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 # Revision 2: uses functions from built-in time module
   9
  10 # Import functions and variables from time module
  11 from time import localtime, mktime, strftime
  12
  13 __all__ = ["error","setfirstweekday","firstweekday","isleap",
  14            "leapdays","weekday","monthrange","monthcalendar",
  15            "prmonth","month","prcal","calendar","timegm"]
  16
  17 # Exception raised for bad input (with string parameter for details)
  18 error = ValueError
  19
  20 # Constants for months referenced later
  21 January = 1
  22 February = 2
  23
  24 # Number of days per month (except for February in leap years)
  25 mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
  26
  27 class _localized_name:
  28     def __init__(self, format):
  29         self.format = format
  30     def __getitem__(self, item):
  31         return strftime(self.format, (item,)*9).capitalize()
  32
  33 # Full and abbreviated names of weekdays
  34 day_name = _localized_name('%A')
  35 day_abbr = _localized_name('%a')
  36
  37 # Full and abbreviated names of months (1-based arrays!!!)
  38 month_name = _localized_name('%B')
  39 month_abbr = _localized_name('%b')
  40
  41 # Constants for weekdays
  42 (MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)
  43
  44 _firstweekday = 0                       # 0 = Monday, 6 = Sunday
  45
  46 def firstweekday():
  47     return _firstweekday
  48
  49 def setfirstweekday(weekday):
  50     """Set weekday (Monday=0, Sunday=6) to start each week."""
  51     global _firstweekday
  52     if not MONDAY <= weekday <= SUNDAY:
  53         raise ValueError, \
  54               'bad weekday number; must be 0 (Monday) to 6 (Sunday)'
  55     _firstweekday = weekday
  56
  57 def isleap(year):
  58     """Return 1 for leap years, 0 for non-leap years."""
  59     return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
  60
  61 def leapdays(y1, y2):
  62     """Return number of leap years in range [y1, y2).
  63        Assume y1 <= y2."""
  64     y1 -= 1
  65     y2 -= 1
  66     return (y2/4 - y1/4) - (y2/100 - y1/100) + (y2/400 - y1/400)
  67
  68 def weekday(year, month, day):
  69     """Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12),
  70        day (1-31)."""
  71     secs = mktime((year, month, day, 0, 0, 0, 0, 0, 0))
  72     tuple = localtime(secs)
  73     return tuple[6]
  74
  75 def monthrange(year, month):
  76     """Return weekday (0-6 ~ Mon-Sun) and number of days (28-31) for
  77        year, month."""
  78     if not 1 <= month <= 12:
  79         raise ValueError, 'bad month number'
  80     day1 = weekday(year, month, 1)
  81     ndays = mdays[month] + (month == February and isleap(year))
  82     return day1, ndays
  83
  84 def monthcalendar(year, month):
  85     """Return a matrix representing a month's calendar.
  86        Each row represents a week; days outside this month are zero."""
  87     day1, ndays = monthrange(year, month)
  88     rows = []
  89     r7 = range(7)
  90     day = (_firstweekday - day1 + 6) % 7 - 5   # for leading 0's in first week
  91     while day <= ndays:
  92         row = [0, 0, 0, 0, 0, 0, 0]
  93         for i in r7:
  94             if 1 <= day <= ndays: row[i] = day
  95             day = day + 1
  96         rows.append(row)
  97     return rows
  98
  99 def _center(str, width):
 100     """Center a string in a field."""
 101     n = width - len(str)
 102     if n <= 0:
 103         return str
 104     return ' '*((n+1)/2) + str + ' '*((n)/2)
 105
 106 def prweek(theweek, width):
 107     """Print a single week (no newline)."""
 108     print week(theweek, width),
 109
 110 def week(theweek, width):
 111     """Returns a single week in a string (no newline)."""
 112     days = []
 113     for day in theweek:
 114         if day == 0:
 115             s = ''
 116         else:
 117             s = '%2i' % day             # right-align single-digit days
 118         days.append(_center(s, width))
 119     return ' '.join(days)
 120
 121 def weekheader(width):
 122     """Return a header for a week."""
 123     if width >= 9:
 124         names = day_name
 125     else:
 126         names = day_abbr
 127     days = []
 128     for i in range(_firstweekday, _firstweekday + 7):
 129         days.append(_center(names[i%7][:width], width))
 130     return ' '.join(days)
 131
 132 def prmonth(theyear, themonth, w=0, l=0):
 133     """Print a month's calendar."""
 134     print month(theyear, themonth, w, l),
 135
 136 def month(theyear, themonth, w=0, l=0):
 137     """Return a month's calendar string (multi-line)."""
 138     w = max(2, w)
 139     l = max(1, l)
 140     s = (_center(month_name[themonth] + ' ' + `theyear`,
 141                  7 * (w + 1) - 1).rstrip() +
 142          '\n' * l + weekheader(w).rstrip() + '\n' * l)
 143     for aweek in monthcalendar(theyear, themonth):
 144         s = s + week(aweek, w).rstrip() + '\n' * l
 145     return s[:-l] + '\n'
 146
 147 # Spacing of month columns for 3-column year calendar
 148 _colwidth = 7*3 - 1         # Amount printed by prweek()
 149 _spacing = 6                # Number of spaces between columns
 150
 151 def format3c(a, b, c, colwidth=_colwidth, spacing=_spacing):
 152     """Prints 3-column formatting for year calendars"""
 153     print format3cstring(a, b, c, colwidth, spacing)
 154
 155 def format3cstring(a, b, c, colwidth=_colwidth, spacing=_spacing):
 156     """Returns a string formatted from 3 strings, centered within 3 columns."""
 157     return (_center(a, colwidth) + ' ' * spacing + _center(b, colwidth) +
 158             ' ' * spacing + _center(c, colwidth))
 159
 160 def prcal(year, w=0, l=0, c=_spacing):
 161     """Print a year's calendar."""
 162     print calendar(year, w, l, c),
 163
 164 def calendar(year, w=0, l=0, c=_spacing):
 165     """Returns a year's calendar as a multi-line string."""
 166     w = max(2, w)
 167     l = max(1, l)
 168     c = max(2, c)
 169     colwidth = (w + 1) * 7 - 1
 170     s = _center(`year`, colwidth * 3 + c * 2).rstrip() + '\n' * l
 171     header = weekheader(w)
 172     header = format3cstring(header, header, header, colwidth, c).rstrip()
 173     for q in range(January, January+12, 3):
 174         s = (s + '\n' * l +
 175              format3cstring(month_name[q], month_name[q+1], month_name[q+2],
 176                             colwidth, c).rstrip() +
 177              '\n' * l + header + '\n' * l)
 178         data = []
 179         height = 0
 180         for amonth in range(q, q + 3):
 181             cal = monthcalendar(year, amonth)
 182             if len(cal) > height:
 183                 height = len(cal)
 184             data.append(cal)
 185         for i in range(height):
 186             weeks = []
 187             for cal in data:
 188                 if i >= len(cal):
 189                     weeks.append('')
 190                 else:
 191                     weeks.append(week(cal[i], w))
 192             s = s + format3cstring(weeks[0], weeks[1], weeks[2],
 193                                    colwidth, c).rstrip() + '\n' * l
 194     return s[:-l] + '\n'
 195
 196 EPOCH = 1970
 197 def timegm(tuple):
 198     """Unrelated but handy function to calculate Unix timestamp from GMT."""
 199     year, month, day, hour, minute, second = tuple[:6]
 200     assert year >= EPOCH
 201     assert 1 <= month <= 12
 202     days = 365*(year-EPOCH) + leapdays(EPOCH, year)
 203     for i in range(1, month):
 204         days = days + mdays[i]
 205     if month > 2 and isleap(year):
 206         days = days + 1
 207     days = days + day - 1
 208     hours = days*24 + hour
 209     minutes = hours*60 + minute
 210     seconds = minutes*60 + second
 211     return seconds