UNIX — универсальная среда программирования

  return s->type == UNDEF ? VAR : s->type;
  }
  switch (c) {
  case '>': return follow('=', GE, GT);
  case '<': return follow('=', LE, LT);
  case '=': return follow('=', EQ, '=');
  case '!': return follow('=', NE, NOT);
  case '|': return follow('|', OR, '|');
  case '&': return follow('&', AND, '&');
  case '\n': lineno++; return '\n';
  default: return c;
  }
 }

 follow(expect, ifyes, ifno) /* look ahead for >=, etc. */
 {
  int c = getchar;
  if (c == expect)
  return ifyes;
  ungetc(c, stdin);
  return ifno;
 }

 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);
 }

 main(argc, argv)
  char *argv[];
 {
  int fpecatch;

  progname = argv[0];
  init;
  setjmp(begin);
  signal(SIGFPE, fpecatch);
  for (initcode; yyparse; initcode)
  execute(prog);
  return 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)
  c = getchar; /* flush rest of input line */
  fseek(stdin, 0L, 2); /* flush rest of file */
  longjmp(begin, 0);
 }

3.6.6 init.c

 #include "hoc.h"
 #include "y.tab.h"
 #include <math.h>

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

 static struct { /* Keywords */
  char *name;
  int kval;
 } keywords[] = {
  "if", IF,
  "else", ELSE,
  "while", WHILE,
  "print", PRINT,
  0, 0,
 };

 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,
  "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; keywords[i].name; i++)
  install(keywords[i].name, keywords[i].kval, 0.0);
  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;
  }
 }

3.6.7 makefile

 YFLAGS = -d
 OBJS = hoc.o code.o init.o math.o symbol.o

 hoc5: $(OBJS)
  cc $(OBJS) -lm -o hoc5

 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