cpython/Lib/calendar.py
Raymond Hettinger 61436489f9 SF 685011: calendar module overflow handling
Restored a Py2.2 behavior to not range check the day of the month.
A user application was this exploiting undocumented, accidental "feature".
2003-02-13 22:58:02 +00:00

221 lines
7.3 KiB
Python

"""Calendar printing functions
Note when comparing these calendars to the ones printed by cal(1): By
default, these calendars have Monday as the first day of the week, and
Sunday as the last (the European convention). Use setfirstweekday() to
set the first day of the week (0=Monday, 6=Sunday)."""
import datetime
__all__ = ["error","setfirstweekday","firstweekday","isleap",
"leapdays","weekday","monthrange","monthcalendar",
"prmonth","month","prcal","calendar","timegm",
"month_name", "month_abbr", "day_name", "day_abbr"]
# Exception raised for bad input (with string parameter for details)
error = ValueError
# Constants for months referenced later
January = 1
February = 2
# Number of days per month (except for February in leap years)
mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
# This module used to have hard-coded lists of day and month names, as
# English strings. The classes following emulate a read-only version of
# that, but supply localized names. Note that the values are computed
# fresh on each call, in case the user changes locale between calls.
class _localized_month:
def __init__(self, format):
self.format = format
def __getitem__(self, i):
data = [datetime.date(2001, j, 1).strftime(self.format)
for j in range(1, 13)]
data.insert(0, "")
return data[i]
def __len__(self):
return 13
class _localized_day:
def __init__(self, format):
self.format = format
def __getitem__(self, i):
# January 1, 2001, was a Monday.
data = [datetime.date(2001, 1, j+1).strftime(self.format)
for j in range(7)]
return data[i]
def __len__(self_):
return 7
# Full and abbreviated names of weekdays
day_name = _localized_day('%A')
day_abbr = _localized_day('%a')
# Full and abbreviated names of months (1-based arrays!!!)
month_name = _localized_month('%B')
month_abbr = _localized_month('%b')
# Constants for weekdays
(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)
_firstweekday = 0 # 0 = Monday, 6 = Sunday
def firstweekday():
return _firstweekday
def setfirstweekday(weekday):
"""Set weekday (Monday=0, Sunday=6) to start each week."""
global _firstweekday
if not MONDAY <= weekday <= SUNDAY:
raise ValueError, \
'bad weekday number; must be 0 (Monday) to 6 (Sunday)'
_firstweekday = weekday
def isleap(year):
"""Return 1 for leap years, 0 for non-leap years."""
return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
def leapdays(y1, y2):
"""Return number of leap years in range [y1, y2).
Assume y1 <= y2."""
y1 -= 1
y2 -= 1
return (y2//4 - y1//4) - (y2//100 - y1//100) + (y2//400 - y1//400)
def weekday(year, month, day):
"""Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12),
day (1-31)."""
return datetime.date(year, month, day).weekday()
def monthrange(year, month):
"""Return weekday (0-6 ~ Mon-Sun) and number of days (28-31) for
year, month."""
if not 1 <= month <= 12:
raise ValueError, 'bad month number'
day1 = weekday(year, month, 1)
ndays = mdays[month] + (month == February and isleap(year))
return day1, ndays
def monthcalendar(year, month):
"""Return a matrix representing a month's calendar.
Each row represents a week; days outside this month are zero."""
day1, ndays = monthrange(year, month)
rows = []
r7 = range(7)
day = (_firstweekday - day1 + 6) % 7 - 5 # for leading 0's in first week
while day <= ndays:
row = [0, 0, 0, 0, 0, 0, 0]
for i in r7:
if 1 <= day <= ndays: row[i] = day
day = day + 1
rows.append(row)
return rows
def prweek(theweek, width):
"""Print a single week (no newline)."""
print week(theweek, width),
def week(theweek, width):
"""Returns a single week in a string (no newline)."""
days = []
for day in theweek:
if day == 0:
s = ''
else:
s = '%2i' % day # right-align single-digit days
days.append(s.center(width))
return ' '.join(days)
def weekheader(width):
"""Return a header for a week."""
if width >= 9:
names = day_name
else:
names = day_abbr
days = []
for i in range(_firstweekday, _firstweekday + 7):
days.append(names[i%7][:width].center(width))
return ' '.join(days)
def prmonth(theyear, themonth, w=0, l=0):
"""Print a month's calendar."""
print month(theyear, themonth, w, l),
def month(theyear, themonth, w=0, l=0):
"""Return a month's calendar string (multi-line)."""
w = max(2, w)
l = max(1, l)
s = ((month_name[themonth] + ' ' + `theyear`).center(
7 * (w + 1) - 1).rstrip() +
'\n' * l + weekheader(w).rstrip() + '\n' * l)
for aweek in monthcalendar(theyear, themonth):
s = s + week(aweek, w).rstrip() + '\n' * l
return s[:-l] + '\n'
# Spacing of month columns for 3-column year calendar
_colwidth = 7*3 - 1 # Amount printed by prweek()
_spacing = 6 # Number of spaces between columns
def format3c(a, b, c, colwidth=_colwidth, spacing=_spacing):
"""Prints 3-column formatting for year calendars"""
print format3cstring(a, b, c, colwidth, spacing)
def format3cstring(a, b, c, colwidth=_colwidth, spacing=_spacing):
"""Returns a string formatted from 3 strings, centered within 3 columns."""
return (a.center(colwidth) + ' ' * spacing + b.center(colwidth) +
' ' * spacing + c.center(colwidth))
def prcal(year, w=0, l=0, c=_spacing):
"""Print a year's calendar."""
print calendar(year, w, l, c),
def calendar(year, w=0, l=0, c=_spacing):
"""Returns a year's calendar as a multi-line string."""
w = max(2, w)
l = max(1, l)
c = max(2, c)
colwidth = (w + 1) * 7 - 1
s = `year`.center(colwidth * 3 + c * 2).rstrip() + '\n' * l
header = weekheader(w)
header = format3cstring(header, header, header, colwidth, c).rstrip()
for q in range(January, January+12, 3):
s = (s + '\n' * l +
format3cstring(month_name[q], month_name[q+1], month_name[q+2],
colwidth, c).rstrip() +
'\n' * l + header + '\n' * l)
data = []
height = 0
for amonth in range(q, q + 3):
cal = monthcalendar(year, amonth)
if len(cal) > height:
height = len(cal)
data.append(cal)
for i in range(height):
weeks = []
for cal in data:
if i >= len(cal):
weeks.append('')
else:
weeks.append(week(cal[i], w))
s = s + format3cstring(weeks[0], weeks[1], weeks[2],
colwidth, c).rstrip() + '\n' * l
return s[:-l] + '\n'
EPOCH = 1970
_EPOCH_ORD = datetime.date(EPOCH, 1, 1).toordinal()
def timegm(tuple):
"""Unrelated but handy function to calculate Unix timestamp from GMT."""
year, month, day, hour, minute, second = tuple[:6]
days = datetime.date(year, month, 1).toordinal() - _EPOCH_ORD + day - 1
hours = days*24 + hour
minutes = hours*60 + minute
seconds = minutes*60 + second
return seconds