Lib/calendar.py

   1 """Calendar printing functions
   2
   3 Note when comparing these calendars to the ones printed by cal(1): By
   4 default, these calendars have Monday as the first day of the week, and
   5 Sunday as the last (the European convention). Use setfirstweekday() to
   6 set the first day of the week (0=Monday, 6=Sunday)."""
   7
   8 import datetime
   9
  10 __all__ = ["error","setfirstweekday","firstweekday","isleap",
  11            "leapdays","weekday","monthrange","monthcalendar",
  12            "prmonth","month","prcal","calendar","timegm",
  13            "month_name", "month_abbr", "day_name", "day_abbr"]
  14
  15 # Exception raised for bad input (with string parameter for details)
  16 error = ValueError
  17
  18 # Constants for months referenced later
  19 January = 1
  20 February = 2
  21
  22 # Number of days per month (except for February in leap years)
  23 mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
  24
  25 # This module used to have hard-coded lists of day and month names, as
  26 # English strings.  The classes following emulate a read-only version of
  27 # that, but supply localized names.  Note that the values are computed
  28 # fresh on each call, in case the user changes locale between calls.
  29
  30 class _localized_month:
  31     def __init__(self, format):
  32         self.format = format
  33
  34     def __getitem__(self, i):
  35         data = [datetime.date(2001, j, 1).strftime(self.format)
  36                      for j in range(1, 13)]
  37         data.insert(0, "")
  38         return data[i]
  39
  40     def __len__(self):
  41         return 13
  42
  43 class _localized_day:
  44     def __init__(self, format):
  45         self.format = format
  46
  47     def __getitem__(self, i):
  48         # January 1, 2001, was a Monday.
  49         data = [datetime.date(2001, 1, j+1).strftime(self.format)
  50                      for j in range(7)]
  51         return data[i]
  52
  53     def __len__(self_):
  54         return 7
  55
  56 # Full and abbreviated names of weekdays
  57 day_name = _localized_day('%A')
  58 day_abbr = _localized_day('%a')
  59
  60 # Full and abbreviated names of months (1-based arrays!!!)
  61 month_name = _localized_month('%B')
  62 month_abbr = _localized_month('%b')
  63
  64 # Constants for weekdays
  65 (MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)
  66
  67 _firstweekday = 0                       # 0 = Monday, 6 = Sunday
  68
  69 def firstweekday():
  70     return _firstweekday
  71
  72 def setfirstweekday(weekday):
  73     """Set weekday (Monday=0, Sunday=6) to start each week."""
  74     global _firstweekday
  75     if not MONDAY <= weekday <= SUNDAY:
  76         raise ValueError, \
  77               'bad weekday number; must be 0 (Monday) to 6 (Sunday)'
  78     _firstweekday = weekday
  79
  80 def isleap(year):
  81     """Return 1 for leap years, 0 for non-leap years."""
  82     return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
  83
  84 def leapdays(y1, y2):
  85     """Return number of leap years in range [y1, y2).
  86        Assume y1 <= y2."""
  87     y1 -= 1
  88     y2 -= 1
  89     return (y2//4 - y1//4) - (y2//100 - y1//100) + (y2//400 - y1//400)
  90
  91 def weekday(year, month, day):
  92     """Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12),
  93        day (1-31)."""
  94     return datetime.date(year, month, day).weekday()
  95
  96 def monthrange(year, month):
  97     """Return weekday (0-6 ~ Mon-Sun) and number of days (28-31) for
  98        year, month."""
  99     if not 1 <= month <= 12:
 100         raise ValueError, 'bad month number'
 101     day1 = weekday(year, month, 1)
 102     ndays = mdays[month] + (month == February and isleap(year))
 103     return day1, ndays
 104
 105 def monthcalendar(year, month):
 106     """Return a matrix representing a month's calendar.
 107        Each row represents a week; days outside this month are zero."""
 108     day1, ndays = monthrange(year, month)
 109     rows = []
 110     r7 = range(7)
 111     day = (_firstweekday - day1 + 6) % 7 - 5   # for leading 0's in first week
 112     while day <= ndays:
 113         row = [0, 0, 0, 0, 0, 0, 0]
 114         for i in r7:
 115             if 1 <= day <= ndays: row[i] = day
 116             day = day + 1
 117         rows.append(row)
 118     return rows
 119
 120 def prweek(theweek, width):
 121     """Print a single week (no newline)."""
 122     print week(theweek, width),
 123
 124 def week(theweek, width):
 125     """Returns a single week in a string (no newline)."""
 126     days = []
 127     for day in theweek:
 128         if day == 0:
 129             s = ''
 130         else:
 131             s = '%2i' % day             # right-align single-digit days
 132         days.append(s.center(width))
 133     return ' '.join(days)
 134
 135 def weekheader(width):
 136     """Return a header for a week."""
 137     if width >= 9:
 138         names = day_name
 139     else:
 140         names = day_abbr
 141     days = []
 142     for i in range(_firstweekday, _firstweekday + 7):
 143         days.append(names[i%7][:width].center(width))
 144     return ' '.join(days)
 145
 146 def prmonth(theyear, themonth, w=0, l=0):
 147     """Print a month's calendar."""
 148     print month(theyear, themonth, w, l),
 149
 150 def month(theyear, themonth, w=0, l=0):
 151     """Return a month's calendar string (multi-line)."""
 152     w = max(2, w)
 153     l = max(1, l)
 154     s = ((month_name[themonth] + ' ' + `theyear`).center(
 155                  7 * (w + 1) - 1).rstrip() +
 156          '\n' * l + weekheader(w).rstrip() + '\n' * l)
 157     for aweek in monthcalendar(theyear, themonth):
 158         s = s + week(aweek, w).rstrip() + '\n' * l
 159     return s[:-l] + '\n'
 160
 161 # Spacing of month columns for 3-column year calendar
 162 _colwidth = 7*3 - 1         # Amount printed by prweek()
 163 _spacing = 6                # Number of spaces between columns
 164
 165 def format3c(a, b, c, colwidth=_colwidth, spacing=_spacing):
 166     """Prints 3-column formatting for year calendars"""
 167     print format3cstring(a, b, c, colwidth, spacing)
 168
 169 def format3cstring(a, b, c, colwidth=_colwidth, spacing=_spacing):
 170     """Returns a string formatted from 3 strings, centered within 3 columns."""
 171     return (a.center(colwidth) + ' ' * spacing + b.center(colwidth) +
 172             ' ' * spacing + c.center(colwidth))
 173
 174 def prcal(year, w=0, l=0, c=_spacing):
 175     """Print a year's calendar."""
 176     print calendar(year, w, l, c),
 177
 178 def calendar(year, w=0, l=0, c=_spacing):
 179     """Returns a year's calendar as a multi-line string."""
 180     w = max(2, w)
 181     l = max(1, l)
 182     c = max(2, c)
 183     colwidth = (w + 1) * 7 - 1
 184     s = `year`.center(colwidth * 3 + c * 2).rstrip() + '\n' * l
 185     header = weekheader(w)
 186     header = format3cstring(header, header, header, colwidth, c).rstrip()
 187     for q in range(January, January+12, 3):
 188         s = (s + '\n' * l +
 189              format3cstring(month_name[q], month_name[q+1], month_name[q+2],
 190                             colwidth, c).rstrip() +
 191              '\n' * l + header + '\n' * l)
 192         data = []
 193         height = 0
 194         for amonth in range(q, q + 3):
 195             cal = monthcalendar(year, amonth)
 196             if len(cal) > height:
 197                 height = len(cal)
 198             data.append(cal)
 199         for i in range(height):
 200             weeks = []
 201             for cal in data:
 202                 if i >= len(cal):
 203                     weeks.append('')
 204                 else:
 205                     weeks.append(week(cal[i], w))
 206             s = s + format3cstring(weeks[0], weeks[1], weeks[2],
 207                                    colwidth, c).rstrip() + '\n' * l
 208     return s[:-l] + '\n'
 209
 210 EPOCH = 1970
 211 _EPOCH_ORD = datetime.date(EPOCH, 1, 1).toordinal()
 212
 213 def timegm(tuple):
 214     """Unrelated but handy function to calculate Unix timestamp from GMT."""
 215     year, month, day, hour, minute, second = tuple[:6]
 216     days = datetime.date(year, month, day).toordinal() - _EPOCH_ORD
 217     hours = days*24 + hour
 218     minutes = hours*60 + minute
 219     seconds = minutes*60 + second
 220     return seconds