exprnpsr.c

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   /*******************************************************/
   /*      "C" Language Integrated Production System      */
   /*                                                     */
   /*             CLIPS Version 6.05  04/09/97            */
   /*                                                     */
   /*              EXPRESSION PARSER MODULE               */
   /*******************************************************/

/*************************************************************/
/* Purpose: Provides routines for parsing expressions.       */
/*                                                           */
/* Principal Programmer(s):                                  */
/*      Gary D. Riley                                        */
/*                                                           */
/* Contributing Programmer(s):                               */
/*      Brian L. Donnell                                     */
/*                                                           */
/* Revision History:                                         */
/*                                                           */
/*************************************************************/

#define _EXPRNPSR_SOURCE_

#include "setup.h"

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

#include "constant.h"
#include "router.h"
#include "strngrtr.h"
#include "scanner.h"
#include "clipsmem.h"
#include "argacces.h"
#include "prntutil.h"
#include "cstrnchk.h"
#include "extnfunc.h"
#include "exprnpsr.h"
#include "modulutl.h"

#if DEFRULE_CONSTRUCT
#include "network.h"
#endif

#if DEFGENERIC_CONSTRUCT
#include "genrccom.h"
#endif

#if DEFFUNCTION_CONSTRUCT
#include "dffnxfun.h"
#endif

/****************************************/
/* GLOBAL INTERNAL VARIABLE DEFINITIONS */
/****************************************/

#if (! RUN_TIME)
   globle SAVED_CONTEXTS      *svContexts = NULL;
   globle int                  ReturnContext;
   globle int                  BreakContext;
#endif
   globle BOOLEAN              SequenceOpMode = CLIPS_FALSE;

#if (! RUN_TIME)

/***************************************************/
/* Function0Parse: Parses a function. Assumes that */
/*   none of the function has been parsed yet.     */
/***************************************************/
globle struct expr *Function0Parse(logicalName)
  char *logicalName;
  {
   struct token theToken;
   struct expr *top;

   /*=================================*/
   /* All functions begin with a '('. */
   /*=================================*/

   GetToken(logicalName,&theToken);
   if (theToken.type != LPAREN)
     {
      SyntaxErrorMessage("function calls");
      return(NULL);
     }

   /*=================================*/
   /* Parse the rest of the function. */
   /*=================================*/

   top = Function1Parse(logicalName);
   return(top);
  }

/*******************************************************/
/* Function1Parse: Parses a function. Assumes that the */
/*   opening left parenthesis has already been parsed. */
/*******************************************************/
globle struct expr *Function1Parse(logicalName)
  char *logicalName;
  {
   struct token theToken;
   struct expr *top;

   /*========================*/
   /* Get the function name. */
   /*========================*/

   GetToken(logicalName,&theToken);
   if (theToken.type != SYMBOL)
     {
      PrintErrorID("EXPRNPSR",1,CLIPS_TRUE);
      PrintCLIPS(WERROR,"A function name must be a symbol\n");
      return(NULL);
     }

   /*=================================*/
   /* Parse the rest of the function. */
   /*=================================*/

   top = Function2Parse(logicalName,ValueToString(theToken.value));
   return(top);
  }

/****************************************************/
/* Function2Parse: Parses a function. Assumes that  */
/*   the opening left parenthesis and function name */
/*   have already been parsed.                      */
/****************************************************/
globle struct expr *Function2Parse(logicalName,name)
  char *logicalName, *name;
  {
   struct FunctionDefinition *theFunction;
   struct expr *top;
#if DEFGENERIC_CONSTRUCT
   VOID *gfunc;
#endif
#if DEFFUNCTION_CONSTRUCT
   VOID *dptr;
#endif

   /*=========================================================*/
   /* Module specification cannot be used in a function call. */
   /*=========================================================*/
   
   if (FindModuleSeparator(name))
     {
      IllegalModuleSpecifierMessage();
      return(NULL);
     }
   
   /*================================*/
   /* Has the function been defined? */
   /*================================*/

   theFunction = FindFunction(name);

#if DEFGENERIC_CONSTRUCT
   gfunc = (VOID *) LookupDefgenericInScope(name);
#endif

#if DEFFUNCTION_CONSTRUCT
   if ((theFunction == NULL)
#if DEFGENERIC_CONSTRUCT
        && (gfunc == NULL)
#endif
     )
     dptr = (VOID *) LookupDeffunctionInScope(name);
   else
     dptr = NULL;
#endif

   /*=============================*/
   /* Define top level structure. */
   /*=============================*/

#if DEFFUNCTION_CONSTRUCT
   if (dptr != NULL)
     top = GenConstant(PCALL,dptr);
   else
#endif
#if DEFGENERIC_CONSTRUCT
   if (gfunc != NULL)
     top = GenConstant(GCALL,gfunc);
   else
#endif
   if (theFunction != NULL)
     top = GenConstant(FCALL,theFunction);
   else
     {      
      PrintErrorID("EXPRNPSR",3,CLIPS_TRUE);
      PrintCLIPS(WERROR,"Missing function declaration for ");
      PrintCLIPS(WERROR,name);
      PrintCLIPS(WERROR,".\n");
      return(NULL);
     }
      
   /*=======================================================*/
   /* Check to see if function has its own parsing routine. */
   /*=======================================================*/
   
   PushRtnBrkContexts();
   ReturnContext = CLIPS_FALSE;
   BreakContext = CLIPS_FALSE;
   
#if DEFGENERIC_CONSTRUCT || DEFFUNCTION_CONSTRUCT
   if (top->type == FCALL)
#endif
     {
      if (theFunction->parser != NULL)
        {
         top = (*theFunction->parser)(top,logicalName);
         PopRtnBrkContexts();
         if (top == NULL) return(NULL);
         if (ReplaceSequenceExpansionOps(top->argList,top,FindFunction("(expansion-call)"),
                                         FindFunction("expand$")))
           {
            ReturnExpression(top);
            return(NULL);
           }
         return(top);
        }
     }

   /*========================================*/
   /* Default parsing routine for functions. */
   /*========================================*/
   
   top = CollectArguments(top,logicalName);
   PopRtnBrkContexts();
   if (top == NULL) return(NULL);

   if (ReplaceSequenceExpansionOps(top->argList,top,FindFunction("(expansion-call)"),
                                    FindFunction("expand$")))
     {
      ReturnExpression(top);
      return(NULL);
     }
     
   /*============================================================*/
   /* If the function call uses the sequence expansion operator, */
   /* its arguments cannot be checked until runtime.             */
   /*============================================================*/
   
   if (top->value == (VOID *) FindFunction("(expansion-call)"))
     { return(top); }
     
   /*============================*/
   /* Check for argument errors. */
   /*============================*/

   if ((top->type == FCALL) && GetStaticConstraintChecking())
     {
      if (CheckExpressionAgainstRestrictions(top,theFunction->restrictions,name))
        {
         ReturnExpression(top);
         return(NULL);
        }
     }
     
#if DEFFUNCTION_CONSTRUCT 
   else if (top->type == PCALL)
     {
      if (CheckDeffunctionCall(top->value,CountArguments(top->argList)) == CLIPS_FALSE)
        {
         ReturnExpression(top);
         return(NULL);
        }
     }
#endif
        
   /*========================*/
   /* Return the expression. */
   /*========================*/
   
   return(top);
  }

/***********************************************************************
  NAME         : ReplaceSequenceExpansionOps
  DESCRIPTION  : Replaces function calls which have multifield
                   references as arguments into a call to a 
                   special function which expands the multifield
                   into single arguments at run-time.
                 Multifield references which are not function
                   arguments are errors
  INPUTS       : 1) The expression
                 2) The current function call
                 3) The address of the internal CLIPS function
                    (expansion-call)
                 4) The address of the CLIPS function expand$
  RETURNS      : FALSE if OK, TRUE on errors
  SIDE EFFECTS : Function call expressions modified, if necessary
  NOTES        : Function calls which truly want a multifield
                   to be passed need use only a single-field
                   refernce (i.e. ? instead of $? - the $ is
                   being treated as a special expansion operator)
 **********************************************************************/
globle BOOLEAN ReplaceSequenceExpansionOps(actions,fcallexp,expcall,expmult)
  EXPRESSION *actions,*fcallexp;
  VOID *expcall,*expmult;
  {
   EXPRESSION *exp;
   
   while (actions != NULL)
     {
      if ((SequenceOpMode == CLIPS_FALSE) && (actions->type == MF_VARIABLE))
        actions->type = SF_VARIABLE;
      if ((actions->type == MF_VARIABLE) || (actions->type == MF_GBL_VARIABLE) ||
          (actions->value == expmult))
        {
         if ((fcallexp->type != FCALL) ? CLIPS_FALSE :
             (((struct FunctionDefinition *) fcallexp->value)->sequenceuseok == CLIPS_FALSE))
           {       
            PrintErrorID("EXPRNPSR",4,CLIPS_FALSE);
            PrintCLIPS(WERROR,"$ Sequence operator not a valid argument for ");
            PrintCLIPS(WERROR,ValueToString(((struct FunctionDefinition *) 
                              fcallexp->value)->callFunctionName));
            PrintCLIPS(WERROR,".\n");
            return(TRUE);
           }
         if (fcallexp->value != expcall)
           {
            exp = GenConstant(fcallexp->type,fcallexp->value);
            exp->argList = fcallexp->argList;
            exp->nextArg = NULL;
            fcallexp->type = FCALL;
            fcallexp->value = expcall;
            fcallexp->argList = exp;
           }
         if (actions->value != expmult)
           {
            exp = GenConstant(SF_VARIABLE,actions->value);
            if (actions->type == MF_GBL_VARIABLE)
              exp->type = GBL_VARIABLE;
            actions->argList = exp;
            actions->type = FCALL;
            actions->value = expmult;
           }
        }
      if (actions->argList != NULL)
        {
         if ((actions->type == GCALL) ||
             (actions->type == PCALL) ||
             (actions->type == FCALL))
           exp = actions;
         else
           exp = fcallexp;
         if (ReplaceSequenceExpansionOps(actions->argList,exp,expcall,expmult))
           return(TRUE);
        }
      actions = actions->nextArg;
     }
   return(FALSE);
  }
  
/*************************************************/
/* PushRtnBrkContexts: Saves the current context */
/*   for the break/return functions.             */
/*************************************************/
globle VOID PushRtnBrkContexts()
  {
   SAVED_CONTEXTS *svtmp;
   
   svtmp = get_struct(saved_contexts);
   svtmp->rtn = ReturnContext;
   svtmp->brk = BreakContext;
   svtmp->nxt = svContexts;
   svContexts = svtmp;
  }
  
/***************************************************/
/* PopRtnBrkContexts: Restores the current context */
/*   for the break/return functions.               */
/***************************************************/
globle VOID PopRtnBrkContexts()
  {
   SAVED_CONTEXTS *svtmp;
   
   ReturnContext = svContexts->rtn;
   BreakContext = svContexts->brk;
   svtmp = svContexts;
   svContexts = svContexts->nxt;
   rtn_struct(saved_contexts,svtmp);
  }

/*****************************************************************/
/* CheckExpressionAgainstRestrictions: Compares the arguments to */
/*   a function to the set of restrictions for that function to  */
/*   determine if any incompatibilities exist. If so, the value  */
/*   TRUE is returned, otherwise FALSE is returned.              */
/*****************************************************************/
globle int CheckExpressionAgainstRestrictions(theExpression,restrictions,functionName)
  struct expr *theExpression;
  char *restrictions;
  char *functionName;
  {
   char theChar[2];
   int i = 0, j = 1;
   int number1, number2;
   int argCount;
   char defaultRestriction, argRestriction;
   struct expr *argPtr;
   int theRestriction;
   
   theChar[0] = '0'; 
   theChar[1] = '\0';
   
   /*============================================*/
   /* If there are no restrictions, then there's */
   /* no need to check the function.             */
   /*============================================*/
   
   if (restrictions == NULL) return(CLIPS_FALSE);

   /*=========================================*/
   /* Count the number of function arguments. */
   /*=========================================*/
   
   argCount = CountArguments(theExpression->argList);

   /*======================================*/
   /* Get the minimum number of arguments. */
   /*======================================*/

   theChar[0] = restrictions[i++];

   if (isdigit(theChar[0]))
     { number1 = atoi(theChar); }
   else if (theChar[0] == '*')
     { number1 = -1; }
   else