parser.c

OpenFVM-v1.1 open source cfd code

/* file calcu.c */
/* (c) Donald Axel GPL - license */
/* ANSI - C program demonstration, command line calculator */
/* Recursive descent parser */
/* Improve: Make a HELP command. Add more variables.       */

// modified original file calcu.c by OpenFVM team in 12/12/2005

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "parser.h"

/* Description: */
/* Test the application with a given string.            */

/*
int main(int argc, char *argv[])
{
    
    int i, rv, jj;
    
    cx = 2.0;
    cy = 1.0;
    cz = 0.0;

    jj = 0;
    while (++jj < argc) {
        strcat(gs, argv[jj]);
    }
    
    if (argc == 1)
        return calcu();
    
    strcat(gs, "\n");
    
    for (i = 0; i < 21; i++)
    {
    	
    	y = (double) i / 20.0 * 0.4;
	  
    	strcat(gs, "6*1.0/0.4^2*(2*y*0.2-y^2)\n");
    
    	rv = evaluate(gs, &oldval);
  
    	if (!rv)
        	printf("%.3f\n", oldval);
    	else
        	printf("Calc:%s\n%*s\n", gs, rv, "^Error");
    }
    
    return rv;
    
}*/

/* Description: */
/* calcu() sets up a string which is then evaluated as an expression  */
/* If (argc>1) main sets up string for evaluate() and prints result.  */
/* stricmp does not stop at '\n' - so we have to compare with "xx\n"  */
/* gettok() could solve that problem. TRY to use gettok().            */

int
nextchar ()
{
  ++ctp;
  while (*ctp == ' ')
    ++ctp;
  return *ctp;
}


int
eatspace ()
{
  while (*ctp == ' ')
    ++ctp;
  return *ctp;
}

int
calcu ()
{
  FILE *ifil;
  char line[MAXL];
  int rpos;
  double r;

  ifil = stdin;
  while (1)
    {
      errorp = NULL;
      //printf ("Calc:");

      if (!fgets (line, MAXL, ifil))
	break;

#ifdef WIN32
      if (strlen (line) && strnicmp (line, "QUIT", 4)
	  && stricmp (line, "Q\n"))
	rpos = evaluate (line, &r);
      else
	break;
#endif

#ifndef WIN32
      if (strlen (line) && strncasecmp (line, "QUIT", 4)
	  && strcasecmp (line, "Q\n"))
	rpos = evaluate (line, &r);
      else
	break;
#endif

      if (!rpos)
	{
	  printf ("%-18g\n", r);
	  oldval = r;
	}
      else
	{			/* prints Error in field min. 12 wide */
	  printf ("%*s\n", rpos, "^Error");
	}
    }
  return rpos;			/* if interactive rpos should always be 0 */
}

int
evaluate (char *s, double *r)
{
  ctp = s;
  eatspace ();
  *r = expression ();
  eatspace ();
  if (*ctp == '\n' && !errorp)
    return (0);
  else
    return (ctp - s) + 11;
}


double
expression ()
{
  double e;
  int opera2;

  /* printf("test arg:%s\n",ctp); */

  e = product ();
  while ((opera2 = *ctp) == '+' || opera2 == '-')
    {
      nextchar ();
      if (opera2 == '+')
	e += product ();
      else
	e -= product ();
    }
  eatspace ();
  return e;
}


double
product ()
{
  double dp;
  int ope;

  dp = potens ();
  while ((ope = *ctp) == '*' || ope == '/')
    {
      nextchar ();
      if (ope == '*')
	dp *= potens ();
      else
	dp /= potens ();
    }
  eatspace ();
  return dp;
}


double
potens ()
{
  double dpo;

  dpo = signedfactor ();
  while (*ctp == '^')
    {
      nextchar ();
      dpo = exp (log (dpo) * signedfactor ());
    }
  eatspace ();
  return dpo;
}


double
signedfactor ()
{
  double ds;
  if (*ctp == '-')
    {
      nextchar ();
      ds = -factor ();
    }
  else
    ds = factor ();
  eatspace ();
  return ds;
}


double
factor ()
{
  double df;

  /* while (*ctp!='\n') {
     putchar(*ctp++);
     } 
   */

  switch (*ctp)
    {
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      df = strtod (ctp, &ctp);
      break;
    case '(':
      nextchar ();
      df = expression ();
      if (*ctp == ')')
	nextchar ();
      else
	errorp = ctp;
      break;
    case 'M':
      nextchar ();
      df = oldval;
      break;

    case 'x':
      nextchar ();
      df = cx;
      break;

    case 'y':
      nextchar ();
      df = cy;
      break;

    case 'z':
      nextchar ();
      df = cz;
      break;

    default:
      df = stdfunc ();
    }
  /* printf("ddt: df = %lf, *ctp = %c\n",df,*ctp); */

  eatspace ();
  return df;
}


char *functionname[] = {
  "abs", "sqrt", "sin", "cos", "atan", "log", "exp", "\0"
};

double
stdfunc ()
{
  double dsf;
  char **fnptr;
  int jj;

  eatspace ();
  jj = 0;
  fnptr = functionname;
  while (**fnptr)
    {
      /* printf("%s\n",*fnptr); */
      if (strncmp (*fnptr, ctp, strlen (*fnptr)) == 0)
	break;

      ++fnptr;
      ++jj;
    }
  if (!**fnptr)
    {
      errorp = ctp;
      return 1;
    }
  ctp += (strlen (*fnptr) - 1);
  nextchar ();
  dsf = factor ();
  switch (jj)
    {
    case 0:
      dsf = fabs (dsf);
      break;
    case 1:
      dsf = sqrt (dsf);
      break;
    case 2:
      dsf = sin (dsf);
      break;
    case 3:
      dsf = cos (dsf);
      break;
    case 4:
      dsf = atan (dsf);
      break;
    case 5:
      dsf = log (dsf);
      break;
    case 6:
      dsf = exp (dsf);
      break;
    default:
      {
	errorp = ctp;
	return 4;
      }
    }
  eatspace ();
  return dsf;
}


/* end calcu.c */