partime.c

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/* Parse an initial prefix of S; it must denote a time zone.
   Set *ZONE to the number of seconds east of GMT,
   or to TM_LOCAL_ZONE if it is the local time zone.
   Return the first character after the prefix, or 0 if it wasn't parsed.  */
char *
parzone (s, zone)
     char const *s;
     long *zone;
{
  char sign;
  int hh, mm, ss;
  int minutesEastOfUTC;
  long offset, z;

  /* The formats are LT, n, n DST, nDST, no, o
     where n is a time zone name
     and o is a time zone offset of the form [-+]hh[:mm[:ss]].  */
  switch (*s)
    {
    case '-':
    case '+':
      z = 0;
      break;

    default:
      minutesEastOfUTC = lookup (s, zone_names);
      if (minutesEastOfUTC == -1)
	return 0;

      /* Don't bother to check rest of spelling.  */
      while (ISALPHA ((unsigned char) *s))
	s++;

      /* Don't modify LT.  */
      if (minutesEastOfUTC == 1)
	{
	  *zone = TM_LOCAL_ZONE;
	  return (char *) s;
	}

      z = minutesEastOfUTC * 60L;

      /* Look for trailing " DST".  */
      if ((s[-1] == 'T' || s[-1] == 't')
	  && (s[-2] == 'S' || s[-2] == 's')
	  && (s[-3] == 'D' || s[-3] == 'd'))
	goto trailing_dst;
      while (ISSPACE ((unsigned char) *s))
	s++;
      if ((s[0] == 'D' || s[0] == 'd')
	  && (s[1] == 'S' || s[1] == 's')
	  && (s[2] == 'T' || s[2] == 't'))
	{
	  s += 3;
	trailing_dst:
	  *zone = z + 60*60;
	  return (char *) s;
	}

      switch (*s)
	{
	case '-':
	case '+':
	  break;

	default:
	  *zone = z;
	  return (char *) s;
	}

      break;
    }

  sign = *s++;

  if (! (s = parse_ranged (s, 2, 0, 23, &hh)))
    return 0;
  mm = ss = 0;
  if (*s == ':')
    s++;
  if (ISDIGIT (*s))
    {
      if (! (s = parse_ranged (s, 2, 0, 59, &mm)))
	return 0;
      if (*s == ':' && s[-3] == ':' && ISDIGIT (s[1])
	  && ! (s = parse_ranged (s + 1, 2, 0, 59, &ss)))
	return 0;
    }
  if (ISDIGIT (*s))
    return 0;
  offset = (hh * 60 + mm) * 60L + ss;
  *zone = z + (sign == '-' ? -offset : offset);
  /* ?? Are fractions allowed here?  If so, they're not implemented.  */
  return (char *) s;
}

/* Parse an initial prefix of S, matching the pattern whose code is C.
   Set *T accordingly.
   Return the first character after the prefix, or 0 if it wasn't parsed.  */
static char const *
parse_pattern_letter (s, c, t)
     char const *s;
     int c;
     struct partime *t;
{
  switch (c)
    {
    case '$': /* The next character must be a non-digit.  */
      if (ISDIGIT (*s))
	return 0;
      break;

    case '-':
    case '/':
    case ':':
      /* These characters stand for themselves.  */
      if (*s++ != c)
	return 0;
      break;

    case '4': /* 4-digit year */
      s = parse_fixed (s, 4, &t->tm.tm_year);
      break;

    case '=': /* optional '-' */
      s += *s == '-';
      break;

    case 'A': /* AM or PM */
      /* This matches the regular expression [AaPp][Mm]?.
         It must not be followed by a letter or digit;
         otherwise it would match prefixes of strings like "PST".  */
      switch (*s++)
	{
	case 'A':
	case 'a':
	  if (t->tm.tm_hour == 12)
	    t->tm.tm_hour = 0;
	  break;

	case 'P':
	case 'p':
	  if (t->tm.tm_hour != 12)
	    t->tm.tm_hour += 12;
	  break;

	default:
	  return 0;
	}
      switch (*s)
	{
	case 'M':
	case 'm':
	  s++;
	  break;
	}
      if (ISALNUM ((unsigned char) *s))
	return 0;
      break;

    case 'D': /* day of month [01-31] */
      s = parse_ranged (s, 2, 1, 31, &t->tm.tm_mday);
      break;

    case 'd': /* day of year [001-366] */
      s = parse_ranged (s, 3, 1, 366, &t->tm.tm_yday);
      t->tm.tm_yday--;
      break;

    case 'E': /* extended day of month [1-9, 01-31] */
      s = parse_ranged (s, (ISDIGIT (s[0]) && ISDIGIT (s[1])) + 1, 1, 31,
			&t->tm.tm_mday);
      break;

    case 'h': /* hour [00-23 followed by optional fraction] */
      {
	int frac;
	s = parse_decimal (s, 2, 0, 23, 60 * 60, &t->tm.tm_hour, &frac);
	t->tm.tm_min = frac / 60;
	t->tm.tm_sec = frac % 60;
      }
      break;

    case 'm': /* minute [00-59 followed by optional fraction] */
      s = parse_decimal (s, 2, 0, 59, 60, &t->tm.tm_min, &t->tm.tm_sec);
      break;

    case 'n': /* month name [e.g. "Jan"] */
      if (! TM_DEFINED (t->tm.tm_mon = lookup (s, month_names)))
	return 0;
      /* Don't bother to check rest of spelling.  */
      while (ISALPHA ((unsigned char) *s))
	s++;
      break;

    case 'N': /* month [01-12] */
      s = parse_ranged (s, 2, 1, 12, &t->tm.tm_mon);
      t->tm.tm_mon--;
      break;

    case 'r': /* year % 10 (remainder in origin-0 decade) [0-9] */
      s = parse_fixed (s, 1, &t->tm.tm_year);
      t->ymodulus = 10;
      break;

    case_R:
    case 'R': /* year % 100 (remainder in origin-0 century) [00-99] */
      s = parse_fixed (s, 2, &t->tm.tm_year);
      t->ymodulus = 100;
      break;

    case 's': /* second [00-60 followed by optional fraction] */
      {
	int frac;
	s = parse_decimal (s, 2, 0, 60, 1, &t->tm.tm_sec, &frac);
	t->tm.tm_sec += frac;
      }
      break;

    case 'T': /* 'T' or 't' */
      switch (*s++)
	{
	case 'T':
	case 't':
	  break;
	default:
	  return 0;
	}
      break;

    case 't': /* traditional hour [1-9 or 01-12] */
      s = parse_ranged (s, (ISDIGIT (s[0]) && ISDIGIT (s[1])) + 1, 1, 12,
			&t->tm.tm_hour);
      break;

    case 'w': /* 'W' or 'w' only (stands for current week) */
      switch (*s++)
	{
	case 'W':
	case 'w':
	  break;
	default:
	  return 0;
	}
      break;

    case 'W': /* 'W' or 'w', followed by a week of year [00-53] */
      switch (*s++)
	{
	case 'W':
	case 'w':
	  break;
	default:
	  return 0;
	}
      s = parse_ranged (s, 2, 0, 53, &t->yweek);
      break;

    case 'X': /* weekday (1=Mon ... 7=Sun) [1-7] */
      s = parse_ranged (s, 1, 1, 7, &t->tm.tm_wday);
      t->tm.tm_wday--;
      break;

    case 'x': /* weekday name [e.g. "Sun"] */
      if (! TM_DEFINED (t->tm.tm_wday = lookup (s, weekday_names)))
	return 0;
      /* Don't bother to check rest of spelling.  */
      while (ISALPHA ((unsigned char) *s))
	s++;
      break;

    case 'y': /* either R or Y */
      if (ISDIGIT (s[0]) && ISDIGIT (s[1]) && ! ISDIGIT (s[2]))
	goto case_R;
      /* fall into */
    case 'Y': /* year in full [4 or more digits] */
      {
	int len = 0;
	while (ISDIGIT (s[len]))
	  len++;
	if (len < 4)
	  return 0;
	s = parse_fixed (s, len, &t->tm.tm_year);
      }
      break;

    case 'Z': /* time zone */
      s = parzone (s, &t->zone);
      break;

    case '_': /* possibly empty sequence of non-alphanumerics */
      while (! ISALNUM ((unsigned char) *s) && *s)
	s++;
      break;

    default: /* bad pattern */
      return 0;
    }

  return s;
}

/* If there is no conflict, merge into *T the additional information in *U
   and return 0.  Otherwise do nothing and return -1.  */
static int
merge_partime (t, u)
     struct partime *t;
     struct partime const *u;
{
# define conflict(a,b) ((a) != (b)  &&  TM_DEFINED (a)  &&  TM_DEFINED (b))
  if (conflict (t->tm.tm_sec, u->tm.tm_sec)
      || conflict (t->tm.tm_min, u->tm.tm_min)
      || conflict (t->tm.tm_hour, u->tm.tm_hour)
      || conflict (t->tm.tm_mday, u->tm.tm_mday)
      || conflict (t->tm.tm_mon, u->tm.tm_mon)
      || conflict (t->tm.tm_year, u->tm.tm_year)
      || conflict (t->tm.tm_wday, u->tm.tm_yday)
      || conflict (t->ymodulus, u->ymodulus)
      || conflict (t->yweek, u->yweek)
      || (t->zone != u->zone
	  && t->zone != TM_UNDEFINED_ZONE
	  && u->zone != TM_UNDEFINED_ZONE))
    return -1;
# undef conflict
# define merge_(a,b) if (TM_DEFINED (b)) (a) = (b);
  merge_ (t->tm.tm_sec, u->tm.tm_sec)
  merge_ (t->tm.tm_min, u->tm.tm_min)
  merge_ (t->tm.tm_hour, u->tm.tm_hour)
  merge_ (t->tm.tm_mday, u->tm.tm_mday)
  merge_ (t->tm.tm_mon, u->tm.tm_mon)
  merge_ (t->tm.tm_year, u->tm.tm_year)
  merge_ (t->tm.tm_wday, u->tm.tm_yday)
  merge_ (t->ymodulus, u->ymodulus)
  merge_ (t->yweek, u->yweek)
# undef merge_
  if (u->zone != TM_UNDEFINED_ZONE)
    t->zone = u->zone;
  return 0;
}

/* Parse a date/time prefix of S, putting the parsed result into *T.
   Return the first character after the prefix.
   The prefix may contain no useful information;
   in that case, *T will contain only undefined values.  */
char *
partime (s, t)
     char const *s;
     struct partime *t;
{
  struct partime p;

  undefine (t);

  while (*s)
    {
      int i = 0;
      char const *s1;

      do
	{
	  if (! (s1 = parse_prefix (s, &p, &i)))
	    return (char *) s;
	}
      while (merge_partime (t, &p) != 0);

      s = s1;
    }

  return (char *) s;
}