UNIX

 if (c == '.' || isdigit(c)) { /* number */

  double d;

  ungetc(c, stdin);

  scanf ("%lf", &d);

  yylval.sym = install("", NUMBER, d);

  return NUMBER;

 }

 if (isalpha(c)) {

  Symbol *s;

  char sbuf[100], *p = sbuf;

  do {

   *p++ = c;

  } while ((c=getchar()) != EOF && isalnum(c));

  ungetc(c, stdin);

  *p = '\0';

  if ((s=lookup(sbuf)) == 0)

   s = install(sbuf, UNDEF, 0.0);

  yylval.sym = s;

  return s->type == UNDEF ? VAR : s->type;

 }

 if (c == '\n')

 lineno++;

 return c;

}

yyerror(s)

 char *s;

{

 warning(s, (char *)0);

}

execerror(s, t) /* recover from run-time error */

 char *s, *t;

{

 warning(s, t);

 longjmp(begin, 0);

}

fpecatch() /* catch floating point exceptions */

{

 execerror("floating point exception", (char*)0);

}

warning(s, t)

 char *s, *t;

{

 fprintf(stderr, "%s: %s", progname, s);

 if (t && *t)

  fprintf(stderr, " %s", t);

 fprintf(stderr, " near line %d\n", lineno);

 while (c != '\n' && с != EOF)

  с = getchar(); /* flush rest of input line */

}

3.5.4 init.c

#include "hoc.h"

#include "y.tab.h"

#include

extern double Log(), Log10(), Exp(), Sqrt(), integer();

static struct { /* Constants */

 char *name;

 double eval;

} consts[] = {

 "PI",    3.14159265358979323846,

 "E",     2.71828182845904523536,

 "GAMMA", 0.57721566490153286060, /* Euler */

 "DEG",  57.29577951308232087680, /* deg/radian */

 "PHI",   1.61803398874989484820, /* golden ratio */

 0,       0

};

static struct { /* Built-ins */

 char *name;

 double (*func)();

} builtins [] = {

 "sin",   sin,

 "cos",   cos,

 "atan",  atan,

 "log",   Log, /* checks argument */

 "log10", Log10, /* checks argument */

 "exp",   Exp, /* checks argument */

 "sqrt",  Sqrt, /* checks argument */

 "int",   integer,

 "abs",   fabs,

 0,       0

};

init() /* install constants and built-ins in table */

{

 int i;

 Symbol *s;

 for (i = 0; consts[i].name; i++)

  install(consts[i].name, VAR, consts[i].eval);

 for (i = 0; builtins[i].name; i++) {

  s = install(builtins[i].name, BLTIN, 0.0);

  s->u.ptr = builtins[i].func;

 }

}

3.5.5. makefile

YFLAGS = -d

OBJS = hoc.o code.o init.o math.o symbol.o

hoc4: $(OBJS)

      cc $(OBJS) -lm -o hoc4

hoc.o code.o init.o symbol.o: hoc.h

code.o init.o symbol.o: x.tab.h

x.tab.h: y.tab.h

      -cmp -s x.tab.h y.tab.h || cp y.tab.h x.tab.h

pr: hoc.y hoc.h code.c init.c math.c symbol.c

      @pr $?

      @touch pr

clean:

      rm -f $(OBJS) [xy].tab.[ch]

3.5.6. math.c

#include

#include

extern int errno;

double errcheck();

double Log(x)

 double x;

{

 return errcheck(log(x), "log");

}

double Log10(x)

 double x;

{

 return errcheck(log10(x), "log10");

}

double Sqrt(x)

 double x;

{

 return errcheck(sqrt(x), "sqrt");

}

double Exp(x)

 double x;

{

 return errcheck(exp(x), "exp");

}

double Pow(x, y)

 double x, y;

{