicalName(readSource)
  char *readSource;
  {
   int constructFlag;
   struct token theToken;
   int noErrors = CLIPS_TRUE;
   int foundConstruct;
 
   /*=========================================*/
   /* Reset the halt execution and evaluation */
   /* error flags in preparation for parsing. */
   /*=========================================*/
   
   if (CurrentEvaluationDepth == 0) SetHaltExecution(CLIPS_FALSE);
   SetEvaluationError(CLIPS_FALSE);
   
   /*========================================================*/
   /* Find the beginning of the first construct in the file. */
   /*========================================================*/
   
   GetToken(readSource,&theToken);
   foundConstruct = FindConstructBeginning(readSource,&theToken,CLIPS_FALSE,&noErrors);

   /*==================================================*/
   /* Parse the file until the end of file is reached. */
   /*==================================================*/

   while ((foundConstruct == CLIPS_TRUE) && (GetHaltExecution() == CLIPS_FALSE))
     {
      /*===========================================================*/
      /* Clear the pretty print buffer in preparation for parsing. */
      /*===========================================================*/
      
      FlushPPBuffer();
      
      /*======================*/
      /* Parse the construct. */
      /*======================*/
      
      constructFlag = ParseConstruct(ValueToString(theToken.value),readSource);
      
      /*==============================================================*/
      /* If an error occurred while parsing, then find the beginning  */
      /* of the next construct (but don't generate any more error     */
      /* messages--in effect, skip everything until another construct */
      /* is found).                                                   */
      /*==============================================================*/
      
      if (constructFlag == 1)
        {
         PrintCLIPS(WERROR,"\nERROR:\n");
         PrintInChunks(WERROR,GetPPBuffer());
         PrintCLIPS(WERROR,"\n");
         noErrors = CLIPS_FALSE;
         GetToken(readSource,&theToken);
         foundConstruct = FindConstructBeginning(readSource,&theToken,CLIPS_TRUE,&noErrors); 
        }

      /*======================================================*/
      /* Otherwise, find the beginning of the next construct. */
      /*======================================================*/
      
      else
        { 
         GetToken(readSource,&theToken);
         foundConstruct = FindConstructBeginning(readSource,&theToken,CLIPS_FALSE,&noErrors);
        }      
        
      /*=====================================================*/
      /* Yield time if necessary to foreground applications. */
      /*=====================================================*/

       if (foundConstruct)
         { IncrementSymbolCount(theToken.value); }                      
       CurrentEvaluationDepth--;
       PeriodicCleanup(FALSE,TRUE);
       YieldTime();
       CurrentEvaluationDepth++;
       if (foundConstruct)
         { DecrementSymbolCount(theToken.value); }
     }

   /*========================================================*/
   /* Print a carriage return if a single character is being */
   /* printed to indicate constructs are being processed.    */
   /*========================================================*/

#if DEBUGGING_FUNCTIONS
   if ((GetWatchItem("compilations") != CLIPS_TRUE) && GetPrintWhileLoading())
#else
   if (GetPrintWhileLoading())
#endif
     { PrintCLIPS(WDIALOG,"\n"); }
     
   /*=============================================================*/
   /* Once the load is complete, destroy the pretty print buffer. */
   /* This frees up any memory that was used to create the pretty */
   /* print forms for constructs during parsing. Thus calls to    */
   /* the mem-used function will accurately reflect the amount of */
   /* memory being used after a load command.                     */
   /*=============================================================*/
                  
   DestroyPPBuffer();
   
   /*==========================================================*/
   /* Return a boolean flag which indicates whether any errors */
   /* were encountered while loading the constructs.           */
   /*==========================================================*/
   
   return(noErrors);
  }

/********************************************************************/
/* FindConstructBeginning: Searches for a left parenthesis followed */
/*   by the name of a valid construct. Used by the load command to  */
/*   find the next construct to be parsed. Returns TRUE is the      */
/*   beginning of a construct was found, otherwise FALSE.           */
/********************************************************************/
static int FindConstructBeginning(readSource,theToken,errorCorrection,noErrors)
  char *readSource;
  struct token *theToken;
  int errorCorrection;
  int *noErrors;
  {
   int leftParenthesisFound = CLIPS_FALSE;
   int firstAttempt = CLIPS_TRUE;
   
   /*===================================================*/
   /* Process tokens until the beginning of a construct */
   /* is found or there are no more tokens.             */
   /*===================================================*/
   
   while (theToken->type != STOP)
     {
      /*=====================================================*/
      /* Constructs begin with a left parenthesis. Make note */
      /* that the opening parenthesis has been found.        */
      /*=====================================================*/
      
      if (theToken->type == LPAREN) 
        { leftParenthesisFound = CLIPS_TRUE; }
        
      /*=================================================================*/
      /* The name of the construct follows the opening left parenthesis. */
      /* If it is the name of a valid construct, then return TRUE.       */
      /* Otherwise, reset the flags to look for the beginning of a       */
      /* construct. If error correction is being performed (i.e. the     */
      /* last construct parsed had an error in it), then don't bother to */
      /* print an error message, otherwise, print an error message.      */
      /*=================================================================*/
      
      else if ((theToken->type == SYMBOL) && (leftParenthesisFound == CLIPS_TRUE))
        {
         /*===========================================================*/
         /* Is this a valid construct name (e.g., defrule, deffacts). */
         /*===========================================================*/
         
         if (FindConstruct(ValueToString(theToken->value)) != NULL) return(CLIPS_TRUE);
         
         /*===============================================*/
         /* The construct name is invalid. Print an error */
         /* message if one hasn't already been printed.   */
         /*===============================================*/
         
         if (firstAttempt && (! errorCorrection))
           {
            errorCorrection = CLIPS_TRUE;
            *noErrors = CLIPS_FALSE;
            PrintErrorID("CSTRCPSR",1,CLIPS_TRUE);
            PrintCLIPS(WERROR,"Expected the beginning of a construct.\n");
           }
           
         /*======================================================*/
         /* Indicate that an error has been found and that we're */
         /* looking for a left parenthesis again.                */
         /*======================================================*/
         
         firstAttempt = CLIPS_FALSE;
         leftParenthesisFound = CLIPS_FALSE;
        }
        
      /*====================================================================*/
      /* Any token encountered other than a left parenthesis or a construct */
      /* name following a left parenthesis is illegal. Again, if error      */
      /* correction is in progress, no error message is printed, otherwise, */
      /*  an error message is printed.                                      */
      /*====================================================================*/
      
      else
        { 
         if (firstAttempt && (! errorCorrection))
           {
            errorCorrection = CLIPS_TRUE;
            *noErrors = CLIPS_FALSE;
            PrintErrorID("CSTRCPSR",1,CLIPS_TRUE);
            PrintCLIPS(WERROR,"Expected the beginning of a construct.\n");
           }
           
         firstAttempt = CLIPS_FALSE;
         leftParenthesisFound = CLIPS_FALSE;
        }
        
      /*============================================*/
      /* Move on to the next token to be processed. */
      /*============================================*/
      
      GetToken(readSource,theToken);
     }
     
   /*===================================================================*/
   /* Couldn't find the beginning of a construct, so FALSE is returned. */
   /*===================================================================*/
     
   return(CLIPS_FALSE);
  }

/***********************************************************/
/* ParseConstruct: Parses a construct. Returns an integer. */
/*   -1 if the construct name has no parsing function, 0   */
/*   if the construct was parsed successfully, and 1 if    */
/*   the construct was parsed unsuccessfully.              */
/***********************************************************/
globle int ParseConstruct(name,logicalName)
  char *name, *logicalName;